1 //===- StackSlotColoring.cpp - Stack slot coloring pass. ------------------===//
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 stack slot coloring pass.
10 //
11 //===----------------------------------------------------------------------===//
12
13 #include "llvm/CodeGen/StackSlotColoring.h"
14 #include "llvm/ADT/BitVector.h"
15 #include "llvm/ADT/SmallVector.h"
16 #include "llvm/ADT/Statistic.h"
17 #include "llvm/CodeGen/LiveDebugVariables.h"
18 #include "llvm/CodeGen/LiveInterval.h"
19 #include "llvm/CodeGen/LiveIntervalUnion.h"
20 #include "llvm/CodeGen/LiveIntervals.h"
21 #include "llvm/CodeGen/LiveStacks.h"
22 #include "llvm/CodeGen/MachineBasicBlock.h"
23 #include "llvm/CodeGen/MachineBlockFrequencyInfo.h"
24 #include "llvm/CodeGen/MachineDominators.h"
25 #include "llvm/CodeGen/MachineFrameInfo.h"
26 #include "llvm/CodeGen/MachineFunction.h"
27 #include "llvm/CodeGen/MachineFunctionPass.h"
28 #include "llvm/CodeGen/MachineInstr.h"
29 #include "llvm/CodeGen/MachineMemOperand.h"
30 #include "llvm/CodeGen/MachineOperand.h"
31 #include "llvm/CodeGen/Passes.h"
32 #include "llvm/CodeGen/PseudoSourceValue.h"
33 #include "llvm/CodeGen/PseudoSourceValueManager.h"
34 #include "llvm/CodeGen/SlotIndexes.h"
35 #include "llvm/CodeGen/TargetInstrInfo.h"
36 #include "llvm/CodeGen/TargetSubtargetInfo.h"
37 #include "llvm/InitializePasses.h"
38 #include "llvm/Pass.h"
39 #include "llvm/Support/Casting.h"
40 #include "llvm/Support/CommandLine.h"
41 #include "llvm/Support/Debug.h"
42 #include "llvm/Support/raw_ostream.h"
43 #include <cassert>
44 #include <cstdint>
45 #include <iterator>
46 #include <vector>
47
48 using namespace llvm;
49
50 #define DEBUG_TYPE "stack-slot-coloring"
51
52 static cl::opt<bool>
53 DisableSharing("no-stack-slot-sharing",
54 cl::init(false), cl::Hidden,
55 cl::desc("Suppress slot sharing during stack coloring"));
56
57 static cl::opt<int> DCELimit("ssc-dce-limit", cl::init(-1), cl::Hidden);
58
59 STATISTIC(NumEliminated, "Number of stack slots eliminated due to coloring");
60 STATISTIC(NumDead, "Number of trivially dead stack accesses eliminated");
61
62 namespace {
63
64 class StackSlotColoring {
65 MachineFrameInfo *MFI = nullptr;
66 const TargetInstrInfo *TII = nullptr;
67 LiveStacks *LS = nullptr;
68 const MachineBlockFrequencyInfo *MBFI = nullptr;
69 SlotIndexes *Indexes = nullptr;
70
71 // SSIntervals - Spill slot intervals.
72 std::vector<LiveInterval *> SSIntervals;
73
74 // SSRefs - Keep a list of MachineMemOperands for each spill slot.
75 // MachineMemOperands can be shared between instructions, so we need
76 // to be careful that renames like [FI0, FI1] -> [FI1, FI2] do not
77 // become FI0 -> FI1 -> FI2.
78 SmallVector<SmallVector<MachineMemOperand *, 8>, 16> SSRefs;
79
80 // OrigAlignments - Alignments of stack objects before coloring.
81 SmallVector<Align, 16> OrigAlignments;
82
83 // OrigSizes - Sizes of stack objects before coloring.
84 SmallVector<unsigned, 16> OrigSizes;
85
86 // AllColors - If index is set, it's a spill slot, i.e. color.
87 // FIXME: This assumes PEI locate spill slot with smaller indices
88 // closest to stack pointer / frame pointer. Therefore, smaller
89 // index == better color. This is per stack ID.
90 SmallVector<BitVector, 2> AllColors;
91
92 // NextColor - Next "color" that's not yet used. This is per stack ID.
