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
46	using namespace llvm;
47
48	namespace {
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
64	template <typename ImplT, typename IteratorT, typename CollectionT>
65	class CalcLiveRangeUtilBase {
66	protected:
67	LiveRange *LR;
68
69	protected:
70	CalcLiveRangeUtilBase(LiveRange *LR) : LR(LR) {}
71
72	public:
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
268	private:
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
281	class CalcLiveRangeUtilVector;
282	using CalcLiveRangeUtilVectorBase =
283	CalcLiveRangeUtilBase<CalcLiveRangeUtilVector, LiveRange::iterator,
284	LiveRange::Segments>;
285
286	class CalcLiveRangeUtilVector : public CalcLiveRangeUtilVectorBase {
287	public:
288	CalcLiveRangeUtilVector(LiveRange *LR) : CalcLiveRangeUtilVectorBase(LR) {}
289
290	private:
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
307	class CalcLiveRangeUtilSet;
308	using CalcLiveRangeUtilSetBase =
309	CalcLiveRangeUtilBase<CalcLiveRangeUtilSet, LiveRange::SegmentSet::iterator,
310	LiveRange::SegmentSet>;
311
312	class CalcLiveRangeUtilSet : public CalcLiveRangeUtilSetBase {
313	public:
314	CalcLiveRangeUtilSet(LiveRange *LR) : CalcLiveRangeUtilSetBase(LR) {}
315
316	private:
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
350	LiveRange::iterator LiveRange::find(SlotIndex Pos) {
351	return llvm::partition_point(Range&: *this,
352	P: [&](const Segment &X) { return X.end <= Pos; });
353	}
354
355	VNInfo *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
363	VNInfo *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	//
389	bool 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
430	bool 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).
473	bool 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
479	bool 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.
504	void 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.
516	void 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
529	void LiveRange::addSegmentToSet(Segment S) {
530	CalcLiveRangeUtilSet(this).addSegment(S);
531	}
532
533	LiveRange::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
543	void 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
549	std::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
558	VNInfo *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
566	void 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
606	LiveRange::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
614	void 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.
621	void 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
629	void LiveRange::join(LiveRange &Other,
630	const int *LHSValNoAssignments,
631	const int *RHSValNoAssignments,
632	SmallVectorImpl<VNInfo *> &NewVNInfo) {
633	verify();
634	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.
713	void 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.
725	void 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.
738	VNInfo *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
793	void 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	verify();
801	}
802
803	bool 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
837	void LiveInterval::freeSubRange(SubRange *S) {
838	S->~SubRange();
839	// Memory was allocated with BumpPtr allocator and is not freed here.
840	}
841
842	void 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
861	void 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.
872	static void stripValuesNotDefiningMask(unsigned 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 (!Register::isVirtualRegister(Reg) || !Reg)
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
919	void 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
958	unsigned 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
965	void 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
989	raw_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)
994	LLVM_DUMP_METHOD void LiveRange::Segment::dump() const {
995	dbgs() << *this << '\n';
996	}
997	#endif
998
999	void 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
1029	void LiveInterval::SubRange::print(raw_ostream &OS) const {
1030	OS << " L" << PrintLaneMask(LaneMask) << ' '
1031	<< static_cast<const LiveRange &>(*this);
1032	}
1033
1034	void 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)
1044	LLVM_DUMP_METHOD void LiveRange::dump() const {
1045	dbgs() << *this << '\n';
1046	}
1047
1048	LLVM_DUMP_METHOD void LiveInterval::SubRange::dump() const {
1049	dbgs() << *this << '\n';
1050	}
1051
1052	LLVM_DUMP_METHOD void LiveInterval::dump() const {
1053	dbgs() << *this << '\n';
1054	}
1055	#endif
1056
1057	#ifndef NDEBUG
1058	void LiveRange::verify() const {
1059	for (const_iterator I = begin(), E = end(); I != E; ++I) {
1060	assert(I->start.isValid());
1061	assert(I->end.isValid());
1062	assert(I->start < I->end);
1063	assert(I->valno != nullptr);
1064	assert(I->valno->id < valnos.size());
1065	assert(I->valno == valnos[I->valno->id]);
1066	if (std::next(x: I) != E) {
1067	assert(I->end <= std::next(I)->start);
1068	if (I->end == std::next(x: I)->start)
1069	assert(I->valno != std::next(I)->valno);
1070	}
1071	}
1072	}
1073
1074	void LiveInterval::verify(const MachineRegisterInfo *MRI) const {
1075	super::verify();
1076
1077	// Make sure SubRanges are fine and LaneMasks are disjunct.
