1//===- LiveInterval.cpp - Live Interval Representation --------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file implements the LiveRange and LiveInterval classes. Given some
10// numbering of each the machine instructions an interval [i, j) is said to be a
11// live range for register v if there is no instruction with number j' >= j
12// such that v is live at j' and there is no instruction with number i' < i such
13// that v is live at i'. In this implementation ranges can have holes,
14// i.e. a range might look like [1,20), [50,65), [1000,1001). Each
15// individual segment is represented as an instance of LiveRange::Segment,
16// and the whole range is represented as an instance of LiveRange.
17//
18//===----------------------------------------------------------------------===//
19
20#include "llvm/CodeGen/LiveInterval.h"
21#include "LiveRangeUtils.h"
22#include "RegisterCoalescer.h"
23#include "llvm/ADT/ArrayRef.h"
24#include "llvm/ADT/STLExtras.h"
25#include "llvm/ADT/SmallPtrSet.h"
26#include "llvm/ADT/SmallVector.h"
27#include "llvm/ADT/iterator_range.h"
28#include "llvm/CodeGen/LiveIntervals.h"
29#include "llvm/CodeGen/MachineBasicBlock.h"
30#include "llvm/CodeGen/MachineInstr.h"
31#include "llvm/CodeGen/MachineOperand.h"
32#include "llvm/CodeGen/MachineRegisterInfo.h"
33#include "llvm/CodeGen/SlotIndexes.h"
34#include "llvm/CodeGen/TargetRegisterInfo.h"
35#include "llvm/Config/llvm-config.h"
36#include "llvm/MC/LaneBitmask.h"
37#include "llvm/Support/Compiler.h"
38#include "llvm/Support/Debug.h"
39#include "llvm/Support/raw_ostream.h"
40#include <algorithm>
41#include <cassert>
42#include <cstddef>
43#include <iterator>
44#include <utility>
45
46using namespace llvm;
47
48namespace {
49
50//===----------------------------------------------------------------------===//
51// Implementation of various methods necessary for calculation of live ranges.
52// The implementation of the methods abstracts from the concrete type of the
53// segment collection.
54//
55// Implementation of the class follows the Template design pattern. The base
56// class contains generic algorithms that call collection-specific methods,
57// which are provided in concrete subclasses. In order to avoid virtual calls
58// these methods are provided by means of C++ template instantiation.
59// The base class calls the methods of the subclass through method impl(),
60// which casts 'this' pointer to the type of the subclass.
61//
62//===----------------------------------------------------------------------===//
63
64template <typename ImplT, typename IteratorT, typename CollectionT>
65class CalcLiveRangeUtilBase {
66protected:
67 LiveRange *LR;
68
69protected:
70 CalcLiveRangeUtilBase(LiveRange *LR) : LR(LR) {}
71
72public:
73 using Segment = LiveRange::Segment;
74 using iterator = IteratorT;
75
76 /// A counterpart of LiveRange::createDeadDef: Make sure the range has a
77 /// value defined at @p Def.
78 /// If @p ForVNI is null, and there is no value defined at @p Def, a new
79 /// value will be allocated using @p VNInfoAllocator.
80 /// If @p ForVNI is null, the return value is the value defined at @p Def,
81 /// either a pre-existing one, or the one newly created.
82 /// If @p ForVNI is not null, then @p Def should be the location where
83 /// @p ForVNI is defined. If the range does not have a value defined at
84 /// @p Def, the value @p ForVNI will be used instead of allocating a new
85 /// one. If the range already has a value defined at @p Def, it must be
86 /// same as @p ForVNI. In either case, @p ForVNI will be the return value.
87 VNInfo *createDeadDef(SlotIndex Def, VNInfo::Allocator *VNInfoAllocator,
88 VNInfo *ForVNI) {
89 assert(!Def.isDead() && "Cannot define a value at the dead slot");
90 assert((!ForVNI || ForVNI->def == Def) &&
91 "If ForVNI is specified, it must match Def");
92 iterator I = impl().find(Def);
93 if (I == segments().end()) {
94 VNInfo *VNI = ForVNI ? ForVNI : LR->getNextValue(Def, VNInfoAllocator&: *VNInfoAllocator);
95 impl().insertAtEnd(Segment(Def, Def.getDeadSlot(), VNI));
96 return VNI;
97 }
98
99 Segment *S = segmentAt(I);
100 if (SlotIndex::isSameInstr(A: Def, B: S->start)) {
101 assert((!ForVNI || ForVNI == S->valno) && "Value number mismatch");
102 assert(S->valno->def == S->start && "Inconsistent existing value def");
103
104 // It is possible to have both normal and early-clobber defs of the same
105 // register on an instruction. It doesn't make a lot of sense, but it is
106 // possible to specify in inline assembly.
107 //
108 // Just convert everything to early-clobber.
109 Def = std::min(a: Def, b: S->start);
110 if (Def != S->start)
111 S->start = S->valno->def = Def;
112 return S->valno;
113 }
114 assert(SlotIndex::isEarlierInstr(Def, S->start) && "Already live at def");
115 VNInfo *VNI = ForVNI ? ForVNI : LR->getNextValue(Def, VNInfoAllocator&: *VNInfoAllocator);
116 segments().insert(I, Segment(Def, Def.getDeadSlot(), VNI));
117 return VNI;
118 }
119
120 VNInfo *extendInBlock(SlotIndex StartIdx, SlotIndex Use) {
121 if (segments().empty())
122 return nullptr;
123 iterator I =
124 impl().findInsertPos(Segment(Use.getPrevSlot(), Use, nullptr));
125 if (I == segments().begin())
126 return nullptr;
127 --I;
128 if (I->end <= StartIdx)
129 return nullptr;
130 if (I->end < Use)
131 extendSegmentEndTo(I, NewEnd: Use);
132 return I->valno;
133 }
134
135 std::pair<VNInfo*,bool> extendInBlock(ArrayRef<SlotIndex> Undefs,
136 SlotIndex StartIdx, SlotIndex Use) {
137 if (segments().empty())
138 return std::make_pair(x: nullptr, y: false);
139 SlotIndex BeforeUse = Use.getPrevSlot();
140 iterator I = impl().findInsertPos(Segment(BeforeUse, Use, nullptr));
141 if (I == segments().begin())
142 return std::make_pair(x: nullptr, y: LR->isUndefIn(Undefs, Begin: StartIdx, End: BeforeUse));
143 --I;
144 if (I->end <= StartIdx)
145 return std::make_pair(x: nullptr, y: LR->isUndefIn(Undefs, Begin: StartIdx, End: BeforeUse));
146 if (I->end < Use) {
147 if (LR->isUndefIn(Undefs, Begin: I->end, End: BeforeUse))
148 return std::make_pair(x: nullptr, y: true);
149 extendSegmentEndTo(I, NewEnd: Use);
150 }
151 return std::make_pair(I->valno, false);
152 }
153
154 /// This method is used when we want to extend the segment specified
155 /// by I to end at the specified endpoint. To do this, we should
156 /// merge and eliminate all segments that this will overlap
157 /// with. The iterator is not invalidated.