93 SmallVector<int, 2> NextColors = {-1};
94
95 // UsedColors - "Colors" that have been assigned. This is per stack ID
96 SmallVector<BitVector, 2> UsedColors;
97
98 // Join all intervals sharing one color into a single LiveIntervalUnion to
99 // speedup range overlap test.
100 class ColorAssignmentInfo {
101 // Single liverange (used to avoid creation of LiveIntervalUnion).
102 LiveInterval *SingleLI = nullptr;
103 // LiveIntervalUnion to perform overlap test.
104 LiveIntervalUnion *LIU = nullptr;
105 // LiveIntervalUnion has a parameter in its constructor so doing this
106 // dirty magic.
107 uint8_t LIUPad[sizeof(LiveIntervalUnion)];
108
109 public:
~ColorAssignmentInfo()110 ~ColorAssignmentInfo() {
111 if (LIU)
112 LIU->~LiveIntervalUnion(); // Dirty magic again.
113 }
114
115 // Return true if LiveInterval overlaps with any
116 // intervals that have already been assigned to this color.
overlaps(LiveInterval * LI) const117 bool overlaps(LiveInterval *LI) const {
118 if (LIU)
119 return LiveIntervalUnion::Query(*LI, *LIU).checkInterference();
120 return SingleLI ? SingleLI->overlaps(*LI) : false;
121 }
122
123 // Add new LiveInterval to this color.
add(LiveInterval * LI,LiveIntervalUnion::Allocator & Alloc)124 void add(LiveInterval *LI, LiveIntervalUnion::Allocator &Alloc) {
125 assert(!overlaps(LI));
126 if (LIU) {
127 LIU->unify(*LI, *LI);
128 } else if (SingleLI) {
129 LIU = new (LIUPad) LiveIntervalUnion(Alloc);
130 LIU->unify(*SingleLI, *SingleLI);
131 LIU->unify(*LI, *LI);
132 SingleLI = nullptr;
133 } else
134 SingleLI = LI;
135 }
136 };
137
138 LiveIntervalUnion::Allocator LIUAlloc;
139
140 // Assignments - Color to intervals mapping.
141 SmallVector<ColorAssignmentInfo, 16> Assignments;
142
143 public:
StackSlotColoring(MachineFunction & MF,LiveStacks * LS,MachineBlockFrequencyInfo * MBFI,SlotIndexes * Indexes)144 StackSlotColoring(MachineFunction &MF, LiveStacks *LS,
145 MachineBlockFrequencyInfo *MBFI, SlotIndexes *Indexes)
146 : MFI(&MF.getFrameInfo()), TII(MF.getSubtarget().getInstrInfo()), LS(LS),
147 MBFI(MBFI), Indexes(Indexes) {}
148 bool run(MachineFunction &MF);
149
150 private:
151 void InitializeSlots();
152 void ScanForSpillSlotRefs(MachineFunction &MF);
153 int ColorSlot(LiveInterval *li);
154 bool ColorSlots(MachineFunction &MF);
155 void RewriteInstruction(MachineInstr &MI, SmallVectorImpl<int> &SlotMapping,
156 MachineFunction &MF);
157 bool RemoveDeadStores(MachineBasicBlock *MBB);
158 };
159
160 class StackSlotColoringLegacy : public MachineFunctionPass {
161 public:
162 static char ID; // Pass identification
163
StackSlotColoringLegacy()164 StackSlotColoringLegacy() : MachineFunctionPass(ID) {
165 initializeStackSlotColoringLegacyPass(*PassRegistry::getPassRegistry());
166 }
167
getAnalysisUsage(AnalysisUsage & AU) const168 void getAnalysisUsage(AnalysisUsage &AU) const override {
169 AU.setPreservesCFG();
170 AU.addRequired<SlotIndexesWrapperPass>();
171 AU.addPreserved<SlotIndexesWrapperPass>();
172 AU.addRequired<LiveStacksWrapperLegacy>();
173 AU.addRequired<MachineBlockFrequencyInfoWrapperPass>();
174 AU.addPreserved<MachineBlockFrequencyInfoWrapperPass>();
175 AU.addPreservedID(MachineDominatorsID);
176
177 // In some Target's pipeline, register allocation (RA) might be
178 // split into multiple phases based on register class. So, this pass
179 // may be invoked multiple times requiring it to save these analyses to be
180 // used by RA later.
