1 //===-- SimpleRegisterCoalescing.cpp - Register Coalescing ----------------===//
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 a simple register coalescing pass that attempts to
11 // aggressively coalesce every register copy that it can.
13 //===----------------------------------------------------------------------===//
15 #define DEBUG_TYPE "regcoalescing"
16 #include "SimpleRegisterCoalescing.h"
17 #include "VirtRegMap.h"
18 #include "llvm/CodeGen/LiveIntervalAnalysis.h"
19 #include "llvm/Value.h"
20 #include "llvm/CodeGen/MachineFrameInfo.h"
21 #include "llvm/CodeGen/MachineInstr.h"
22 #include "llvm/CodeGen/MachineLoopInfo.h"
23 #include "llvm/CodeGen/MachineRegisterInfo.h"
24 #include "llvm/CodeGen/Passes.h"
25 #include "llvm/CodeGen/RegisterCoalescer.h"
26 #include "llvm/Target/TargetInstrInfo.h"
27 #include "llvm/Target/TargetMachine.h"
28 #include "llvm/Target/TargetOptions.h"
29 #include "llvm/Support/CommandLine.h"
30 #include "llvm/Support/Debug.h"
31 #include "llvm/ADT/SmallSet.h"
32 #include "llvm/ADT/Statistic.h"
33 #include "llvm/ADT/STLExtras.h"
38 STATISTIC(numJoins , "Number of interval joins performed");
39 STATISTIC(numCrossRCs , "Number of cross class joins performed");
40 STATISTIC(numCommutes , "Number of instruction commuting performed");
41 STATISTIC(numExtends , "Number of copies extended");
42 STATISTIC(NumReMats , "Number of instructions re-materialized");
43 STATISTIC(numPeep , "Number of identity moves eliminated after coalescing");
44 STATISTIC(numAborts , "Number of times interval joining aborted");
45 STATISTIC(numDeadValNo, "Number of valno def marked dead");
47 char SimpleRegisterCoalescing::ID = 0;
49 EnableJoining("join-liveintervals",
50 cl::desc("Coalesce copies (default=true)"),
54 NewHeuristic("new-coalescer-heuristic",
55 cl::desc("Use new coalescer heuristic"),
56 cl::init(false), cl::Hidden);
59 CrossClassJoin("join-cross-class-copies",
60 cl::desc("Coalesce cross register class copies"),
61 cl::init(false), cl::Hidden);
64 PhysJoinTweak("tweak-phys-join-heuristics",
65 cl::desc("Tweak heuristics for joining phys reg with vr"),
66 cl::init(false), cl::Hidden);
68 static RegisterPass<SimpleRegisterCoalescing>
69 X("simple-register-coalescing", "Simple Register Coalescing");
71 // Declare that we implement the RegisterCoalescer interface
72 static RegisterAnalysisGroup<RegisterCoalescer, true/*The Default*/> V(X);
74 const PassInfo *const llvm::SimpleRegisterCoalescingID = &X;
76 void SimpleRegisterCoalescing::getAnalysisUsage(AnalysisUsage &AU) const {
77 AU.addRequired<LiveIntervals>();
78 AU.addPreserved<LiveIntervals>();
79 AU.addRequired<MachineLoopInfo>();
80 AU.addPreserved<MachineLoopInfo>();
81 AU.addPreservedID(MachineDominatorsID);
83 AU.addPreservedID(StrongPHIEliminationID);
85 AU.addPreservedID(PHIEliminationID);
86 AU.addPreservedID(TwoAddressInstructionPassID);
87 MachineFunctionPass::getAnalysisUsage(AU);
90 /// AdjustCopiesBackFrom - We found a non-trivially-coalescable copy with IntA
91 /// being the source and IntB being the dest, thus this defines a value number
92 /// in IntB. If the source value number (in IntA) is defined by a copy from B,
93 /// see if we can merge these two pieces of B into a single value number,
94 /// eliminating a copy. For example:
98 /// B1 = A3 <- this copy
100 /// In this case, B0 can be extended to where the B1 copy lives, allowing the B1
101 /// value number to be replaced with B0 (which simplifies the B liveinterval).
103 /// This returns true if an interval was modified.
105 bool SimpleRegisterCoalescing::AdjustCopiesBackFrom(LiveInterval &IntA,
107 MachineInstr *CopyMI) {
108 unsigned CopyIdx = li_->getDefIndex(li_->getInstructionIndex(CopyMI));
110 // BValNo is a value number in B that is defined by a copy from A. 'B3' in
111 // the example above.
112 LiveInterval::iterator BLR = IntB.FindLiveRangeContaining(CopyIdx);
113 assert(BLR != IntB.end() && "Live range not found!");
114 VNInfo *BValNo = BLR->valno;
116 // Get the location that B is defined at. Two options: either this value has
117 // an unknown definition point or it is defined at CopyIdx. If unknown, we
119 if (!BValNo->copy) return false;
120 assert(BValNo->def == CopyIdx && "Copy doesn't define the value?");
122 // AValNo is the value number in A that defines the copy, A3 in the example.
123 LiveInterval::iterator ALR = IntA.FindLiveRangeContaining(CopyIdx-1);
124 assert(ALR != IntA.end() && "Live range not found!");
125 VNInfo *AValNo = ALR->valno;
126 // If it's re-defined by an early clobber somewhere in the live range, then
127 // it's not safe to eliminate the copy. FIXME: This is a temporary workaround.
129 // 172 %ECX<def> = MOV32rr %reg1039<kill>
130 // 180 INLINEASM <es:subl $5,$1
131 // sbbl $3,$0>, 10, %EAX<def>, 14, %ECX<earlyclobber,def>, 9, %EAX<kill>,
132 // 36, <fi#0>, 1, %reg0, 0, 9, %ECX<kill>, 36, <fi#1>, 1, %reg0, 0
133 // 188 %EAX<def> = MOV32rr %EAX<kill>
134 // 196 %ECX<def> = MOV32rr %ECX<kill>
135 // 204 %ECX<def> = MOV32rr %ECX<kill>
136 // 212 %EAX<def> = MOV32rr %EAX<kill>
137 // 220 %EAX<def> = MOV32rr %EAX
138 // 228 %reg1039<def> = MOV32rr %ECX<kill>
139 // The early clobber operand ties ECX input to the ECX def.
141 // The live interval of ECX is represented as this:
142 // %reg20,inf = [46,47:1)[174,230:0) 0@174-(230) 1@46-(47)
143 // The coalescer has no idea there was a def in the middle of [174,230].
144 if (AValNo->hasRedefByEC())
147 // If AValNo is defined as a copy from IntB, we can potentially process this.
148 // Get the instruction that defines this value number.
149 unsigned SrcReg = li_->getVNInfoSourceReg(AValNo);
150 if (!SrcReg) return false; // Not defined by a copy.
152 // If the value number is not defined by a copy instruction, ignore it.
154 // If the source register comes from an interval other than IntB, we can't
156 if (SrcReg != IntB.reg) return false;
158 // Get the LiveRange in IntB that this value number starts with.
159 LiveInterval::iterator ValLR = IntB.FindLiveRangeContaining(AValNo->def-1);
160 assert(ValLR != IntB.end() && "Live range not found!");
162 // Make sure that the end of the live range is inside the same block as
164 MachineInstr *ValLREndInst = li_->getInstructionFromIndex(ValLR->end-1);
166 ValLREndInst->getParent() != CopyMI->getParent()) return false;
168 // Okay, we now know that ValLR ends in the same block that the CopyMI
169 // live-range starts. If there are no intervening live ranges between them in
170 // IntB, we can merge them.
171 if (ValLR+1 != BLR) return false;
173 // If a live interval is a physical register, conservatively check if any
174 // of its sub-registers is overlapping the live interval of the virtual
175 // register. If so, do not coalesce.
176 if (TargetRegisterInfo::isPhysicalRegister(IntB.reg) &&
177 *tri_->getSubRegisters(IntB.reg)) {
178 for (const unsigned* SR = tri_->getSubRegisters(IntB.reg); *SR; ++SR)
179 if (li_->hasInterval(*SR) && IntA.overlaps(li_->getInterval(*SR))) {
180 DOUT << "Interfere with sub-register ";
181 DEBUG(li_->getInterval(*SR).print(DOUT, tri_));
186 DOUT << "\nExtending: "; IntB.print(DOUT, tri_);
188 unsigned FillerStart = ValLR->end, FillerEnd = BLR->start;
189 // We are about to delete CopyMI, so need to remove it as the 'instruction
190 // that defines this value #'. Update the the valnum with the new defining
192 BValNo->def = FillerStart;
195 // Okay, we can merge them. We need to insert a new liverange:
196 // [ValLR.end, BLR.begin) of either value number, then we merge the
197 // two value numbers.
198 IntB.addRange(LiveRange(FillerStart, FillerEnd, BValNo));
200 // If the IntB live range is assigned to a physical register, and if that
201 // physreg has sub-registers, update their live intervals as well.
202 if (TargetRegisterInfo::isPhysicalRegister(IntB.reg)) {
203 for (const unsigned *SR = tri_->getSubRegisters(IntB.reg); *SR; ++SR) {
204 LiveInterval &SRLI = li_->getInterval(*SR);
205 SRLI.addRange(LiveRange(FillerStart, FillerEnd,
206 SRLI.getNextValue(FillerStart, 0, true,
207 li_->getVNInfoAllocator())));
211 // Okay, merge "B1" into the same value number as "B0".
