1 //===- RegisterCoalescer.cpp - Generic Register Coalescing Interface -------==//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the generic RegisterCoalescer interface which
11 // is used as the common interface used by all clients and
12 // implementations of register coalescing.
14 //===----------------------------------------------------------------------===//
16 #define DEBUG_TYPE "regalloc"
17 #include "RegisterCoalescer.h"
18 #include "LiveDebugVariables.h"
19 #include "RegisterClassInfo.h"
20 #include "VirtRegMap.h"
22 #include "llvm/Pass.h"
23 #include "llvm/Value.h"
24 #include "llvm/CodeGen/LiveIntervalAnalysis.h"
25 #include "llvm/CodeGen/MachineInstr.h"
26 #include "llvm/CodeGen/MachineRegisterInfo.h"
27 #include "llvm/Target/TargetInstrInfo.h"
28 #include "llvm/Target/TargetRegisterInfo.h"
29 #include "llvm/CodeGen/LiveIntervalAnalysis.h"
30 #include "llvm/Analysis/AliasAnalysis.h"
31 #include "llvm/CodeGen/MachineFrameInfo.h"
32 #include "llvm/CodeGen/MachineInstr.h"
33 #include "llvm/CodeGen/MachineLoopInfo.h"
34 #include "llvm/CodeGen/MachineRegisterInfo.h"
35 #include "llvm/CodeGen/Passes.h"
36 #include "llvm/Target/TargetInstrInfo.h"
37 #include "llvm/Target/TargetMachine.h"
38 #include "llvm/Target/TargetOptions.h"
39 #include "llvm/Support/CommandLine.h"
40 #include "llvm/Support/Debug.h"
41 #include "llvm/Support/ErrorHandling.h"
42 #include "llvm/Support/raw_ostream.h"
43 #include "llvm/ADT/OwningPtr.h"
44 #include "llvm/ADT/SmallSet.h"
45 #include "llvm/ADT/Statistic.h"
46 #include "llvm/ADT/STLExtras.h"
51 STATISTIC(numJoins , "Number of interval joins performed");
52 STATISTIC(numCrossRCs , "Number of cross class joins performed");
53 STATISTIC(numCommutes , "Number of instruction commuting performed");
54 STATISTIC(numExtends , "Number of copies extended");
55 STATISTIC(NumReMats , "Number of instructions re-materialized");
56 STATISTIC(numPeep , "Number of identity moves eliminated after coalescing");
57 STATISTIC(numAborts , "Number of times interval joining aborted");
58 STATISTIC(NumInflated , "Number of register classes inflated");
61 EnableJoining("join-liveintervals",
62 cl::desc("Coalesce copies (default=true)"),
66 EnablePhysicalJoin("join-physregs",
67 cl::desc("Join physical register copies"),
68 cl::init(false), cl::Hidden);
71 VerifyCoalescing("verify-coalescing",
72 cl::desc("Verify machine instrs before and after register coalescing"),
76 class RegisterCoalescer : public MachineFunctionPass {
78 MachineRegisterInfo* MRI;
79 const TargetMachine* TM;
80 const TargetRegisterInfo* TRI;
81 const TargetInstrInfo* TII;
83 LiveDebugVariables *LDV;
84 const MachineLoopInfo* Loops;
86 RegisterClassInfo RegClassInfo;
88 /// JoinedCopies - Keep track of copies eliminated due to coalescing.
90 SmallPtrSet<MachineInstr*, 32> JoinedCopies;
92 /// ReMatCopies - Keep track of copies eliminated due to remat.
94 SmallPtrSet<MachineInstr*, 32> ReMatCopies;
96 /// ReMatDefs - Keep track of definition instructions which have
98 SmallPtrSet<MachineInstr*, 8> ReMatDefs;
100 /// joinAllIntervals - join compatible live intervals
101 void joinAllIntervals();
103 /// copyCoalesceInMBB - Coalesce copies in the specified MBB, putting
104 /// copies that cannot yet be coalesced into the "TryAgain" list.
105 void copyCoalesceInMBB(MachineBasicBlock *MBB,
106 std::vector<MachineInstr*> &TryAgain);
108 /// joinCopy - Attempt to join intervals corresponding to SrcReg/DstReg,
109 /// which are the src/dst of the copy instruction CopyMI. This returns
110 /// true if the copy was successfully coalesced away. If it is not
111 /// currently possible to coalesce this interval, but it may be possible if
112 /// other things get coalesced, then it returns true by reference in
114 bool joinCopy(MachineInstr *TheCopy, bool &Again);
116 /// joinIntervals - Attempt to join these two intervals. On failure, this
117 /// returns false. The output "SrcInt" will not have been modified, so we
118 /// can use this information below to update aliases.
119 bool joinIntervals(CoalescerPair &CP);
121 /// Attempt joining with a reserved physreg.
122 bool joinReservedPhysReg(CoalescerPair &CP);
124 /// Check for interference with a normal unreserved physreg.
125 bool canJoinPhysReg(CoalescerPair &CP);
127 /// adjustCopiesBackFrom - We found a non-trivially-coalescable copy. If
128 /// the source value number is defined by a copy from the destination reg
129 /// see if we can merge these two destination reg valno# into a single
130 /// value number, eliminating a copy.
131 bool adjustCopiesBackFrom(const CoalescerPair &CP, MachineInstr *CopyMI);
133 /// hasOtherReachingDefs - Return true if there are definitions of IntB
134 /// other than BValNo val# that can reach uses of AValno val# of IntA.
135 bool hasOtherReachingDefs(LiveInterval &IntA, LiveInterval &IntB,
136 VNInfo *AValNo, VNInfo *BValNo);
138 /// removeCopyByCommutingDef - We found a non-trivially-coalescable copy.
139 /// If the source value number is defined by a commutable instruction and
140 /// its other operand is coalesced to the copy dest register, see if we
141 /// can transform the copy into a noop by commuting the definition.
142 bool removeCopyByCommutingDef(const CoalescerPair &CP,MachineInstr *CopyMI);
144 /// reMaterializeTrivialDef - If the source of a copy is defined by a
145 /// trivial computation, replace the copy by rematerialize the definition.
146 /// If PreserveSrcInt is true, make sure SrcInt is valid after the call.
147 bool reMaterializeTrivialDef(LiveInterval &SrcInt, bool PreserveSrcInt,
148 unsigned DstReg, MachineInstr *CopyMI);
150 /// shouldJoinPhys - Return true if a physreg copy should be joined.
151 bool shouldJoinPhys(CoalescerPair &CP);
153 /// updateRegDefsUses - Replace all defs and uses of SrcReg to DstReg and
154 /// update the subregister number if it is not zero. If DstReg is a
155 /// physical register and the existing subregister number of the def / use
156 /// being updated is not zero, make sure to set it to the correct physical
158 void updateRegDefsUses(unsigned SrcReg, unsigned DstReg, unsigned SubIdx);
160 /// removeDeadDef - If a def of a live interval is now determined dead,
161 /// remove the val# it defines. If the live interval becomes empty, remove
163 bool removeDeadDef(LiveInterval &li, MachineInstr *DefMI);
165 /// markAsJoined - Remember that CopyMI has already been joined.
166 void markAsJoined(MachineInstr *CopyMI);
168 /// eliminateUndefCopy - Handle copies of undef values.
169 bool eliminateUndefCopy(MachineInstr *CopyMI, const CoalescerPair &CP);
172 static char ID; // Class identification, replacement for typeinfo
173 RegisterCoalescer() : MachineFunctionPass(ID) {
174 initializeRegisterCoalescerPass(*PassRegistry::getPassRegistry());
177 virtual void getAnalysisUsage(AnalysisUsage &AU) const;
179 virtual void releaseMemory();
181 /// runOnMachineFunction - pass entry point
182 virtual bool runOnMachineFunction(MachineFunction&);
184 /// print - Implement the dump method.
185 virtual void print(raw_ostream &O, const Module* = 0) const;
187 } /// end anonymous namespace
189 char &llvm::RegisterCoalescerID = RegisterCoalescer::ID;
191 INITIALIZE_PASS_BEGIN(RegisterCoalescer, "simple-register-coalescing",
192 "Simple Register Coalescing", false, false)
193 INITIALIZE_PASS_DEPENDENCY(LiveIntervals)
194 INITIALIZE_PASS_DEPENDENCY(LiveDebugVariables)
195 INITIALIZE_PASS_DEPENDENCY(SlotIndexes)
196 INITIALIZE_PASS_DEPENDENCY(MachineLoopInfo)
197 INITIALIZE_AG_DEPENDENCY(AliasAnalysis)
198 INITIALIZE_PASS_END(RegisterCoalescer, "simple-register-coalescing",
199 "Simple Register Coalescing", false, false)
201 char RegisterCoalescer::ID = 0;
203 static unsigned compose(const TargetRegisterInfo &tri, unsigned a, unsigned b) {
206 return tri.composeSubRegIndices(a, b);
209 static bool isMoveInstr(const TargetRegisterInfo &tri, const MachineInstr *MI,
210 unsigned &Src, unsigned &Dst,
211 unsigned &SrcSub, unsigned &DstSub) {
213 Dst = MI->getOperand(0).getReg();
214 DstSub = MI->getOperand(0).getSubReg();
215 Src = MI->getOperand(1).getReg();
216 SrcSub = MI->getOperand(1).getSubReg();
217 } else if (MI->isSubregToReg()) {
218 Dst = MI->getOperand(0).getReg();
219 DstSub = compose(tri, MI->getOperand(0).getSubReg(),
220 MI->getOperand(3).getImm());
221 Src = MI->getOperand(2).getReg();
222 SrcSub = MI->getOperand(2).getSubReg();
228 bool CoalescerPair::setRegisters(const MachineInstr *MI) {
232 Flipped = CrossClass = false;
234 unsigned Src, Dst, SrcSub, DstSub;
235 if (!isMoveInstr(TRI, MI, Src, Dst, SrcSub, DstSub))
237 Partial = SrcSub || DstSub;
239 // If one register is a physreg, it must be Dst.
