1 //===-- LiveIntervalAnalysis.cpp - Live Interval Analysis -----------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file implements the LiveInterval analysis pass which is used
11 // by the Linear Scan Register allocator. This pass linearizes the
12 // basic blocks of the function in DFS order and uses the
13 // LiveVariables pass to conservatively compute live intervals for
14 // each virtual and physical register.
15 //
16 //===----------------------------------------------------------------------===//
18 #include "llvm/CodeGen/LiveIntervalAnalysis.h"
19 #include "LiveRangeCalc.h"
20 #include "llvm/ADT/DenseSet.h"
21 #include "llvm/ADT/STLExtras.h"
22 #include "llvm/Analysis/AliasAnalysis.h"
23 #include "llvm/CodeGen/LiveVariables.h"
24 #include "llvm/CodeGen/MachineBlockFrequencyInfo.h"
25 #include "llvm/CodeGen/MachineDominators.h"
26 #include "llvm/CodeGen/MachineInstr.h"
27 #include "llvm/CodeGen/MachineRegisterInfo.h"
28 #include "llvm/CodeGen/Passes.h"
29 #include "llvm/CodeGen/VirtRegMap.h"
30 #include "llvm/IR/Value.h"
31 #include "llvm/Support/BlockFrequency.h"
32 #include "llvm/Support/CommandLine.h"
33 #include "llvm/Support/Debug.h"
34 #include "llvm/Support/ErrorHandling.h"
35 #include "llvm/Support/Format.h"
36 #include "llvm/Support/raw_ostream.h"
37 #include "llvm/Target/TargetInstrInfo.h"
38 #include "llvm/Target/TargetRegisterInfo.h"
39 #include "llvm/Target/TargetSubtargetInfo.h"
40 #include <algorithm>
41 #include <cmath>
42 #include <limits>
43 using namespace llvm;
45 #define DEBUG_TYPE "regalloc"
47 char LiveIntervals::ID = 0;
48 char &llvm::LiveIntervalsID = LiveIntervals::ID;
49 INITIALIZE_PASS_BEGIN(LiveIntervals, "liveintervals",
50 "Live Interval Analysis", false, false)
51 INITIALIZE_AG_DEPENDENCY(AliasAnalysis)
52 INITIALIZE_PASS_DEPENDENCY(LiveVariables)
53 INITIALIZE_PASS_DEPENDENCY(MachineDominatorTree)
54 INITIALIZE_PASS_DEPENDENCY(SlotIndexes)
55 INITIALIZE_PASS_END(LiveIntervals, "liveintervals",
56 "Live Interval Analysis", false, false)
58 #ifndef NDEBUG
59 static cl::opt<bool> EnablePrecomputePhysRegs(
60 "precompute-phys-liveness", cl::Hidden,
61 cl::desc("Eagerly compute live intervals for all physreg units."));
62 #else
63 static bool EnablePrecomputePhysRegs = false;
64 #endif // NDEBUG
66 static cl::opt<bool> EnableSubRegLiveness(
67 "enable-subreg-liveness", cl::Hidden, cl::init(true),
68 cl::desc("Enable subregister liveness tracking."));
70 void LiveIntervals::getAnalysisUsage(AnalysisUsage &AU) const {
71 AU.setPreservesCFG();
72 AU.addRequired<AliasAnalysis>();
73 AU.addPreserved<AliasAnalysis>();
74 // LiveVariables isn't really required by this analysis, it is only required
75 // here to make sure it is live during TwoAddressInstructionPass and
76 // PHIElimination. This is temporary.
77 AU.addRequired<LiveVariables>();
78 AU.addPreserved<LiveVariables>();
79 AU.addPreservedID(MachineLoopInfoID);
80 AU.addRequiredTransitiveID(MachineDominatorsID);
81 AU.addPreservedID(MachineDominatorsID);
82 AU.addPreserved<SlotIndexes>();
83 AU.addRequiredTransitive<SlotIndexes>();
84 MachineFunctionPass::getAnalysisUsage(AU);
85 }
87 LiveIntervals::LiveIntervals() : MachineFunctionPass(ID),
88 DomTree(nullptr), LRCalc(nullptr) {
89 initializeLiveIntervalsPass(*PassRegistry::getPassRegistry());
90 }
92 LiveIntervals::~LiveIntervals() {
93 delete LRCalc;
94 }
96 void LiveIntervals::releaseMemory() {
97 // Free the live intervals themselves.
98 for (unsigned i = 0, e = VirtRegIntervals.size(); i != e; ++i)
99 delete VirtRegIntervals[TargetRegisterInfo::index2VirtReg(i)];
100 VirtRegIntervals.clear();
101 RegMaskSlots.clear();
102 RegMaskBits.clear();
103 RegMaskBlocks.clear();
105 for (unsigned i = 0, e = RegUnitRanges.size(); i != e; ++i)
106 delete RegUnitRanges[i];
107 RegUnitRanges.clear();
109 // Release VNInfo memory regions, VNInfo objects don't need to be dtor'd.
110 VNInfoAllocator.Reset();
111 }
113 /// runOnMachineFunction - calculates LiveIntervals
114 ///
115 bool LiveIntervals::runOnMachineFunction(MachineFunction &fn) {
116 MF = &fn;
117 MRI = &MF->getRegInfo();
118 TRI = MF->getSubtarget().getRegisterInfo();
119 TII = MF->getSubtarget().getInstrInfo();
120 AA = &getAnalysis<AliasAnalysis>();
121 Indexes = &getAnalysis<SlotIndexes>();
122 DomTree = &getAnalysis<MachineDominatorTree>();
124 if (EnableSubRegLiveness && MF->getSubtarget().enableSubRegLiveness())
125 MRI->enableSubRegLiveness(true);
127 if (!LRCalc)
128 LRCalc = new LiveRangeCalc();
130 // Allocate space for all virtual registers.
131 VirtRegIntervals.resize(MRI->getNumVirtRegs());
133 computeVirtRegs();
134 computeRegMasks();
135 computeLiveInRegUnits();
137 if (EnablePrecomputePhysRegs) {
138 // For stress testing, precompute live ranges of all physical register
139 // units, including reserved registers.
140 for (unsigned i = 0, e = TRI->getNumRegUnits(); i != e; ++i)
141 getRegUnit(i);
142 }
143 DEBUG(dump());
144 return true;
145 }
147 /// print - Implement the dump method.
148 void LiveIntervals::print(raw_ostream &OS, const Module* ) const {
149 OS << "********** INTERVALS **********\n";
151 // Dump the regunits.
152 for (unsigned i = 0, e = RegUnitRanges.size(); i != e; ++i)
153 if (LiveRange *LR = RegUnitRanges[i])
154 OS << PrintRegUnit(i, TRI) << ' ' << *LR << '\n';
156 // Dump the virtregs.
157 for (unsigned i = 0, e = MRI->getNumVirtRegs(); i != e; ++i) {
158 unsigned Reg = TargetRegisterInfo::index2VirtReg(i);
159 if (hasInterval(Reg))
160 OS << getInterval(Reg) << '\n';
161 }
163 OS << "RegMasks:";
164 for (unsigned i = 0, e = RegMaskSlots.size(); i != e; ++i)
165 OS << ' ' << RegMaskSlots[i];
166 OS << '\n';
168 printInstrs(OS);
169 }
171 void LiveIntervals::printInstrs(raw_ostream &OS) const {
172 OS << "********** MACHINEINSTRS **********\n";
173 MF->print(OS, Indexes);
174 }
176 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
177 void LiveIntervals::dumpInstrs() const {
178 printInstrs(dbgs());
179 }
180 #endif
182 LiveInterval* LiveIntervals::createInterval(unsigned reg) {
183 float Weight = TargetRegisterInfo::isPhysicalRegister(reg) ?