212 if (BValNo != ValLR->valno) {
213 IntB.addKills(ValLR->valno, BValNo->kills);
214 IntB.MergeValueNumberInto(BValNo, ValLR->valno);
216 DOUT << " result = "; IntB.print(DOUT, tri_);
219 // If the source instruction was killing the source register before the
220 // merge, unset the isKill marker given the live range has been extended.
221 int UIdx = ValLREndInst->findRegisterUseOperandIdx(IntB.reg, true);
223 ValLREndInst->getOperand(UIdx).setIsKill(false);
224 IntB.removeKill(ValLR->valno, FillerStart);
231 /// HasOtherReachingDefs - Return true if there are definitions of IntB
232 /// other than BValNo val# that can reach uses of AValno val# of IntA.
233 bool SimpleRegisterCoalescing::HasOtherReachingDefs(LiveInterval &IntA,
237 for (LiveInterval::iterator AI = IntA.begin(), AE = IntA.end();
239 if (AI->valno != AValNo) continue;
240 LiveInterval::Ranges::iterator BI =
241 std::upper_bound(IntB.ranges.begin(), IntB.ranges.end(), AI->start);
242 if (BI != IntB.ranges.begin())
244 for (; BI != IntB.ranges.end() && AI->end >= BI->start; ++BI) {
245 if (BI->valno == BValNo)
247 if (BI->start <= AI->start && BI->end > AI->start)
249 if (BI->start > AI->start && BI->start < AI->end)
256 /// RemoveCopyByCommutingDef - We found a non-trivially-coalescable copy with IntA
257 /// being the source and IntB being the dest, thus this defines a value number
258 /// in IntB. If the source value number (in IntA) is defined by a commutable
259 /// instruction and its other operand is coalesced to the copy dest register,
260 /// see if we can transform the copy into a noop by commuting the definition. For
263 /// A3 = op A2 B0<kill>
265 /// B1 = A3 <- this copy
267 /// = op A3 <- more uses
271 /// B2 = op B0 A2<kill>
273 /// B1 = B2 <- now an identify copy
275 /// = op B2 <- more uses
277 /// This returns true if an interval was modified.
279 bool SimpleRegisterCoalescing::RemoveCopyByCommutingDef(LiveInterval &IntA,
281 MachineInstr *CopyMI) {
282 unsigned CopyIdx = li_->getDefIndex(li_->getInstructionIndex(CopyMI));
284 // FIXME: For now, only eliminate the copy by commuting its def when the
285 // source register is a virtual register. We want to guard against cases
286 // where the copy is a back edge copy and commuting the def lengthen the
287 // live interval of the source register to the entire loop.
288 if (TargetRegisterInfo::isPhysicalRegister(IntA.reg))
291 // BValNo is a value number in B that is defined by a copy from A. 'B3' in
292 // the example above.
293 LiveInterval::iterator BLR = IntB.FindLiveRangeContaining(CopyIdx);
294 assert(BLR != IntB.end() && "Live range not found!");
295 VNInfo *BValNo = BLR->valno;
297 // Get the location that B is defined at. Two options: either this value has
298 // an unknown definition point or it is defined at CopyIdx. If unknown, we
300 if (!BValNo->copy) return false;
301 assert(BValNo->def == CopyIdx && "Copy doesn't define the value?");
303 // AValNo is the value number in A that defines the copy, A3 in the example.
304 LiveInterval::iterator ALR = IntA.FindLiveRangeContaining(CopyIdx-1);
305 assert(ALR != IntA.end() && "Live range not found!");
306 VNInfo *AValNo = ALR->valno;
307 // If other defs can reach uses of this def, then it's not safe to perform
308 // the optimization. FIXME: Do isPHIDef and isDefAccurate both need to be
310 if (AValNo->isPHIDef() || !AValNo->isDefAccurate() ||
311 AValNo->isUnused() || AValNo->hasPHIKill())
313 MachineInstr *DefMI = li_->getInstructionFromIndex(AValNo->def);
314 const TargetInstrDesc &TID = DefMI->getDesc();
316 if (!TID.isCommutable() ||
317 !tii_->CommuteChangesDestination(DefMI, NewDstIdx))
320 MachineOperand &NewDstMO = DefMI->getOperand(NewDstIdx);
321 unsigned NewReg = NewDstMO.getReg();
322 if (NewReg != IntB.reg || !NewDstMO.isKill())
325 // Make sure there are no other definitions of IntB that would reach the
326 // uses which the new definition can reach.
327 if (HasOtherReachingDefs(IntA, IntB, AValNo, BValNo))
330 // If some of the uses of IntA.reg is already coalesced away, return false.
331 // It's not possible to determine whether it's safe to perform the coalescing.
332 for (MachineRegisterInfo::use_iterator UI = mri_->use_begin(IntA.reg),
333 UE = mri_->use_end(); UI != UE; ++UI) {
334 MachineInstr *UseMI = &*UI;
335 unsigned UseIdx = li_->getInstructionIndex(UseMI);
336 LiveInterval::iterator ULR = IntA.FindLiveRangeContaining(UseIdx);
337 if (ULR == IntA.end())
339 if (ULR->valno == AValNo && JoinedCopies.count(UseMI))
343 // At this point we have decided that it is legal to do this
344 // transformation. Start by commuting the instruction.
345 MachineBasicBlock *MBB = DefMI->getParent();
346 MachineInstr *NewMI = tii_->commuteInstruction(DefMI);
349 if (NewMI != DefMI) {
350 li_->ReplaceMachineInstrInMaps(DefMI, NewMI);
351 MBB->insert(DefMI, NewMI);
354 unsigned OpIdx = NewMI->findRegisterUseOperandIdx(IntA.reg, false);
355 NewMI->getOperand(OpIdx).setIsKill();
357 bool BHasPHIKill = BValNo->hasPHIKill();
358 SmallVector<VNInfo*, 4> BDeadValNos;
359 SmallVector<unsigned, 4> BKills;
360 std::map<unsigned, unsigned> BExtend;
362 // If ALR and BLR overlaps and end of BLR extends beyond end of ALR, e.g.
371 // then do not add kills of A to the newly created B interval.
372 bool Extended = BLR->end > ALR->end && ALR->end != ALR->start;
374 BExtend[ALR->end] = BLR->end;
376 // Update uses of IntA of the specific Val# with IntB.
377 bool BHasSubRegs = false;
378 if (TargetRegisterInfo::isPhysicalRegister(IntB.reg))
379 BHasSubRegs = *tri_->getSubRegisters(IntB.reg);
380 for (MachineRegisterInfo::use_iterator UI = mri_->use_begin(IntA.reg),
381 UE = mri_->use_end(); UI != UE;) {
382 MachineOperand &UseMO = UI.getOperand();
383 MachineInstr *UseMI = &*UI;
385 if (JoinedCopies.count(UseMI))
387 unsigned UseIdx = li_->getInstructionIndex(UseMI);
388 LiveInterval::iterator ULR = IntA.FindLiveRangeContaining(UseIdx);
389 if (ULR == IntA.end() || ULR->valno != AValNo)
391 UseMO.setReg(NewReg);
394 if (UseMO.isKill()) {
396 UseMO.setIsKill(false);
398 BKills.push_back(li_->getUseIndex(UseIdx)+1);
400 unsigned SrcReg, DstReg, SrcSubIdx, DstSubIdx;
401 if (!tii_->isMoveInstr(*UseMI, SrcReg, DstReg, SrcSubIdx, DstSubIdx))
403 if (DstReg == IntB.reg) {
404 // This copy will become a noop. If it's defining a new val#,
405 // remove that val# as well. However this live range is being
406 // extended to the end of the existing live range defined by the copy.
407 unsigned DefIdx = li_->getDefIndex(UseIdx);
408 const LiveRange *DLR = IntB.getLiveRangeContaining(DefIdx);
409 BHasPHIKill |= DLR->valno->hasPHIKill();
410 assert(DLR->valno->def == DefIdx);
411 BDeadValNos.push_back(DLR->valno);
412 BExtend[DLR->start] = DLR->end;
413 JoinedCopies.insert(UseMI);
414 // If this is a kill but it's going to be removed, the last use
415 // of the same val# is the new kill.
421 // We need to insert a new liverange: [ALR.start, LastUse). It may be we can
422 // simply extend BLR if CopyMI doesn't end the range.
423 DOUT << "\nExtending: "; IntB.print(DOUT, tri_);
425 // Remove val#'s defined by copies that will be coalesced away.
426 for (unsigned i = 0, e = BDeadValNos.size(); i != e; ++i) {
427 VNInfo *DeadVNI = BDeadValNos[i];
429 for (const unsigned *SR = tri_->getSubRegisters(IntB.reg); *SR; ++SR) {
430 LiveInterval &SRLI = li_->getInterval(*SR);
431 const LiveRange *SRLR = SRLI.getLiveRangeContaining(DeadVNI->def);
432 SRLI.removeValNo(SRLR->valno);
435 IntB.removeValNo(BDeadValNos[i]);
438 // Extend BValNo by merging in IntA live ranges of AValNo. Val# definition
439 // is updated. Kills are also updated.