240 if (TargetRegisterInfo::isPhysicalRegister(Src)) {
241 if (TargetRegisterInfo::isPhysicalRegister(Dst))
244 std::swap(SrcSub, DstSub);
248 const MachineRegisterInfo &MRI = MI->getParent()->getParent()->getRegInfo();
250 if (TargetRegisterInfo::isPhysicalRegister(Dst)) {
251 // Eliminate DstSub on a physreg.
253 Dst = TRI.getSubReg(Dst, DstSub);
254 if (!Dst) return false;
258 // Eliminate SrcSub by picking a corresponding Dst superregister.
260 Dst = TRI.getMatchingSuperReg(Dst, SrcSub, MRI.getRegClass(Src));
261 if (!Dst) return false;
263 } else if (!MRI.getRegClass(Src)->contains(Dst)) {
267 // Both registers are virtual.
268 const TargetRegisterClass *SrcRC = MRI.getRegClass(Src);
269 const TargetRegisterClass *DstRC = MRI.getRegClass(Dst);
271 // Both registers have subreg indices.
272 if (SrcSub && DstSub) {
273 // Copies between different sub-registers are never coalescable.
274 if (Src == Dst && SrcSub != DstSub)
277 NewRC = TRI.getCommonSuperRegClass(SrcRC, SrcSub, DstRC, DstSub,
282 // We cannot handle the case where both Src and Dst would be a
283 // sub-register. Yet.
284 if (SrcIdx && DstIdx) {
285 DEBUG(dbgs() << "\tCannot handle " << NewRC->getName()
286 << " with subregs " << TRI.getSubRegIndexName(SrcIdx)
287 << " and " << TRI.getSubRegIndexName(DstIdx) << '\n');
291 // SrcReg will be merged with a sub-register of DstReg.
293 NewRC = TRI.getMatchingSuperRegClass(DstRC, SrcRC, DstSub);
295 // DstReg will be merged with a sub-register of SrcReg.
297 NewRC = TRI.getMatchingSuperRegClass(SrcRC, DstRC, SrcSub);
299 // This is a straight copy without sub-registers.
300 NewRC = TRI.getCommonSubClass(DstRC, SrcRC);
303 // The combined constraint may be impossible to satisfy.
307 // Prefer SrcReg to be a sub-register of DstReg.
308 // FIXME: Coalescer should support subregs symmetrically.
309 if (DstIdx && !SrcIdx) {
311 std::swap(SrcIdx, DstIdx);
315 CrossClass = NewRC != DstRC || NewRC != SrcRC;
317 // Check our invariants
318 assert(TargetRegisterInfo::isVirtualRegister(Src) && "Src must be virtual");
319 assert(!(TargetRegisterInfo::isPhysicalRegister(Dst) && DstSub) &&
320 "Cannot have a physical SubIdx");
326 bool CoalescerPair::flip() {
327 if (TargetRegisterInfo::isPhysicalRegister(DstReg))
329 std::swap(SrcReg, DstReg);
330 std::swap(SrcIdx, DstIdx);
335 bool CoalescerPair::isCoalescable(const MachineInstr *MI) const {
338 unsigned Src, Dst, SrcSub, DstSub;
339 if (!isMoveInstr(TRI, MI, Src, Dst, SrcSub, DstSub))
342 // Find the virtual register that is SrcReg.
345 std::swap(SrcSub, DstSub);
346 } else if (Src != SrcReg) {
350 // Now check that Dst matches DstReg.
351 if (TargetRegisterInfo::isPhysicalRegister(DstReg)) {
352 if (!TargetRegisterInfo::isPhysicalRegister(Dst))
354 assert(!DstIdx && !SrcIdx && "Inconsistent CoalescerPair state.");
355 // DstSub could be set for a physreg from INSERT_SUBREG.
357 Dst = TRI.getSubReg(Dst, DstSub);
360 return DstReg == Dst;
361 // This is a partial register copy. Check that the parts match.
362 return TRI.getSubReg(DstReg, SrcSub) == Dst;
364 // DstReg is virtual.
367 // Registers match, do the subregisters line up?
368 return compose(TRI, SrcIdx, SrcSub) == compose(TRI, DstIdx, DstSub);
372 void RegisterCoalescer::getAnalysisUsage(AnalysisUsage &AU) const {
373 AU.setPreservesCFG();
374 AU.addRequired<AliasAnalysis>();
375 AU.addRequired<LiveIntervals>();
376 AU.addPreserved<LiveIntervals>();
377 AU.addRequired<LiveDebugVariables>();
378 AU.addPreserved<LiveDebugVariables>();
379 AU.addPreserved<SlotIndexes>();
380 AU.addRequired<MachineLoopInfo>();
381 AU.addPreserved<MachineLoopInfo>();
382 AU.addPreservedID(MachineDominatorsID);
383 MachineFunctionPass::getAnalysisUsage(AU);
386 void RegisterCoalescer::markAsJoined(MachineInstr *CopyMI) {
387 /// Joined copies are not deleted immediately, but kept in JoinedCopies.
388 JoinedCopies.insert(CopyMI);
390 /// Mark all register operands of CopyMI as <undef> so they won't affect dead
391 /// code elimination.
392 for (MachineInstr::mop_iterator I = CopyMI->operands_begin(),
393 E = CopyMI->operands_end(); I != E; ++I)
398 /// adjustCopiesBackFrom - We found a non-trivially-coalescable copy with IntA
399 /// being the source and IntB being the dest, thus this defines a value number
400 /// in IntB. If the source value number (in IntA) is defined by a copy from B,
401 /// see if we can merge these two pieces of B into a single value number,
402 /// eliminating a copy. For example:
406 /// B1 = A3 <- this copy
408 /// In this case, B0 can be extended to where the B1 copy lives, allowing the B1
409 /// value number to be replaced with B0 (which simplifies the B liveinterval).
411 /// This returns true if an interval was modified.
413 bool RegisterCoalescer::adjustCopiesBackFrom(const CoalescerPair &CP,
414 MachineInstr *CopyMI) {
415 assert(!CP.isPartial() && "This doesn't work for partial copies.");
417 // Bail if there is no dst interval - can happen when merging physical subreg
419 if (!LIS->hasInterval(CP.getDstReg()))
423 LIS->getInterval(CP.isFlipped() ? CP.getDstReg() : CP.getSrcReg());
425 LIS->getInterval(CP.isFlipped() ? CP.getSrcReg() : CP.getDstReg());
426 SlotIndex CopyIdx = LIS->getInstructionIndex(CopyMI).getRegSlot();
428 // BValNo is a value number in B that is defined by a copy from A. 'B3' in
429 // the example above.
430 LiveInterval::iterator BLR = IntB.FindLiveRangeContaining(CopyIdx);
431 if (BLR == IntB.end()) return false;
432 VNInfo *BValNo = BLR->valno;
434 // Get the location that B is defined at. Two options: either this value has
435 // an unknown definition point or it is defined at CopyIdx. If unknown, we
437 if (BValNo->def != CopyIdx) return false;
439 // AValNo is the value number in A that defines the copy, A3 in the example.
440 SlotIndex CopyUseIdx = CopyIdx.getRegSlot(true);
441 LiveInterval::iterator ALR = IntA.FindLiveRangeContaining(CopyUseIdx);
442 // The live range might not exist after fun with physreg coalescing.
443 if (ALR == IntA.end()) return false;
444 VNInfo *AValNo = ALR->valno;
446 // If AValNo is defined as a copy from IntB, we can potentially process this.
447 // Get the instruction that defines this value number.
448 MachineInstr *ACopyMI = LIS->getInstructionFromIndex(AValNo->def);
449 if (!CP.isCoalescable(ACopyMI))
452 // Get the LiveRange in IntB that this value number starts with.
453 LiveInterval::iterator ValLR =
454 IntB.FindLiveRangeContaining(AValNo->def.getPrevSlot());
455 if (ValLR == IntB.end())
458 // Make sure that the end of the live range is inside the same block as
460 MachineInstr *ValLREndInst =
461 LIS->getInstructionFromIndex(ValLR->end.getPrevSlot());
462 if (!ValLREndInst || ValLREndInst->getParent() != CopyMI->getParent())
465 // Okay, we now know that ValLR ends in the same block that the CopyMI
466 // live-range starts. If there are no intervening live ranges between them in
467 // IntB, we can merge them.
468 if (ValLR+1 != BLR) return false;
470 // If a live interval is a physical register, conservatively check if any
471 // of its aliases is overlapping the live interval of the virtual register.
472 // If so, do not coalesce.
473 if (TargetRegisterInfo::isPhysicalRegister(IntB.reg)) {
474 for (const uint16_t *AS = TRI->getAliasSet(IntB.reg); *AS; ++AS)
475 if (LIS->hasInterval(*AS) && IntA.overlaps(LIS->getInterval(*AS))) {
477 dbgs() << "\t\tInterfere with alias ";
478 LIS->getInterval(*AS).print(dbgs(), TRI);
485 dbgs() << "Extending: ";
486 IntB.print(dbgs(), TRI);
489 SlotIndex FillerStart = ValLR->end, FillerEnd = BLR->start;
490 // We are about to delete CopyMI, so need to remove it as the 'instruction
491 // that defines this value #'. Update the valnum with the new defining
493 BValNo->def = FillerStart;
495 // Okay, we can merge them. We need to insert a new liverange:
496 // [ValLR.end, BLR.begin) of either value number, then we merge the
497 // two value numbers.