181 AU.addPreserved<LiveIntervalsWrapperPass>();
182 AU.addPreserved<LiveDebugVariablesWrapperLegacy>();
183
184 MachineFunctionPass::getAnalysisUsage(AU);
185 }
186
187 bool runOnMachineFunction(MachineFunction &MF) override;
188 };
189
190 } // end anonymous namespace
191
192 char StackSlotColoringLegacy::ID = 0;
193
194 char &llvm::StackSlotColoringID = StackSlotColoringLegacy::ID;
195
196 INITIALIZE_PASS_BEGIN(StackSlotColoringLegacy, DEBUG_TYPE,
197 "Stack Slot Coloring", false, false)
198 INITIALIZE_PASS_DEPENDENCY(SlotIndexesWrapperPass)
199 INITIALIZE_PASS_DEPENDENCY(LiveStacksWrapperLegacy)
200 INITIALIZE_PASS_DEPENDENCY(MachineLoopInfoWrapperPass)
201 INITIALIZE_PASS_END(StackSlotColoringLegacy, DEBUG_TYPE, "Stack Slot Coloring",
202 false, false)
203
204 namespace {
205
206 // IntervalSorter - Comparison predicate that sort live intervals by
207 // their weight.
208 struct IntervalSorter {
operator ()__anonb7b65c290211::IntervalSorter209 bool operator()(LiveInterval* LHS, LiveInterval* RHS) const {
210 return LHS->weight() > RHS->weight();
211 }
212 };
213
214 } // end anonymous namespace
215
216 /// ScanForSpillSlotRefs - Scan all the machine instructions for spill slot
217 /// references and update spill slot weights.
ScanForSpillSlotRefs(MachineFunction & MF)218 void StackSlotColoring::ScanForSpillSlotRefs(MachineFunction &MF) {
219 SSRefs.resize(MFI->getObjectIndexEnd());
220
221 // FIXME: Need the equivalent of MachineRegisterInfo for frameindex operands.
222 for (MachineBasicBlock &MBB : MF) {
223 for (MachineInstr &MI : MBB) {
224 for (const MachineOperand &MO : MI.operands()) {
225 if (!MO.isFI())
226 continue;
227 int FI = MO.getIndex();
228 if (FI < 0)
229 continue;
230 if (!LS->hasInterval(FI))
231 continue;
232 LiveInterval &li = LS->getInterval(FI);
233 if (!MI.isDebugInstr())
234 li.incrementWeight(
235 LiveIntervals::getSpillWeight(false, true, MBFI, MI));
236 }
237 for (MachineMemOperand *MMO : MI.memoperands()) {
238 if (const FixedStackPseudoSourceValue *FSV =
239 dyn_cast_or_null<FixedStackPseudoSourceValue>(
240 MMO->getPseudoValue())) {
241 int FI = FSV->getFrameIndex();
242 if (FI >= 0)
243 SSRefs[FI].push_back(MMO);
244 }
245 }
246 }
247 }
248 }
249
250 /// InitializeSlots - Process all spill stack slot liveintervals and add them
251 /// to a sorted (by weight) list.
InitializeSlots()252 void StackSlotColoring::InitializeSlots() {
253 int LastFI = MFI->getObjectIndexEnd();
254
255 // There is always at least one stack ID.
256 AllColors.resize(1);
257 UsedColors.resize(1);
258
259 OrigAlignments.resize(LastFI);
260 OrigSizes.resize(LastFI);
261 AllColors[0].resize(LastFI);
262 UsedColors[0].resize(LastFI);
263 Assignments.resize(LastFI);
264
265 using Pair = std::iterator_traits<LiveStacks::iterator>::value_type;
266
267 SmallVector<Pair *, 16> Intervals;
268
269 Intervals.reserve(LS->getNumIntervals());
270 for (auto &I : *LS)
271 Intervals.push_back(&I);
272 llvm::sort(Intervals,
273 [](Pair *LHS, Pair *RHS) { return LHS->first < RHS->first; });
274
275 // Gather all spill slots into a list.
276 LLVM_DEBUG(dbgs() << "Spill slot intervals:\n");
277 for (auto *I : Intervals) {
278 LiveInterval &li = I->second;
279 LLVM_DEBUG(li.dump());
280 int FI = li.reg().stackSlotIndex();
281 if (MFI->isDeadObjectIndex(FI))
282 continue;
283
284 SSIntervals.push_back(&li);
285 OrigAlignments[FI] = MFI->getObjectAlign(FI);
286 OrigSizes[FI] = MFI->getObjectSize(FI);
287
288 auto StackID = MFI->getStackID(FI);
289 if (StackID != 0) {
290 if (StackID >= AllColors.size()) {
291 AllColors.resize(StackID + 1);
292 UsedColors.resize(StackID + 1);
293 }
294 AllColors[StackID].resize(LastFI);
295 UsedColors[StackID].resize(LastFI);
296 }
297
298 AllColors[StackID].set(FI);
299 }
300 LLVM_DEBUG(dbgs() << '\n');
301
302 // Sort them by weight.