1078	LaneBitmask Mask;
1079	LaneBitmask MaxMask = MRI != nullptr ? MRI->getMaxLaneMaskForVReg(Reg: reg())
1080	: LaneBitmask::getAll();
1081	for (const SubRange &SR : subranges()) {
1082	// Subrange lanemask should be disjunct to any previous subrange masks.
1083	assert((Mask & SR.LaneMask).none());
1084	Mask |= SR.LaneMask;
1085
1086	// subrange mask should not contained in maximum lane mask for the vreg.
1087	assert((Mask & ~MaxMask).none());
1088	// empty subranges must be removed.
1089	assert(!SR.empty());
1090
1091	SR.verify();
1092	// Main liverange should cover subrange.
1093	assert(covers(SR));
1094	}
1095	}
1096	#endif
1097
1098	//===----------------------------------------------------------------------===//
1099	// LiveRangeUpdater class
1100	//===----------------------------------------------------------------------===//
1101	//
1102	// The LiveRangeUpdater class always maintains these invariants:
1103	//
1104	// - When LastStart is invalid, Spills is empty and the iterators are invalid.
1105	// This is the initial state, and the state created by flush().
1106	// In this state, isDirty() returns false.
1107	//
1108	// Otherwise, segments are kept in three separate areas:
1109	//
1110	// 1. [begin; WriteI) at the front of LR.
1111	// 2. [ReadI; end) at the back of LR.
1112	// 3. Spills.
1113	//
1114	// - LR.begin() <= WriteI <= ReadI <= LR.end().
1115	// - Segments in all three areas are fully ordered and coalesced.
1116	// - Segments in area 1 precede and can't coalesce with segments in area 2.
1117	// - Segments in Spills precede and can't coalesce with segments in area 2.
1118	// - No coalescing is possible between segments in Spills and segments in area
1119	// 1, and there are no overlapping segments.
1120	//
1121	// The segments in Spills are not ordered with respect to the segments in area
1122	// 1. They need to be merged.
1123	//
1124	// When they exist, Spills.back().start <= LastStart,
1125	// and WriteI[-1].start <= LastStart.
1126
1127	#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
1128	void LiveRangeUpdater::print(raw_ostream &OS) const {
1129	if (!isDirty()) {
1130	if (LR)
1131	OS << "Clean updater: " << *LR << '\n';
1132	else
1133	OS << "Null updater.\n";
1134	return;
1135	}
1136	assert(LR && "Can't have null LR in dirty updater.");
1137	OS << " updater with gap = " << (ReadI - WriteI)
1138	<< ", last start = " << LastStart
1139	<< ":\n Area 1:";
1140	for (const auto &S : make_range(x: LR->begin(), y: WriteI))
1141	OS << ' ' << S;
1142	OS << "\n Spills:";
1143	for (unsigned I = 0, E = Spills.size(); I != E; ++I)
1144	OS << ' ' << Spills[I];
1145	OS << "\n Area 2:";
1146	for (const auto &S : make_range(x: ReadI, y: LR->end()))
1147	OS << ' ' << S;
1148	OS << '\n';
1149	}
1150
1151	LLVM_DUMP_METHOD void LiveRangeUpdater::dump() const {
1152	print(OS&: errs());
1153	}
1154	#endif
1155
1156	// Determine if A and B should be coalesced.