498 IntB.addRange(LiveRange(FillerStart, FillerEnd, BValNo));
500 // If the IntB live range is assigned to a physical register, and if that
501 // physreg has sub-registers, update their live intervals as well.
502 if (TargetRegisterInfo::isPhysicalRegister(IntB.reg)) {
503 for (const uint16_t *SR = TRI->getSubRegisters(IntB.reg); *SR; ++SR) {
504 if (!LIS->hasInterval(*SR))
506 LiveInterval &SRLI = LIS->getInterval(*SR);
507 SRLI.addRange(LiveRange(FillerStart, FillerEnd,
508 SRLI.getNextValue(FillerStart,
509 LIS->getVNInfoAllocator())));
513 // Okay, merge "B1" into the same value number as "B0".
514 if (BValNo != ValLR->valno) {
515 // If B1 is killed by a PHI, then the merged live range must also be killed
516 // by the same PHI, as B0 and B1 can not overlap.
517 bool HasPHIKill = BValNo->hasPHIKill();
518 IntB.MergeValueNumberInto(BValNo, ValLR->valno);
520 ValLR->valno->setHasPHIKill(true);
523 dbgs() << " result = ";
524 IntB.print(dbgs(), TRI);
528 // If the source instruction was killing the source register before the
529 // merge, unset the isKill marker given the live range has been extended.
530 int UIdx = ValLREndInst->findRegisterUseOperandIdx(IntB.reg, true);
532 ValLREndInst->getOperand(UIdx).setIsKill(false);
535 // Rewrite the copy. If the copy instruction was killing the destination
536 // register before the merge, find the last use and trim the live range. That
537 // will also add the isKill marker.
538 CopyMI->substituteRegister(IntA.reg, IntB.reg, 0, *TRI);
539 if (ALR->end == CopyIdx)
540 LIS->shrinkToUses(&IntA);
546 /// hasOtherReachingDefs - Return true if there are definitions of IntB
547 /// other than BValNo val# that can reach uses of AValno val# of IntA.
548 bool RegisterCoalescer::hasOtherReachingDefs(LiveInterval &IntA,
552 for (LiveInterval::iterator AI = IntA.begin(), AE = IntA.end();
554 if (AI->valno != AValNo) continue;
555 LiveInterval::Ranges::iterator BI =
556 std::upper_bound(IntB.ranges.begin(), IntB.ranges.end(), AI->start);
557 if (BI != IntB.ranges.begin())
559 for (; BI != IntB.ranges.end() && AI->end >= BI->start; ++BI) {
560 if (BI->valno == BValNo)
562 if (BI->start <= AI->start && BI->end > AI->start)
564 if (BI->start > AI->start && BI->start < AI->end)
571 /// removeCopyByCommutingDef - We found a non-trivially-coalescable copy with
572 /// IntA being the source and IntB being the dest, thus this defines a value
573 /// number in IntB. If the source value number (in IntA) is defined by a
574 /// commutable instruction and its other operand is coalesced to the copy dest
575 /// register, see if we can transform the copy into a noop by commuting the
576 /// definition. For example,
578 /// A3 = op A2 B0<kill>
580 /// B1 = A3 <- this copy
582 /// = op A3 <- more uses
586 /// B2 = op B0 A2<kill>
588 /// B1 = B2 <- now an identify copy
590 /// = op B2 <- more uses
592 /// This returns true if an interval was modified.
594 bool RegisterCoalescer::removeCopyByCommutingDef(const CoalescerPair &CP,
595 MachineInstr *CopyMI) {
596 // FIXME: For now, only eliminate the copy by commuting its def when the
597 // source register is a virtual register. We want to guard against cases
598 // where the copy is a back edge copy and commuting the def lengthen the
599 // live interval of the source register to the entire loop.
600 if (CP.isPhys() && CP.isFlipped())
603 // Bail if there is no dst interval.
604 if (!LIS->hasInterval(CP.getDstReg()))
607 SlotIndex CopyIdx = LIS->getInstructionIndex(CopyMI).getRegSlot();
610 LIS->getInterval(CP.isFlipped() ? CP.getDstReg() : CP.getSrcReg());
612 LIS->getInterval(CP.isFlipped() ? CP.getSrcReg() : CP.getDstReg());
614 // BValNo is a value number in B that is defined by a copy from A. 'B3' in
615 // the example above.
616 VNInfo *BValNo = IntB.getVNInfoAt(CopyIdx);
617 if (!BValNo || BValNo->def != CopyIdx)
620 assert(BValNo->def == CopyIdx && "Copy doesn't define the value?");
622 // AValNo is the value number in A that defines the copy, A3 in the example.
623 VNInfo *AValNo = IntA.getVNInfoAt(CopyIdx.getRegSlot(true));
624 assert(AValNo && "COPY source not live");
626 // If other defs can reach uses of this def, then it's not safe to perform
628 if (AValNo->isPHIDef() || AValNo->isUnused() || AValNo->hasPHIKill())
630 MachineInstr *DefMI = LIS->getInstructionFromIndex(AValNo->def);
633 if (!DefMI->isCommutable())
635 // If DefMI is a two-address instruction then commuting it will change the
636 // destination register.
637 int DefIdx = DefMI->findRegisterDefOperandIdx(IntA.reg);
638 assert(DefIdx != -1);
640 if (!DefMI->isRegTiedToUseOperand(DefIdx, &UseOpIdx))
642 unsigned Op1, Op2, NewDstIdx;
643 if (!TII->findCommutedOpIndices(DefMI, Op1, Op2))
647 else if (Op2 == UseOpIdx)
652 MachineOperand &NewDstMO = DefMI->getOperand(NewDstIdx);
653 unsigned NewReg = NewDstMO.getReg();
654 if (NewReg != IntB.reg || !NewDstMO.isKill())
657 // Make sure there are no other definitions of IntB that would reach the
658 // uses which the new definition can reach.
659 if (hasOtherReachingDefs(IntA, IntB, AValNo, BValNo))
662 // Abort if the aliases of IntB.reg have values that are not simply the
663 // clobbers from the superreg.
664 if (TargetRegisterInfo::isPhysicalRegister(IntB.reg))
665 for (const uint16_t *AS = TRI->getAliasSet(IntB.reg); *AS; ++AS)
666 if (LIS->hasInterval(*AS) &&
667 hasOtherReachingDefs(IntA, LIS->getInterval(*AS), AValNo, 0))
670 // If some of the uses of IntA.reg is already coalesced away, return false.
671 // It's not possible to determine whether it's safe to perform the coalescing.
672 for (MachineRegisterInfo::use_nodbg_iterator UI =
673 MRI->use_nodbg_begin(IntA.reg),
674 UE = MRI->use_nodbg_end(); UI != UE; ++UI) {
675 MachineInstr *UseMI = &*UI;
676 SlotIndex UseIdx = LIS->getInstructionIndex(UseMI);
677 LiveInterval::iterator ULR = IntA.FindLiveRangeContaining(UseIdx);
678 if (ULR == IntA.end())
680 if (ULR->valno == AValNo && JoinedCopies.count(UseMI))
684 DEBUG(dbgs() << "\tremoveCopyByCommutingDef: " << AValNo->def << '\t'
687 // At this point we have decided that it is legal to do this
688 // transformation. Start by commuting the instruction.
689 MachineBasicBlock *MBB = DefMI->getParent();
690 MachineInstr *NewMI = TII->commuteInstruction(DefMI);
693 if (TargetRegisterInfo::isVirtualRegister(IntA.reg) &&
694 TargetRegisterInfo::isVirtualRegister(IntB.reg) &&
695 !MRI->constrainRegClass(IntB.reg, MRI->getRegClass(IntA.reg)))
697 if (NewMI != DefMI) {
698 LIS->ReplaceMachineInstrInMaps(DefMI, NewMI);
699 MachineBasicBlock::iterator Pos = DefMI;
700 MBB->insert(Pos, NewMI);
703 unsigned OpIdx = NewMI->findRegisterUseOperandIdx(IntA.reg, false);
704 NewMI->getOperand(OpIdx).setIsKill();
706 // If ALR and BLR overlaps and end of BLR extends beyond end of ALR, e.g.
715 // Update uses of IntA of the specific Val# with IntB.
716 for (MachineRegisterInfo::use_iterator UI = MRI->use_begin(IntA.reg),
717 UE = MRI->use_end(); UI != UE;) {
718 MachineOperand &UseMO = UI.getOperand();
719 MachineInstr *UseMI = &*UI;
721 if (JoinedCopies.count(UseMI))
723 if (UseMI->isDebugValue()) {
724 // FIXME These don't have an instruction index. Not clear we have enough
725 // info to decide whether to do this replacement or not. For now do it.