440 VNInfo *ValNo = BValNo;
441 ValNo->def = AValNo->def;
443 for (unsigned j = 0, ee = ValNo->kills.size(); j != ee; ++j) {
444 unsigned Kill = ValNo->kills[j];
445 if (Kill != BLR->end)
446 BKills.push_back(Kill);
448 ValNo->kills.clear();
449 for (LiveInterval::iterator AI = IntA.begin(), AE = IntA.end();
451 if (AI->valno != AValNo) continue;
452 unsigned End = AI->end;
453 std::map<unsigned, unsigned>::iterator EI = BExtend.find(End);
454 if (EI != BExtend.end())
456 IntB.addRange(LiveRange(AI->start, End, ValNo));
458 // If the IntB live range is assigned to a physical register, and if that
459 // physreg has sub-registers, update their live intervals as well.
461 for (const unsigned *SR = tri_->getSubRegisters(IntB.reg); *SR; ++SR) {
462 LiveInterval &SRLI = li_->getInterval(*SR);
463 SRLI.MergeInClobberRange(AI->start, End, li_->getVNInfoAllocator());
467 IntB.addKills(ValNo, BKills);
468 ValNo->setHasPHIKill(BHasPHIKill);
470 DOUT << " result = "; IntB.print(DOUT, tri_);
473 DOUT << "\nShortening: "; IntA.print(DOUT, tri_);
474 IntA.removeValNo(AValNo);
475 DOUT << " result = "; IntA.print(DOUT, tri_);
482 /// isSameOrFallThroughBB - Return true if MBB == SuccMBB or MBB simply
483 /// fallthoughs to SuccMBB.
484 static bool isSameOrFallThroughBB(MachineBasicBlock *MBB,
485 MachineBasicBlock *SuccMBB,
486 const TargetInstrInfo *tii_) {
489 MachineBasicBlock *TBB = 0, *FBB = 0;
490 SmallVector<MachineOperand, 4> Cond;
491 return !tii_->AnalyzeBranch(*MBB, TBB, FBB, Cond) && !TBB && !FBB &&
492 MBB->isSuccessor(SuccMBB);
495 /// removeRange - Wrapper for LiveInterval::removeRange. This removes a range
496 /// from a physical register live interval as well as from the live intervals
497 /// of its sub-registers.
498 static void removeRange(LiveInterval &li, unsigned Start, unsigned End,
499 LiveIntervals *li_, const TargetRegisterInfo *tri_) {
500 li.removeRange(Start, End, true);
501 if (TargetRegisterInfo::isPhysicalRegister(li.reg)) {
502 for (const unsigned* SR = tri_->getSubRegisters(li.reg); *SR; ++SR) {
503 if (!li_->hasInterval(*SR))
505 LiveInterval &sli = li_->getInterval(*SR);
506 unsigned RemoveEnd = Start;
507 while (RemoveEnd != End) {
508 LiveInterval::iterator LR = sli.FindLiveRangeContaining(Start);
511 RemoveEnd = (LR->end < End) ? LR->end : End;
512 sli.removeRange(Start, RemoveEnd, true);
519 /// TrimLiveIntervalToLastUse - If there is a last use in the same basic block
520 /// as the copy instruction, trim the live interval to the last use and return
523 SimpleRegisterCoalescing::TrimLiveIntervalToLastUse(unsigned CopyIdx,
524 MachineBasicBlock *CopyMBB,
526 const LiveRange *LR) {
527 unsigned MBBStart = li_->getMBBStartIdx(CopyMBB);
529 MachineOperand *LastUse = lastRegisterUse(LR->start, CopyIdx-1, li.reg,
532 MachineInstr *LastUseMI = LastUse->getParent();
533 if (!isSameOrFallThroughBB(LastUseMI->getParent(), CopyMBB, tii_)) {
540 // r1025<dead> = r1024<kill>
541 if (MBBStart < LR->end)
542 removeRange(li, MBBStart, LR->end, li_, tri_);
546 // There are uses before the copy, just shorten the live range to the end
548 LastUse->setIsKill();
549 removeRange(li, li_->getDefIndex(LastUseIdx), LR->end, li_, tri_);
550 li.addKill(LR->valno, LastUseIdx+1);
551 unsigned SrcReg, DstReg, SrcSubIdx, DstSubIdx;
552 if (tii_->isMoveInstr(*LastUseMI, SrcReg, DstReg, SrcSubIdx, DstSubIdx) &&
554 // Last use is itself an identity code.
555 int DeadIdx = LastUseMI->findRegisterDefOperandIdx(li.reg, false, tri_);
556 LastUseMI->getOperand(DeadIdx).setIsDead();
562 if (LR->start <= MBBStart && LR->end > MBBStart) {
563 if (LR->start == 0) {
564 assert(TargetRegisterInfo::isPhysicalRegister(li.reg));
565 // Live-in to the function but dead. Remove it from entry live-in set.
566 mf_->begin()->removeLiveIn(li.reg);
568 // FIXME: Shorten intervals in BBs that reaches this BB.
574 /// ReMaterializeTrivialDef - If the source of a copy is defined by a trivial
575 /// computation, replace the copy by rematerialize the definition.
576 bool SimpleRegisterCoalescing::ReMaterializeTrivialDef(LiveInterval &SrcInt,
578 MachineInstr *CopyMI) {
579 unsigned CopyIdx = li_->getUseIndex(li_->getInstructionIndex(CopyMI));
580 LiveInterval::iterator SrcLR = SrcInt.FindLiveRangeContaining(CopyIdx);
581 assert(SrcLR != SrcInt.end() && "Live range not found!");
582 VNInfo *ValNo = SrcLR->valno;
583 // If other defs can reach uses of this def, then it's not safe to perform
584 // the optimization. FIXME: Do isPHIDef and isDefAccurate both need to be
586 if (ValNo->isPHIDef() || !ValNo->isDefAccurate() ||
587 ValNo->isUnused() || ValNo->hasPHIKill())
589 MachineInstr *DefMI = li_->getInstructionFromIndex(ValNo->def);
590 const TargetInstrDesc &TID = DefMI->getDesc();
591 if (!TID.isAsCheapAsAMove())
593 if (!DefMI->getDesc().isRematerializable() ||
594 !tii_->isTriviallyReMaterializable(DefMI))
596 bool SawStore = false;
597 if (!DefMI->isSafeToMove(tii_, SawStore))
600 unsigned DefIdx = li_->getDefIndex(CopyIdx);
601 const LiveRange *DLR= li_->getInterval(DstReg).getLiveRangeContaining(DefIdx);
602 DLR->valno->copy = NULL;
603 // Don't forget to update sub-register intervals.
604 if (TargetRegisterInfo::isPhysicalRegister(DstReg)) {
605 for (const unsigned* SR = tri_->getSubRegisters(DstReg); *SR; ++SR) {
606 if (!li_->hasInterval(*SR))
608 DLR = li_->getInterval(*SR).getLiveRangeContaining(DefIdx);
609 if (DLR && DLR->valno->copy == CopyMI)
610 DLR->valno->copy = NULL;
614 // If copy kills the source register, find the last use and propagate
616 bool checkForDeadDef = false;
617 MachineBasicBlock *MBB = CopyMI->getParent();
618 if (CopyMI->killsRegister(SrcInt.reg))
619 if (!TrimLiveIntervalToLastUse(CopyIdx, MBB, SrcInt, SrcLR)) {
620 checkForDeadDef = true;
623 MachineBasicBlock::iterator MII = next(MachineBasicBlock::iterator(CopyMI));
624 tii_->reMaterialize(*MBB, MII, DstReg, DefMI);
625 MachineInstr *NewMI = prior(MII);
627 if (checkForDeadDef) {
628 // PR4090 fix: Trim interval failed because there was no use of the
629 // source interval in this MBB. If the def is in this MBB too then we
630 // should mark it dead:
631 if (DefMI->getParent() == MBB) {
632 DefMI->addRegisterDead(SrcInt.reg, tri_);
633 SrcLR->end = SrcLR->start + 1;
637 // CopyMI may have implicit operands, transfer them over to the newly
638 // rematerialized instruction. And update implicit def interval valnos.
639 for (unsigned i = CopyMI->getDesc().getNumOperands(),
640 e = CopyMI->getNumOperands(); i != e; ++i) {
641 MachineOperand &MO = CopyMI->getOperand(i);
642 if (MO.isReg() && MO.isImplicit())
643 NewMI->addOperand(MO);
644 if (MO.isDef() && li_->hasInterval(MO.getReg())) {
645 unsigned Reg = MO.getReg();
646 DLR = li_->getInterval(Reg).getLiveRangeContaining(DefIdx);
647 if (DLR && DLR->valno->copy == CopyMI)
648 DLR->valno->copy = NULL;
652 li_->ReplaceMachineInstrInMaps(CopyMI, NewMI);
653 CopyMI->eraseFromParent();
654 ReMatCopies.insert(CopyMI);
655 ReMatDefs.insert(DefMI);
660 /// isBackEdgeCopy - Returns true if CopyMI is a back edge copy.