1157	static inline bool coalescable(const LiveRange::Segment &A,
1158	const LiveRange::Segment &B) {
1159	assert(A.start <= B.start && "Unordered live segments.");
1160	if (A.end == B.start)
1161	return A.valno == B.valno;
1162	if (A.end < B.start)
1163	return false;
1164	assert(A.valno == B.valno && "Cannot overlap different values");
1165	return true;
1166	}
1167
1168	void LiveRangeUpdater::add(LiveRange::Segment Seg) {
1169	assert(LR && "Cannot add to a null destination");
1170
1171	// Fall back to the regular add method if the live range
1172	// is using the segment set instead of the segment vector.
1173	if (LR->segmentSet != nullptr) {
1174	LR->addSegmentToSet(S: Seg);
1175	return;
1176	}
1177
1178	// Flush the state if Start moves backwards.
1179	if (!LastStart.isValid() || LastStart > Seg.start) {
1180	if (isDirty())
1181	flush();
1182	// This brings us to an uninitialized state. Reinitialize.
1183	assert(Spills.empty() && "Leftover spilled segments");
1184	WriteI = ReadI = LR->begin();
1185	}
1186
1187	// Remember start for next time.
1188	LastStart = Seg.start;
1189
1190	// Advance ReadI until it ends after Seg.start.
1191	LiveRange::iterator E = LR->end();
1192	if (ReadI != E && ReadI->end <= Seg.start) {
1193	// First try to close the gap between WriteI and ReadI with spills.
1194	if (ReadI != WriteI)
1195	mergeSpills();
1196	// Then advance ReadI.
1197	if (ReadI == WriteI)
1198	ReadI = WriteI = LR->find(Pos: Seg.start);
1199	else
1200	while (ReadI != E && ReadI->end <= Seg.start)
1201	*WriteI++ = *ReadI++;
1202	}
1203
1204	assert(ReadI == E || ReadI->end > Seg.start);
1205
1206	// Check if the ReadI segment begins early.
1207	if (ReadI != E && ReadI->start <= Seg.start) {
1208	assert(ReadI->valno == Seg.valno && "Cannot overlap different values");
1209	// Bail if Seg is completely contained in ReadI.
1210	if (ReadI->end >= Seg.end)
1211	return;
1212	// Coalesce into Seg.
1213	Seg.start = ReadI->start;
1214	++ReadI;
1215	}
1216
1217	// Coalesce as much as possible from ReadI into Seg.
1218	while (ReadI != E && coalescable(A: Seg, B: *ReadI)) {
1219	Seg.end = std::max(a: Seg.end, b: ReadI->end);
1220	++ReadI;
1221	}
1222
1223	// Try coalescing Spills.back() into Seg.
1224	if (!Spills.empty() && coalescable(A: Spills.back(), B: Seg)) {
1225	Seg.start = Spills.back().start;
1226	Seg.end = std::max(a: Spills.back().end, b: Seg.end);
1227	Spills.pop_back();
1228	}
1229
1230	// Try coalescing Seg into WriteI[-1].
1231	if (WriteI != LR->begin() && coalescable(A: WriteI[-1], B: Seg)) {
1232	WriteI[-1].end = std::max(a: WriteI[-1].end, b: Seg.end);
1233	return;
1234	}
1235
1236	// Seg doesn't coalesce with anything, and needs to be inserted somewhere.
1237	if (WriteI != ReadI) {
1238	*WriteI++ = Seg;
1239	return;
1240	}
1241
1242	// Finally, append to LR or Spills.
1243	if (WriteI == E) {
1244	LR->segments.push_back(Elt: Seg);
1245	WriteI = ReadI = LR->end();
1246	} else
1247	Spills.push_back(Elt: Seg);
1248	}
1249
1250	// Merge as many spilled segments as possible into the gap between WriteI
1251	// and ReadI. Advance WriteI to reflect the inserted instructions.