158 void extendSegmentEndTo(iterator I, SlotIndex NewEnd) {
159 assert(I != segments().end() && "Not a valid segment!");
160 Segment *S = segmentAt(I);
161 VNInfo *ValNo = I->valno;
162
163 // Search for the first segment that we can't merge with.
164 iterator MergeTo = std::next(I);
165 for (; MergeTo != segments().end() && NewEnd >= MergeTo->end; ++MergeTo)
166 assert(MergeTo->valno == ValNo && "Cannot merge with differing values!");
167
168 // If NewEnd was in the middle of a segment, make sure to get its endpoint.
169 S->end = std::max(NewEnd, std::prev(MergeTo)->end);
170
171 // If the newly formed segment now touches the segment after it and if they
172 // have the same value number, merge the two segments into one segment.
173 if (MergeTo != segments().end() && MergeTo->start <= I->end &&
174 MergeTo->valno == ValNo) {
175 S->end = MergeTo->end;
176 ++MergeTo;
177 }
178
179 // Erase any dead segments.
180 segments().erase(std::next(I), MergeTo);
181 }
182
183 /// This method is used when we want to extend the segment specified
184 /// by I to start at the specified endpoint. To do this, we should
185 /// merge and eliminate all segments that this will overlap with.
186 iterator extendSegmentStartTo(iterator I, SlotIndex NewStart) {
187 assert(I != segments().end() && "Not a valid segment!");
188 Segment *S = segmentAt(I);
189 VNInfo *ValNo = I->valno;
190
191 // Search for the first segment that we can't merge with.
192 iterator MergeTo = I;
193 do {
194 if (MergeTo == segments().begin()) {
195 S->start = NewStart;
196 segments().erase(MergeTo, I);
197 return I;
198 }
199 assert(MergeTo->valno == ValNo && "Cannot merge with differing values!");
200 --MergeTo;
201 } while (NewStart <= MergeTo->start);
202
203 // If we start in the middle of another segment, just delete a range and
204 // extend that segment.
205 if (MergeTo->end >= NewStart && MergeTo->valno == ValNo) {
206 segmentAt(I: MergeTo)->end = S->end;
207 } else {
208 // Otherwise, extend the segment right after.
209 ++MergeTo;
210 Segment *MergeToSeg = segmentAt(I: MergeTo);
211 MergeToSeg->start = NewStart;
212 MergeToSeg->end = S->end;
213 }
214
215 segments().erase(std::next(MergeTo), std::next(I));
216 return MergeTo;
217 }
218
219 iterator addSegment(Segment S) {
220 SlotIndex Start = S.start, End = S.end;
221 iterator I = impl().findInsertPos(S);
222
223 // If the inserted segment starts in the middle or right at the end of
224 // another segment, just extend that segment to contain the segment of S.
225 if (I != segments().begin()) {
226 iterator B = std::prev(I);
227 if (S.valno == B->valno) {
228 if (B->start <= Start && B->end >= Start) {
229 extendSegmentEndTo(I: B, NewEnd: End);
230 return B;
231 }
232 } else {
233 // Check to make sure that we are not overlapping two live segments with
234 // different valno's.
235 assert(B->end <= Start &&
236 "Cannot overlap two segments with differing ValID's"
237 " (did you def the same reg twice in a MachineInstr?)");
238 }
239 }
240
241 // Otherwise, if this segment ends in the middle of, or right next
242 // to, another segment, merge it into that segment.
243 if (I != segments().end()) {
244 if (S.valno == I->valno) {
245 if (I->start <= End) {
246 I = extendSegmentStartTo(I, NewStart: Start);
247
248 // If S is a complete superset of a segment, we may need to grow its
249 // endpoint as well.
250 if (End > I->end)
251 extendSegmentEndTo(I, NewEnd: End);
252 return I;
253 }
254 } else {
255 // Check to make sure that we are not overlapping two live segments with
256 // different valno's.
257 assert(I->start >= End &&
258 "Cannot overlap two segments with differing ValID's");
259 }
260 }
261
262 // Otherwise, this is just a new segment that doesn't interact with
263 // anything.
264 // Insert it.
265 return segments().insert(I, S);
266 }
267
268private:
269 ImplT &impl() { return *static_cast<ImplT *>(this); }
270
271 CollectionT &segments() { return impl().segmentsColl(); }
272
273 Segment *segmentAt(iterator I) { return const_cast<Segment *>(&(*I)); }
274};
275
276//===----------------------------------------------------------------------===//
277// Instantiation of the methods for calculation of live ranges
278// based on a segment vector.
279//===----------------------------------------------------------------------===//
280
281class CalcLiveRangeUtilVector;
282using CalcLiveRangeUtilVectorBase =
283 CalcLiveRangeUtilBase<CalcLiveRangeUtilVector, LiveRange::iterator,
284 LiveRange::Segments>;
285
286class CalcLiveRangeUtilVector : public CalcLiveRangeUtilVectorBase {
287public:
288 CalcLiveRangeUtilVector(LiveRange *LR) : CalcLiveRangeUtilVectorBase(LR) {}
289
290private:
291 friend CalcLiveRangeUtilVectorBase;
292
293 LiveRange::Segments &segmentsColl() { return LR->segments; }
294
295 void insertAtEnd(const Segment &S) { LR->segments.push_back(Elt: S); }
296
297 iterator find(SlotIndex Pos) { return LR->find(Pos); }
298
299 iterator findInsertPos(Segment S) { return llvm::upper_bound(Range&: *LR, Value&: S.start); }
300};
301
302//===----------------------------------------------------------------------===//
303// Instantiation of the methods for calculation of live ranges
304// based on a segment set.
305//===----------------------------------------------------------------------===//
306
307class CalcLiveRangeUtilSet;
308using CalcLiveRangeUtilSetBase =
309 CalcLiveRangeUtilBase<CalcLiveRangeUtilSet, LiveRange::SegmentSet::iterator,
310 LiveRange::SegmentSet>;
311
312class CalcLiveRangeUtilSet : public CalcLiveRangeUtilSetBase {
313public:
314 CalcLiveRangeUtilSet(LiveRange *LR) : CalcLiveRangeUtilSetBase(LR) {}
315
316private:
317 friend CalcLiveRangeUtilSetBase;
318
319 LiveRange::SegmentSet &segmentsColl() { return *LR->segmentSet; }
320
321 void insertAtEnd(const Segment &S) {
322 LR->segmentSet->insert(position: LR->segmentSet->end(), x: S);
323 }
324
325 iterator find(SlotIndex Pos) {
326 iterator I =
327 LR->segmentSet->upper_bound(x: Segment(Pos, Pos.getNextSlot(), nullptr));
328 if (I == LR->segmentSet->begin())
329 return I;
330 iterator PrevI = std::prev(x: I);
331 if (Pos < (*PrevI).end)
332 return PrevI;
333 return I;
334 }
335
336 iterator findInsertPos(Segment S) {
337 iterator I = LR->segmentSet->upper_bound(x: S);
338 if (I != LR->segmentSet->end() && !(S.start < *I))
339 ++I;
340 return I;
341 }
342};
343
344} // end anonymous namespace
345
346//===----------------------------------------------------------------------===//
347// LiveRange methods
348//===----------------------------------------------------------------------===//
349
350LiveRange::iterator LiveRange::find(SlotIndex Pos) {
351 return llvm::partition_point(Range&: *this,
352 P: [&](const Segment &X) { return X.end <= Pos; });
353}
354
355VNInfo *LiveRange::createDeadDef(SlotIndex Def, VNInfo::Allocator &VNIAlloc) {
356 // Use the segment set, if it is available.