726 UseMO.setReg(NewReg);
729 SlotIndex UseIdx = LIS->getInstructionIndex(UseMI).getRegSlot(true);
730 LiveInterval::iterator ULR = IntA.FindLiveRangeContaining(UseIdx);
731 if (ULR == IntA.end() || ULR->valno != AValNo)
733 if (TargetRegisterInfo::isPhysicalRegister(NewReg))
734 UseMO.substPhysReg(NewReg, *TRI);
736 UseMO.setReg(NewReg);
739 if (!UseMI->isCopy())
741 if (UseMI->getOperand(0).getReg() != IntB.reg ||
742 UseMI->getOperand(0).getSubReg())
745 // This copy will become a noop. If it's defining a new val#, merge it into
747 SlotIndex DefIdx = UseIdx.getRegSlot();
748 VNInfo *DVNI = IntB.getVNInfoAt(DefIdx);
751 DEBUG(dbgs() << "\t\tnoop: " << DefIdx << '\t' << *UseMI);
752 assert(DVNI->def == DefIdx);
753 BValNo = IntB.MergeValueNumberInto(BValNo, DVNI);
757 // Extend BValNo by merging in IntA live ranges of AValNo. Val# definition
759 VNInfo *ValNo = BValNo;
760 ValNo->def = AValNo->def;
761 for (LiveInterval::iterator AI = IntA.begin(), AE = IntA.end();
763 if (AI->valno != AValNo) continue;
764 IntB.addRange(LiveRange(AI->start, AI->end, ValNo));
766 DEBUG(dbgs() << "\t\textended: " << IntB << '\n');
768 IntA.removeValNo(AValNo);
769 DEBUG(dbgs() << "\t\ttrimmed: " << IntA << '\n');
774 /// reMaterializeTrivialDef - If the source of a copy is defined by a trivial
775 /// computation, replace the copy by rematerialize the definition.
776 bool RegisterCoalescer::reMaterializeTrivialDef(LiveInterval &SrcInt,
779 MachineInstr *CopyMI) {
780 SlotIndex CopyIdx = LIS->getInstructionIndex(CopyMI).getRegSlot(true);
781 LiveInterval::iterator SrcLR = SrcInt.FindLiveRangeContaining(CopyIdx);
782 assert(SrcLR != SrcInt.end() && "Live range not found!");
783 VNInfo *ValNo = SrcLR->valno;
784 if (ValNo->isPHIDef() || ValNo->isUnused())
786 MachineInstr *DefMI = LIS->getInstructionFromIndex(ValNo->def);
789 assert(DefMI && "Defining instruction disappeared");
790 if (!DefMI->isAsCheapAsAMove())
792 if (!TII->isTriviallyReMaterializable(DefMI, AA))
794 bool SawStore = false;
795 if (!DefMI->isSafeToMove(TII, AA, SawStore))
797 const MCInstrDesc &MCID = DefMI->getDesc();
798 if (MCID.getNumDefs() != 1)
800 if (!DefMI->isImplicitDef()) {
801 // Make sure the copy destination register class fits the instruction
802 // definition register class. The mismatch can happen as a result of earlier
803 // extract_subreg, insert_subreg, subreg_to_reg coalescing.
804 const TargetRegisterClass *RC = TII->getRegClass(MCID, 0, TRI, *MF);
805 if (TargetRegisterInfo::isVirtualRegister(DstReg)) {
806 if (MRI->getRegClass(DstReg) != RC)
808 } else if (!RC->contains(DstReg))
812 MachineBasicBlock *MBB = CopyMI->getParent();
813 MachineBasicBlock::iterator MII =
814 llvm::next(MachineBasicBlock::iterator(CopyMI));
815 TII->reMaterialize(*MBB, MII, DstReg, 0, DefMI, *TRI);
816 MachineInstr *NewMI = prior(MII);
818 // NewMI may have dead implicit defs (E.g. EFLAGS for MOV<bits>r0 on X86).
819 // We need to remember these so we can add intervals once we insert
820 // NewMI into SlotIndexes.
821 SmallVector<unsigned, 4> NewMIImplDefs;
822 for (unsigned i = NewMI->getDesc().getNumOperands(),
823 e = NewMI->getNumOperands(); i != e; ++i) {
824 MachineOperand &MO = NewMI->getOperand(i);
826 assert(MO.isDef() && MO.isImplicit() && MO.isDead() &&
827 TargetRegisterInfo::isPhysicalRegister(MO.getReg()));
828 NewMIImplDefs.push_back(MO.getReg());
832 // CopyMI may have implicit operands, transfer them over to the newly
833 // rematerialized instruction. And update implicit def interval valnos.
834 for (unsigned i = CopyMI->getDesc().getNumOperands(),
835 e = CopyMI->getNumOperands(); i != e; ++i) {
836 MachineOperand &MO = CopyMI->getOperand(i);
838 assert(MO.isImplicit() && "No explicit operands after implict operands.");
839 // Discard VReg implicit defs.
840 if (TargetRegisterInfo::isPhysicalRegister(MO.getReg())) {
841 NewMI->addOperand(MO);
846 LIS->ReplaceMachineInstrInMaps(CopyMI, NewMI);
848 SlotIndex NewMIIdx = LIS->getInstructionIndex(NewMI);
849 for (unsigned i = 0, e = NewMIImplDefs.size(); i != e; ++i) {
850 unsigned reg = NewMIImplDefs[i];
851 LiveInterval &li = LIS->getInterval(reg);
852 VNInfo *DeadDefVN = li.getNextValue(NewMIIdx.getRegSlot(),
853 LIS->getVNInfoAllocator());
854 LiveRange lr(NewMIIdx.getRegSlot(), NewMIIdx.getDeadSlot(), DeadDefVN);
858 CopyMI->eraseFromParent();
859 ReMatCopies.insert(CopyMI);
860 ReMatDefs.insert(DefMI);
861 DEBUG(dbgs() << "Remat: " << *NewMI);
864 // The source interval can become smaller because we removed a use.
866 LIS->shrinkToUses(&SrcInt);
871 /// eliminateUndefCopy - ProcessImpicitDefs may leave some copies of <undef>
872 /// values, it only removes local variables. When we have a copy like:
874 /// %vreg1 = COPY %vreg2<undef>
876 /// We delete the copy and remove the corresponding value number from %vreg1.
877 /// Any uses of that value number are marked as <undef>.
878 bool RegisterCoalescer::eliminateUndefCopy(MachineInstr *CopyMI,
879 const CoalescerPair &CP) {
880 SlotIndex Idx = LIS->getInstructionIndex(CopyMI);
881 LiveInterval *SrcInt = &LIS->getInterval(CP.getSrcReg());
882 if (SrcInt->liveAt(Idx))
884 LiveInterval *DstInt = &LIS->getInterval(CP.getDstReg());
885 if (DstInt->liveAt(Idx))
888 // No intervals are live-in to CopyMI - it is undef.
893 VNInfo *DeadVNI = DstInt->getVNInfoAt(Idx.getRegSlot());
894 assert(DeadVNI && "No value defined in DstInt");
895 DstInt->removeValNo(DeadVNI);
897 // Find new undef uses.
898 for (MachineRegisterInfo::reg_nodbg_iterator
899 I = MRI->reg_nodbg_begin(DstInt->reg), E = MRI->reg_nodbg_end();
901 MachineOperand &MO = I.getOperand();
902 if (MO.isDef() || MO.isUndef())
904 MachineInstr *MI = MO.getParent();
905 SlotIndex Idx = LIS->getInstructionIndex(MI);
906 if (DstInt->liveAt(Idx))
909 DEBUG(dbgs() << "\tnew undef: " << Idx << '\t' << *MI);
914 /// updateRegDefsUses - Replace all defs and uses of SrcReg to DstReg and
915 /// update the subregister number if it is not zero. If DstReg is a
916 /// physical register and the existing subregister number of the def / use
917 /// being updated is not zero, make sure to set it to the correct physical
919 void RegisterCoalescer::updateRegDefsUses(unsigned SrcReg,
922 bool DstIsPhys = TargetRegisterInfo::isPhysicalRegister(DstReg);
924 // Update LiveDebugVariables.
925 LDV->renameRegister(SrcReg, DstReg, SubIdx);
927 for (MachineRegisterInfo::reg_iterator I = MRI->reg_begin(SrcReg);
928 MachineInstr *UseMI = I.skipInstruction();) {
929 // A PhysReg copy that won't be coalesced can perhaps be rematerialized
932 if (UseMI->isFullCopy() &&
933 UseMI->getOperand(1).getReg() == SrcReg &&
934 UseMI->getOperand(0).getReg() != SrcReg &&
935 UseMI->getOperand(0).getReg() != DstReg &&
936 !JoinedCopies.count(UseMI) &&
937 reMaterializeTrivialDef(LIS->getInterval(SrcReg), false,
938 UseMI->getOperand(0).getReg(), UseMI))
942 SmallVector<unsigned,8> Ops;
944 tie(Reads, Writes) = UseMI->readsWritesVirtualRegister(SrcReg, &Ops);
946 // Replace SrcReg with DstReg in all UseMI operands.
947 for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
948 MachineOperand &MO = UseMI->getOperand(Ops[i]);
950 // Make sure we don't create read-modify-write defs accidentally. We
951 // assume here that a SrcReg def cannot be joined into a live DstReg. If
952 // RegisterCoalescer starts tracking partially live registers, we will
953 // need to check the actual LiveInterval to determine if DstReg is live
955 if (SubIdx && !Reads)
959 MO.substPhysReg(DstReg, *TRI);
961 MO.substVirtReg(DstReg, SubIdx, *TRI);
964 // This instruction is a copy that will be removed.
965 if (JoinedCopies.count(UseMI))
969 dbgs() << "\t\tupdated: ";
970 if (!UseMI->isDebugValue())
971 dbgs() << LIS->getInstructionIndex(UseMI) << "\t";
977 /// removeIntervalIfEmpty - Check if the live interval of a physical register
978 /// is empty, if so remove it and also remove the empty intervals of its
979 /// sub-registers. Return true if live interval is removed.
980 static bool removeIntervalIfEmpty(LiveInterval &li, LiveIntervals *LIS,
981 const TargetRegisterInfo *TRI) {
983 if (TargetRegisterInfo::isPhysicalRegister(li.reg))
984 for (const uint16_t* SR = TRI->getSubRegisters(li.reg); *SR; ++SR) {
985 if (!LIS->hasInterval(*SR))
987 LiveInterval &sli = LIS->getInterval(*SR);
989 LIS->removeInterval(*SR);
991 LIS->removeInterval(li.reg);
997 /// removeDeadDef - If a def of a live interval is now determined dead, remove
998 /// the val# it defines. If the live interval becomes empty, remove it as well.