303 llvm::stable_sort(SSIntervals, IntervalSorter());
304
305 NextColors.resize(AllColors.size());
306
307 // Get first "color".
308 for (unsigned I = 0, E = AllColors.size(); I != E; ++I)
309 NextColors[I] = AllColors[I].find_first();
310 }
311
312 /// ColorSlot - Assign a "color" (stack slot) to the specified stack slot.
ColorSlot(LiveInterval * li)313 int StackSlotColoring::ColorSlot(LiveInterval *li) {
314 int Color = -1;
315 bool Share = false;
316 int FI = li->reg().stackSlotIndex();
317 uint8_t StackID = MFI->getStackID(FI);
318
319 if (!DisableSharing) {
320
321 // Check if it's possible to reuse any of the used colors.
322 Color = UsedColors[StackID].find_first();
323 while (Color != -1) {
324 if (!Assignments[Color].overlaps(li)) {
325 Share = true;
326 ++NumEliminated;
327 break;
328 }
329 Color = UsedColors[StackID].find_next(Color);
330 }
331 }
332
333 if (Color != -1 && MFI->getStackID(Color) != MFI->getStackID(FI)) {
334 LLVM_DEBUG(dbgs() << "cannot share FIs with different stack IDs\n");
335 Share = false;
336 }
337
338 // Assign it to the first available color (assumed to be the best) if it's
339 // not possible to share a used color with other objects.
340 if (!Share) {
341 assert(NextColors[StackID] != -1 && "No more spill slots?");
342 Color = NextColors[StackID];
343 UsedColors[StackID].set(Color);
344 NextColors[StackID] = AllColors[StackID].find_next(NextColors[StackID]);
345 }
346
347 assert(MFI->getStackID(Color) == MFI->getStackID(FI));
348
349 // Record the assignment.
350 Assignments[Color].add(li, LIUAlloc);
351 LLVM_DEBUG(dbgs() << "Assigning fi#" << FI << " to fi#" << Color << "\n");
352
353 // Change size and alignment of the allocated slot. If there are multiple
354 // objects sharing the same slot, then make sure the size and alignment
355 // are large enough for all.
356 Align Alignment = OrigAlignments[FI];
357 if (!Share || Alignment > MFI->getObjectAlign(Color))
358 MFI->setObjectAlignment(Color, Alignment);
359 int64_t Size = OrigSizes[FI];
360 if (!Share || Size > MFI->getObjectSize(Color))
361 MFI->setObjectSize(Color, Size);
362 return Color;
363 }
364
365 /// Colorslots - Color all spill stack slots and rewrite all frameindex machine
366 /// operands in the function.
ColorSlots(MachineFunction & MF)367 bool StackSlotColoring::ColorSlots(MachineFunction &MF) {
368 unsigned NumObjs = MFI->getObjectIndexEnd();
369 SmallVector<int, 16> SlotMapping(NumObjs, -1);
370 SmallVector<float, 16> SlotWeights(NumObjs, 0.0);
371 SmallVector<SmallVector<int, 4>, 16> RevMap(NumObjs);
372 BitVector UsedColors(NumObjs);
373
374 LLVM_DEBUG(dbgs() << "Color spill slot intervals:\n");
375 bool Changed = false;
376 for (LiveInterval *li : SSIntervals) {
377 int SS = li->reg().stackSlotIndex();
378 int NewSS = ColorSlot(li);
379 assert(NewSS >= 0 && "Stack coloring failed?");
380 SlotMapping[SS] = NewSS;
381 RevMap[NewSS].push_back(SS);
382 SlotWeights[NewSS] += li->weight();
383 UsedColors.set(NewSS);
384 Changed |= (SS != NewSS);
385 }
386
387 LLVM_DEBUG(dbgs() << "\nSpill slots after coloring:\n");
388 for (LiveInterval *li : SSIntervals) {
389 int SS = li->reg().stackSlotIndex();
390 li->setWeight(SlotWeights[SS]);
391 }
392 // Sort them by new weight.