357 if (segmentSet != nullptr)
358 return CalcLiveRangeUtilSet(this).createDeadDef(Def, VNInfoAllocator: &VNIAlloc, ForVNI: nullptr);
359 // Otherwise use the segment vector.
360 return CalcLiveRangeUtilVector(this).createDeadDef(Def, VNInfoAllocator: &VNIAlloc, ForVNI: nullptr);
361}
362
363VNInfo *LiveRange::createDeadDef(VNInfo *VNI) {
364 // Use the segment set, if it is available.
365 if (segmentSet != nullptr)
366 return CalcLiveRangeUtilSet(this).createDeadDef(Def: VNI->def, VNInfoAllocator: nullptr, ForVNI: VNI);
367 // Otherwise use the segment vector.
368 return CalcLiveRangeUtilVector(this).createDeadDef(Def: VNI->def, VNInfoAllocator: nullptr, ForVNI: VNI);
369}
370
371// overlaps - Return true if the intersection of the two live ranges is
372// not empty.
373//
374// An example for overlaps():
375//
376// 0: A = ...
377// 4: B = ...
378// 8: C = A + B ;; last use of A
379//
380// The live ranges should look like:
381//
382// A = [3, 11)
383// B = [7, x)
384// C = [11, y)
385//
386// A->overlaps(C) should return false since we want to be able to join
387// A and C.
388//
389bool LiveRange::overlapsFrom(const LiveRange& other,
390 const_iterator StartPos) const {
391 assert(!empty() && "empty range");
392 const_iterator i = begin();
393 const_iterator ie = end();
394 const_iterator j = StartPos;
395 const_iterator je = other.end();
396
397 assert((StartPos->start <= i->start || StartPos == other.begin()) &&
398 StartPos != other.end() && "Bogus start position hint!");
399
400 if (i->start < j->start) {
401 i = std::upper_bound(first: i, last: ie, val: j->start);
402 if (i != begin()) --i;
403 } else if (j->start < i->start) {
404 ++StartPos;
405 if (StartPos != other.end() && StartPos->start <= i->start) {
406 assert(StartPos < other.end() && i < end());
407 j = std::upper_bound(first: j, last: je, val: i->start);
408 if (j != other.begin()) --j;
409 }
410 } else {
411 return true;
412 }
413
414 if (j == je) return false;
415
416 while (i != ie) {
417 if (i->start > j->start) {
418 std::swap(a&: i, b&: j);
419 std::swap(a&: ie, b&: je);
420 }
421
422 if (i->end > j->start)
423 return true;
424 ++i;
425 }
426
427 return false;
428}
429
430bool LiveRange::overlaps(const LiveRange &Other, const CoalescerPair &CP,
431 const SlotIndexes &Indexes) const {
432 assert(!empty() && "empty range");
433 if (Other.empty())
434 return false;
435
436 // Use binary searches to find initial positions.
437 const_iterator I = find(Pos: Other.beginIndex());
438 const_iterator IE = end();
439 if (I == IE)
440 return false;
441 const_iterator J = Other.find(Pos: I->start);
442 const_iterator JE = Other.end();
443 if (J == JE)
444 return false;
445
446 while (true) {
447 // J has just been advanced to satisfy:
448 assert(J->end > I->start);
449 // Check for an overlap.
450 if (J->start < I->end) {
451 // I and J are overlapping. Find the later start.
452 SlotIndex Def = std::max(a: I->start, b: J->start);
453 // Allow the overlap if Def is a coalescable copy.
454 if (Def.isBlock() ||
455 !CP.isCoalescable(Indexes.getInstructionFromIndex(index: Def)))
456 return true;
457 }
458 // Advance the iterator that ends first to check for more overlaps.
459 if (J->end > I->end) {
460 std::swap(a&: I, b&: J);
461 std::swap(a&: IE, b&: JE);
462 }
463 // Advance J until J->end > I->start.
464 do
465 if (++J == JE)
466 return false;
467 while (J->end <= I->start);
468 }
469}
470
471/// overlaps - Return true if the live range overlaps an interval specified
472/// by [Start, End).
473bool LiveRange::overlaps(SlotIndex Start, SlotIndex End) const {
474 assert(Start < End && "Invalid range");
475 const_iterator I = lower_bound(Range: *this, Value&: End);
476 return I != begin() && (--I)->end > Start;
477}
478
479bool LiveRange::covers(const LiveRange &Other) const {
480 if (empty())
481 return Other.empty();
482
483 const_iterator I = begin();
484 for (const Segment &O : Other.segments) {
485 I = advanceTo(I, Pos: O.start);
486 if (I == end() || I->start > O.start)
487 return false;
488
489 // Check adjacent live segments and see if we can get behind O.end.
490 while (I->end < O.end) {
491 const_iterator Last = I;
492 // Get next segment and abort if it was not adjacent.
493 ++I;
494 if (I == end() || Last->end != I->start)
495 return false;
496 }
497 }
498 return true;
499}
500
501/// ValNo is dead, remove it. If it is the largest value number, just nuke it
502/// (and any other deleted values neighboring it), otherwise mark it as ~1U so
503/// it can be nuked later.
504void LiveRange::markValNoForDeletion(VNInfo *ValNo) {
505 if (ValNo->id == getNumValNums()-1) {
506 do {
507 valnos.pop_back();
508 } while (!valnos.empty() && valnos.back()->isUnused());
509 } else {
510 ValNo->markUnused();
511 }
512}
513
514/// RenumberValues - Renumber all values in order of appearance and delete the
515/// remaining unused values.
516void LiveRange::RenumberValues() {
517 SmallPtrSet<VNInfo*, 8> Seen;
518 valnos.clear();
519 for (const Segment &S : segments) {
520 VNInfo *VNI = S.valno;
521 if (!Seen.insert(Ptr: VNI).second)
522 continue;
523 assert(!VNI->isUnused() && "Unused valno used by live segment");
524 VNI->id = (unsigned)valnos.size();
525 valnos.push_back(Elt: VNI);
526 }
527}
528
529void LiveRange::addSegmentToSet(Segment S) {
530 CalcLiveRangeUtilSet(this).addSegment(S);
531}
532
533LiveRange::iterator LiveRange::addSegment(Segment S) {
534 // Use the segment set, if it is available.
535 if (segmentSet != nullptr) {
536 addSegmentToSet(S);
537 return end();
538 }
539 // Otherwise use the segment vector.
540 return CalcLiveRangeUtilVector(this).addSegment(S);
541}
542
543void LiveRange::append(const Segment S) {
544 // Check that the segment belongs to the back of the list.
545 assert(segments.empty() || segments.back().end <= S.start);
546 segments.push_back(Elt: S);
547}
548
549std::pair<VNInfo*,bool> LiveRange::extendInBlock(ArrayRef<SlotIndex> Undefs,
550 SlotIndex StartIdx, SlotIndex Kill) {
551 // Use the segment set, if it is available.