662 bool SimpleRegisterCoalescing::isBackEdgeCopy(MachineInstr *CopyMI,
663 unsigned DstReg) const {
664 MachineBasicBlock *MBB = CopyMI->getParent();
665 const MachineLoop *L = loopInfo->getLoopFor(MBB);
668 if (MBB != L->getLoopLatch())
671 LiveInterval &LI = li_->getInterval(DstReg);
672 unsigned DefIdx = li_->getInstructionIndex(CopyMI);
673 LiveInterval::const_iterator DstLR =
674 LI.FindLiveRangeContaining(li_->getDefIndex(DefIdx));
675 if (DstLR == LI.end())
677 unsigned KillIdx = li_->getMBBEndIdx(MBB) + 1;
678 if (DstLR->valno->kills.size() == 1 &&
679 DstLR->valno->kills[0] == KillIdx && DstLR->valno->hasPHIKill())
684 /// UpdateRegDefsUses - Replace all defs and uses of SrcReg to DstReg and
685 /// update the subregister number if it is not zero. If DstReg is a
686 /// physical register and the existing subregister number of the def / use
687 /// being updated is not zero, make sure to set it to the correct physical
690 SimpleRegisterCoalescing::UpdateRegDefsUses(unsigned SrcReg, unsigned DstReg,
692 bool DstIsPhys = TargetRegisterInfo::isPhysicalRegister(DstReg);
693 if (DstIsPhys && SubIdx) {
694 // Figure out the real physical register we are updating with.
695 DstReg = tri_->getSubReg(DstReg, SubIdx);
699 for (MachineRegisterInfo::reg_iterator I = mri_->reg_begin(SrcReg),
700 E = mri_->reg_end(); I != E; ) {
701 MachineOperand &O = I.getOperand();
702 MachineInstr *UseMI = &*I;
704 unsigned OldSubIdx = O.getSubReg();
706 unsigned UseDstReg = DstReg;
708 UseDstReg = tri_->getSubReg(DstReg, OldSubIdx);
710 unsigned CopySrcReg, CopyDstReg, CopySrcSubIdx, CopyDstSubIdx;
711 if (tii_->isMoveInstr(*UseMI, CopySrcReg, CopyDstReg,
712 CopySrcSubIdx, CopyDstSubIdx) &&
713 CopySrcReg != CopyDstReg &&
714 CopySrcReg == SrcReg && CopyDstReg != UseDstReg) {
715 // If the use is a copy and it won't be coalesced away, and its source
716 // is defined by a trivial computation, try to rematerialize it instead.
717 if (ReMaterializeTrivialDef(li_->getInterval(SrcReg), CopyDstReg,UseMI))
726 // Sub-register indexes goes from small to large. e.g.
727 // RAX: 1 -> AL, 2 -> AX, 3 -> EAX
728 // EAX: 1 -> AL, 2 -> AX
729 // So RAX's sub-register 2 is AX, RAX's sub-regsiter 3 is EAX, whose
730 // sub-register 2 is also AX.
731 if (SubIdx && OldSubIdx && SubIdx != OldSubIdx)
732 assert(OldSubIdx < SubIdx && "Conflicting sub-register index!");
735 // Remove would-be duplicated kill marker.
736 if (O.isKill() && UseMI->killsRegister(DstReg))
740 // After updating the operand, check if the machine instruction has
741 // become a copy. If so, update its val# information.
742 const TargetInstrDesc &TID = UseMI->getDesc();
743 unsigned CopySrcReg, CopyDstReg, CopySrcSubIdx, CopyDstSubIdx;
744 if (TID.getNumDefs() == 1 && TID.getNumOperands() > 2 &&
745 tii_->isMoveInstr(*UseMI, CopySrcReg, CopyDstReg,
746 CopySrcSubIdx, CopyDstSubIdx) &&
747 CopySrcReg != CopyDstReg &&
748 (TargetRegisterInfo::isVirtualRegister(CopyDstReg) ||
749 allocatableRegs_[CopyDstReg])) {
750 LiveInterval &LI = li_->getInterval(CopyDstReg);
751 unsigned DefIdx = li_->getDefIndex(li_->getInstructionIndex(UseMI));
752 const LiveRange *DLR = LI.getLiveRangeContaining(DefIdx);
753 if (DLR->valno->def == DefIdx)
754 DLR->valno->copy = UseMI;
759 /// RemoveDeadImpDef - Remove implicit_def instructions which are "re-defining"
760 /// registers due to insert_subreg coalescing. e.g.
762 /// r1025 = implicit_def
763 /// r1025 = insert_subreg r1025, r1024
767 /// r1025 = implicit_def
768 /// r1025 = insert_subreg r1025, r1025
771 SimpleRegisterCoalescing::RemoveDeadImpDef(unsigned Reg, LiveInterval &LI) {
772 for (MachineRegisterInfo::reg_iterator I = mri_->reg_begin(Reg),
773 E = mri_->reg_end(); I != E; ) {
774 MachineOperand &O = I.getOperand();
775 MachineInstr *DefMI = &*I;
779 if (DefMI->getOpcode() != TargetInstrInfo::IMPLICIT_DEF)
781 if (!LI.liveBeforeAndAt(li_->getInstructionIndex(DefMI)))
783 li_->RemoveMachineInstrFromMaps(DefMI);
784 DefMI->eraseFromParent();
788 /// RemoveUnnecessaryKills - Remove kill markers that are no longer accurate
789 /// due to live range lengthening as the result of coalescing.
790 void SimpleRegisterCoalescing::RemoveUnnecessaryKills(unsigned Reg,
792 for (MachineRegisterInfo::use_iterator UI = mri_->use_begin(Reg),
793 UE = mri_->use_end(); UI != UE; ++UI) {
794 MachineOperand &UseMO = UI.getOperand();
795 if (UseMO.isKill()) {
796 MachineInstr *UseMI = UseMO.getParent();
797 unsigned UseIdx = li_->getUseIndex(li_->getInstructionIndex(UseMI));
798 const LiveRange *UI = LI.getLiveRangeContaining(UseIdx);
799 if (!UI || !LI.isKill(UI->valno, UseIdx+1))
800 UseMO.setIsKill(false);
805 /// removeIntervalIfEmpty - Check if the live interval of a physical register
806 /// is empty, if so remove it and also remove the empty intervals of its
807 /// sub-registers. Return true if live interval is removed.
808 static bool removeIntervalIfEmpty(LiveInterval &li, LiveIntervals *li_,
809 const TargetRegisterInfo *tri_) {
811 if (TargetRegisterInfo::isPhysicalRegister(li.reg))
812 for (const unsigned* SR = tri_->getSubRegisters(li.reg); *SR; ++SR) {
813 if (!li_->hasInterval(*SR))
815 LiveInterval &sli = li_->getInterval(*SR);
817 li_->removeInterval(*SR);
819 li_->removeInterval(li.reg);
825 /// ShortenDeadCopyLiveRange - Shorten a live range defined by a dead copy.
826 /// Return true if live interval is removed.
827 bool SimpleRegisterCoalescing::ShortenDeadCopyLiveRange(LiveInterval &li,
828 MachineInstr *CopyMI) {
829 unsigned CopyIdx = li_->getInstructionIndex(CopyMI);
830 LiveInterval::iterator MLR =
831 li.FindLiveRangeContaining(li_->getDefIndex(CopyIdx));
833 return false; // Already removed by ShortenDeadCopySrcLiveRange.
834 unsigned RemoveStart = MLR->start;
835 unsigned RemoveEnd = MLR->end;
836 // Remove the liverange that's defined by this.
837 if (RemoveEnd == li_->getDefIndex(CopyIdx)+1) {
838 removeRange(li, RemoveStart, RemoveEnd, li_, tri_);
839 return removeIntervalIfEmpty(li, li_, tri_);
844 /// RemoveDeadDef - If a def of a live interval is now determined dead, remove
845 /// the val# it defines. If the live interval becomes empty, remove it as well.
846 bool SimpleRegisterCoalescing::RemoveDeadDef(LiveInterval &li,
847 MachineInstr *DefMI) {
848 unsigned DefIdx = li_->getDefIndex(li_->getInstructionIndex(DefMI));
849 LiveInterval::iterator MLR = li.FindLiveRangeContaining(DefIdx);
850 if (DefIdx != MLR->valno->def)
852 li.removeValNo(MLR->valno);
853 return removeIntervalIfEmpty(li, li_, tri_);
856 /// PropagateDeadness - Propagate the dead marker to the instruction which
857 /// defines the val#.
858 static void PropagateDeadness(LiveInterval &li, MachineInstr *CopyMI,
859 unsigned &LRStart, LiveIntervals *li_,
860 const TargetRegisterInfo* tri_) {
861 MachineInstr *DefMI =
862 li_->getInstructionFromIndex(li_->getDefIndex(LRStart));
863 if (DefMI && DefMI != CopyMI) {
864 int DeadIdx = DefMI->findRegisterDefOperandIdx(li.reg, false, tri_);
866 DefMI->getOperand(DeadIdx).setIsDead();
867 // A dead def should have a single cycle interval.
873 /// ShortenDeadCopySrcLiveRange - Shorten a live range as it's artificially
874 /// extended by a dead copy. Mark the last use (if any) of the val# as kill as
875 /// ends the live range there. If there isn't another use, then this live range
876 /// is dead. Return true if live interval is removed.