184 llvm::huge_valf : 0.0F;
185 return new LiveInterval(reg, Weight);
186 }
189 /// computeVirtRegInterval - Compute the live interval of a virtual register,
190 /// based on defs and uses.
191 void LiveIntervals::computeVirtRegInterval(LiveInterval &LI) {
192 assert(LRCalc && "LRCalc not initialized.");
193 assert(LI.empty() && "Should only compute empty intervals.");
194 LRCalc->reset(MF, getSlotIndexes(), DomTree, &getVNInfoAllocator());
195 LRCalc->calculate(LI);
196 computeDeadValues(LI, nullptr);
197 }
199 void LiveIntervals::computeVirtRegs() {
200 for (unsigned i = 0, e = MRI->getNumVirtRegs(); i != e; ++i) {
201 unsigned Reg = TargetRegisterInfo::index2VirtReg(i);
202 if (MRI->reg_nodbg_empty(Reg))
203 continue;
204 createAndComputeVirtRegInterval(Reg);
205 }
206 }
208 void LiveIntervals::computeRegMasks() {
209 RegMaskBlocks.resize(MF->getNumBlockIDs());
211 // Find all instructions with regmask operands.
212 for (MachineFunction::iterator MBBI = MF->begin(), E = MF->end();
213 MBBI != E; ++MBBI) {
214 MachineBasicBlock *MBB = MBBI;
215 std::pair<unsigned, unsigned> &RMB = RegMaskBlocks[MBB->getNumber()];
216 RMB.first = RegMaskSlots.size();
217 for (MachineBasicBlock::iterator MI = MBB->begin(), ME = MBB->end();
218 MI != ME; ++MI)
219 for (MIOperands MO(MI); MO.isValid(); ++MO) {
220 if (!MO->isRegMask())
221 continue;
222 RegMaskSlots.push_back(Indexes->getInstructionIndex(MI).getRegSlot());
223 RegMaskBits.push_back(MO->getRegMask());
224 }
225 // Compute the number of register mask instructions in this block.
226 RMB.second = RegMaskSlots.size() - RMB.first;
227 }
228 }
230 //===----------------------------------------------------------------------===//
231 // Register Unit Liveness
232 //===----------------------------------------------------------------------===//
233 //
234 // Fixed interference typically comes from ABI boundaries: Function arguments
235 // and return values are passed in fixed registers, and so are exception
236 // pointers entering landing pads. Certain instructions require values to be
237 // present in specific registers. That is also represented through fixed
238 // interference.
239 //
241 /// computeRegUnitInterval - Compute the live range of a register unit, based
242 /// on the uses and defs of aliasing registers. The range should be empty,
243 /// or contain only dead phi-defs from ABI blocks.
244 void LiveIntervals::computeRegUnitRange(LiveRange &LR, unsigned Unit) {
245 assert(LRCalc && "LRCalc not initialized.");
246 LRCalc->reset(MF, getSlotIndexes(), DomTree, &getVNInfoAllocator());
248 // The physregs aliasing Unit are the roots and their super-registers.
249 // Create all values as dead defs before extending to uses. Note that roots
250 // may share super-registers. That's OK because createDeadDefs() is
251 // idempotent. It is very rare for a register unit to have multiple roots, so
252 // uniquing super-registers is probably not worthwhile.
253 for (MCRegUnitRootIterator Roots(Unit, TRI); Roots.isValid(); ++Roots) {
254 for (MCSuperRegIterator Supers(*Roots, TRI, /*IncludeSelf=*/true);
255 Supers.isValid(); ++Supers) {
256 if (!MRI->reg_empty(*Supers))
257 LRCalc->createDeadDefs(LR, *Supers);
258 }
259 }
261 // Now extend LR to reach all uses.
262 // Ignore uses of reserved registers. We only track defs of those.
263 for (MCRegUnitRootIterator Roots(Unit, TRI); Roots.isValid(); ++Roots) {
264 for (MCSuperRegIterator Supers(*Roots, TRI, /*IncludeSelf=*/true);
265 Supers.isValid(); ++Supers) {
266 unsigned Reg = *Supers;
267 if (!MRI->isReserved(Reg) && !MRI->reg_empty(Reg))
268 LRCalc->extendToUses(LR, Reg);
269 }
270 }
271 }
274 /// computeLiveInRegUnits - Precompute the live ranges of any register units
275 /// that are live-in to an ABI block somewhere. Register values can appear
276 /// without a corresponding def when entering the entry block or a landing pad.
277 ///
278 void LiveIntervals::computeLiveInRegUnits() {
279 RegUnitRanges.resize(TRI->getNumRegUnits());
280 DEBUG(dbgs() << "Computing live-in reg-units in ABI blocks.\n");
282 // Keep track of the live range sets allocated.
283 SmallVector<unsigned, 8> NewRanges;
285 // Check all basic blocks for live-ins.
286 for (MachineFunction::const_iterator MFI = MF->begin(), MFE = MF->end();
287 MFI != MFE; ++MFI) {
288 const MachineBasicBlock *MBB = MFI;
290 // We only care about ABI blocks: Entry + landing pads.
291 if ((MFI != MF->begin() && !MBB->isLandingPad()) || MBB->livein_empty())
292 continue;
294 // Create phi-defs at Begin for all live-in registers.
295 SlotIndex Begin = Indexes->getMBBStartIdx(MBB);
296 DEBUG(dbgs() << Begin << "\tBB#" << MBB->getNumber());
297 for (MachineBasicBlock::livein_iterator LII = MBB->livein_begin(),
298 LIE = MBB->livein_end(); LII != LIE; ++LII) {
299 for (MCRegUnitIterator Units(*LII, TRI); Units.isValid(); ++Units) {
300 unsigned Unit = *Units;
301 LiveRange *LR = RegUnitRanges[Unit];
302 if (!LR) {
303 LR = RegUnitRanges[Unit] = new LiveRange();
304 NewRanges.push_back(Unit);
305 }
306 VNInfo *VNI = LR->createDeadDef(Begin, getVNInfoAllocator());
307 (void)VNI;
308 DEBUG(dbgs() << ' ' << PrintRegUnit(Unit, TRI) << '#' << VNI->id);
309 }
310 }
311 DEBUG(dbgs() << '\n');
312 }
313 DEBUG(dbgs() << "Created " << NewRanges.size() << " new intervals.\n");
315 // Compute the 'normal' part of the ranges.
316 for (unsigned i = 0, e = NewRanges.size(); i != e; ++i) {
317 unsigned Unit = NewRanges[i];
318 computeRegUnitRange(*RegUnitRanges[Unit], Unit);
319 }
320 }
323 static void createSegmentsForValues(LiveRange &LR,
324 iterator_range<LiveInterval::vni_iterator> VNIs) {
325 for (auto VNI : VNIs) {
326 if (VNI->isUnused())
327 continue;
328 SlotIndex Def = VNI->def;
329 LR.addSegment(LiveRange::Segment(Def, Def.getDeadSlot(), VNI));
330 }
331 }
333 typedef SmallVector<std::pair<SlotIndex, VNInfo*>, 16> ShrinkToUsesWorkList;
335 static void extendSegmentsToUses(LiveRange &LR, const SlotIndexes &Indexes,
336 ShrinkToUsesWorkList &WorkList,
337 const LiveRange &OldRange) {
338 // Keep track of the PHIs that are in use.
339 SmallPtrSet<VNInfo*, 8> UsedPHIs;
340 // Blocks that have already been added to WorkList as live-out.
341 SmallPtrSet<MachineBasicBlock*, 16> LiveOut;
343 // Extend intervals to reach all uses in WorkList.
344 while (!WorkList.empty()) {
345 SlotIndex Idx = WorkList.back().first;
346 VNInfo *VNI = WorkList.back().second;
347 WorkList.pop_back();
348 const MachineBasicBlock *MBB = Indexes.getMBBFromIndex(Idx.getPrevSlot());
349 SlotIndex BlockStart = Indexes.getMBBStartIdx(MBB);
351 // Extend the live range for VNI to be live at Idx.