552 if (segmentSet != nullptr)
553 return CalcLiveRangeUtilSet(this).extendInBlock(Undefs, StartIdx, Use: Kill);
554 // Otherwise use the segment vector.
555 return CalcLiveRangeUtilVector(this).extendInBlock(Undefs, StartIdx, Use: Kill);
556}
557
558VNInfo *LiveRange::extendInBlock(SlotIndex StartIdx, SlotIndex Kill) {
559 // Use the segment set, if it is available.
560 if (segmentSet != nullptr)
561 return CalcLiveRangeUtilSet(this).extendInBlock(StartIdx, Use: Kill);
562 // Otherwise use the segment vector.
563 return CalcLiveRangeUtilVector(this).extendInBlock(StartIdx, Use: Kill);
564}
565
566void LiveRange::removeSegment(SlotIndex Start, SlotIndex End,
567 bool RemoveDeadValNo) {
568 // Find the Segment containing this span.
569 iterator I = find(Pos: Start);
570
571 // No Segment found, so nothing to do.
572 if (I == end())
573 return;
574
575 assert(I->containsInterval(Start, End)
576 && "Segment is not entirely in range!");
577
578 // If the span we are removing is at the start of the Segment, adjust it.
579 VNInfo *ValNo = I->valno;
580 if (I->start == Start) {
581 if (I->end == End) {
582 segments.erase(CI: I); // Removed the whole Segment.
583
584 if (RemoveDeadValNo)
585 removeValNoIfDead(ValNo);
586 } else
587 I->start = End;
588 return;
589 }
590
591 // Otherwise if the span we are removing is at the end of the Segment,
592 // adjust the other way.
593 if (I->end == End) {
594 I->end = Start;
595 return;
596 }
597
598 // Otherwise, we are splitting the Segment into two pieces.
599 SlotIndex OldEnd = I->end;
600 I->end = Start; // Trim the old segment.
601
602 // Insert the new one.
603 segments.insert(I: std::next(x: I), Elt: Segment(End, OldEnd, ValNo));
604}
605
606LiveRange::iterator LiveRange::removeSegment(iterator I, bool RemoveDeadValNo) {
607 VNInfo *ValNo = I->valno;
608 I = segments.erase(CI: I);
609 if (RemoveDeadValNo)
610 removeValNoIfDead(ValNo);
611 return I;
612}
613
614void LiveRange::removeValNoIfDead(VNInfo *ValNo) {
615 if (none_of(Range&: *this, P: [=](const Segment &S) { return S.valno == ValNo; }))
616 markValNoForDeletion(ValNo);
617}
618
619/// removeValNo - Remove all the segments defined by the specified value#.
620/// Also remove the value# from value# list.
621void LiveRange::removeValNo(VNInfo *ValNo) {
622 if (empty()) return;
623 llvm::erase_if(C&: segments,
624 P: [ValNo](const Segment &S) { return S.valno == ValNo; });
625 // Now that ValNo is dead, remove it.
626 markValNoForDeletion(ValNo);
627}
628
629void LiveRange::join(LiveRange &Other,
630 const int *LHSValNoAssignments,
631 const int *RHSValNoAssignments,
632 SmallVectorImpl<VNInfo *> &NewVNInfo) {
633 assert(verify());
634 assert(Other.verify());
635
636 // Determine if any of our values are mapped. This is uncommon, so we want
637 // to avoid the range scan if not.
638 bool MustMapCurValNos = false;
639 unsigned NumVals = getNumValNums();
640 unsigned NumNewVals = NewVNInfo.size();
641 for (unsigned i = 0; i != NumVals; ++i) {
642 unsigned LHSValID = LHSValNoAssignments[i];
643 if (i != LHSValID ||
644 (NewVNInfo[LHSValID] && NewVNInfo[LHSValID] != getValNumInfo(ValNo: i))) {
645 MustMapCurValNos = true;
646 break;
647 }
648 }
649
650 // If we have to apply a mapping to our base range assignment, rewrite it now.
651 if (MustMapCurValNos && !empty()) {
652 // Map the first live range.
653
654 iterator OutIt = begin();
655 OutIt->valno = NewVNInfo[LHSValNoAssignments[OutIt->valno->id]];
656 for (iterator I = std::next(x: OutIt), E = end(); I != E; ++I) {
657 VNInfo* nextValNo = NewVNInfo[LHSValNoAssignments[I->valno->id]];
658 assert(nextValNo && "Huh?");
659
660 // If this live range has the same value # as its immediate predecessor,
661 // and if they are neighbors, remove one Segment. This happens when we
662 // have [0,4:0)[4,7:1) and map 0/1 onto the same value #.
663 if (OutIt->valno == nextValNo && OutIt->end == I->start) {
664 OutIt->end = I->end;
665 } else {
666 // Didn't merge. Move OutIt to the next segment,
667 ++OutIt;
668 OutIt->valno = nextValNo;
669 if (OutIt != I) {
670 OutIt->start = I->start;
671 OutIt->end = I->end;
672 }
673 }
674 }
675 // If we merge some segments, chop off the end.
676 ++OutIt;
677 segments.erase(CS: OutIt, CE: end());
678 }
679
680 // Rewrite Other values before changing the VNInfo ids.
681 // This can leave Other in an invalid state because we're not coalescing
682 // touching segments that now have identical values. That's OK since Other is
683 // not supposed to be valid after calling join();
684 for (Segment &S : Other.segments)
685 S.valno = NewVNInfo[RHSValNoAssignments[S.valno->id]];
686
687 // Update val# info. Renumber them and make sure they all belong to this
688 // LiveRange now. Also remove dead val#'s.
689 unsigned NumValNos = 0;
690 for (unsigned i = 0; i < NumNewVals; ++i) {
691 VNInfo *VNI = NewVNInfo[i];
692 if (VNI) {
693 if (NumValNos >= NumVals)
694 valnos.push_back(Elt: VNI);
695 else
696 valnos[NumValNos] = VNI;
697 VNI->id = NumValNos++; // Renumber val#.
698 }
699 }
700 if (NumNewVals < NumVals)
701 valnos.resize(N: NumNewVals); // shrinkify
702
703 // Okay, now insert the RHS live segments into the LHS.
704 LiveRangeUpdater Updater(this);
705 for (Segment &S : Other.segments)
706 Updater.add(S);
707}
708
709/// Merge all of the segments in RHS into this live range as the specified
710/// value number. The segments in RHS are allowed to overlap with segments in
711/// the current range, but only if the overlapping segments have the
712/// specified value number.
713void LiveRange::MergeSegmentsInAsValue(const LiveRange &RHS,
714 VNInfo *LHSValNo) {
715 LiveRangeUpdater Updater(this);
716 for (const Segment &S : RHS.segments)
717 Updater.add(Start: S.start, End: S.end, VNI: LHSValNo);
718}
719
720/// MergeValueInAsValue - Merge all of the live segments of a specific val#
721/// in RHS into this live range as the specified value number.
722/// The segments in RHS are allowed to overlap with segments in the
723/// current range, it will replace the value numbers of the overlaped
724/// segments with the specified value number.