999 bool RegisterCoalescer::removeDeadDef(LiveInterval &li, MachineInstr *DefMI) {
1000 SlotIndex DefIdx = LIS->getInstructionIndex(DefMI).getRegSlot();
1001 LiveInterval::iterator MLR = li.FindLiveRangeContaining(DefIdx);
1002 if (DefIdx != MLR->valno->def)
1004 li.removeValNo(MLR->valno);
1005 return removeIntervalIfEmpty(li, LIS, TRI);
1008 /// shouldJoinPhys - Return true if a copy involving a physreg should be joined.
1009 /// We need to be careful about coalescing a source physical register with a
1010 /// virtual register. Once the coalescing is done, it cannot be broken and these
1011 /// are not spillable! If the destination interval uses are far away, think
1012 /// twice about coalescing them!
1013 bool RegisterCoalescer::shouldJoinPhys(CoalescerPair &CP) {
1014 bool Allocatable = LIS->isAllocatable(CP.getDstReg());
1015 LiveInterval &JoinVInt = LIS->getInterval(CP.getSrcReg());
1017 /// Always join simple intervals that are defined by a single copy from a
1018 /// reserved register. This doesn't increase register pressure, so it is
1019 /// always beneficial.
1020 if (!Allocatable && CP.isFlipped() && JoinVInt.containsOneValue())
1023 if (!EnablePhysicalJoin) {
1024 DEBUG(dbgs() << "\tPhysreg joins disabled.\n");
1028 // Only coalesce to allocatable physreg, we don't want to risk modifying
1029 // reserved registers.
1031 DEBUG(dbgs() << "\tRegister is an unallocatable physreg.\n");
1032 return false; // Not coalescable.
1035 // Don't join with physregs that have a ridiculous number of live
1036 // ranges. The data structure performance is really bad when that
1038 if (LIS->hasInterval(CP.getDstReg()) &&
1039 LIS->getInterval(CP.getDstReg()).ranges.size() > 1000) {
1042 << "\tPhysical register live interval too complicated, abort!\n");
1046 // FIXME: Why are we skipping this test for partial copies?
1047 // CodeGen/X86/phys_subreg_coalesce-3.ll needs it.
1048 if (!CP.isPartial()) {
1049 const TargetRegisterClass *RC = MRI->getRegClass(CP.getSrcReg());
1050 unsigned Threshold = RegClassInfo.getNumAllocatableRegs(RC) * 2;
1051 unsigned Length = LIS->getApproximateInstructionCount(JoinVInt);
1052 if (Length > Threshold) {
1054 DEBUG(dbgs() << "\tMay tie down a physical register, abort!\n");
1062 /// joinCopy - Attempt to join intervals corresponding to SrcReg/DstReg,
1063 /// which are the src/dst of the copy instruction CopyMI. This returns true
1064 /// if the copy was successfully coalesced away. If it is not currently
1065 /// possible to coalesce this interval, but it may be possible if other
1066 /// things get coalesced, then it returns true by reference in 'Again'.
1067 bool RegisterCoalescer::joinCopy(MachineInstr *CopyMI, bool &Again) {
1070 if (JoinedCopies.count(CopyMI) || ReMatCopies.count(CopyMI))
1071 return false; // Already done.
1073 DEBUG(dbgs() << LIS->getInstructionIndex(CopyMI) << '\t' << *CopyMI);
1075 CoalescerPair CP(*TII, *TRI);
1076 if (!CP.setRegisters(CopyMI)) {
1077 DEBUG(dbgs() << "\tNot coalescable.\n");
1081 // If they are already joined we continue.
1082 if (CP.getSrcReg() == CP.getDstReg()) {
1083 markAsJoined(CopyMI);
1084 DEBUG(dbgs() << "\tCopy already coalesced.\n");
1085 return false; // Not coalescable.
1088 // Eliminate undefs.
1089 if (!CP.isPhys() && eliminateUndefCopy(CopyMI, CP)) {
1090 markAsJoined(CopyMI);
1091 DEBUG(dbgs() << "\tEliminated copy of <undef> value.\n");
1092 return false; // Not coalescable.
1095 // Enforce policies.
1097 DEBUG(dbgs() << "\tConsidering merging " << PrintReg(CP.getSrcReg(), TRI)
1098 << " with " << PrintReg(CP.getDstReg(), TRI, CP.getSrcIdx())
1100 if (!shouldJoinPhys(CP)) {
1101 // Before giving up coalescing, if definition of source is defined by
1102 // trivial computation, try rematerializing it.
1103 if (!CP.isFlipped() &&
1104 reMaterializeTrivialDef(LIS->getInterval(CP.getSrcReg()), true,
1105 CP.getDstReg(), CopyMI))
1111 dbgs() << "\tConsidering merging to " << CP.getNewRC()->getName()
1113 if (CP.getDstIdx() && CP.getSrcIdx())
1114 dbgs() << PrintReg(CP.getDstReg()) << " in "
1115 << TRI->getSubRegIndexName(CP.getDstIdx()) << " and "
1116 << PrintReg(CP.getSrcReg()) << " in "
1117 << TRI->getSubRegIndexName(CP.getSrcIdx()) << '\n';
1119 dbgs() << PrintReg(CP.getSrcReg(), TRI) << " in "
1120 << PrintReg(CP.getDstReg(), TRI, CP.getSrcIdx()) << '\n';
1123 // When possible, let DstReg be the larger interval.
1124 if (!CP.isPartial() && LIS->getInterval(CP.getSrcReg()).ranges.size() >
1125 LIS->getInterval(CP.getDstReg()).ranges.size())
1129 // Okay, attempt to join these two intervals. On failure, this returns false.
1130 // Otherwise, if one of the intervals being joined is a physreg, this method
1131 // always canonicalizes DstInt to be it. The output "SrcInt" will not have
1132 // been modified, so we can use this information below to update aliases.
1133 if (!joinIntervals(CP)) {
1134 // Coalescing failed.
1136 // If definition of source is defined by trivial computation, try
1137 // rematerializing it.
1138 if (!CP.isFlipped() &&
1139 reMaterializeTrivialDef(LIS->getInterval(CP.getSrcReg()), true,
1140 CP.getDstReg(), CopyMI))
1143 // If we can eliminate the copy without merging the live ranges, do so now.
1144 if (!CP.isPartial()) {
1145 if (adjustCopiesBackFrom(CP, CopyMI) ||
1146 removeCopyByCommutingDef(CP, CopyMI)) {
1147 markAsJoined(CopyMI);
1148 DEBUG(dbgs() << "\tTrivial!\n");
1153 // Otherwise, we are unable to join the intervals.
1154 DEBUG(dbgs() << "\tInterference!\n");
1155 Again = true; // May be possible to coalesce later.
1159 // Coalescing to a virtual register that is of a sub-register class of the
1160 // other. Make sure the resulting register is set to the right register class.
1161 if (CP.isCrossClass()) {
1163 MRI->setRegClass(CP.getDstReg(), CP.getNewRC());
1166 // Remember to delete the copy instruction.
1167 markAsJoined(CopyMI);
1169 // Rewrite all SrcReg operands to DstReg.
1170 // Also update DstReg operands to include DstIdx if it is set.
1172 updateRegDefsUses(CP.getDstReg(), CP.getDstReg(), CP.getDstIdx());
1173 updateRegDefsUses(CP.getSrcReg(), CP.getDstReg(), CP.getSrcIdx());
1175 // If we have extended the live range of a physical register, make sure we
1176 // update live-in lists as well.
1178 SmallVector<MachineBasicBlock*, 16> BlockSeq;
1179 // joinIntervals invalidates the VNInfos in SrcInt, but we only need the
1180 // ranges for this, and they are preserved.
1181 LiveInterval &SrcInt = LIS->getInterval(CP.getSrcReg());
1182 for (LiveInterval::const_iterator I = SrcInt.begin(), E = SrcInt.end();
1184 LIS->findLiveInMBBs(I->start, I->end, BlockSeq);
1185 for (unsigned idx = 0, size = BlockSeq.size(); idx != size; ++idx) {
1186 MachineBasicBlock &block = *BlockSeq[idx];
1187 if (!block.isLiveIn(CP.getDstReg()))
1188 block.addLiveIn(CP.getDstReg());
1194 // SrcReg is guaranteed to be the register whose live interval that is
1196 LIS->removeInterval(CP.getSrcReg());
1198 // Update regalloc hint.
1199 TRI->UpdateRegAllocHint(CP.getSrcReg(), CP.getDstReg(), *MF);
1202 LiveInterval &DstInt = LIS->getInterval(CP.getDstReg());
1203 dbgs() << "\tJoined. Result = ";
1204 DstInt.print(dbgs(), TRI);
1212 /// Attempt joining with a reserved physreg.
1213 bool RegisterCoalescer::joinReservedPhysReg(CoalescerPair &CP) {
1214 assert(CP.isPhys() && "Must be a physreg copy");
1215 assert(RegClassInfo.isReserved(CP.getDstReg()) && "Not a reserved register");
1216 LiveInterval &RHS = LIS->getInterval(CP.getSrcReg());
1217 DEBUG({ dbgs() << "\t\tRHS = "; RHS.print(dbgs(), TRI); dbgs() << "\n"; });
1219 assert(CP.isFlipped() && RHS.containsOneValue() &&
1220 "Invalid join with reserved register");
1222 // Optimization for reserved registers like ESP. We can only merge with a
1223 // reserved physreg if RHS has a single value that is a copy of CP.DstReg().