878 SimpleRegisterCoalescing::ShortenDeadCopySrcLiveRange(LiveInterval &li,
879 MachineInstr *CopyMI) {
880 unsigned CopyIdx = li_->getInstructionIndex(CopyMI);
882 // FIXME: special case: function live in. It can be a general case if the
883 // first instruction index starts at > 0 value.
884 assert(TargetRegisterInfo::isPhysicalRegister(li.reg));
885 // Live-in to the function but dead. Remove it from entry live-in set.
886 if (mf_->begin()->isLiveIn(li.reg))
887 mf_->begin()->removeLiveIn(li.reg);
888 const LiveRange *LR = li.getLiveRangeContaining(CopyIdx);
889 removeRange(li, LR->start, LR->end, li_, tri_);
890 return removeIntervalIfEmpty(li, li_, tri_);
893 LiveInterval::iterator LR = li.FindLiveRangeContaining(CopyIdx-1);
895 // Livein but defined by a phi.
898 unsigned RemoveStart = LR->start;
899 unsigned RemoveEnd = li_->getDefIndex(CopyIdx)+1;
900 if (LR->end > RemoveEnd)
901 // More uses past this copy? Nothing to do.
904 // If there is a last use in the same bb, we can't remove the live range.
905 // Shorten the live interval and return.
906 MachineBasicBlock *CopyMBB = CopyMI->getParent();
907 if (TrimLiveIntervalToLastUse(CopyIdx, CopyMBB, li, LR))
910 MachineBasicBlock *StartMBB = li_->getMBBFromIndex(RemoveStart);
911 if (!isSameOrFallThroughBB(StartMBB, CopyMBB, tii_))
912 // If the live range starts in another mbb and the copy mbb is not a fall
913 // through mbb, then we can only cut the range from the beginning of the
915 RemoveStart = li_->getMBBStartIdx(CopyMBB) + 1;
917 if (LR->valno->def == RemoveStart) {
918 // If the def MI defines the val# and this copy is the only kill of the
919 // val#, then propagate the dead marker.
920 if (li.isOnlyLROfValNo(LR)) {
921 PropagateDeadness(li, CopyMI, RemoveStart, li_, tri_);
924 if (li.isKill(LR->valno, RemoveEnd))
925 li.removeKill(LR->valno, RemoveEnd);
928 removeRange(li, RemoveStart, RemoveEnd, li_, tri_);
929 return removeIntervalIfEmpty(li, li_, tri_);
932 /// CanCoalesceWithImpDef - Returns true if the specified copy instruction
933 /// from an implicit def to another register can be coalesced away.
934 bool SimpleRegisterCoalescing::CanCoalesceWithImpDef(MachineInstr *CopyMI,
936 LiveInterval &ImpLi) const{
937 if (!CopyMI->killsRegister(ImpLi.reg))
939 unsigned CopyIdx = li_->getDefIndex(li_->getInstructionIndex(CopyMI));
940 LiveInterval::iterator LR = li.FindLiveRangeContaining(CopyIdx);
943 if (LR->valno->hasPHIKill())
945 if (LR->valno->def != CopyIdx)
947 // Make sure all of val# uses are copies.
948 for (MachineRegisterInfo::use_iterator UI = mri_->use_begin(li.reg),
949 UE = mri_->use_end(); UI != UE;) {
950 MachineInstr *UseMI = &*UI;
952 if (JoinedCopies.count(UseMI))
954 unsigned UseIdx = li_->getUseIndex(li_->getInstructionIndex(UseMI));
955 LiveInterval::iterator ULR = li.FindLiveRangeContaining(UseIdx);
956 if (ULR == li.end() || ULR->valno != LR->valno)
958 // If the use is not a use, then it's not safe to coalesce the move.
959 unsigned SrcReg, DstReg, SrcSubIdx, DstSubIdx;
960 if (!tii_->isMoveInstr(*UseMI, SrcReg, DstReg, SrcSubIdx, DstSubIdx)) {
961 if (UseMI->getOpcode() == TargetInstrInfo::INSERT_SUBREG &&
962 UseMI->getOperand(1).getReg() == li.reg)
971 /// TurnCopiesFromValNoToImpDefs - The specified value# is defined by an
972 /// implicit_def and it is being removed. Turn all copies from this value#
973 /// into implicit_defs.
974 void SimpleRegisterCoalescing::TurnCopiesFromValNoToImpDefs(LiveInterval &li,
976 SmallVector<MachineInstr*, 4> ImpDefs;
977 MachineOperand *LastUse = NULL;
978 unsigned LastUseIdx = li_->getUseIndex(VNI->def);
979 for (MachineRegisterInfo::reg_iterator RI = mri_->reg_begin(li.reg),
980 RE = mri_->reg_end(); RI != RE;) {
981 MachineOperand *MO = &RI.getOperand();
982 MachineInstr *MI = &*RI;
985 if (MI->getOpcode() == TargetInstrInfo::IMPLICIT_DEF)
986 ImpDefs.push_back(MI);
989 if (JoinedCopies.count(MI))
991 unsigned UseIdx = li_->getUseIndex(li_->getInstructionIndex(MI));
992 LiveInterval::iterator ULR = li.FindLiveRangeContaining(UseIdx);
993 if (ULR == li.end() || ULR->valno != VNI)
995 // If the use is a copy, turn it into an identity copy.
996 unsigned SrcReg, DstReg, SrcSubIdx, DstSubIdx;
997 if (tii_->isMoveInstr(*MI, SrcReg, DstReg, SrcSubIdx, DstSubIdx) &&
999 // Change it to an implicit_def.
1000 MI->setDesc(tii_->get(TargetInstrInfo::IMPLICIT_DEF));
1001 for (int i = MI->getNumOperands() - 1, e = 0; i > e; --i)
1002 MI->RemoveOperand(i);
1003 // It's no longer a copy, update the valno it defines.
1004 unsigned DefIdx = li_->getDefIndex(UseIdx);
1005 LiveInterval &DstInt = li_->getInterval(DstReg);
1006 LiveInterval::iterator DLR = DstInt.FindLiveRangeContaining(DefIdx);
1007 assert(DLR != DstInt.end() && "Live range not found!");
1008 assert(DLR->valno->copy == MI);
1009 DLR->valno->copy = NULL;
1010 ReMatCopies.insert(MI);
1011 } else if (UseIdx > LastUseIdx) {
1012 LastUseIdx = UseIdx;
1017 LastUse->setIsKill();
1018 li.addKill(VNI, LastUseIdx+1);
1020 // Remove dead implicit_def's.
1021 while (!ImpDefs.empty()) {
1022 MachineInstr *ImpDef = ImpDefs.back();
1024 li_->RemoveMachineInstrFromMaps(ImpDef);
1025 ImpDef->eraseFromParent();
1030 /// isWinToJoinVRWithSrcPhysReg - Return true if it's worth while to join a
1031 /// a virtual destination register with physical source register.
1033 SimpleRegisterCoalescing::isWinToJoinVRWithSrcPhysReg(MachineInstr *CopyMI,
1034 MachineBasicBlock *CopyMBB,
1035 LiveInterval &DstInt,
1036 LiveInterval &SrcInt) {
1037 // If the virtual register live interval is long but it has low use desity,
1038 // do not join them, instead mark the physical register as its allocation
1040 const TargetRegisterClass *RC = mri_->getRegClass(DstInt.reg);
1041 unsigned Threshold = allocatableRCRegs_[RC].count() * 2;
1042 unsigned Length = li_->getApproximateInstructionCount(DstInt);
1043 if (Length > Threshold &&
1044 (((float)std::distance(mri_->use_begin(DstInt.reg),
1045 mri_->use_end()) / Length) < (1.0 / Threshold)))
1048 // If the virtual register live interval extends into a loop, turn down
1050 unsigned CopyIdx = li_->getDefIndex(li_->getInstructionIndex(CopyMI));
1051 const MachineLoop *L = loopInfo->getLoopFor(CopyMBB);
1053 // Let's see if the virtual register live interval extends into the loop.
1054 LiveInterval::iterator DLR = DstInt.FindLiveRangeContaining(CopyIdx);
1055 assert(DLR != DstInt.end() && "Live range not found!");
1056 DLR = DstInt.FindLiveRangeContaining(DLR->end+1);
1057 if (DLR != DstInt.end()) {
1058 CopyMBB = li_->getMBBFromIndex(DLR->start);
1059 L = loopInfo->getLoopFor(CopyMBB);
1063 if (!L || Length <= Threshold)
1066 unsigned UseIdx = li_->getUseIndex(CopyIdx);
1067 LiveInterval::iterator SLR = SrcInt.FindLiveRangeContaining(UseIdx);
1068 MachineBasicBlock *SMBB = li_->getMBBFromIndex(SLR->start);
1069 if (loopInfo->getLoopFor(SMBB) != L) {
1070 if (!loopInfo->isLoopHeader(CopyMBB))
1072 // If vr's live interval extends pass the loop header, do not join.
1073 for (MachineBasicBlock::succ_iterator SI = CopyMBB->succ_begin(),
1074 SE = CopyMBB->succ_end(); SI != SE; ++SI) {
1075 MachineBasicBlock *SuccMBB = *SI;
1076 if (SuccMBB == CopyMBB)
1078 if (DstInt.overlaps(li_->getMBBStartIdx(SuccMBB),
1079 li_->getMBBEndIdx(SuccMBB)+1))
1086 /// isWinToJoinVRWithDstPhysReg - Return true if it's worth while to join a
1087 /// copy from a virtual source register to a physical destination register.