725void LiveRange::MergeValueInAsValue(const LiveRange &RHS,
726 const VNInfo *RHSValNo,
727 VNInfo *LHSValNo) {
728 LiveRangeUpdater Updater(this);
729 for (const Segment &S : RHS.segments)
730 if (S.valno == RHSValNo)
731 Updater.add(Start: S.start, End: S.end, VNI: LHSValNo);
732}
733
734/// MergeValueNumberInto - This method is called when two value nubmers
735/// are found to be equivalent. This eliminates V1, replacing all
736/// segments with the V1 value number with the V2 value number. This can
737/// cause merging of V1/V2 values numbers and compaction of the value space.
738VNInfo *LiveRange::MergeValueNumberInto(VNInfo *V1, VNInfo *V2) {
739 assert(V1 != V2 && "Identical value#'s are always equivalent!");
740
741 // This code actually merges the (numerically) larger value number into the
742 // smaller value number, which is likely to allow us to compactify the value
743 // space. The only thing we have to be careful of is to preserve the
744 // instruction that defines the result value.
745
746 // Make sure V2 is smaller than V1.
747 if (V1->id < V2->id) {
748 V1->copyFrom(src&: *V2);
749 std::swap(a&: V1, b&: V2);
750 }
751
752 // Merge V1 segments into V2.
753 for (iterator I = begin(); I != end(); ) {
754 iterator S = I++;
755 if (S->valno != V1) continue; // Not a V1 Segment.
756
757 // Okay, we found a V1 live range. If it had a previous, touching, V2 live
758 // range, extend it.
759 if (S != begin()) {
760 iterator Prev = S-1;
761 if (Prev->valno == V2 && Prev->end == S->start) {
762 Prev->end = S->end;
763
764 // Erase this live-range.
765 segments.erase(CI: S);
766 I = Prev+1;
767 S = Prev;
768 }
769 }
770
771 // Okay, now we have a V1 or V2 live range that is maximally merged forward.
772 // Ensure that it is a V2 live-range.
773 S->valno = V2;
774
775 // If we can merge it into later V2 segments, do so now. We ignore any
776 // following V1 segments, as they will be merged in subsequent iterations
777 // of the loop.
778 if (I != end()) {
779 if (I->start == S->end && I->valno == V2) {
780 S->end = I->end;
781 segments.erase(CI: I);
782 I = S+1;
783 }
784 }
785 }
786
787 // Now that V1 is dead, remove it.
788 markValNoForDeletion(ValNo: V1);
789
790 return V2;
791}
792
793void LiveRange::flushSegmentSet() {
794 assert(segmentSet != nullptr && "segment set must have been created");
795 assert(
796 segments.empty() &&
797 "segment set can be used only initially before switching to the array");
798 segments.append(in_start: segmentSet->begin(), in_end: segmentSet->end());
799 segmentSet = nullptr;
800 assert(verify());
801}
802
803bool LiveRange::isLiveAtIndexes(ArrayRef<SlotIndex> Slots) const {
804 ArrayRef<SlotIndex>::iterator SlotI = Slots.begin();
805 ArrayRef<SlotIndex>::iterator SlotE = Slots.end();
806
807 // If there are no regmask slots, we have nothing to search.
808 if (SlotI == SlotE)
809 return false;
810
811 // Start our search at the first segment that ends after the first slot.
812 const_iterator SegmentI = find(Pos: *SlotI);
813 const_iterator SegmentE = end();
814
815 // If there are no segments that end after the first slot, we're done.
816 if (SegmentI == SegmentE)
817 return false;
818
819 // Look for each slot in the live range.
820 for ( ; SlotI != SlotE; ++SlotI) {
821 // Go to the next segment that ends after the current slot.
822 // The slot may be within a hole in the range.
823 SegmentI = advanceTo(I: SegmentI, Pos: *SlotI);
824 if (SegmentI == SegmentE)
825 return false;
826
827 // If this segment contains the slot, we're done.
828 if (SegmentI->contains(I: *SlotI))
829 return true;
830 // Otherwise, look for the next slot.
831 }
832
833 // We didn't find a segment containing any of the slots.
834 return false;
835}
836
837void LiveInterval::freeSubRange(SubRange *S) {
838 S->~SubRange();
839 // Memory was allocated with BumpPtr allocator and is not freed here.
840}
841
842void LiveInterval::removeEmptySubRanges() {
843 SubRange **NextPtr = &SubRanges;
844 SubRange *I = *NextPtr;
845 while (I != nullptr) {
846 if (!I->empty()) {
847 NextPtr = &I->Next;
848 I = *NextPtr;
849 continue;
850 }
851 // Skip empty subranges until we find the first nonempty one.
852 do {
853 SubRange *Next = I->Next;
854 freeSubRange(S: I);
855 I = Next;
856 } while (I != nullptr && I->empty());
857 *NextPtr = I;
858 }
859}
860
861void LiveInterval::clearSubRanges() {
862 for (SubRange *I = SubRanges, *Next; I != nullptr; I = Next) {
863 Next = I->Next;
864 freeSubRange(S: I);
865 }
866 SubRanges = nullptr;
867}
868
869/// For each VNI in \p SR, check whether or not that value defines part
870/// of the mask describe by \p LaneMask and if not, remove that value
871/// from \p SR.
872static void stripValuesNotDefiningMask(Register Reg, LiveInterval::SubRange &SR,
873 LaneBitmask LaneMask,
874 const SlotIndexes &Indexes,
875 const TargetRegisterInfo &TRI,
876 unsigned ComposeSubRegIdx) {
877 // Phys reg should not be tracked at subreg level.
878 // Same for noreg (Reg == 0).
879 if (!Reg || !Reg.isVirtual())
880 return;
881 // Remove the values that don't define those lanes.
882 SmallVector<VNInfo *, 8> ToBeRemoved;
883 for (VNInfo *VNI : SR.valnos) {
884 if (VNI->isUnused())
885 continue;
886 // PHI definitions don't have MI attached, so there is nothing
887 // we can use to strip the VNI.
888 if (VNI->isPHIDef())
889 continue;
890 const MachineInstr *MI = Indexes.getInstructionFromIndex(index: VNI->def);
891 assert(MI && "Cannot find the definition of a value");
892 bool hasDef = false;
893 for (ConstMIBundleOperands MOI(*MI); MOI.isValid(); ++MOI) {
894 if (!MOI->isReg() || !MOI->isDef())
895 continue;
896 if (MOI->getReg() != Reg)
897 continue;
898 LaneBitmask OrigMask = TRI.getSubRegIndexLaneMask(SubIdx: MOI->getSubReg());
899 LaneBitmask ExpectedDefMask =
900 ComposeSubRegIdx
901 ? TRI.composeSubRegIndexLaneMask(IdxA: ComposeSubRegIdx, Mask: OrigMask)
902 : OrigMask;
903 if ((ExpectedDefMask & LaneMask).none())
904 continue;
905 hasDef = true;
906 break;
907 }
908
909 if (!hasDef)
910 ToBeRemoved.push_back(Elt: VNI);
911 }
912 for (VNInfo *VNI : ToBeRemoved)
913 SR.removeValNo(ValNo: VNI);
914
915 // If the subrange is empty at this point, the MIR is invalid. Do not assert
916 // and let the verifier catch this case.