352 if (VNInfo *ExtVNI = LR.extendInBlock(BlockStart, Idx)) {
353 assert(ExtVNI == VNI && "Unexpected existing value number");
354 (void)ExtVNI;
355 // Is this a PHIDef we haven't seen before?
356 if (!VNI->isPHIDef() || VNI->def != BlockStart ||
357 !UsedPHIs.insert(VNI).second)
358 continue;
359 // The PHI is live, make sure the predecessors are live-out.
360 for (auto &Pred : MBB->predecessors()) {
361 if (!LiveOut.insert(Pred).second)
362 continue;
363 SlotIndex Stop = Indexes.getMBBEndIdx(Pred);
364 // A predecessor is not required to have a live-out value for a PHI.
365 if (VNInfo *PVNI = OldRange.getVNInfoBefore(Stop))
366 WorkList.push_back(std::make_pair(Stop, PVNI));
367 }
368 continue;
369 }
371 // VNI is live-in to MBB.
372 DEBUG(dbgs() << " live-in at " << BlockStart << '\n');
373 LR.addSegment(LiveRange::Segment(BlockStart, Idx, VNI));
375 // Make sure VNI is live-out from the predecessors.
376 for (auto &Pred : MBB->predecessors()) {
377 if (!LiveOut.insert(Pred).second)
378 continue;
379 SlotIndex Stop = Indexes.getMBBEndIdx(Pred);
380 assert(OldRange.getVNInfoBefore(Stop) == VNI &&
381 "Wrong value out of predecessor");
382 WorkList.push_back(std::make_pair(Stop, VNI));
383 }
384 }
385 }
387 /// shrinkToUses - After removing some uses of a register, shrink its live
388 /// range to just the remaining uses. This method does not compute reaching
389 /// defs for new uses, and it doesn't remove dead defs.
390 bool LiveIntervals::shrinkToUses(LiveInterval *li,
391 SmallVectorImpl<MachineInstr*> *dead) {
392 DEBUG(dbgs() << "Shrink: " << *li << '\n');
393 assert(TargetRegisterInfo::isVirtualRegister(li->reg)
394 && "Can only shrink virtual registers");
396 // Shrink subregister live ranges.
397 for (LiveInterval::SubRange &S : li->subranges()) {
398 shrinkToUses(S, li->reg);
399 }
401 // Find all the values used, including PHI kills.
402 ShrinkToUsesWorkList WorkList;
404 // Visit all instructions reading li->reg.
405 for (MachineRegisterInfo::reg_instr_iterator
406 I = MRI->reg_instr_begin(li->reg), E = MRI->reg_instr_end();
407 I != E; ) {
408 MachineInstr *UseMI = &*(I++);
409 if (UseMI->isDebugValue() || !UseMI->readsVirtualRegister(li->reg))
410 continue;
411 SlotIndex Idx = getInstructionIndex(UseMI).getRegSlot();
412 LiveQueryResult LRQ = li->Query(Idx);
413 VNInfo *VNI = LRQ.valueIn();
414 if (!VNI) {
415 // This shouldn't happen: readsVirtualRegister returns true, but there is
416 // no live value. It is likely caused by a target getting <undef> flags
417 // wrong.
418 DEBUG(dbgs() << Idx << '\t' << *UseMI
419 << "Warning: Instr claims to read non-existent value in "
420 << *li << '\n');
421 continue;
422 }
423 // Special case: An early-clobber tied operand reads and writes the
424 // register one slot early.
425 if (VNInfo *DefVNI = LRQ.valueDefined())
426 Idx = DefVNI->def;
428 WorkList.push_back(std::make_pair(Idx, VNI));
429 }
431 // Create new live ranges with only minimal live segments per def.
432 LiveRange NewLR;
433 createSegmentsForValues(NewLR, make_range(li->vni_begin(), li->vni_end()));
434 extendSegmentsToUses(NewLR, *Indexes, WorkList, *li);
436 // Move the trimmed segments back.
437 li->segments.swap(NewLR.segments);
439 // Handle dead values.
440 bool CanSeparate = computeDeadValues(*li, dead);
441 DEBUG(dbgs() << "Shrunk: " << *li << '\n');
442 return CanSeparate;
443 }
445 bool LiveIntervals::computeDeadValues(LiveInterval &LI,
446 SmallVectorImpl<MachineInstr*> *dead) {
447 bool PHIRemoved = false;
448 for (auto VNI : LI.valnos) {
449 if (VNI->isUnused())
450 continue;
451 SlotIndex Def = VNI->def;
452 LiveRange::iterator I = LI.FindSegmentContaining(Def);
453 assert(I != LI.end() && "Missing segment for VNI");
455 // Is the register live before? Otherwise we may have to add a read-undef
456 // flag for subregister defs.
457 if (MRI->tracksSubRegLiveness()) {
458 if ((I == LI.begin() || std::prev(I)->end < Def) && !VNI->isPHIDef()) {
459 MachineInstr *MI = getInstructionFromIndex(Def);
460 MI->addRegisterDefReadUndef(LI.reg);
461 }
462 }
464 if (I->end != Def.getDeadSlot())
465 continue;
466 if (VNI->isPHIDef()) {
467 // This is a dead PHI. Remove it.
468 VNI->markUnused();
469 LI.removeSegment(I);
470 DEBUG(dbgs() << "Dead PHI at " << Def << " may separate interval\n");
471 PHIRemoved = true;
472 } else {
473 // This is a dead def. Make sure the instruction knows.
474 MachineInstr *MI = getInstructionFromIndex(Def);
475 assert(MI && "No instruction defining live value");
476 MI->addRegisterDead(LI.reg, TRI);
477 if (dead && MI->allDefsAreDead()) {
478 DEBUG(dbgs() << "All defs dead: " << Def << '\t' << *MI);
479 dead->push_back(MI);
480 }
481 }
482 }
483 return PHIRemoved;
484 }
486 void LiveIntervals::shrinkToUses(LiveInterval::SubRange &SR, unsigned Reg)
487 {
488 DEBUG(dbgs() << "Shrink: " << SR << '\n');
489 assert(TargetRegisterInfo::isVirtualRegister(Reg)
490 && "Can only shrink virtual registers");
491 // Find all the values used, including PHI kills.
492 ShrinkToUsesWorkList WorkList;
494 // Visit all instructions reading Reg.
495 SlotIndex LastIdx;
496 for (MachineOperand &MO : MRI->reg_operands(Reg)) {
497 MachineInstr *UseMI = MO.getParent();
498 if (UseMI->isDebugValue())
499 continue;
500 // Maybe the operand is for a subregister we don't care about.
501 unsigned SubReg = MO.getSubReg();
502 if (SubReg != 0) {
503 unsigned SubRegMask = TRI->getSubRegIndexLaneMask(SubReg);
504 if ((SubRegMask & SR.LaneMask) == 0)
505 continue;
506 }
507 // We only need to visit each instruction once.
508 SlotIndex Idx = getInstructionIndex(UseMI).getRegSlot();
509 if (Idx == LastIdx)
510 continue;
511 LastIdx = Idx;
513 LiveQueryResult LRQ = SR.Query(Idx);
514 VNInfo *VNI = LRQ.valueIn();
515 // For Subranges it is possible that only undef values are left in that
516 // part of the subregister, so there is no real liverange at the use
517 if (!VNI)
518 continue;
520 // Special case: An early-clobber tied operand reads and writes the
521 // register one slot early.
522 if (VNInfo *DefVNI = LRQ.valueDefined())
523 Idx = DefVNI->def;
525 WorkList.push_back(std::make_pair(Idx, VNI));
526 }
528 // Create a new live ranges with only minimal live segments per def.