1089 SimpleRegisterCoalescing::isWinToJoinVRWithDstPhysReg(MachineInstr *CopyMI,
1090 MachineBasicBlock *CopyMBB,
1091 LiveInterval &DstInt,
1092 LiveInterval &SrcInt) {
1093 // If the virtual register live interval is long but it has low use desity,
1094 // do not join them, instead mark the physical register as its allocation
1096 const TargetRegisterClass *RC = mri_->getRegClass(SrcInt.reg);
1097 unsigned Threshold = allocatableRCRegs_[RC].count() * 2;
1098 unsigned Length = li_->getApproximateInstructionCount(SrcInt);
1099 if (Length > Threshold &&
1100 (((float)std::distance(mri_->use_begin(SrcInt.reg),
1101 mri_->use_end()) / Length) < (1.0 / Threshold)))
1105 // Must be implicit_def.
1108 // If the virtual register live interval is defined or cross a loop, turn
1109 // down aggressiveness.
1110 unsigned CopyIdx = li_->getDefIndex(li_->getInstructionIndex(CopyMI));
1111 unsigned UseIdx = li_->getUseIndex(CopyIdx);
1112 LiveInterval::iterator SLR = SrcInt.FindLiveRangeContaining(UseIdx);
1113 assert(SLR != SrcInt.end() && "Live range not found!");
1114 SLR = SrcInt.FindLiveRangeContaining(SLR->start-1);
1115 if (SLR == SrcInt.end())
1117 MachineBasicBlock *SMBB = li_->getMBBFromIndex(SLR->start);
1118 const MachineLoop *L = loopInfo->getLoopFor(SMBB);
1120 if (!L || Length <= Threshold)
1123 if (loopInfo->getLoopFor(CopyMBB) != L) {
1124 if (SMBB != L->getLoopLatch())
1126 // If vr's live interval is extended from before the loop latch, do not
1128 for (MachineBasicBlock::pred_iterator PI = SMBB->pred_begin(),
1129 PE = SMBB->pred_end(); PI != PE; ++PI) {
1130 MachineBasicBlock *PredMBB = *PI;
1131 if (PredMBB == SMBB)
1133 if (SrcInt.overlaps(li_->getMBBStartIdx(PredMBB),
1134 li_->getMBBEndIdx(PredMBB)+1))
1141 /// isWinToJoinCrossClass - Return true if it's profitable to coalesce
1142 /// two virtual registers from different register classes.
1144 SimpleRegisterCoalescing::isWinToJoinCrossClass(unsigned LargeReg,
1146 unsigned Threshold) {
1147 // Then make sure the intervals are *short*.
1148 LiveInterval &LargeInt = li_->getInterval(LargeReg);
1149 LiveInterval &SmallInt = li_->getInterval(SmallReg);
1150 unsigned LargeSize = li_->getApproximateInstructionCount(LargeInt);
1151 unsigned SmallSize = li_->getApproximateInstructionCount(SmallInt);
1152 if (SmallSize > Threshold || LargeSize > Threshold)
1153 if ((float)std::distance(mri_->use_begin(SmallReg),
1154 mri_->use_end()) / SmallSize <
1155 (float)std::distance(mri_->use_begin(LargeReg),
1156 mri_->use_end()) / LargeSize)
1161 /// HasIncompatibleSubRegDefUse - If we are trying to coalesce a virtual
1162 /// register with a physical register, check if any of the virtual register
1163 /// operand is a sub-register use or def. If so, make sure it won't result
1164 /// in an illegal extract_subreg or insert_subreg instruction. e.g.
1165 /// vr1024 = extract_subreg vr1025, 1
1167 /// vr1024 = mov8rr AH
1168 /// If vr1024 is coalesced with AH, the extract_subreg is now illegal since
1169 /// AH does not have a super-reg whose sub-register 1 is AH.
1171 SimpleRegisterCoalescing::HasIncompatibleSubRegDefUse(MachineInstr *CopyMI,
1174 for (MachineRegisterInfo::reg_iterator I = mri_->reg_begin(VirtReg),
1175 E = mri_->reg_end(); I != E; ++I) {
1176 MachineOperand &O = I.getOperand();
1177 MachineInstr *MI = &*I;
1178 if (MI == CopyMI || JoinedCopies.count(MI))
1180 unsigned SubIdx = O.getSubReg();
1181 if (SubIdx && !tri_->getSubReg(PhysReg, SubIdx))
1183 if (MI->getOpcode() == TargetInstrInfo::EXTRACT_SUBREG) {
1184 SubIdx = MI->getOperand(2).getImm();
1185 if (O.isUse() && !tri_->getSubReg(PhysReg, SubIdx))
1188 unsigned SrcReg = MI->getOperand(1).getReg();
1189 const TargetRegisterClass *RC =
1190 TargetRegisterInfo::isPhysicalRegister(SrcReg)
1191 ? tri_->getPhysicalRegisterRegClass(SrcReg)
1192 : mri_->getRegClass(SrcReg);
1193 if (!tri_->getMatchingSuperReg(PhysReg, SubIdx, RC))
1197 if (MI->getOpcode() == TargetInstrInfo::INSERT_SUBREG ||
1198 MI->getOpcode() == TargetInstrInfo::SUBREG_TO_REG) {
1199 SubIdx = MI->getOperand(3).getImm();
1200 if (VirtReg == MI->getOperand(0).getReg()) {
1201 if (!tri_->getSubReg(PhysReg, SubIdx))
1204 unsigned DstReg = MI->getOperand(0).getReg();
1205 const TargetRegisterClass *RC =
1206 TargetRegisterInfo::isPhysicalRegister(DstReg)
1207 ? tri_->getPhysicalRegisterRegClass(DstReg)
1208 : mri_->getRegClass(DstReg);
1209 if (!tri_->getMatchingSuperReg(PhysReg, SubIdx, RC))
1218 /// CanJoinExtractSubRegToPhysReg - Return true if it's possible to coalesce
1219 /// an extract_subreg where dst is a physical register, e.g.
1220 /// cl = EXTRACT_SUBREG reg1024, 1
1222 SimpleRegisterCoalescing::CanJoinExtractSubRegToPhysReg(unsigned DstReg,
1223 unsigned SrcReg, unsigned SubIdx,
1224 unsigned &RealDstReg) {
1225 const TargetRegisterClass *RC = mri_->getRegClass(SrcReg);
1226 RealDstReg = tri_->getMatchingSuperReg(DstReg, SubIdx, RC);
1227 assert(RealDstReg && "Invalid extract_subreg instruction!");
1229 // For this type of EXTRACT_SUBREG, conservatively
1230 // check if the live interval of the source register interfere with the
1231 // actual super physical register we are trying to coalesce with.
1232 LiveInterval &RHS = li_->getInterval(SrcReg);
1233 if (li_->hasInterval(RealDstReg) &&
1234 RHS.overlaps(li_->getInterval(RealDstReg))) {
1235 DOUT << "Interfere with register ";
1236 DEBUG(li_->getInterval(RealDstReg).print(DOUT, tri_));
1237 return false; // Not coalescable
1239 for (const unsigned* SR = tri_->getSubRegisters(RealDstReg); *SR; ++SR)
1240 if (li_->hasInterval(*SR) && RHS.overlaps(li_->getInterval(*SR))) {
1241 DOUT << "Interfere with sub-register ";
1242 DEBUG(li_->getInterval(*SR).print(DOUT, tri_));
1243 return false; // Not coalescable
1248 /// CanJoinInsertSubRegToPhysReg - Return true if it's possible to coalesce
1249 /// an insert_subreg where src is a physical register, e.g.
1250 /// reg1024 = INSERT_SUBREG reg1024, c1, 0
1252 SimpleRegisterCoalescing::CanJoinInsertSubRegToPhysReg(unsigned DstReg,
1253 unsigned SrcReg, unsigned SubIdx,
1254 unsigned &RealSrcReg) {
1255 const TargetRegisterClass *RC = mri_->getRegClass(DstReg);
1256 RealSrcReg = tri_->getMatchingSuperReg(SrcReg, SubIdx, RC);
1257 assert(RealSrcReg && "Invalid extract_subreg instruction!");
1259 LiveInterval &RHS = li_->getInterval(DstReg);
1260 if (li_->hasInterval(RealSrcReg) &&
1261 RHS.overlaps(li_->getInterval(RealSrcReg))) {
1262 DOUT << "Interfere with register ";
1263 DEBUG(li_->getInterval(RealSrcReg).print(DOUT, tri_));
1264 return false; // Not coalescable
1266 for (const unsigned* SR = tri_->getSubRegisters(RealSrcReg); *SR; ++SR)
1267 if (li_->hasInterval(*SR) && RHS.overlaps(li_->getInterval(*SR))) {
1268 DOUT << "Interfere with sub-register ";
1269 DEBUG(li_->getInterval(*SR).print(DOUT, tri_));
1270 return false; // Not coalescable
1275 /// getRegAllocPreference - Return register allocation preference register.