1224 // The live range of the reserved register will look like a set of dead defs
1225 // - we don't properly track the live range of reserved registers.
1227 // Deny any overlapping intervals. This depends on all the reserved
1228 // register live ranges to look like dead defs.
1229 for (const uint16_t *AS = TRI->getOverlaps(CP.getDstReg()); *AS; ++AS) {
1230 if (!LIS->hasInterval(*AS)) {
1231 // Make sure at least DstReg itself exists before attempting a join.
1232 if (*AS == CP.getDstReg())
1233 LIS->getOrCreateInterval(CP.getDstReg());
1236 if (RHS.overlaps(LIS->getInterval(*AS))) {
1237 DEBUG(dbgs() << "\t\tInterference: " << PrintReg(*AS, TRI) << '\n');
1241 // Skip any value computations, we are not adding new values to the
1242 // reserved register. Also skip merging the live ranges, the reserved
1243 // register live range doesn't need to be accurate as long as all the
1248 bool RegisterCoalescer::canJoinPhysReg(CoalescerPair &CP) {
1249 assert(CP.isPhys() && "Must be a physreg copy");
1250 // If a live interval is a physical register, check for interference with any
1251 // aliases. The interference check implemented here is a bit more
1252 // conservative than the full interfeence check below. We allow overlapping
1253 // live ranges only when one is a copy of the other.
1254 LiveInterval &RHS = LIS->getInterval(CP.getSrcReg());
1255 DEBUG({ dbgs() << "\t\tRHS = "; RHS.print(dbgs(), TRI); dbgs() << "\n"; });
1257 // Check if a register mask clobbers DstReg.
1258 BitVector UsableRegs;
1259 if (LIS->checkRegMaskInterference(RHS, UsableRegs) &&
1260 !UsableRegs.test(CP.getDstReg())) {
1261 DEBUG(dbgs() << "\t\tRegister mask interference.\n");
1265 for (const uint16_t *AS = TRI->getAliasSet(CP.getDstReg()); *AS; ++AS){
1266 if (!LIS->hasInterval(*AS))
1268 const LiveInterval &LHS = LIS->getInterval(*AS);
1269 LiveInterval::const_iterator LI = LHS.begin();
1270 for (LiveInterval::const_iterator RI = RHS.begin(), RE = RHS.end();
1272 LI = std::lower_bound(LI, LHS.end(), RI->start);
1273 // Does LHS have an overlapping live range starting before RI?
1274 if ((LI != LHS.begin() && LI[-1].end > RI->start) &&
1275 (RI->start != RI->valno->def ||
1276 !CP.isCoalescable(LIS->getInstructionFromIndex(RI->start)))) {
1278 dbgs() << "\t\tInterference from alias: ";
1279 LHS.print(dbgs(), TRI);
1280 dbgs() << "\n\t\tOverlap at " << RI->start << " and no copy.\n";
1285 // Check that LHS ranges beginning in this range are copies.
1286 for (; LI != LHS.end() && LI->start < RI->end; ++LI) {
1287 if (LI->start != LI->valno->def ||
1288 !CP.isCoalescable(LIS->getInstructionFromIndex(LI->start))) {
1290 dbgs() << "\t\tInterference from alias: ";
1291 LHS.print(dbgs(), TRI);
1292 dbgs() << "\n\t\tDef at " << LI->start << " is not a copy.\n";
1302 /// ComputeUltimateVN - Assuming we are going to join two live intervals,
1303 /// compute what the resultant value numbers for each value in the input two
1304 /// ranges will be. This is complicated by copies between the two which can
1305 /// and will commonly cause multiple value numbers to be merged into one.
1307 /// VN is the value number that we're trying to resolve. InstDefiningValue
1308 /// keeps track of the new InstDefiningValue assignment for the result
1309 /// LiveInterval. ThisFromOther/OtherFromThis are sets that keep track of
1310 /// whether a value in this or other is a copy from the opposite set.
1311 /// ThisValNoAssignments/OtherValNoAssignments keep track of value #'s that have
1312 /// already been assigned.
1314 /// ThisFromOther[x] - If x is defined as a copy from the other interval, this
1315 /// contains the value number the copy is from.
1317 static unsigned ComputeUltimateVN(VNInfo *VNI,
1318 SmallVector<VNInfo*, 16> &NewVNInfo,
1319 DenseMap<VNInfo*, VNInfo*> &ThisFromOther,
1320 DenseMap<VNInfo*, VNInfo*> &OtherFromThis,
1321 SmallVector<int, 16> &ThisValNoAssignments,
1322 SmallVector<int, 16> &OtherValNoAssignments) {
1323 unsigned VN = VNI->id;
1325 // If the VN has already been computed, just return it.
1326 if (ThisValNoAssignments[VN] >= 0)
1327 return ThisValNoAssignments[VN];
1328 assert(ThisValNoAssignments[VN] != -2 && "Cyclic value numbers");
1330 // If this val is not a copy from the other val, then it must be a new value
1331 // number in the destination.
1332 DenseMap<VNInfo*, VNInfo*>::iterator I = ThisFromOther.find(VNI);
1333 if (I == ThisFromOther.end()) {
1334 NewVNInfo.push_back(VNI);
1335 return ThisValNoAssignments[VN] = NewVNInfo.size()-1;
1337 VNInfo *OtherValNo = I->second;
1339 // Otherwise, this *is* a copy from the RHS. If the other side has already
1340 // been computed, return it.
1341 if (OtherValNoAssignments[OtherValNo->id] >= 0)
1342 return ThisValNoAssignments[VN] = OtherValNoAssignments[OtherValNo->id];
1344 // Mark this value number as currently being computed, then ask what the
1345 // ultimate value # of the other value is.
1346 ThisValNoAssignments[VN] = -2;
1347 unsigned UltimateVN =
1348 ComputeUltimateVN(OtherValNo, NewVNInfo, OtherFromThis, ThisFromOther,
1349 OtherValNoAssignments, ThisValNoAssignments);
1350 return ThisValNoAssignments[VN] = UltimateVN;
1354 // Find out if we have something like
1357 // if so, we can pretend this is actually
1360 // which allows us to coalesce A and B.
1361 // VNI is the definition of B. LR is the life range of A that includes
1362 // the slot just before B. If we return true, we add "B = X" to DupCopies.
1363 // This implies that A dominates B.
1364 static bool RegistersDefinedFromSameValue(LiveIntervals &li,
1365 const TargetRegisterInfo &tri,
1369 SmallVector<MachineInstr*, 8> &DupCopies) {
1370 // FIXME: This is very conservative. For example, we don't handle
1371 // physical registers.
1373 MachineInstr *MI = li.getInstructionFromIndex(VNI->def);
1375 if (!MI || !MI->isFullCopy() || CP.isPartial() || CP.isPhys())
1378 unsigned Dst = MI->getOperand(0).getReg();
1379 unsigned Src = MI->getOperand(1).getReg();
1381 if (!TargetRegisterInfo::isVirtualRegister(Src) ||
1382 !TargetRegisterInfo::isVirtualRegister(Dst))
1385 unsigned A = CP.getDstReg();
1386 unsigned B = CP.getSrcReg();
1392 VNInfo *Other = LR->valno;
1393 const MachineInstr *OtherMI = li.getInstructionFromIndex(Other->def);
1395 if (!OtherMI || !OtherMI->isFullCopy())
1398 unsigned OtherDst = OtherMI->getOperand(0).getReg();
1399 unsigned OtherSrc = OtherMI->getOperand(1).getReg();
1401 if (!TargetRegisterInfo::isVirtualRegister(OtherSrc) ||
1402 !TargetRegisterInfo::isVirtualRegister(OtherDst))
1405 assert(OtherDst == B);
1407 if (Src != OtherSrc)
1410 // If the copies use two different value numbers of X, we cannot merge
1412 LiveInterval &SrcInt = li.getInterval(Src);
1413 // getVNInfoBefore returns NULL for undef copies. In this case, the
1414 // optimization is still safe.
1415 if (SrcInt.getVNInfoBefore(Other->def) != SrcInt.getVNInfoBefore(VNI->def))
1418 DupCopies.push_back(MI);
1423 /// joinIntervals - Attempt to join these two intervals. On failure, this
1425 bool RegisterCoalescer::joinIntervals(CoalescerPair &CP) {
1426 // Handle physreg joins separately.
1428 if (RegClassInfo.isReserved(CP.getDstReg()))
1429 return joinReservedPhysReg(CP);
1430 if (!canJoinPhysReg(CP))
1434 LiveInterval &RHS = LIS->getInterval(CP.getSrcReg());
1435 DEBUG({ dbgs() << "\t\tRHS = "; RHS.print(dbgs(), TRI); dbgs() << "\n"; });
1437 // Compute the final value assignment, assuming that the live ranges can be
1439 SmallVector<int, 16> LHSValNoAssignments;
1440 SmallVector<int, 16> RHSValNoAssignments;
1441 DenseMap<VNInfo*, VNInfo*> LHSValsDefinedFromRHS;
1442 DenseMap<VNInfo*, VNInfo*> RHSValsDefinedFromLHS;
1443 SmallVector<VNInfo*, 16> NewVNInfo;
1445 SmallVector<MachineInstr*, 8> DupCopies;
1447 LiveInterval &LHS = LIS->getOrCreateInterval(CP.getDstReg());
1448 DEBUG({ dbgs() << "\t\tLHS = "; LHS.print(dbgs(), TRI); dbgs() << "\n"; });
1450 // Loop over the value numbers of the LHS, seeing if any are defined from
1452 for (LiveInterval::vni_iterator i = LHS.vni_begin(), e = LHS.vni_end();
1455 if (VNI->isUnused() || VNI->isPHIDef())
1457 MachineInstr *MI = LIS->getInstructionFromIndex(VNI->def);
1458 assert(MI && "Missing def");
1459 if (!MI->isCopyLike()) // Src not defined by a copy?