917}
918
919void LiveInterval::refineSubRanges(
920 BumpPtrAllocator &Allocator, LaneBitmask LaneMask,
921 std::function<void(LiveInterval::SubRange &)> Apply,
922 const SlotIndexes &Indexes, const TargetRegisterInfo &TRI,
923 unsigned ComposeSubRegIdx) {
924 LaneBitmask ToApply = LaneMask;
925 for (SubRange &SR : subranges()) {
926 LaneBitmask SRMask = SR.LaneMask;
927 LaneBitmask Matching = SRMask & LaneMask;
928 if (Matching.none())
929 continue;
930
931 SubRange *MatchingRange;
932 if (SRMask == Matching) {
933 // The subrange fits (it does not cover bits outside \p LaneMask).
934 MatchingRange = &SR;
935 } else {
936 // We have to split the subrange into a matching and non-matching part.
937 // Reduce lanemask of existing lane to non-matching part.
938 SR.LaneMask = SRMask & ~Matching;
939 // Create a new subrange for the matching part
940 MatchingRange = createSubRangeFrom(Allocator, LaneMask: Matching, CopyFrom: SR);
941 // Now that the subrange is split in half, make sure we
942 // only keep in the subranges the VNIs that touch the related half.
943 stripValuesNotDefiningMask(Reg: reg(), SR&: *MatchingRange, LaneMask: Matching, Indexes, TRI,
944 ComposeSubRegIdx);
945 stripValuesNotDefiningMask(Reg: reg(), SR, LaneMask: SR.LaneMask, Indexes, TRI,
946 ComposeSubRegIdx);
947 }
948 Apply(*MatchingRange);
949 ToApply &= ~Matching;
950 }
951 // Create a new subrange if there are uncovered bits left.
952 if (ToApply.any()) {
953 SubRange *NewRange = createSubRange(Allocator, LaneMask: ToApply);
954 Apply(*NewRange);
955 }
956}
957
958unsigned LiveInterval::getSize() const {
959 unsigned Sum = 0;
960 for (const Segment &S : segments)
961 Sum += S.start.distance(other: S.end);
962 return Sum;
963}
964
965void LiveInterval::computeSubRangeUndefs(SmallVectorImpl<SlotIndex> &Undefs,
966 LaneBitmask LaneMask,
967 const MachineRegisterInfo &MRI,
968 const SlotIndexes &Indexes) const {
969 assert(reg().isVirtual());
970 LaneBitmask VRegMask = MRI.getMaxLaneMaskForVReg(Reg: reg());
971 assert((VRegMask & LaneMask).any());
972 const TargetRegisterInfo &TRI = *MRI.getTargetRegisterInfo();
973 for (const MachineOperand &MO : MRI.def_operands(Reg: reg())) {
974 if (!MO.isUndef())
975 continue;
976 unsigned SubReg = MO.getSubReg();
977 assert(SubReg != 0 && "Undef should only be set on subreg defs");
978 LaneBitmask DefMask = TRI.getSubRegIndexLaneMask(SubIdx: SubReg);
979 LaneBitmask UndefMask = VRegMask & ~DefMask;
980 if ((UndefMask & LaneMask).any()) {
981 const MachineInstr &MI = *MO.getParent();
982 bool EarlyClobber = MO.isEarlyClobber();
983 SlotIndex Pos = Indexes.getInstructionIndex(MI).getRegSlot(EC: EarlyClobber);
984 Undefs.push_back(Elt: Pos);
985 }
986 }
987}
988
989raw_ostream& llvm::operator<<(raw_ostream& OS, const LiveRange::Segment &S) {
990 return OS << '[' << S.start << ',' << S.end << ':' << S.valno->id << ')';
991}
992
993#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
994LLVM_DUMP_METHOD void LiveRange::Segment::dump() const {
995 dbgs() << *this << '\n';
996}
997#endif
998
999void LiveRange::print(raw_ostream &OS) const {
1000 if (empty())
1001 OS << "EMPTY";
1002 else {
1003 for (const Segment &S : segments) {
1004 OS << S;
1005 assert(S.valno == getValNumInfo(S.valno->id) && "Bad VNInfo");
1006 }
1007 }
1008
1009 // Print value number info.
1010 if (getNumValNums()) {
1011 OS << ' ';
1012 unsigned vnum = 0;
1013 for (const_vni_iterator i = vni_begin(), e = vni_end(); i != e;
1014 ++i, ++vnum) {
1015 const VNInfo *vni = *i;
1016 if (vnum) OS << ' ';
1017 OS << vnum << '@';
1018 if (vni->isUnused()) {
1019 OS << 'x';
1020 } else {
1021 OS << vni->def;
1022 if (vni->isPHIDef())
1023 OS << "-phi";
1024 }
1025 }
1026 }
1027}
1028
1029void LiveInterval::SubRange::print(raw_ostream &OS) const {
1030 OS << " L" << PrintLaneMask(LaneMask) << ' '
1031 << static_cast<const LiveRange &>(*this);
1032}
1033
1034void LiveInterval::print(raw_ostream &OS) const {
1035 OS << printReg(Reg: reg()) << ' ';
1036 super::print(OS);
1037 // Print subranges
1038 for (const SubRange &SR : subranges())
1039 OS << SR;
1040 OS << " weight:" << Weight;
1041}
1042
1043#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
1044LLVM_DUMP_METHOD void LiveRange::dump() const {
1045 dbgs() << *this << '\n';
1046}
1047
1048LLVM_DUMP_METHOD void LiveInterval::SubRange::dump() const {
1049 dbgs() << *this << '\n';
1050}
1051
1052LLVM_DUMP_METHOD void LiveInterval::dump() const {
1053 dbgs() << *this << '\n';
1054}
1055#endif
1056
1057#ifndef NDEBUG
1058bool LiveRange::verify() const {
1059 for (const_iterator I = begin(), E = end(); I != E; ++I) {
1060 if (!I->start.isValid())
1061 return false;
1062 if (!I->end.isValid())
1063 return false;
1064 if (I->start >= I->end)
1065 return false;
1066 if (I->valno == nullptr)
1067 return false;
1068 if (I->valno->id >= valnos.size())
1069 return false;
1070 if (I->valno != valnos[I->valno->id])
1071 return false;
1072 if (std::next(I) != E) {
1073 if (I->end > std::next(I)->start)
1074 return false;
1075 if (I->end == std::next(I)->start) {
1076 if (I->valno == std::next(I)->valno)
1077 return false;
1078 }
1079 }
1080 }
1081
1082 return true;
1083}
1084
1085bool LiveInterval::verify(const MachineRegisterInfo *MRI) const {
1086 if (!super::verify())
1087 return false;
1088
1089 // Make sure SubRanges are fine and LaneMasks are disjunct.
1090 LaneBitmask Mask;
1091 LaneBitmask MaxMask = MRI != nullptr ? MRI->getMaxLaneMaskForVReg(reg())
1092 : LaneBitmask::getAll();
1093 for (const SubRange &SR : subranges()) {
1094 // Subrange lanemask should be disjunct to any previous subrange masks.