1277 static unsigned getRegAllocPreference(unsigned Reg, MachineFunction &MF,
1278 MachineRegisterInfo *MRI,
1279 const TargetRegisterInfo *TRI) {
1280 if (TargetRegisterInfo::isPhysicalRegister(Reg))
1282 std::pair<unsigned, unsigned> Hint = MRI->getRegAllocationHint(Reg);
1283 return TRI->ResolveRegAllocHint(Hint.first, Hint.second, MF);
1286 /// JoinCopy - Attempt to join intervals corresponding to SrcReg/DstReg,
1287 /// which are the src/dst of the copy instruction CopyMI. This returns true
1288 /// if the copy was successfully coalesced away. If it is not currently
1289 /// possible to coalesce this interval, but it may be possible if other
1290 /// things get coalesced, then it returns true by reference in 'Again'.
1291 bool SimpleRegisterCoalescing::JoinCopy(CopyRec &TheCopy, bool &Again) {
1292 MachineInstr *CopyMI = TheCopy.MI;
1295 if (JoinedCopies.count(CopyMI) || ReMatCopies.count(CopyMI))
1296 return false; // Already done.
1298 DOUT << li_->getInstructionIndex(CopyMI) << '\t' << *CopyMI;
1300 unsigned SrcReg, DstReg, SrcSubIdx = 0, DstSubIdx = 0;
1301 bool isExtSubReg = CopyMI->getOpcode() == TargetInstrInfo::EXTRACT_SUBREG;
1302 bool isInsSubReg = CopyMI->getOpcode() == TargetInstrInfo::INSERT_SUBREG;
1303 bool isSubRegToReg = CopyMI->getOpcode() == TargetInstrInfo::SUBREG_TO_REG;
1304 unsigned SubIdx = 0;
1306 DstReg = CopyMI->getOperand(0).getReg();
1307 DstSubIdx = CopyMI->getOperand(0).getSubReg();
1308 SrcReg = CopyMI->getOperand(1).getReg();
1309 SrcSubIdx = CopyMI->getOperand(2).getImm();
1310 } else if (isInsSubReg || isSubRegToReg) {
1311 if (CopyMI->getOperand(2).getSubReg()) {
1312 DOUT << "\tSource of insert_subreg is already coalesced "
1313 << "to another register.\n";
1314 return false; // Not coalescable.
1316 DstReg = CopyMI->getOperand(0).getReg();
1317 DstSubIdx = CopyMI->getOperand(3).getImm();
1318 SrcReg = CopyMI->getOperand(2).getReg();
1319 } else if (!tii_->isMoveInstr(*CopyMI, SrcReg, DstReg, SrcSubIdx, DstSubIdx)){
1320 assert(0 && "Unrecognized copy instruction!");
1324 // If they are already joined we continue.
1325 if (SrcReg == DstReg) {
1326 DOUT << "\tCopy already coalesced.\n";
1327 return false; // Not coalescable.
1330 bool SrcIsPhys = TargetRegisterInfo::isPhysicalRegister(SrcReg);
1331 bool DstIsPhys = TargetRegisterInfo::isPhysicalRegister(DstReg);
1333 // If they are both physical registers, we cannot join them.
1334 if (SrcIsPhys && DstIsPhys) {
1335 DOUT << "\tCan not coalesce physregs.\n";
1336 return false; // Not coalescable.
1339 // We only join virtual registers with allocatable physical registers.
1340 if (SrcIsPhys && !allocatableRegs_[SrcReg]) {
1341 DOUT << "\tSrc reg is unallocatable physreg.\n";
1342 return false; // Not coalescable.
1344 if (DstIsPhys && !allocatableRegs_[DstReg]) {
1345 DOUT << "\tDst reg is unallocatable physreg.\n";
1346 return false; // Not coalescable.
1349 // Check that a physical source register is compatible with dst regclass
1351 unsigned SrcSubReg = SrcSubIdx ?
1352 tri_->getSubReg(SrcReg, SrcSubIdx) : SrcReg;
1353 const TargetRegisterClass *DstRC = mri_->getRegClass(DstReg);
1354 const TargetRegisterClass *DstSubRC = DstRC;
1356 DstSubRC = DstRC->getSubRegisterRegClass(DstSubIdx);
1357 assert(DstSubRC && "Illegal subregister index");
1358 if (!DstSubRC->contains(SrcSubReg)) {
1359 DOUT << "\tIncompatible destination regclass: "
1360 << tri_->getName(SrcSubReg) << " not in " << DstSubRC->getName()
1362 return false; // Not coalescable.
1366 // Check that a physical dst register is compatible with source regclass
1368 unsigned DstSubReg = DstSubIdx ?
1369 tri_->getSubReg(DstReg, DstSubIdx) : DstReg;
1370 const TargetRegisterClass *SrcRC = mri_->getRegClass(SrcReg);
1371 const TargetRegisterClass *SrcSubRC = SrcRC;
1373 SrcSubRC = SrcRC->getSubRegisterRegClass(SrcSubIdx);
1374 assert(SrcSubRC && "Illegal subregister index");
1375 if (!SrcSubRC->contains(DstReg)) {
1376 DOUT << "\tIncompatible source regclass: "
1377 << tri_->getName(DstSubReg) << " not in " << SrcSubRC->getName()
1379 return false; // Not coalescable.
1383 // Should be non-null only when coalescing to a sub-register class.
1384 bool CrossRC = false;
1385 const TargetRegisterClass *NewRC = NULL;
1386 MachineBasicBlock *CopyMBB = CopyMI->getParent();
1387 unsigned RealDstReg = 0;
1388 unsigned RealSrcReg = 0;
1389 if (isExtSubReg || isInsSubReg || isSubRegToReg) {
1390 SubIdx = CopyMI->getOperand(isExtSubReg ? 2 : 3).getImm();
1391 if (SrcIsPhys && isExtSubReg) {
1392 // r1024 = EXTRACT_SUBREG EAX, 0 then r1024 is really going to be
1393 // coalesced with AX.
1394 unsigned DstSubIdx = CopyMI->getOperand(0).getSubReg();
1396 // r1024<2> = EXTRACT_SUBREG EAX, 2. Then r1024 has already been
1397 // coalesced to a larger register so the subreg indices cancel out.
1398 if (DstSubIdx != SubIdx) {
1399 DOUT << "\t Sub-register indices mismatch.\n";
1400 return false; // Not coalescable.
1403 SrcReg = tri_->getSubReg(SrcReg, SubIdx);
1405 } else if (DstIsPhys && (isInsSubReg || isSubRegToReg)) {
1406 // EAX = INSERT_SUBREG EAX, r1024, 0
1407 unsigned SrcSubIdx = CopyMI->getOperand(2).getSubReg();
1409 // EAX = INSERT_SUBREG EAX, r1024<2>, 2 Then r1024 has already been
1410 // coalesced to a larger register so the subreg indices cancel out.
1411 if (SrcSubIdx != SubIdx) {
1412 DOUT << "\t Sub-register indices mismatch.\n";
1413 return false; // Not coalescable.
1416 DstReg = tri_->getSubReg(DstReg, SubIdx);
1418 } else if ((DstIsPhys && isExtSubReg) ||
1419 (SrcIsPhys && (isInsSubReg || isSubRegToReg))) {
1420 if (!isSubRegToReg && CopyMI->getOperand(1).getSubReg()) {
1421 DOUT << "\tSrc of extract_subreg already coalesced with reg"
1422 << " of a super-class.\n";
1423 return false; // Not coalescable.
1427 if (!CanJoinExtractSubRegToPhysReg(DstReg, SrcReg, SubIdx, RealDstReg))
1428 return false; // Not coalescable
1430 if (!CanJoinInsertSubRegToPhysReg(DstReg, SrcReg, SubIdx, RealSrcReg))
1431 return false; // Not coalescable
1435 unsigned OldSubIdx = isExtSubReg ? CopyMI->getOperand(0).getSubReg()
1436 : CopyMI->getOperand(2).getSubReg();
1438 if (OldSubIdx == SubIdx && !differingRegisterClasses(SrcReg, DstReg))
1439 // r1024<2> = EXTRACT_SUBREG r1025, 2. Then r1024 has already been
1440 // coalesced to a larger register so the subreg indices cancel out.
1441 // Also check if the other larger register is of the same register
1442 // class as the would be resulting register.
1445 DOUT << "\t Sub-register indices mismatch.\n";
1446 return false; // Not coalescable.
1450 unsigned LargeReg = isExtSubReg ? SrcReg : DstReg;
1451 unsigned SmallReg = isExtSubReg ? DstReg : SrcReg;
1452 unsigned Limit= allocatableRCRegs_[mri_->getRegClass(SmallReg)].count();
1453 if (!isWinToJoinCrossClass(LargeReg, SmallReg, Limit)) {
1454 Again = true; // May be possible to coalesce later.
1459 } else if (differingRegisterClasses(SrcReg, DstReg)) {
1460 if (!CrossClassJoin)
1464 // FIXME: What if the result of a EXTRACT_SUBREG is then coalesced
1465 // with another? If it's the resulting destination register, then
1466 // the subidx must be propagated to uses (but only those defined
1467 // by the EXTRACT_SUBREG). If it's being coalesced into another
1468 // register, it should be safe because register is assumed to have
1469 // the register class of the super-register.
1471 // Process moves where one of the registers have a sub-register index.