529 LiveRange NewLR;
530 createSegmentsForValues(NewLR, make_range(SR.vni_begin(), SR.vni_end()));
531 extendSegmentsToUses(NewLR, *Indexes, WorkList, SR);
533 // Move the trimmed ranges back.
534 SR.segments.swap(NewLR.segments);
536 // Remove dead PHI value numbers
537 for (auto VNI : SR.valnos) {
538 if (VNI->isUnused())
539 continue;
540 const LiveRange::Segment *Segment = SR.getSegmentContaining(VNI->def);
541 assert(Segment != nullptr && "Missing segment for VNI");
542 if (Segment->end != VNI->def.getDeadSlot())
543 continue;
544 if (VNI->isPHIDef()) {
545 // This is a dead PHI. Remove it.
546 VNI->markUnused();
547 SR.removeSegment(*Segment);
548 DEBUG(dbgs() << "Dead PHI at " << VNI->def << " may separate interval\n");
549 }
550 }
552 DEBUG(dbgs() << "Shrunk: " << SR << '\n');
553 }
555 void LiveIntervals::extendToIndices(LiveRange &LR,
556 ArrayRef<SlotIndex> Indices) {
557 assert(LRCalc && "LRCalc not initialized.");
558 LRCalc->reset(MF, getSlotIndexes(), DomTree, &getVNInfoAllocator());
559 for (unsigned i = 0, e = Indices.size(); i != e; ++i)
560 LRCalc->extend(LR, Indices[i]);
561 }
563 void LiveIntervals::pruneValue(LiveRange &LR, SlotIndex Kill,
564 SmallVectorImpl<SlotIndex> *EndPoints) {
565 LiveQueryResult LRQ = LR.Query(Kill);
566 VNInfo *VNI = LRQ.valueOutOrDead();
567 if (!VNI)
568 return;
570 MachineBasicBlock *KillMBB = Indexes->getMBBFromIndex(Kill);
571 SlotIndex MBBEnd = Indexes->getMBBEndIdx(KillMBB);
573 // If VNI isn't live out from KillMBB, the value is trivially pruned.
574 if (LRQ.endPoint() < MBBEnd) {
575 LR.removeSegment(Kill, LRQ.endPoint());
576 if (EndPoints) EndPoints->push_back(LRQ.endPoint());
577 return;
578 }
580 // VNI is live out of KillMBB.
581 LR.removeSegment(Kill, MBBEnd);
582 if (EndPoints) EndPoints->push_back(MBBEnd);
584 // Find all blocks that are reachable from KillMBB without leaving VNI's live
585 // range. It is possible that KillMBB itself is reachable, so start a DFS
586 // from each successor.
587 typedef SmallPtrSet<MachineBasicBlock*, 9> VisitedTy;
588 VisitedTy Visited;
589 for (MachineBasicBlock::succ_iterator
590 SuccI = KillMBB->succ_begin(), SuccE = KillMBB->succ_end();
591 SuccI != SuccE; ++SuccI) {
592 for (df_ext_iterator<MachineBasicBlock*, VisitedTy>
593 I = df_ext_begin(*SuccI, Visited), E = df_ext_end(*SuccI, Visited);
594 I != E;) {
595 MachineBasicBlock *MBB = *I;
597 // Check if VNI is live in to MBB.
598 SlotIndex MBBStart, MBBEnd;
599 std::tie(MBBStart, MBBEnd) = Indexes->getMBBRange(MBB);
600 LiveQueryResult LRQ = LR.Query(MBBStart);
601 if (LRQ.valueIn() != VNI) {
602 // This block isn't part of the VNI segment. Prune the search.
603 I.skipChildren();
604 continue;
605 }
607 // Prune the search if VNI is killed in MBB.
608 if (LRQ.endPoint() < MBBEnd) {
609 LR.removeSegment(MBBStart, LRQ.endPoint());
610 if (EndPoints) EndPoints->push_back(LRQ.endPoint());
611 I.skipChildren();
612 continue;
613 }
615 // VNI is live through MBB.
616 LR.removeSegment(MBBStart, MBBEnd);
617 if (EndPoints) EndPoints->push_back(MBBEnd);
618 ++I;
619 }
620 }
621 }
623 //===----------------------------------------------------------------------===//
624 // Register allocator hooks.
625 //
627 void LiveIntervals::addKillFlags(const VirtRegMap *VRM) {
628 // Keep track of regunit ranges.
629 SmallVector<std::pair<const LiveRange*, LiveRange::const_iterator>, 8> RU;
630 // Keep track of subregister ranges.
631 SmallVector<std::pair<const LiveInterval::SubRange*,
632 LiveRange::const_iterator>, 4> SRs;
634 for (unsigned i = 0, e = MRI->getNumVirtRegs(); i != e; ++i) {
635 unsigned Reg = TargetRegisterInfo::index2VirtReg(i);
636 if (MRI->reg_nodbg_empty(Reg))
637 continue;
638 const LiveInterval &LI = getInterval(Reg);
639 if (LI.empty())
640 continue;
642 // Find the regunit intervals for the assigned register. They may overlap
643 // the virtual register live range, cancelling any kills.
644 RU.clear();
645 for (MCRegUnitIterator Units(VRM->getPhys(Reg), TRI); Units.isValid();
646 ++Units) {
647 const LiveRange &RURange = getRegUnit(*Units);
648 if (RURange.empty())
649 continue;
650 RU.push_back(std::make_pair(&RURange, RURange.find(LI.begin()->end)));
651 }
653 if (MRI->tracksSubRegLiveness()) {
654 SRs.clear();
655 for (const LiveInterval::SubRange &SR : LI.subranges()) {
656 SRs.push_back(std::make_pair(&SR, SR.find(LI.begin()->end)));
657 }
658 }
660 // Every instruction that kills Reg corresponds to a segment range end
661 // point.
662 for (LiveInterval::const_iterator RI = LI.begin(), RE = LI.end(); RI != RE;
663 ++RI) {
664 // A block index indicates an MBB edge.
665 if (RI->end.isBlock())
666 continue;
667 MachineInstr *MI = getInstructionFromIndex(RI->end);
668 if (!MI)
669 continue;
671 // Check if any of the regunits are live beyond the end of RI. That could
672 // happen when a physreg is defined as a copy of a virtreg:
673 //
674 // %EAX = COPY %vreg5
675 // FOO %vreg5 <--- MI, cancel kill because %EAX is live.
676 // BAR %EAX<kill>
677 //
678 // There should be no kill flag on FOO when %vreg5 is rewritten as %EAX.
679 for (auto &RUP : RU) {
680 const LiveRange &RURange = *RUP.first;
681 LiveRange::const_iterator &I = RUP.second;
682 if (I == RURange.end())
683 continue;
684 I = RURange.advanceTo(I, RI->end);
685 if (I == RURange.end() || I->start >= RI->end)
686 continue;
687 // I is overlapping RI.
688 goto CancelKill;
689 }
691 if (MRI->tracksSubRegLiveness()) {
692 // When reading a partial undefined value we must not add a kill flag.
693 // The regalloc might have used the undef lane for something else.
694 // Example:
695 // %vreg1 = ... ; R32: %vreg1
696 // %vreg2:high16 = ... ; R64: %vreg2
697 // = read %vreg2<kill> ; R64: %vreg2
698 // = read %vreg1 ; R32: %vreg1
699 // The <kill> flag is correct for %vreg2, but the register allocator may
700 // assign R0L to %vreg1, and R0 to %vreg2 because the low 32bits of R0
701 // are actually never written by %vreg2. After assignment the <kill>
702 // flag at the read instruction is invalid.
703 unsigned DefinedLanesMask;
704 if (!SRs.empty()) {
705 // Compute a mask of lanes that are defined.