393 llvm::stable_sort(SSIntervals, IntervalSorter());
394
395 #ifndef NDEBUG
396 for (LiveInterval *li : SSIntervals)
397 LLVM_DEBUG(li->dump());
398 LLVM_DEBUG(dbgs() << '\n');
399 #endif
400
401 if (!Changed)
402 return false;
403
404 // Rewrite all MachineMemOperands.
405 for (unsigned SS = 0, SE = SSRefs.size(); SS != SE; ++SS) {
406 int NewFI = SlotMapping[SS];
407 if (NewFI == -1 || (NewFI == (int)SS))
408 continue;
409
410 const PseudoSourceValue *NewSV = MF.getPSVManager().getFixedStack(NewFI);
411 SmallVectorImpl<MachineMemOperand *> &RefMMOs = SSRefs[SS];
412 for (MachineMemOperand *MMO : RefMMOs)
413 MMO->setValue(NewSV);
414 }
415
416 // Rewrite all MO_FrameIndex operands. Look for dead stores.
417 for (MachineBasicBlock &MBB : MF) {
418 for (MachineInstr &MI : MBB)
419 RewriteInstruction(MI, SlotMapping, MF);
420 RemoveDeadStores(&MBB);
421 }
422
423 // Delete unused stack slots.
424 for (int StackID = 0, E = AllColors.size(); StackID != E; ++StackID) {
425 int NextColor = NextColors[StackID];
426 while (NextColor != -1) {
427 LLVM_DEBUG(dbgs() << "Removing unused stack object fi#" << NextColor << "\n");
428 MFI->RemoveStackObject(NextColor);
429 NextColor = AllColors[StackID].find_next(NextColor);
430 }
431 }
432
433 return true;
434 }
435
436 /// RewriteInstruction - Rewrite specified instruction by replacing references
437 /// to old frame index with new one.
RewriteInstruction(MachineInstr & MI,SmallVectorImpl<int> & SlotMapping,MachineFunction & MF)438 void StackSlotColoring::RewriteInstruction(MachineInstr &MI,
439 SmallVectorImpl<int> &SlotMapping,
440 MachineFunction &MF) {
441 // Update the operands.
442 for (MachineOperand &MO : MI.operands()) {
443 if (!MO.isFI())
444 continue;
445 int OldFI = MO.getIndex();
446 if (OldFI < 0)
447 continue;
448 int NewFI = SlotMapping[OldFI];
449 if (NewFI == -1 || NewFI == OldFI)
450 continue;
451
452 assert(MFI->getStackID(OldFI) == MFI->getStackID(NewFI));
453 MO.setIndex(NewFI);
454 }
455
456 // The MachineMemOperands have already been updated.
457 }
458
459 /// RemoveDeadStores - Scan through a basic block and look for loads followed
460 /// by stores. If they're both using the same stack slot, then the store is
461 /// definitely dead. This could obviously be much more aggressive (consider
462 /// pairs with instructions between them), but such extensions might have a
463 /// considerable compile time impact.
RemoveDeadStores(MachineBasicBlock * MBB)464 bool StackSlotColoring::RemoveDeadStores(MachineBasicBlock* MBB) {
465 // FIXME: This could be much more aggressive, but we need to investigate
466 // the compile time impact of doing so.
467 bool changed = false;
468
469 SmallVector<MachineInstr*, 4> toErase;
470
471 for (MachineBasicBlock::iterator I = MBB->begin(), E = MBB->end();
472 I != E; ++I) {
473 if (DCELimit != -1 && (int)NumDead >= DCELimit)
474 break;
475 int FirstSS, SecondSS;
476 if (TII->isStackSlotCopy(*I, FirstSS, SecondSS) && FirstSS == SecondSS &&
477 FirstSS != -1) {
478 ++NumDead;
479 changed = true;
480 toErase.push_back(&*I);
481 continue;
482 }
483
484 MachineBasicBlock::iterator NextMI = std::next(I);
485 MachineBasicBlock::iterator ProbableLoadMI = I;
486
487 Register LoadReg;
488 Register StoreReg;
489 TypeSize LoadSize = TypeSize::getZero();
490 TypeSize StoreSize = TypeSize::getZero();
491 if (!(LoadReg = TII->isLoadFromStackSlot(*I, FirstSS, LoadSize)))
492 continue;
493 // Skip the ...pseudo debugging... instructions between a load and store.