1095 if ((Mask & SR.LaneMask).any())
1096 return false;
1097
1098 Mask |= SR.LaneMask;
1099
1100 // subrange mask should not contained in maximum lane mask for the vreg.
1101 if ((Mask & ~MaxMask).any())
1102 return false;
1103
1104 // empty subranges must be removed.
1105 if (SR.empty())
1106 return false;
1107
1108 if (!SR.verify())
1109 return false;
1110
1111 // Main liverange should cover subrange.
1112 if (!covers(SR))
1113 return false;
1114 }
1115
1116 return true;
1117}
1118#endif
1119
1120//===----------------------------------------------------------------------===//
1121// LiveRangeUpdater class
1122//===----------------------------------------------------------------------===//
1123//
1124// The LiveRangeUpdater class always maintains these invariants:
1125//
1126// - When LastStart is invalid, Spills is empty and the iterators are invalid.
1127// This is the initial state, and the state created by flush().
1128// In this state, isDirty() returns false.
1129//
1130// Otherwise, segments are kept in three separate areas:
1131//
1132// 1. [begin; WriteI) at the front of LR.
1133// 2. [ReadI; end) at the back of LR.
1134// 3. Spills.
1135//
1136// - LR.begin() <= WriteI <= ReadI <= LR.end().
1137// - Segments in all three areas are fully ordered and coalesced.
1138// - Segments in area 1 precede and can't coalesce with segments in area 2.
1139// - Segments in Spills precede and can't coalesce with segments in area 2.
1140// - No coalescing is possible between segments in Spills and segments in area
1141// 1, and there are no overlapping segments.
1142//
1143// The segments in Spills are not ordered with respect to the segments in area
1144// 1. They need to be merged.
1145//
1146// When they exist, Spills.back().start <= LastStart,
1147// and WriteI[-1].start <= LastStart.
1148
1149#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
1150void LiveRangeUpdater::print(raw_ostream &OS) const {
1151 if (!isDirty()) {
1152 if (LR)
1153 OS << "Clean updater: " << *LR << '\n';
1154 else
1155 OS << "Null updater.\n";
1156 return;
1157 }
1158 assert(LR && "Can't have null LR in dirty updater.");
1159 OS << " updater with gap = " << (ReadI - WriteI)
1160 << ", last start = " << LastStart
1161 << ":\n Area 1:";
1162 for (const auto &S : make_range(LR->begin(), WriteI))
1163 OS << ' ' << S;
1164 OS << "\n Spills:";
1165 for (const LiveRange::Segment &Spill : Spills)
1166 OS << ' ' << Spill;
1167 OS << "\n Area 2:";
1168 for (const auto &S : make_range(ReadI, LR->end()))
1169 OS << ' ' << S;
1170 OS << '\n';
1171}
1172
1173LLVM_DUMP_METHOD void LiveRangeUpdater::dump() const {
1174 print(errs());
1175}
1176#endif
1177
1178// Determine if A and B should be coalesced.
1179static inline bool coalescable(const LiveRange::Segment &A,
1180 const LiveRange::Segment &B) {
1181 assert(A.start <= B.start && "Unordered live segments.");
1182 if (A.end == B.start)
1183 return A.valno == B.valno;
1184 if (A.end < B.start)
1185 return false;
1186 assert(A.valno == B.valno && "Cannot overlap different values");
1187 return true;
1188}
1189
1190void LiveRangeUpdater::add(LiveRange::Segment Seg) {
1191 assert(LR && "Cannot add to a null destination");
1192
1193 // Fall back to the regular add method if the live range
1194 // is using the segment set instead of the segment vector.
1195 if (LR->segmentSet != nullptr) {
1196 LR->addSegmentToSet(S: Seg);
1197 return;
1198 }
1199
1200 // Flush the state if Start moves backwards.
1201 if (!LastStart.isValid() || LastStart > Seg.start) {
1202 if (isDirty())
1203 flush();
1204 // This brings us to an uninitialized state. Reinitialize.
1205 assert(Spills.empty() && "Leftover spilled segments");
1206 WriteI = ReadI = LR->begin();
1207 }
1208
1209 // Remember start for next time.
1210 LastStart = Seg.start;
1211
1212 // Advance ReadI until it ends after Seg.start.
1213 LiveRange::iterator E = LR->end();
1214 if (ReadI != E && ReadI->end <= Seg.start) {
1215 // First try to close the gap between WriteI and ReadI with spills.
1216 if (ReadI != WriteI)
1217 mergeSpills();
1218 // Then advance ReadI.
1219 if (ReadI == WriteI)
1220 ReadI = WriteI = LR->find(Pos: Seg.start);
1221 else
1222 while (ReadI != E && ReadI->end <= Seg.start)
1223 *WriteI++ = *ReadI++;
1224 }
1225
1226 assert(ReadI == E || ReadI->end > Seg.start);
1227
1228 // Check if the ReadI segment begins early.
1229 if (ReadI != E && ReadI->start <= Seg.start) {
1230 assert(ReadI->valno == Seg.valno && "Cannot overlap different values");
1231 // Bail if Seg is completely contained in ReadI.
1232 if (ReadI->end >= Seg.end)
1233 return;
1234 // Coalesce into Seg.
1235 Seg.start = ReadI->start;
1236 ++ReadI;
1237 }
1238
1239 // Coalesce as much as possible from ReadI into Seg.
1240 while (ReadI != E && coalescable(A: Seg, B: *ReadI)) {
1241 Seg.end = std::max(a: Seg.end, b: ReadI->end);
1242 ++ReadI;
1243 }
1244
1245 // Try coalescing Spills.back() into Seg.
1246 if (!Spills.empty() && coalescable(A: Spills.back(), B: Seg)) {
1247 Seg.start = Spills.back().start;
1248 Seg.end = std::max(a: Spills.back().end, b: Seg.end);
1249 Spills.pop_back();
1250 }
1251
1252 // Try coalescing Seg into WriteI[-1].
1253 if (WriteI != LR->begin() && coalescable(A: WriteI[-1], B: Seg)) {
1254 WriteI[-1].end = std::max(a: WriteI[-1].end, b: Seg.end);
1255 return;
1256 }
1257
1258 // Seg doesn't coalesce with anything, and needs to be inserted somewhere.
1259 if (WriteI != ReadI) {
1260 *WriteI++ = Seg;
1261 return;
1262 }
1263
1264 // Finally, append to LR or Spills.
1265 if (WriteI == E) {
1266 LR->segments.push_back(Elt: Seg);
1267 WriteI = ReadI = LR->end();
1268 } else
1269 Spills.push_back(Elt: Seg);
1270}
1271
1272// Merge as many spilled segments as possible into the gap between WriteI
1273// and ReadI. Advance WriteI to reflect the inserted instructions.
1274void LiveRangeUpdater::mergeSpills() {
1275 // Perform a backwards merge of Spills and [SpillI;WriteI).
1276 size_t GapSize = ReadI - WriteI;
1277 size_t NumMoved = std::min(a: Spills.size(), b: GapSize);
1278 LiveRange::iterator Src = WriteI;
1279 LiveRange::iterator Dst = Src + NumMoved;
1280 LiveRange::iterator SpillSrc = Spills.end();
1281 LiveRange::iterator B = LR->begin();
1282
1283 // This is the new WriteI position after merging spills.