1252	void LiveRangeUpdater::mergeSpills() {
1253	// Perform a backwards merge of Spills and [SpillI;WriteI).
1254	size_t GapSize = ReadI - WriteI;
1255	size_t NumMoved = std::min(a: Spills.size(), b: GapSize);
1256	LiveRange::iterator Src = WriteI;
1257	LiveRange::iterator Dst = Src + NumMoved;
1258	LiveRange::iterator SpillSrc = Spills.end();
1259	LiveRange::iterator B = LR->begin();
1260
1261	// This is the new WriteI position after merging spills.
1262	WriteI = Dst;
1263
1264	// Now merge Src and Spills backwards.
1265	while (Src != Dst) {
1266	if (Src != B && Src[-1].start > SpillSrc[-1].start)
1267	*--Dst = *--Src;
1268	else
1269	*--Dst = *--SpillSrc;
1270	}
1271	assert(NumMoved == size_t(Spills.end() - SpillSrc));
1272	Spills.erase(CS: SpillSrc, CE: Spills.end());
1273	}
1274
1275	void LiveRangeUpdater::flush() {
1276	if (!isDirty())
1277	return;
1278	// Clear the dirty state.
1279	LastStart = SlotIndex();
1280
1281	assert(LR && "Cannot add to a null destination");
1282
1283	// Nothing to merge?
1284	if (Spills.empty()) {
1285	LR->segments.erase(CS: WriteI, CE: ReadI);
1286	LR->verify();
1287	return;
1288	}
1289
1290	// Resize the WriteI - ReadI gap to match Spills.
1291	size_t GapSize = ReadI - WriteI;
1292	if (GapSize < Spills.size()) {
1293	// The gap is too small. Make some room.
1294	size_t WritePos = WriteI - LR->begin();
1295	LR->segments.insert(I: ReadI, NumToInsert: Spills.size() - GapSize, Elt: LiveRange::Segment());
1296	// This also invalidated ReadI, but it is recomputed below.
1297	WriteI = LR->begin() + WritePos;
1298	} else {
1299	// Shrink the gap if necessary.
1300	LR->segments.erase(CS: WriteI + Spills.size(), CE: ReadI);
1301	}
1302	ReadI = WriteI + Spills.size();
1303	mergeSpills();
1304	LR->verify();
1305	}
1306
1307	unsigned ConnectedVNInfoEqClasses::Classify(const LiveRange &LR) {
1308	// Create initial equivalence classes.
1309	EqClass.clear();
1310	EqClass.grow(N: LR.getNumValNums());
1311
1312	const VNInfo *used = nullptr, *unused = nullptr;
1313
1314	// Determine connections.
1315	for (const VNInfo *VNI : LR.valnos) {
1316	// Group all unused values into one class.
1317	if (VNI->isUnused()) {
1318	if (unused)
1319	EqClass.join(a: unused->id, b: VNI->id);
1320	unused = VNI;
1321	continue;
1322	}
1323	used = VNI;
1324	if (VNI->isPHIDef()) {
1325	const MachineBasicBlock *MBB = LIS.getMBBFromIndex(index: VNI->def);
1326	assert(MBB && "Phi-def has no defining MBB");
1327	// Connect to values live out of predecessors.
1328	for (MachineBasicBlock *Pred : MBB->predecessors())
1329	if (const VNInfo *PVNI = LR.getVNInfoBefore(Idx: LIS.getMBBEndIdx(mbb: Pred)))
1330	EqClass.join(a: VNI->id, b: PVNI->id);
1331	} else {
1332	// Normal value defined by an instruction. Check for two-addr redef.
1333	// FIXME: This could be coincidental. Should we really check for a tied
1334	// operand constraint?
1335	// Note that VNI->def may be a use slot for an early clobber def.