706 DefinedLanesMask = 0;
707 for (auto &SRP : SRs) {
708 const LiveInterval::SubRange &SR = *SRP.first;
709 LiveRange::const_iterator &I = SRP.second;
710 if (I == SR.end())
711 continue;
712 I = SR.advanceTo(I, RI->end);
713 if (I == SR.end() || I->start >= RI->end)
714 continue;
715 // I is overlapping RI
716 DefinedLanesMask |= SR.LaneMask;
717 }
718 } else
719 DefinedLanesMask = ~0u;
721 bool IsFullWrite = false;
722 for (const MachineOperand &MO : MI->operands()) {
723 if (!MO.isReg() || MO.getReg() != Reg)
724 continue;
725 if (MO.isUse()) {
726 // Reading any undefined lanes?
727 unsigned UseMask = TRI->getSubRegIndexLaneMask(MO.getSubReg());
728 if ((UseMask & ~DefinedLanesMask) != 0)
729 goto CancelKill;
730 } else if (MO.getSubReg() == 0) {
731 // Writing to the full register?
732 assert(MO.isDef());
733 IsFullWrite = true;
734 }
735 }
737 // If an instruction writes to a subregister, a new segment starts in
738 // the LiveInterval. But as this is only overriding part of the register
739 // adding kill-flags is not correct here after registers have been
740 // assigned.
741 if (!IsFullWrite) {
742 // Next segment has to be adjacent in the subregister write case.
743 LiveRange::const_iterator N = std::next(RI);
744 if (N != LI.end() && N->start == RI->end)
745 goto CancelKill;
746 }
747 }
749 MI->addRegisterKilled(Reg, nullptr);
750 continue;
751 CancelKill:
752 MI->clearRegisterKills(Reg, nullptr);
753 }
754 }
755 }
757 MachineBasicBlock*
758 LiveIntervals::intervalIsInOneMBB(const LiveInterval &LI) const {
759 // A local live range must be fully contained inside the block, meaning it is
760 // defined and killed at instructions, not at block boundaries. It is not
761 // live in or or out of any block.
762 //
763 // It is technically possible to have a PHI-defined live range identical to a
764 // single block, but we are going to return false in that case.
766 SlotIndex Start = LI.beginIndex();
767 if (Start.isBlock())
768 return nullptr;
770 SlotIndex Stop = LI.endIndex();
771 if (Stop.isBlock())
772 return nullptr;
774 // getMBBFromIndex doesn't need to search the MBB table when both indexes
775 // belong to proper instructions.
776 MachineBasicBlock *MBB1 = Indexes->getMBBFromIndex(Start);
777 MachineBasicBlock *MBB2 = Indexes->getMBBFromIndex(Stop);
778 return MBB1 == MBB2 ? MBB1 : nullptr;
779 }
781 bool
782 LiveIntervals::hasPHIKill(const LiveInterval &LI, const VNInfo *VNI) const {
783 for (const VNInfo *PHI : LI.valnos) {
784 if (PHI->isUnused() || !PHI->isPHIDef())
785 continue;
786 const MachineBasicBlock *PHIMBB = getMBBFromIndex(PHI->def);
787 // Conservatively return true instead of scanning huge predecessor lists.
788 if (PHIMBB->pred_size() > 100)
789 return true;
790 for (MachineBasicBlock::const_pred_iterator
791 PI = PHIMBB->pred_begin(), PE = PHIMBB->pred_end(); PI != PE; ++PI)
792 if (VNI == LI.getVNInfoBefore(Indexes->getMBBEndIdx(*PI)))
793 return true;
794 }
795 return false;
796 }
798 float
799 LiveIntervals::getSpillWeight(bool isDef, bool isUse,
800 const MachineBlockFrequencyInfo *MBFI,
801 const MachineInstr *MI) {
802 BlockFrequency Freq = MBFI->getBlockFreq(MI->getParent());
803 const float Scale = 1.0f / MBFI->getEntryFreq();
804 return (isDef + isUse) * (Freq.getFrequency() * Scale);
805 }
807 LiveRange::Segment
808 LiveIntervals::addSegmentToEndOfBlock(unsigned reg, MachineInstr* startInst) {
809 LiveInterval& Interval = createEmptyInterval(reg);
810 VNInfo* VN = Interval.getNextValue(
811 SlotIndex(getInstructionIndex(startInst).getRegSlot()),
812 getVNInfoAllocator());
813 LiveRange::Segment S(
814 SlotIndex(getInstructionIndex(startInst).getRegSlot()),
815 getMBBEndIdx(startInst->getParent()), VN);
816 Interval.addSegment(S);
818 return S;
819 }
822 //===----------------------------------------------------------------------===//
823 // Register mask functions
824 //===----------------------------------------------------------------------===//
826 bool LiveIntervals::checkRegMaskInterference(LiveInterval &LI,
827 BitVector &UsableRegs) {
828 if (LI.empty())
829 return false;
830 LiveInterval::iterator LiveI = LI.begin(), LiveE = LI.end();
832 // Use a smaller arrays for local live ranges.
833 ArrayRef<SlotIndex> Slots;
834 ArrayRef<const uint32_t*> Bits;
835 if (MachineBasicBlock *MBB = intervalIsInOneMBB(LI)) {
836 Slots = getRegMaskSlotsInBlock(MBB->getNumber());
837 Bits = getRegMaskBitsInBlock(MBB->getNumber());
838 } else {
839 Slots = getRegMaskSlots();
840 Bits = getRegMaskBits();
841 }
843 // We are going to enumerate all the register mask slots contained in LI.
844 // Start with a binary search of RegMaskSlots to find a starting point.
845 ArrayRef<SlotIndex>::iterator SlotI =
846 std::lower_bound(Slots.begin(), Slots.end(), LiveI->start);
847 ArrayRef<SlotIndex>::iterator SlotE = Slots.end();
849 // No slots in range, LI begins after the last call.
850 if (SlotI == SlotE)
851 return false;
853 bool Found = false;
854 for (;;) {
855 assert(*SlotI >= LiveI->start);
856 // Loop over all slots overlapping this segment.
857 while (*SlotI < LiveI->end) {
858 // *SlotI overlaps LI. Collect mask bits.
859 if (!Found) {
860 // This is the first overlap. Initialize UsableRegs to all ones.
861 UsableRegs.clear();
862 UsableRegs.resize(TRI->getNumRegs(), true);
863 Found = true;
864 }
865 // Remove usable registers clobbered by this mask.
866 UsableRegs.clearBitsNotInMask(Bits[SlotI-Slots.begin()]);
867 if (++SlotI == SlotE)
868 return Found;
869 }
870 // *SlotI is beyond the current LI segment.
871 LiveI = LI.advanceTo(LiveI, *SlotI);
872 if (LiveI == LiveE)
873 return Found;
874 // Advance SlotI until it overlaps.
875 while (*SlotI < LiveI->start)
876 if (++SlotI == SlotE)
877 return Found;
878 }
879 }
881 //===----------------------------------------------------------------------===//
882 // IntervalUpdate class.
883 //===----------------------------------------------------------------------===//
885 // HMEditor is a toolkit used by handleMove to trim or extend live intervals.
886 class LiveIntervals::HMEditor {
887 private:
888 LiveIntervals& LIS;
889 const MachineRegisterInfo& MRI;
890 const TargetRegisterInfo& TRI;
891 SlotIndex OldIdx;
892 SlotIndex NewIdx;
893 SmallPtrSet<LiveRange*, 8> Updated;
894 bool UpdateFlags;
896 public:
897 HMEditor(LiveIntervals& LIS, const MachineRegisterInfo& MRI,
898 const TargetRegisterInfo& TRI,
899 SlotIndex OldIdx, SlotIndex NewIdx, bool UpdateFlags)
900 : LIS(LIS), MRI(MRI), TRI(TRI), OldIdx(OldIdx), NewIdx(NewIdx),
901 UpdateFlags(UpdateFlags) {}
903 // FIXME: UpdateFlags is a workaround that creates live intervals for all
904 // physregs, even those that aren't needed for regalloc, in order to update
905 // kill flags. This is wasteful. Eventually, LiveVariables will strip all kill
906 // flags, and postRA passes will use a live register utility instead.