1462 // Figure out the value # from the RHS.
1463 LiveRange *lr = RHS.getLiveRangeContaining(VNI->def.getPrevSlot());
1464 // The copy could be to an aliased physreg.
1467 // DstReg is known to be a register in the LHS interval. If the src is
1468 // from the RHS interval, we can use its value #.
1469 if (!CP.isCoalescable(MI) &&
1470 !RegistersDefinedFromSameValue(*LIS, *TRI, CP, VNI, lr, DupCopies))
1473 LHSValsDefinedFromRHS[VNI] = lr->valno;
1476 // Loop over the value numbers of the RHS, seeing if any are defined from
1478 for (LiveInterval::vni_iterator i = RHS.vni_begin(), e = RHS.vni_end();
1481 if (VNI->isUnused() || VNI->isPHIDef())
1483 MachineInstr *MI = LIS->getInstructionFromIndex(VNI->def);
1484 assert(MI && "Missing def");
1485 if (!MI->isCopyLike()) // Src not defined by a copy?
1488 // Figure out the value # from the LHS.
1489 LiveRange *lr = LHS.getLiveRangeContaining(VNI->def.getPrevSlot());
1490 // The copy could be to an aliased physreg.
1493 // DstReg is known to be a register in the RHS interval. If the src is
1494 // from the LHS interval, we can use its value #.
1495 if (!CP.isCoalescable(MI) &&
1496 !RegistersDefinedFromSameValue(*LIS, *TRI, CP, VNI, lr, DupCopies))
1499 RHSValsDefinedFromLHS[VNI] = lr->valno;
1502 LHSValNoAssignments.resize(LHS.getNumValNums(), -1);
1503 RHSValNoAssignments.resize(RHS.getNumValNums(), -1);
1504 NewVNInfo.reserve(LHS.getNumValNums() + RHS.getNumValNums());
1506 for (LiveInterval::vni_iterator i = LHS.vni_begin(), e = LHS.vni_end();
1509 unsigned VN = VNI->id;
1510 if (LHSValNoAssignments[VN] >= 0 || VNI->isUnused())
1512 ComputeUltimateVN(VNI, NewVNInfo,
1513 LHSValsDefinedFromRHS, RHSValsDefinedFromLHS,
1514 LHSValNoAssignments, RHSValNoAssignments);
1516 for (LiveInterval::vni_iterator i = RHS.vni_begin(), e = RHS.vni_end();
1519 unsigned VN = VNI->id;
1520 if (RHSValNoAssignments[VN] >= 0 || VNI->isUnused())
1522 // If this value number isn't a copy from the LHS, it's a new number.
1523 if (RHSValsDefinedFromLHS.find(VNI) == RHSValsDefinedFromLHS.end()) {
1524 NewVNInfo.push_back(VNI);
1525 RHSValNoAssignments[VN] = NewVNInfo.size()-1;
1529 ComputeUltimateVN(VNI, NewVNInfo,
1530 RHSValsDefinedFromLHS, LHSValsDefinedFromRHS,
1531 RHSValNoAssignments, LHSValNoAssignments);
1534 // Armed with the mappings of LHS/RHS values to ultimate values, walk the
1535 // interval lists to see if these intervals are coalescable.
1536 LiveInterval::const_iterator I = LHS.begin();
1537 LiveInterval::const_iterator IE = LHS.end();
1538 LiveInterval::const_iterator J = RHS.begin();
1539 LiveInterval::const_iterator JE = RHS.end();
1541 // Skip ahead until the first place of potential sharing.
1542 if (I != IE && J != JE) {
1543 if (I->start < J->start) {
1544 I = std::upper_bound(I, IE, J->start);
1545 if (I != LHS.begin()) --I;
1546 } else if (J->start < I->start) {
1547 J = std::upper_bound(J, JE, I->start);
1548 if (J != RHS.begin()) --J;
1552 while (I != IE && J != JE) {
1553 // Determine if these two live ranges overlap.
1555 if (I->start < J->start) {
1556 Overlaps = I->end > J->start;
1558 Overlaps = J->end > I->start;
1561 // If so, check value # info to determine if they are really different.
1563 // If the live range overlap will map to the same value number in the
1564 // result liverange, we can still coalesce them. If not, we can't.
1565 if (LHSValNoAssignments[I->valno->id] !=
1566 RHSValNoAssignments[J->valno->id])
1570 if (I->end < J->end)
1576 // Update kill info. Some live ranges are extended due to copy coalescing.
1577 for (DenseMap<VNInfo*, VNInfo*>::iterator I = LHSValsDefinedFromRHS.begin(),
1578 E = LHSValsDefinedFromRHS.end(); I != E; ++I) {
1579 VNInfo *VNI = I->first;
1580 unsigned LHSValID = LHSValNoAssignments[VNI->id];
1581 if (VNI->hasPHIKill())
1582 NewVNInfo[LHSValID]->setHasPHIKill(true);
1585 // Update kill info. Some live ranges are extended due to copy coalescing.
1586 for (DenseMap<VNInfo*, VNInfo*>::iterator I = RHSValsDefinedFromLHS.begin(),
1587 E = RHSValsDefinedFromLHS.end(); I != E; ++I) {
1588 VNInfo *VNI = I->first;
1589 unsigned RHSValID = RHSValNoAssignments[VNI->id];
1590 if (VNI->hasPHIKill())
1591 NewVNInfo[RHSValID]->setHasPHIKill(true);
1594 if (LHSValNoAssignments.empty())
1595 LHSValNoAssignments.push_back(-1);
1596 if (RHSValNoAssignments.empty())
1597 RHSValNoAssignments.push_back(-1);
1599 SmallVector<unsigned, 8> SourceRegisters;
1600 for (SmallVector<MachineInstr*, 8>::iterator I = DupCopies.begin(),
1601 E = DupCopies.end(); I != E; ++I) {
1602 MachineInstr *MI = *I;
1604 // We have pretended that the assignment to B in
1607 // was actually a copy from A. Now that we decided to coalesce A and B,
1608 // transform the code into
1611 // and mark the X as coalesced to keep the illusion.
1612 unsigned Src = MI->getOperand(1).getReg();
1613 SourceRegisters.push_back(Src);
1614 MI->getOperand(0).substVirtReg(Src, 0, *TRI);
1619 // If B = X was the last use of X in a liverange, we have to shrink it now
1620 // that B = X is gone.
1621 for (SmallVector<unsigned, 8>::iterator I = SourceRegisters.begin(),
1622 E = SourceRegisters.end(); I != E; ++I) {
1623 LIS->shrinkToUses(&LIS->getInterval(*I));
1626 // If we get here, we know that we can coalesce the live ranges. Ask the
1627 // intervals to coalesce themselves now.
1628 LHS.join(RHS, &LHSValNoAssignments[0], &RHSValNoAssignments[0], NewVNInfo,
1634 // DepthMBBCompare - Comparison predicate that sort first based on the loop
1635 // depth of the basic block (the unsigned), and then on the MBB number.
1636 struct DepthMBBCompare {
1637 typedef std::pair<unsigned, MachineBasicBlock*> DepthMBBPair;
1638 bool operator()(const DepthMBBPair &LHS, const DepthMBBPair &RHS) const {
1639 // Deeper loops first
1640 if (LHS.first != RHS.first)
1641 return LHS.first > RHS.first;
1643 // Prefer blocks that are more connected in the CFG. This takes care of
1644 // the most difficult copies first while intervals are short.
1645 unsigned cl = LHS.second->pred_size() + LHS.second->succ_size();
1646 unsigned cr = RHS.second->pred_size() + RHS.second->succ_size();
1650 // As a last resort, sort by block number.
1651 return LHS.second->getNumber() < RHS.second->getNumber();
1657 RegisterCoalescer::copyCoalesceInMBB(MachineBasicBlock *MBB,
1658 std::vector<MachineInstr*> &TryAgain) {
1659 DEBUG(dbgs() << MBB->getName() << ":\n");
1661 SmallVector<MachineInstr*, 8> VirtCopies;
1662 SmallVector<MachineInstr*, 8> PhysCopies;
1663 SmallVector<MachineInstr*, 8> ImpDefCopies;
1664 for (MachineBasicBlock::iterator MII = MBB->begin(), E = MBB->end();
1666 MachineInstr *Inst = MII++;
1668 // If this isn't a copy nor a extract_subreg, we can't join intervals.
1669 unsigned SrcReg, DstReg;
1670 if (Inst->isCopy()) {
1671 DstReg = Inst->getOperand(0).getReg();
1672 SrcReg = Inst->getOperand(1).getReg();
1673 } else if (Inst->isSubregToReg()) {
1674 DstReg = Inst->getOperand(0).getReg();
1675 SrcReg = Inst->getOperand(2).getReg();
1679 bool SrcIsPhys = TargetRegisterInfo::isPhysicalRegister(SrcReg);
1680 bool DstIsPhys = TargetRegisterInfo::isPhysicalRegister(DstReg);
1681 if (LIS->hasInterval(SrcReg) && LIS->getInterval(SrcReg).empty())
1682 ImpDefCopies.push_back(Inst);
1683 else if (SrcIsPhys || DstIsPhys)
1684 PhysCopies.push_back(Inst);
1686 VirtCopies.push_back(Inst);
1689 // Try coalescing implicit copies and insert_subreg <undef> first,
1690 // followed by copies to / from physical registers, then finally copies
1691 // from virtual registers to virtual registers.