1336	if (const VNInfo *UVNI = LR.getVNInfoBefore(Idx: VNI->def))
1337	EqClass.join(a: VNI->id, b: UVNI->id);
1338	}
1339	}
1340
1341	// Lump all the unused values in with the last used value.
1342	if (used && unused)
1343	EqClass.join(a: used->id, b: unused->id);
1344
1345	EqClass.compress();
1346	return EqClass.getNumClasses();
1347	}
1348
1349	void ConnectedVNInfoEqClasses::Distribute(LiveInterval &LI, LiveInterval *LIV[],
1350	MachineRegisterInfo &MRI) {
1351	// Rewrite instructions.
1352	for (MachineOperand &MO :
1353	llvm::make_early_inc_range(Range: MRI.reg_operands(Reg: LI.reg()))) {
1354	MachineInstr *MI = MO.getParent();
1355	const VNInfo *VNI;
1356	if (MI->isDebugValue()) {
1357	// DBG_VALUE instructions don't have slot indexes, so get the index of
1358	// the instruction before them. The value is defined there too.
1359	SlotIndex Idx = LIS.getSlotIndexes()->getIndexBefore(MI: *MI);
1360	VNI = LI.Query(Idx).valueOut();
1361	} else {
1362	SlotIndex Idx = LIS.getInstructionIndex(Instr: *MI);
1363	LiveQueryResult LRQ = LI.Query(Idx);
1364	VNI = MO.readsReg() ? LRQ.valueIn() : LRQ.valueDefined();
1365	}
1366	// In the case of an <undef> use that isn't tied to any def, VNI will be
1367	// NULL. If the use is tied to a def, VNI will be the defined value.
1368	if (!VNI)
1369	continue;
1370	if (unsigned EqClass = getEqClass(VNI))
1371	MO.setReg(LIV[EqClass - 1]->reg());
1372	}
1373
1374	// Distribute subregister liveranges.
1375	if (LI.hasSubRanges()) {
1376	unsigned NumComponents = EqClass.getNumClasses();
1377	SmallVector<unsigned, 8> VNIMapping;
1378	SmallVector<LiveInterval::SubRange*, 8> SubRanges;
1379	BumpPtrAllocator &Allocator = LIS.getVNInfoAllocator();
1380	for (LiveInterval::SubRange &SR : LI.subranges()) {
1381	// Create new subranges in the split intervals and construct a mapping
1382	// for the VNInfos in the subrange.
1383	unsigned NumValNos = SR.valnos.size();
1384	VNIMapping.clear();
1385	VNIMapping.reserve(N: NumValNos);
1386	SubRanges.clear();
1387	SubRanges.resize(N: NumComponents-1, NV: nullptr);
1388	for (unsigned I = 0; I < NumValNos; ++I) {
1389	const VNInfo &VNI = *SR.valnos[I];
1390	unsigned ComponentNum;
1391	if (VNI.isUnused()) {
1392	ComponentNum = 0;
1393	} else {
1394	const VNInfo *MainRangeVNI = LI.getVNInfoAt(Idx: VNI.def);
1395	assert(MainRangeVNI != nullptr
1396	&& "SubRange def must have corresponding main range def");
1397	ComponentNum = getEqClass(VNI: MainRangeVNI);
1398	if (ComponentNum > 0 && SubRanges[ComponentNum-1] == nullptr) {
1399	SubRanges[ComponentNum-1]
1400	= LIV[ComponentNum-1]->createSubRange(Allocator, LaneMask: SR.LaneMask);
1401	}
1402	}
1403	VNIMapping.push_back(Elt: ComponentNum);
1404	}
1405	DistributeRange(LR&: SR, SplitLRs: SubRanges.data(), VNIClasses: VNIMapping);
1406	}
1407	LI.removeEmptySubRanges();
1408	}
1409
1410	// Distribute main liverange.
1411	DistributeRange(LR&: LI, SplitLRs: LIV, VNIClasses: EqClass);
1412	}
1413