1284 WriteI = Dst;
1285
1286 // Now merge Src and Spills backwards.
1287 while (Src != Dst) {
1288 if (Src != B && Src[-1].start > SpillSrc[-1].start)
1289 *--Dst = *--Src;
1290 else
1291 *--Dst = *--SpillSrc;
1292 }
1293 assert(NumMoved == size_t(Spills.end() - SpillSrc));
1294 Spills.erase(CS: SpillSrc, CE: Spills.end());
1295}
1296
1297void LiveRangeUpdater::flush() {
1298 if (!isDirty())
1299 return;
1300 // Clear the dirty state.
1301 LastStart = SlotIndex();
1302
1303 assert(LR && "Cannot add to a null destination");
1304
1305 // Nothing to merge?
1306 if (Spills.empty()) {
1307 LR->segments.erase(CS: WriteI, CE: ReadI);
1308 assert(LR->verify());
1309 return;
1310 }
1311
1312 // Resize the WriteI - ReadI gap to match Spills.
1313 size_t GapSize = ReadI - WriteI;
1314 if (GapSize < Spills.size()) {
1315 // The gap is too small. Make some room.
1316 size_t WritePos = WriteI - LR->begin();
1317 LR->segments.insert(I: ReadI, NumToInsert: Spills.size() - GapSize, Elt: LiveRange::Segment());
1318 // This also invalidated ReadI, but it is recomputed below.
1319 WriteI = LR->begin() + WritePos;
1320 } else {
1321 // Shrink the gap if necessary.
1322 LR->segments.erase(CS: WriteI + Spills.size(), CE: ReadI);
1323 }
1324 ReadI = WriteI + Spills.size();
1325 mergeSpills();
1326 assert(LR->verify());
1327}
1328
1329unsigned ConnectedVNInfoEqClasses::Classify(const LiveRange &LR) {
1330 // Create initial equivalence classes.
1331 EqClass.clear();
1332 EqClass.grow(N: LR.getNumValNums());
1333
1334 const VNInfo *used = nullptr, *unused = nullptr;
1335
1336 // Determine connections.
1337 for (const VNInfo *VNI : LR.valnos) {
1338 // Group all unused values into one class.
1339 if (VNI->isUnused()) {
1340 if (unused)
1341 EqClass.join(a: unused->id, b: VNI->id);
1342 unused = VNI;
1343 continue;
1344 }
1345 used = VNI;
1346 if (VNI->isPHIDef()) {
1347 const MachineBasicBlock *MBB = LIS.getMBBFromIndex(index: VNI->def);
1348 assert(MBB && "Phi-def has no defining MBB");
1349 // Connect to values live out of predecessors.
1350 for (MachineBasicBlock *Pred : MBB->predecessors())
1351 if (const VNInfo *PVNI = LR.getVNInfoBefore(Idx: LIS.getMBBEndIdx(mbb: Pred)))
1352 EqClass.join(a: VNI->id, b: PVNI->id);
1353 } else {
1354 // Normal value defined by an instruction. Check for two-addr redef.
1355 // FIXME: This could be coincidental. Should we really check for a tied
1356 // operand constraint?
1357 // Note that VNI->def may be a use slot for an early clobber def.
1358 if (const VNInfo *UVNI = LR.getVNInfoBefore(Idx: VNI->def))
1359 EqClass.join(a: VNI->id, b: UVNI->id);
1360 }
1361 }
1362
1363 // Lump all the unused values in with the last used value.
1364 if (used && unused)
1365 EqClass.join(a: used->id, b: unused->id);
1366
1367 EqClass.compress();
1368 return EqClass.getNumClasses();
1369}
1370
1371void ConnectedVNInfoEqClasses::Distribute(LiveInterval &LI, LiveInterval *LIV[],
1372 MachineRegisterInfo &MRI) {
1373 // Rewrite instructions.
1374 for (MachineOperand &MO :
1375 llvm::make_early_inc_range(Range: MRI.reg_operands(Reg: LI.reg()))) {
1376 MachineInstr *MI = MO.getParent();
1377 const VNInfo *VNI;
1378 if (MI->isDebugValue()) {
1379 // DBG_VALUE instructions don't have slot indexes, so get the index of
1380 // the instruction before them. The value is defined there too.
1381 SlotIndex Idx = LIS.getSlotIndexes()->getIndexBefore(MI: *MI);
1382 VNI = LI.Query(Idx).valueOut();
1383 } else {
1384 SlotIndex Idx = LIS.getInstructionIndex(Instr: *MI);
1385 LiveQueryResult LRQ = LI.Query(Idx);
1386 VNI = MO.readsReg() ? LRQ.valueIn() : LRQ.valueDefined();
1387 }
1388 // In the case of an <undef> use that isn't tied to any def, VNI will be
1389 // NULL. If the use is tied to a def, VNI will be the defined value.
1390 if (!VNI)
1391 continue;
1392 if (unsigned EqClass = getEqClass(VNI))
1393 MO.setReg(LIV[EqClass - 1]->reg());
1394 }
1395
1396 // Distribute subregister liveranges.
1397 if (LI.hasSubRanges()) {
1398 unsigned NumComponents = EqClass.getNumClasses();
1399 SmallVector<unsigned, 8> VNIMapping;
1400 SmallVector<LiveInterval::SubRange*, 8> SubRanges;
1401 BumpPtrAllocator &Allocator = LIS.getVNInfoAllocator();
1402 for (LiveInterval::SubRange &SR : LI.subranges()) {
1403 // Create new subranges in the split intervals and construct a mapping
1404 // for the VNInfos in the subrange.
1405 unsigned NumValNos = SR.valnos.size();
1406 VNIMapping.clear();
1407 VNIMapping.reserve(N: NumValNos);
1408 SubRanges.clear();
1409 SubRanges.resize(N: NumComponents-1, NV: nullptr);
1410 for (unsigned I = 0; I < NumValNos; ++I) {
1411 const VNInfo &VNI = *SR.valnos[I];
1412 unsigned ComponentNum;
1413 if (VNI.isUnused()) {
1414 ComponentNum = 0;
1415 } else {
1416 const VNInfo *MainRangeVNI = LI.getVNInfoAt(Idx: VNI.def);
1417 assert(MainRangeVNI != nullptr
1418 && "SubRange def must have corresponding main range def");
1419 ComponentNum = getEqClass(VNI: MainRangeVNI);
1420 if (ComponentNum > 0 && SubRanges[ComponentNum-1] == nullptr) {
1421 SubRanges[ComponentNum-1]
1422 = LIV[ComponentNum-1]->createSubRange(Allocator, LaneMask: SR.LaneMask);
1423 }
1424 }
1425 VNIMapping.push_back(Elt: ComponentNum);
1426 }
1427 DistributeRange(LR&: SR, SplitLRs: SubRanges.data(), VNIClasses: VNIMapping);
1428 }
1429 LI.removeEmptySubRanges();
1430 }
1431
1432 // Distribute main liverange.
1433 DistributeRange(LR&: LI, SplitLRs: LIV, VNIClasses: EqClass);
1434}
1435