907 LiveRange *getRegUnitLI(unsigned Unit) {
908 if (UpdateFlags)
909 return &LIS.getRegUnit(Unit);
910 return LIS.getCachedRegUnit(Unit);
911 }
913 /// Update all live ranges touched by MI, assuming a move from OldIdx to
914 /// NewIdx.
915 void updateAllRanges(MachineInstr *MI) {
916 DEBUG(dbgs() << "handleMove " << OldIdx << " -> " << NewIdx << ": " << *MI);
917 bool hasRegMask = false;
918 for (MIOperands MO(MI); MO.isValid(); ++MO) {
919 if (MO->isRegMask())
920 hasRegMask = true;
921 if (!MO->isReg())
922 continue;
923 // Aggressively clear all kill flags.
924 // They are reinserted by VirtRegRewriter.
925 if (MO->isUse())
926 MO->setIsKill(false);
928 unsigned Reg = MO->getReg();
929 if (!Reg)
930 continue;
931 if (TargetRegisterInfo::isVirtualRegister(Reg)) {
932 LiveInterval &LI = LIS.getInterval(Reg);
933 if (LI.hasSubRanges()) {
934 unsigned SubReg = MO->getSubReg();
935 unsigned LaneMask = TRI.getSubRegIndexLaneMask(SubReg);
936 for (LiveInterval::SubRange &S : LI.subranges()) {
937 if ((S.LaneMask & LaneMask) == 0)
938 continue;
939 updateRange(S, Reg, S.LaneMask);
940 }
941 }
942 updateRange(LI, Reg, 0);
943 continue;
944 }
946 // For physregs, only update the regunits that actually have a
947 // precomputed live range.
948 for (MCRegUnitIterator Units(Reg, &TRI); Units.isValid(); ++Units)
949 if (LiveRange *LR = getRegUnitLI(*Units))
950 updateRange(*LR, *Units, 0);
951 }
952 if (hasRegMask)
953 updateRegMaskSlots();
954 }
956 private:
957 /// Update a single live range, assuming an instruction has been moved from
958 /// OldIdx to NewIdx.
959 void updateRange(LiveRange &LR, unsigned Reg, unsigned LaneMask) {
960 if (!Updated.insert(&LR).second)
961 return;
962 DEBUG({
963 dbgs() << " ";
964 if (TargetRegisterInfo::isVirtualRegister(Reg)) {
965 dbgs() << PrintReg(Reg);
966 if (LaneMask != 0)
967 dbgs() << format(" L%04X", LaneMask);
968 } else {
969 dbgs() << PrintRegUnit(Reg, &TRI);
970 }
971 dbgs() << ":\t" << LR << '\n';
972 });
973 if (SlotIndex::isEarlierInstr(OldIdx, NewIdx))
974 handleMoveDown(LR);
975 else
976 handleMoveUp(LR, Reg, LaneMask);
977 DEBUG(dbgs() << " -->\t" << LR << '\n');
978 LR.verify();
979 }
981 /// Update LR to reflect an instruction has been moved downwards from OldIdx
982 /// to NewIdx.
983 ///
984 /// 1. Live def at OldIdx:
985 /// Move def to NewIdx, assert endpoint after NewIdx.
986 ///
987 /// 2. Live def at OldIdx, killed at NewIdx:
988 /// Change to dead def at NewIdx.
989 /// (Happens when bundling def+kill together).
990 ///
991 /// 3. Dead def at OldIdx:
992 /// Move def to NewIdx, possibly across another live value.
993 ///
994 /// 4. Def at OldIdx AND at NewIdx:
995 /// Remove segment [OldIdx;NewIdx) and value defined at OldIdx.
996 /// (Happens when bundling multiple defs together).
997 ///
998 /// 5. Value read at OldIdx, killed before NewIdx:
999 /// Extend kill to NewIdx.
1000 ///
1001 void handleMoveDown(LiveRange &LR) {
1002 // First look for a kill at OldIdx.
1003 LiveRange::iterator I = LR.find(OldIdx.getBaseIndex());
1004 LiveRange::iterator E = LR.end();
1005 // Is LR even live at OldIdx?
1006 if (I == E || SlotIndex::isEarlierInstr(OldIdx, I->start))
1007 return;
1009 // Handle a live-in value.
1010 if (!SlotIndex::isSameInstr(I->start, OldIdx)) {
1011 bool isKill = SlotIndex::isSameInstr(OldIdx, I->end);
1012 // If the live-in value already extends to NewIdx, there is nothing to do.
1013 if (!SlotIndex::isEarlierInstr(I->end, NewIdx))
1014 return;
1015 // Aggressively remove all kill flags from the old kill point.
1016 // Kill flags shouldn't be used while live intervals exist, they will be
1017 // reinserted by VirtRegRewriter.
1018 if (MachineInstr *KillMI = LIS.getInstructionFromIndex(I->end))
1019 for (MIBundleOperands MO(KillMI); MO.isValid(); ++MO)
1020 if (MO->isReg() && MO->isUse())
1021 MO->setIsKill(false);
1022 // Adjust I->end to reach NewIdx. This may temporarily make LR invalid by
1023 // overlapping ranges. Case 5 above.
1024 I->end = NewIdx.getRegSlot(I->end.isEarlyClobber());
1025 // If this was a kill, there may also be a def. Otherwise we're done.
1026 if (!isKill)
1027 return;
1028 ++I;
1029 }
1031 // Check for a def at OldIdx.
1032 if (I == E || !SlotIndex::isSameInstr(OldIdx, I->start))
1033 return;
1034 // We have a def at OldIdx.
1035 VNInfo *DefVNI = I->valno;
1036 assert(DefVNI->def == I->start && "Inconsistent def");
1037 DefVNI->def = NewIdx.getRegSlot(I->start.isEarlyClobber());
1038 // If the defined value extends beyond NewIdx, just move the def down.
1039 // This is case 1 above.
1040 if (SlotIndex::isEarlierInstr(NewIdx, I->end)) {
1041 I->start = DefVNI->def;
1042 return;
1043 }
1044 // The remaining possibilities are now:
1045 // 2. Live def at OldIdx, killed at NewIdx: isSameInstr(I->end, NewIdx).
1046 // 3. Dead def at OldIdx: I->end = OldIdx.getDeadSlot().
1047 // In either case, it is possible that there is an existing def at NewIdx.
1048 assert((I->end == OldIdx.getDeadSlot() ||
1049 SlotIndex::isSameInstr(I->end, NewIdx)) &&
1050 "Cannot move def below kill");
1051 LiveRange::iterator NewI = LR.advanceTo(I, NewIdx.getRegSlot());
1052 if (NewI != E && SlotIndex::isSameInstr(NewI->start, NewIdx)) {
1053 // There is an existing def at NewIdx, case 4 above. The def at OldIdx is
1054 // coalesced into that value.
1055 assert(NewI->valno != DefVNI && "Multiple defs of value?");
1056 LR.removeValNo(DefVNI);
1057 return;
1058 }
1059 // There was no existing def at NewIdx. Turn *I into a dead def at NewIdx.
1060 // If the def at OldIdx was dead, we allow it to be moved across other LR
1061 // values. The new range should be placed immediately before NewI, move any
1062 // intermediate ranges up.
1063 assert(NewI != I && "Inconsistent iterators");
1064 std::copy(std::next(I), NewI, I);
1065 *std::prev(NewI)
1066 = LiveRange::Segment(DefVNI->def, NewIdx.getDeadSlot(), DefVNI);
1067 }
1069 /// Update LR to reflect an instruction has been moved upwards from OldIdx
1070 /// to NewIdx.