1692 for (unsigned i = 0, e = ImpDefCopies.size(); i != e; ++i) {
1693 MachineInstr *TheCopy = ImpDefCopies[i];
1695 if (!joinCopy(TheCopy, Again))
1697 TryAgain.push_back(TheCopy);
1699 for (unsigned i = 0, e = PhysCopies.size(); i != e; ++i) {
1700 MachineInstr *TheCopy = PhysCopies[i];
1702 if (!joinCopy(TheCopy, Again))
1704 TryAgain.push_back(TheCopy);
1706 for (unsigned i = 0, e = VirtCopies.size(); i != e; ++i) {
1707 MachineInstr *TheCopy = VirtCopies[i];
1709 if (!joinCopy(TheCopy, Again))
1711 TryAgain.push_back(TheCopy);
1715 void RegisterCoalescer::joinAllIntervals() {
1716 DEBUG(dbgs() << "********** JOINING INTERVALS ***********\n");
1718 std::vector<MachineInstr*> TryAgainList;
1719 if (Loops->empty()) {
1720 // If there are no loops in the function, join intervals in function order.
1721 for (MachineFunction::iterator I = MF->begin(), E = MF->end();
1723 copyCoalesceInMBB(I, TryAgainList);
1725 // Otherwise, join intervals in inner loops before other intervals.
1726 // Unfortunately we can't just iterate over loop hierarchy here because
1727 // there may be more MBB's than BB's. Collect MBB's for sorting.
1729 // Join intervals in the function prolog first. We want to join physical
1730 // registers with virtual registers before the intervals got too long.
1731 std::vector<std::pair<unsigned, MachineBasicBlock*> > MBBs;
1732 for (MachineFunction::iterator I = MF->begin(), E = MF->end();I != E;++I){
1733 MachineBasicBlock *MBB = I;
1734 MBBs.push_back(std::make_pair(Loops->getLoopDepth(MBB), I));
1737 // Sort by loop depth.
1738 std::sort(MBBs.begin(), MBBs.end(), DepthMBBCompare());
1740 // Finally, join intervals in loop nest order.
1741 for (unsigned i = 0, e = MBBs.size(); i != e; ++i)
1742 copyCoalesceInMBB(MBBs[i].second, TryAgainList);
1745 // Joining intervals can allow other intervals to be joined. Iteratively join
1746 // until we make no progress.
1747 bool ProgressMade = true;
1748 while (ProgressMade) {
1749 ProgressMade = false;
1751 for (unsigned i = 0, e = TryAgainList.size(); i != e; ++i) {
1752 MachineInstr *&TheCopy = TryAgainList[i];
1757 bool Success = joinCopy(TheCopy, Again);
1758 if (Success || !Again) {
1759 TheCopy= 0; // Mark this one as done.
1760 ProgressMade = true;
1766 void RegisterCoalescer::releaseMemory() {
1767 JoinedCopies.clear();
1768 ReMatCopies.clear();
1772 bool RegisterCoalescer::runOnMachineFunction(MachineFunction &fn) {
1774 MRI = &fn.getRegInfo();
1775 TM = &fn.getTarget();
1776 TRI = TM->getRegisterInfo();
1777 TII = TM->getInstrInfo();
1778 LIS = &getAnalysis<LiveIntervals>();
1779 LDV = &getAnalysis<LiveDebugVariables>();
1780 AA = &getAnalysis<AliasAnalysis>();
1781 Loops = &getAnalysis<MachineLoopInfo>();
1783 DEBUG(dbgs() << "********** SIMPLE REGISTER COALESCING **********\n"
1784 << "********** Function: "
1785 << ((Value*)MF->getFunction())->getName() << '\n');
1787 if (VerifyCoalescing)
1788 MF->verify(this, "Before register coalescing");
1790 RegClassInfo.runOnMachineFunction(fn);
1792 // Join (coalesce) intervals if requested.
1793 if (EnableJoining) {
1796 dbgs() << "********** INTERVALS POST JOINING **********\n";
1797 for (LiveIntervals::iterator I = LIS->begin(), E = LIS->end();
1799 I->second->print(dbgs(), TRI);
1805 // Perform a final pass over the instructions and compute spill weights
1806 // and remove identity moves.
1807 SmallVector<unsigned, 4> DeadDefs, InflateRegs;
1808 for (MachineFunction::iterator mbbi = MF->begin(), mbbe = MF->end();
1809 mbbi != mbbe; ++mbbi) {
1810 MachineBasicBlock* mbb = mbbi;
1811 for (MachineBasicBlock::iterator mii = mbb->begin(), mie = mbb->end();
1813 MachineInstr *MI = mii;
1814 if (JoinedCopies.count(MI)) {
1815 // Delete all coalesced copies.
1816 bool DoDelete = true;
1817 assert(MI->isCopyLike() && "Unrecognized copy instruction");
1818 unsigned SrcReg = MI->getOperand(MI->isSubregToReg() ? 2 : 1).getReg();
1819 unsigned DstReg = MI->getOperand(0).getReg();
1821 // Collect candidates for register class inflation.
1822 if (TargetRegisterInfo::isVirtualRegister(SrcReg) &&
1823 RegClassInfo.isProperSubClass(MRI->getRegClass(SrcReg)))
1824 InflateRegs.push_back(SrcReg);
1825 if (TargetRegisterInfo::isVirtualRegister(DstReg) &&
1826 RegClassInfo.isProperSubClass(MRI->getRegClass(DstReg)))
1827 InflateRegs.push_back(DstReg);
1829 if (TargetRegisterInfo::isPhysicalRegister(SrcReg) &&
1830 MI->getNumOperands() > 2)
1831 // Do not delete extract_subreg, insert_subreg of physical
1832 // registers unless the definition is dead. e.g.
1833 // %DO<def> = INSERT_SUBREG %D0<undef>, %S0<kill>, 1
1834 // or else the scavenger may complain. LowerSubregs will
1835 // delete them later.
1838 if (MI->allDefsAreDead()) {
1839 if (TargetRegisterInfo::isVirtualRegister(SrcReg) &&
1840 LIS->hasInterval(SrcReg))
1841 LIS->shrinkToUses(&LIS->getInterval(SrcReg));
1845 // We need the instruction to adjust liveness, so make it a KILL.
1846 if (MI->isSubregToReg()) {
1847 MI->RemoveOperand(3);
1848 MI->RemoveOperand(1);
1850 MI->setDesc(TII->get(TargetOpcode::KILL));
1851 mii = llvm::next(mii);
1853 LIS->RemoveMachineInstrFromMaps(MI);
1854 mii = mbbi->erase(mii);
1860 // Now check if this is a remat'ed def instruction which is now dead.
1861 if (ReMatDefs.count(MI)) {
1863 for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
1864 const MachineOperand &MO = MI->getOperand(i);
1867 unsigned Reg = MO.getReg();
1870 DeadDefs.push_back(Reg);
1871 if (TargetRegisterInfo::isVirtualRegister(Reg)) {
1872 // Remat may also enable register class inflation.
1873 if (RegClassInfo.isProperSubClass(MRI->getRegClass(Reg)))
1874 InflateRegs.push_back(Reg);
1878 if (TargetRegisterInfo::isPhysicalRegister(Reg) ||
1879 !MRI->use_nodbg_empty(Reg)) {
1885 while (!DeadDefs.empty()) {
1886 unsigned DeadDef = DeadDefs.back();
1887 DeadDefs.pop_back();
1888 removeDeadDef(LIS->getInterval(DeadDef), MI);
1890 LIS->RemoveMachineInstrFromMaps(mii);
1891 mii = mbbi->erase(mii);
1899 // Check for now unnecessary kill flags.
1900 if (LIS->isNotInMIMap(MI)) continue;
1901 SlotIndex DefIdx = LIS->getInstructionIndex(MI).getRegSlot();
1902 for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
1903 MachineOperand &MO = MI->getOperand(i);
1904 if (!MO.isReg() || !MO.isKill()) continue;
1905 unsigned reg = MO.getReg();
1906 if (!reg || !LIS->hasInterval(reg)) continue;
1907 if (!LIS->getInterval(reg).killedAt(DefIdx)) {
1908 MO.setIsKill(false);
1911 // When leaving a kill flag on a physreg, check if any subregs should
1913 if (!TargetRegisterInfo::isPhysicalRegister(reg))
1915 for (const uint16_t *SR = TRI->getSubRegisters(reg);
1916 unsigned S = *SR; ++SR)
1917 if (LIS->hasInterval(S) && LIS->getInterval(S).liveAt(DefIdx))
1918 MI->addRegisterDefined(S, TRI);
1923 // After deleting a lot of copies, register classes may be less constrained.
1924 // Removing sub-register opreands may alow GR32_ABCD -> GR32 and DPR_VFP2 ->
1926 array_pod_sort(InflateRegs.begin(), InflateRegs.end());
1927 InflateRegs.erase(std::unique(InflateRegs.begin(), InflateRegs.end()),
1929 DEBUG(dbgs() << "Trying to inflate " << InflateRegs.size() << " regs.\n");
1930 for (unsigned i = 0, e = InflateRegs.size(); i != e; ++i) {
1931 unsigned Reg = InflateRegs[i];
1932 if (MRI->reg_nodbg_empty(Reg))
1934 if (MRI->recomputeRegClass(Reg, *TM)) {
1935 DEBUG(dbgs() << PrintReg(Reg) << " inflated to "
1936 << MRI->getRegClass(Reg)->getName() << '\n');
1943 if (VerifyCoalescing)
1944 MF->verify(this, "After register coalescing");
1948 /// print - Implement the dump method.
1949 void RegisterCoalescer::print(raw_ostream &O, const Module* m) const {