494 while ((NextMI != E) && NextMI->isDebugInstr()) {
495 ++NextMI;
496 ++I;
497 }
498 if (NextMI == E) continue;
499 if (!(StoreReg = TII->isStoreToStackSlot(*NextMI, SecondSS, StoreSize)))
500 continue;
501 if (FirstSS != SecondSS || LoadReg != StoreReg || FirstSS == -1 ||
502 LoadSize != StoreSize || !MFI->isSpillSlotObjectIndex(FirstSS))
503 continue;
504
505 ++NumDead;
506 changed = true;
507
508 if (NextMI->findRegisterUseOperandIdx(LoadReg, /*TRI=*/nullptr, true) !=
509 -1) {
510 ++NumDead;
511 toErase.push_back(&*ProbableLoadMI);
512 }
513
514 toErase.push_back(&*NextMI);
515 ++I;
516 }
517
518 for (MachineInstr *MI : toErase) {
519 if (Indexes)
520 Indexes->removeMachineInstrFromMaps(*MI);
521 MI->eraseFromParent();
522 }
523
524 return changed;
525 }
526
run(MachineFunction & MF)527 bool StackSlotColoring::run(MachineFunction &MF) {
528 LLVM_DEBUG({
529 dbgs() << "********** Stack Slot Coloring **********\n"
530 << "********** Function: " << MF.getName() << '\n';
531 });
532
533 bool Changed = false;
534
535 unsigned NumSlots = LS->getNumIntervals();
536 if (NumSlots == 0)
537 // Nothing to do!
538 return false;
539
540 // If there are calls to setjmp or sigsetjmp, don't perform stack slot
541 // coloring. The stack could be modified before the longjmp is executed,
542 // resulting in the wrong value being used afterwards.
543 if (MF.exposesReturnsTwice())
544 return false;
545
546 // Gather spill slot references
547 ScanForSpillSlotRefs(MF);
548 InitializeSlots();
549 Changed = ColorSlots(MF);
550
551 for (int &Next : NextColors)
552 Next = -1;
553
554 SSIntervals.clear();
555 for (auto &RefMMOs : SSRefs)
556 RefMMOs.clear();
557 SSRefs.clear();
558 OrigAlignments.clear();
559 OrigSizes.clear();
560 AllColors.clear();
561 UsedColors.clear();
562 Assignments.clear();
563
564 return Changed;
565 }
566
runOnMachineFunction(MachineFunction & MF)567 bool StackSlotColoringLegacy::runOnMachineFunction(MachineFunction &MF) {
568 if (skipFunction(MF.getFunction()))
569 return false;
570
571 LiveStacks *LS = &getAnalysis<LiveStacksWrapperLegacy>().getLS();
572 MachineBlockFrequencyInfo *MBFI =
573 &getAnalysis<MachineBlockFrequencyInfoWrapperPass>().getMBFI();
574 SlotIndexes *Indexes = &getAnalysis<SlotIndexesWrapperPass>().getSI();
575 StackSlotColoring Impl(MF, LS, MBFI, Indexes);
576 return Impl.run(MF);
577 }
578
579 PreservedAnalyses
run(MachineFunction & MF,MachineFunctionAnalysisManager & MFAM)580 StackSlotColoringPass::run(MachineFunction &MF,
581 MachineFunctionAnalysisManager &MFAM) {
582 LiveStacks *LS = &MFAM.getResult<LiveStacksAnalysis>(MF);
583 MachineBlockFrequencyInfo *MBFI =
584 &MFAM.getResult<MachineBlockFrequencyAnalysis>(MF);
585 SlotIndexes *Indexes = &MFAM.getResult<SlotIndexesAnalysis>(MF);
586 StackSlotColoring Impl(MF, LS, MBFI, Indexes);
587 bool Changed = Impl.run(MF);
588 if (!Changed)
589 return PreservedAnalyses::all();
590
591 auto PA = getMachineFunctionPassPreservedAnalyses();
592 PA.preserveSet<CFGAnalyses>();
593 PA.preserve<SlotIndexesAnalysis>();
594 PA.preserve<MachineBlockFrequencyAnalysis>();
595 PA.preserve<MachineDominatorTreeAnalysis>();
596 PA.preserve<LiveIntervalsAnalysis>();
597 PA.preserve<LiveDebugVariablesAnalysis>();
598 return PA;
599 }
600