1071 ///
1072 /// 1. Live def at OldIdx:
1073 /// Hoist def to NewIdx.
1074 ///
1075 /// 2. Dead def at OldIdx:
1076 /// Hoist def+end to NewIdx, possibly move across other values.
1077 ///
1078 /// 3. Dead def at OldIdx AND existing def at NewIdx:
1079 /// Remove value defined at OldIdx, coalescing it with existing value.
1080 ///
1081 /// 4. Live def at OldIdx AND existing def at NewIdx:
1082 /// Remove value defined at NewIdx, hoist OldIdx def to NewIdx.
1083 /// (Happens when bundling multiple defs together).
1084 ///
1085 /// 5. Value killed at OldIdx:
1086 /// Hoist kill to NewIdx, then scan for last kill between NewIdx and
1087 /// OldIdx.
1088 ///
1089 void handleMoveUp(LiveRange &LR, unsigned Reg, unsigned LaneMask) {
1090 // First look for a kill at OldIdx.
1091 LiveRange::iterator I = LR.find(OldIdx.getBaseIndex());
1092 LiveRange::iterator E = LR.end();
1093 // Is LR even live at OldIdx?
1094 if (I == E || SlotIndex::isEarlierInstr(OldIdx, I->start))
1095 return;
1097 // Handle a live-in value.
1098 if (!SlotIndex::isSameInstr(I->start, OldIdx)) {
1099 // If the live-in value isn't killed here, there is nothing to do.
1100 if (!SlotIndex::isSameInstr(OldIdx, I->end))
1101 return;
1102 // Adjust I->end to end at NewIdx. If we are hoisting a kill above
1103 // another use, we need to search for that use. Case 5 above.
1104 I->end = NewIdx.getRegSlot(I->end.isEarlyClobber());
1105 ++I;
1106 // If OldIdx also defines a value, there couldn't have been another use.
1107 if (I == E || !SlotIndex::isSameInstr(I->start, OldIdx)) {
1108 // No def, search for the new kill.
1109 // This can never be an early clobber kill since there is no def.
1110 std::prev(I)->end = findLastUseBefore(Reg, LaneMask).getRegSlot();
1111 return;
1112 }
1113 }
1115 // Now deal with the def at OldIdx.
1116 assert(I != E && SlotIndex::isSameInstr(I->start, OldIdx) && "No def?");
1117 VNInfo *DefVNI = I->valno;
1118 assert(DefVNI->def == I->start && "Inconsistent def");
1119 DefVNI->def = NewIdx.getRegSlot(I->start.isEarlyClobber());
1121 // Check for an existing def at NewIdx.
1122 LiveRange::iterator NewI = LR.find(NewIdx.getRegSlot());
1123 if (SlotIndex::isSameInstr(NewI->start, NewIdx)) {
1124 assert(NewI->valno != DefVNI && "Same value defined more than once?");
1125 // There is an existing def at NewIdx.
1126 if (I->end.isDead()) {
1127 // Case 3: Remove the dead def at OldIdx.
1128 LR.removeValNo(DefVNI);
1129 return;
1130 }
1131 // Case 4: Replace def at NewIdx with live def at OldIdx.
1132 I->start = DefVNI->def;
1133 LR.removeValNo(NewI->valno);
1134 return;
1135 }
1137 // There is no existing def at NewIdx. Hoist DefVNI.
1138 if (!I->end.isDead()) {
1139 // Leave the end point of a live def.
1140 I->start = DefVNI->def;
1141 return;
1142 }
1144 // DefVNI is a dead def. It may have been moved across other values in LR,
1145 // so move I up to NewI. Slide [NewI;I) down one position.
1146 std::copy_backward(NewI, I, std::next(I));
1147 *NewI = LiveRange::Segment(DefVNI->def, NewIdx.getDeadSlot(), DefVNI);
1148 }
1150 void updateRegMaskSlots() {
1151 SmallVectorImpl<SlotIndex>::iterator RI =
1152 std::lower_bound(LIS.RegMaskSlots.begin(), LIS.RegMaskSlots.end(),
1153 OldIdx);
1154 assert(RI != LIS.RegMaskSlots.end() && *RI == OldIdx.getRegSlot() &&
1155 "No RegMask at OldIdx.");
1156 *RI = NewIdx.getRegSlot();
1157 assert((RI == LIS.RegMaskSlots.begin() ||
1158 SlotIndex::isEarlierInstr(*std::prev(RI), *RI)) &&
1159 "Cannot move regmask instruction above another call");
1160 assert((std::next(RI) == LIS.RegMaskSlots.end() ||
1161 SlotIndex::isEarlierInstr(*RI, *std::next(RI))) &&
1162 "Cannot move regmask instruction below another call");
1163 }
1165 // Return the last use of reg between NewIdx and OldIdx.
1166 SlotIndex findLastUseBefore(unsigned Reg, unsigned LaneMask) {
1168 if (TargetRegisterInfo::isVirtualRegister(Reg)) {
1169 SlotIndex LastUse = NewIdx;
1170 for (MachineOperand &MO : MRI.use_nodbg_operands(Reg)) {
1171 unsigned SubReg = MO.getSubReg();
1172 if (SubReg != 0 && LaneMask != 0
1173 && (TRI.getSubRegIndexLaneMask(SubReg) & LaneMask) == 0)
1174 continue;
1176 const MachineInstr *MI = MO.getParent();
1177 SlotIndex InstSlot = LIS.getSlotIndexes()->getInstructionIndex(MI);
1178 if (InstSlot > LastUse && InstSlot < OldIdx)
1179 LastUse = InstSlot;
1180 }
1181 return LastUse;
1182 }
1184 // This is a regunit interval, so scanning the use list could be very
1185 // expensive. Scan upwards from OldIdx instead.
1186 assert(NewIdx < OldIdx && "Expected upwards move");
1187 SlotIndexes *Indexes = LIS.getSlotIndexes();
1188 MachineBasicBlock *MBB = Indexes->getMBBFromIndex(NewIdx);
1190 // OldIdx may not correspond to an instruction any longer, so set MII to
1191 // point to the next instruction after OldIdx, or MBB->end().
1192 MachineBasicBlock::iterator MII = MBB->end();
1193 if (MachineInstr *MI = Indexes->getInstructionFromIndex(
1194 Indexes->getNextNonNullIndex(OldIdx)))
1195 if (MI->getParent() == MBB)
1196 MII = MI;
1198 MachineBasicBlock::iterator Begin = MBB->begin();
1199 while (MII != Begin) {
1200 if ((--MII)->isDebugValue())
1201 continue;
1202 SlotIndex Idx = Indexes->getInstructionIndex(MII);
1204 // Stop searching when NewIdx is reached.
1205 if (!SlotIndex::isEarlierInstr(NewIdx, Idx))
1206 return NewIdx;
1208 // Check if MII uses Reg.
1209 for (MIBundleOperands MO(MII); MO.isValid(); ++MO)
1210 if (MO->isReg() &&
1211 TargetRegisterInfo::isPhysicalRegister(MO->getReg()) &&
1212 TRI.hasRegUnit(MO->getReg(), Reg))
1213 return Idx;
1214 }
1215 // Didn't reach NewIdx. It must be the first instruction in the block.
1216 return NewIdx;
1217 }
1218 };
1220 void LiveIntervals::handleMove(MachineInstr* MI, bool UpdateFlags) {
1221 assert(!MI->isBundled() && "Can't handle bundled instructions yet.");
1222 SlotIndex OldIndex = Indexes->getInstructionIndex(MI);
1223 Indexes->removeMachineInstrFromMaps(MI);
1224 SlotIndex NewIndex = Indexes->insertMachineInstrInMaps(MI);
1225 assert(getMBBStartIdx(MI->getParent()) <= OldIndex &&
1226 OldIndex < getMBBEndIdx(MI->getParent()) &&
1227 "Cannot handle moves across basic block boundaries.");
1229 HMEditor HME(*this, *MRI, *TRI, OldIndex, NewIndex, UpdateFlags);
1230 HME.updateAllRanges(MI);
1231 }
1233 void LiveIntervals::handleMoveIntoBundle(MachineInstr* MI,
1234 MachineInstr* BundleStart,
1235 bool UpdateFlags) {
1236 SlotIndex OldIndex = Indexes->getInstructionIndex(MI);
1237 SlotIndex NewIndex = Indexes->getInstructionIndex(BundleStart);
1238 HMEditor HME(*this, *MRI, *TRI, OldIndex, NewIndex, UpdateFlags);
1239 HME.updateAllRanges(MI);
1240 }
1242 void LiveIntervals::repairOldRegInRange(const MachineBasicBlock::iterator Begin,
1243 const MachineBasicBlock::iterator End,
1244 const SlotIndex endIdx,
1245 LiveRange &LR, const unsigned Reg,
1246 const unsigned LaneMask) {
1247 LiveInterval::iterator LII = LR.find(endIdx);
1248 SlotIndex lastUseIdx;
1249 if (LII != LR.end() && LII->start < endIdx)
1250 lastUseIdx = LII->end;
1251 else
1252 --LII;
1254 for (MachineBasicBlock::iterator I = End; I != Begin;) {
1255 --I;
1256 MachineInstr *MI = I;
1257 if (MI->isDebugValue())
1258 continue;
1260 SlotIndex instrIdx = getInstructionIndex(MI);
1261 bool isStartValid = getInstructionFromIndex(LII->start);
1262 bool isEndValid = getInstructionFromIndex(LII->end);
1264 // FIXME: This doesn't currently handle early-clobber or multiple removed
1265 // defs inside of the region to repair.
1266 for (MachineInstr::mop_iterator OI = MI->operands_begin(),
1267 OE = MI->operands_end(); OI != OE; ++OI) {
1268 const MachineOperand &MO = *OI;
1269 if (!MO.isReg() || MO.getReg() != Reg)
1270 continue;
1272 unsigned SubReg = MO.getSubReg();
1273 unsigned Mask = TRI->getSubRegIndexLaneMask(SubReg);
1274 if ((Mask & LaneMask) == 0)
1275 continue;
1277 if (MO.isDef()) {
1278 if (!isStartValid) {
1279 if (LII->end.isDead()) {
1280 SlotIndex prevStart;
1281 if (LII != LR.begin())
1282 prevStart = std::prev(LII)->start;
1284 // FIXME: This could be more efficient if there was a
1285 // removeSegment method that returned an iterator.
1286 LR.removeSegment(*LII, true);
1287 if (prevStart.isValid())
1288 LII = LR.find(prevStart);
1289 else
1290 LII = LR.begin();
1291 } else {
1292 LII->start = instrIdx.getRegSlot();
1293 LII->valno->def = instrIdx.getRegSlot();
1294 if (MO.getSubReg() && !MO.isUndef())
1295 lastUseIdx = instrIdx.getRegSlot();
1296 else
1297 lastUseIdx = SlotIndex();
1298 continue;
1299 }
1300 }
1302 if (!lastUseIdx.isValid()) {
1303 VNInfo *VNI = LR.getNextValue(instrIdx.getRegSlot(), VNInfoAllocator);
1304 LiveRange::Segment S(instrIdx.getRegSlot(),
1305 instrIdx.getDeadSlot(), VNI);
1306 LII = LR.addSegment(S);
1307 } else if (LII->start != instrIdx.getRegSlot()) {
1308 VNInfo *VNI = LR.getNextValue(instrIdx.getRegSlot(), VNInfoAllocator);
1309 LiveRange::Segment S(instrIdx.getRegSlot(), lastUseIdx, VNI);
1310 LII = LR.addSegment(S);
1311 }
1313 if (MO.getSubReg() && !MO.isUndef())
1314 lastUseIdx = instrIdx.getRegSlot();
1315 else
1316 lastUseIdx = SlotIndex();
1317 } else if (MO.isUse()) {
1318 // FIXME: This should probably be handled outside of this branch,
1319 // either as part of the def case (for defs inside of the region) or
1320 // after the loop over the region.
1321 if (!isEndValid && !LII->end.isBlock())
1322 LII->end = instrIdx.getRegSlot();
1323 if (!lastUseIdx.isValid())
1324 lastUseIdx = instrIdx.getRegSlot();
1325 }
1326 }
1327 }
1328 }
1330 void
1331 LiveIntervals::repairIntervalsInRange(MachineBasicBlock *MBB,
1332 MachineBasicBlock::iterator Begin,
1333 MachineBasicBlock::iterator End,
1334 ArrayRef<unsigned> OrigRegs) {
1335 // Find anchor points, which are at the beginning/end of blocks or at
1336 // instructions that already have indexes.
1337 while (Begin != MBB->begin() && !Indexes->hasIndex(Begin))
1338 --Begin;
1339 while (End != MBB->end() && !Indexes->hasIndex(End))
1340 ++End;
1342 SlotIndex endIdx;
1343 if (End == MBB->end())
1344 endIdx = getMBBEndIdx(MBB).getPrevSlot();
1345 else
1346 endIdx = getInstructionIndex(End);
1348 Indexes->repairIndexesInRange(MBB, Begin, End);
1350 for (MachineBasicBlock::iterator I = End; I != Begin;) {
1351 --I;
1352 MachineInstr *MI = I;
1353 if (MI->isDebugValue())
1354 continue;
1355 for (MachineInstr::const_mop_iterator MOI = MI->operands_begin(),
1356 MOE = MI->operands_end(); MOI != MOE; ++MOI) {
1357 if (MOI->isReg() &&
1358 TargetRegisterInfo::isVirtualRegister(MOI->getReg()) &&
1359 !hasInterval(MOI->getReg())) {
1360 createAndComputeVirtRegInterval(MOI->getReg());
1361 }
1362 }
1363 }
1365 for (unsigned i = 0, e = OrigRegs.size(); i != e; ++i) {
1366 unsigned Reg = OrigRegs[i];
1367 if (!TargetRegisterInfo::isVirtualRegister(Reg))
1368 continue;
1370 LiveInterval &LI = getInterval(Reg);
1371 // FIXME: Should we support undefs that gain defs?
1372 if (!LI.hasAtLeastOneValue())
1373 continue;
1375 for (LiveInterval::SubRange &S : LI.subranges()) {
1376 repairOldRegInRange(Begin, End, endIdx, S, Reg, S.LaneMask);
1377 }
1378 repairOldRegInRange(Begin, End, endIdx, LI, Reg);
1379 }
1380 }
1382 void LiveIntervals::removePhysRegDefAt(unsigned Reg, SlotIndex Pos) {
1383 for (MCRegUnitIterator Units(Reg, TRI); Units.isValid(); ++Units) {
1384 if (LiveRange *LR = getCachedRegUnit(*Units))
1385 if (VNInfo *VNI = LR->getVNInfoAt(Pos))
1386 LR->removeValNo(VNI);
1387 }
1388 }
1390 void LiveIntervals::removeVRegDefAt(LiveInterval &LI, SlotIndex Pos) {
1391 VNInfo *VNI = LI.getVNInfoAt(Pos);
1392 if (VNI == nullptr)
1393 return;
1394 LI.removeValNo(VNI);
1396 // Also remove the value in subranges.
1397 for (LiveInterval::SubRange &S : LI.subranges()) {
1398 if (VNInfo *SVNI = S.getVNInfoAt(Pos))
1399 S.removeValNo(SVNI);
1400 }
1401 LI.removeEmptySubRanges();
1402 }