1472 MachineOperand *DstMO = CopyMI->findRegisterDefOperand(DstReg);
1473 MachineOperand *SrcMO = CopyMI->findRegisterUseOperand(SrcReg);
1474 SubIdx = DstMO->getSubReg();
1476 if (SrcMO->getSubReg())
1477 // FIXME: can we handle this?
1479 // This is not an insert_subreg but it looks like one.
1480 // e.g. %reg1024:4 = MOV32rr %EAX
1483 if (!CanJoinInsertSubRegToPhysReg(DstReg, SrcReg, SubIdx, RealSrcReg))
1484 return false; // Not coalescable
1488 SubIdx = SrcMO->getSubReg();
1490 // This is not a extract_subreg but it looks like one.
1491 // e.g. %cl = MOV16rr %reg1024:1
1494 if (!CanJoinExtractSubRegToPhysReg(DstReg, SrcReg, SubIdx,RealDstReg))
1495 return false; // Not coalescable
1501 const TargetRegisterClass *SrcRC= SrcIsPhys ? 0 : mri_->getRegClass(SrcReg);
1502 const TargetRegisterClass *DstRC= DstIsPhys ? 0 : mri_->getRegClass(DstReg);
1503 unsigned LargeReg = SrcReg;
1504 unsigned SmallReg = DstReg;
1507 // Now determine the register class of the joined register.
1509 if (SubIdx && DstRC && DstRC->isASubClass()) {
1510 // This is a move to a sub-register class. However, the source is a
1511 // sub-register of a larger register class. We don't know what should
1512 // the register class be. FIXME.
1516 Limit = allocatableRCRegs_[DstRC].count();
1517 } else if (!SrcIsPhys && !DstIsPhys) {
1518 NewRC = getCommonSubClass(SrcRC, DstRC);
1520 DOUT << "\tDisjoint regclasses: "
1521 << SrcRC->getName() << ", "
1522 << DstRC->getName() << ".\n";
1523 return false; // Not coalescable.
1525 if (DstRC->getSize() > SrcRC->getSize())
1526 std::swap(LargeReg, SmallReg);
1529 // If we are joining two virtual registers and the resulting register
1530 // class is more restrictive (fewer register, smaller size). Check if it's
1531 // worth doing the merge.
1532 if (!SrcIsPhys && !DstIsPhys &&
1533 (isExtSubReg || DstRC->isASubClass()) &&
1534 !isWinToJoinCrossClass(LargeReg, SmallReg,
1535 allocatableRCRegs_[NewRC].count())) {
1536 DOUT << "\tSrc/Dest are different register classes.\n";
1537 // Allow the coalescer to try again in case either side gets coalesced to
1538 // a physical register that's compatible with the other side. e.g.
1539 // r1024 = MOV32to32_ r1025
1540 // But later r1024 is assigned EAX then r1025 may be coalesced with EAX.
1541 Again = true; // May be possible to coalesce later.
1546 // Will it create illegal extract_subreg / insert_subreg?
1547 if (SrcIsPhys && HasIncompatibleSubRegDefUse(CopyMI, DstReg, SrcReg))
1549 if (DstIsPhys && HasIncompatibleSubRegDefUse(CopyMI, SrcReg, DstReg))
1552 LiveInterval &SrcInt = li_->getInterval(SrcReg);
1553 LiveInterval &DstInt = li_->getInterval(DstReg);
1554 assert(SrcInt.reg == SrcReg && DstInt.reg == DstReg &&
1555 "Register mapping is horribly broken!");
1557 DOUT << "\t\tInspecting "; SrcInt.print(DOUT, tri_);
1558 DOUT << " and "; DstInt.print(DOUT, tri_);
1561 // Save a copy of the virtual register live interval. We'll manually
1562 // merge this into the "real" physical register live interval this is
1564 LiveInterval *SavedLI = 0;
1566 SavedLI = li_->dupInterval(&SrcInt);
1567 else if (RealSrcReg)
1568 SavedLI = li_->dupInterval(&DstInt);
1570 // Check if it is necessary to propagate "isDead" property.
1571 if (!isExtSubReg && !isInsSubReg && !isSubRegToReg) {
1572 MachineOperand *mopd = CopyMI->findRegisterDefOperand(DstReg, false);
1573 bool isDead = mopd->isDead();
1575 // We need to be careful about coalescing a source physical register with a
1576 // virtual register. Once the coalescing is done, it cannot be broken and
1577 // these are not spillable! If the destination interval uses are far away,
1578 // think twice about coalescing them!
1579 if (!isDead && (SrcIsPhys || DstIsPhys)) {
1580 // If the copy is in a loop, take care not to coalesce aggressively if the
1581 // src is coming in from outside the loop (or the dst is out of the loop).
1582 // If it's not in a loop, then determine whether to join them base purely
1583 // by the length of the interval.
1584 if (PhysJoinTweak) {
1586 if (!isWinToJoinVRWithSrcPhysReg(CopyMI, CopyMBB, DstInt, SrcInt)) {
1587 mri_->setRegAllocationHint(DstInt.reg, 0, SrcReg);
1589 DOUT << "\tMay tie down a physical register, abort!\n";
1590 Again = true; // May be possible to coalesce later.
1594 if (!isWinToJoinVRWithDstPhysReg(CopyMI, CopyMBB, DstInt, SrcInt)) {
1595 mri_->setRegAllocationHint(SrcInt.reg, 0, DstReg);
1597 DOUT << "\tMay tie down a physical register, abort!\n";
1598 Again = true; // May be possible to coalesce later.
1603 // If the virtual register live interval is long but it has low use desity,
1604 // do not join them, instead mark the physical register as its allocation
1606 LiveInterval &JoinVInt = SrcIsPhys ? DstInt : SrcInt;
1607 unsigned JoinVReg = SrcIsPhys ? DstReg : SrcReg;
1608 unsigned JoinPReg = SrcIsPhys ? SrcReg : DstReg;
1609 const TargetRegisterClass *RC = mri_->getRegClass(JoinVReg);
1610 unsigned Threshold = allocatableRCRegs_[RC].count() * 2;
1611 if (TheCopy.isBackEdge)
1612 Threshold *= 2; // Favors back edge copies.
1614 unsigned Length = li_->getApproximateInstructionCount(JoinVInt);
1615 float Ratio = 1.0 / Threshold;
1616 if (Length > Threshold &&
1617 (((float)std::distance(mri_->use_begin(JoinVReg),
1618 mri_->use_end()) / Length) < Ratio)) {
1619 mri_->setRegAllocationHint(JoinVInt.reg, 0, JoinPReg);
1621 DOUT << "\tMay tie down a physical register, abort!\n";
1622 Again = true; // May be possible to coalesce later.
1629 // Okay, attempt to join these two intervals. On failure, this returns false.
1630 // Otherwise, if one of the intervals being joined is a physreg, this method
1631 // always canonicalizes DstInt to be it. The output "SrcInt" will not have
1632 // been modified, so we can use this information below to update aliases.
1633 bool Swapped = false;
1634 // If SrcInt is implicitly defined, it's safe to coalesce.
1635 bool isEmpty = SrcInt.empty();
1636 if (isEmpty && !CanCoalesceWithImpDef(CopyMI, DstInt, SrcInt)) {
1637 // Only coalesce an empty interval (defined by implicit_def) with
1638 // another interval which has a valno defined by the CopyMI and the CopyMI
1639 // is a kill of the implicit def.
1640 DOUT << "Not profitable!\n";
1644 if (!isEmpty && !JoinIntervals(DstInt, SrcInt, Swapped)) {
1645 // Coalescing failed.
1647 // If definition of source is defined by trivial computation, try
1648 // rematerializing it.
1649 if (!isExtSubReg && !isInsSubReg && !isSubRegToReg &&
1650 ReMaterializeTrivialDef(SrcInt, DstInt.reg, CopyMI))
1653 // If we can eliminate the copy without merging the live ranges, do so now.
1654 if (!isExtSubReg && !isInsSubReg && !isSubRegToReg &&
1655 (AdjustCopiesBackFrom(SrcInt, DstInt, CopyMI) ||
1656 RemoveCopyByCommutingDef(SrcInt, DstInt, CopyMI))) {
1657 JoinedCopies.insert(CopyMI);
1661 // Otherwise, we are unable to join the intervals.
1662 DOUT << "Interference!\n";
1663 Again = true; // May be possible to coalesce later.
1667 LiveInterval *ResSrcInt = &SrcInt;
1668 LiveInterval *ResDstInt = &DstInt;
1670 std::swap(SrcReg, DstReg);
1671 std::swap(ResSrcInt, ResDstInt);
1673 assert(TargetRegisterInfo::isVirtualRegister(SrcReg) &&
1674 "LiveInterval::join didn't work right!");
1676 // If we're about to merge live ranges into a physical register live interval,
1677 // we have to update any aliased register's live ranges to indicate that they
1678 // have clobbered values for this range.
1679 if (TargetRegisterInfo::isPhysicalRegister(DstReg)) {
1680 // If this is a extract_subreg where dst is a physical register, e.g.
1681 // cl = EXTRACT_SUBREG reg1024, 1
1682 // then create and update the actual physical register allocated to RHS.
1683 if (RealDstReg || RealSrcReg) {
1684 LiveInterval &RealInt =
1685 li_->getOrCreateInterval(RealDstReg ? RealDstReg : RealSrcReg);
1686 for (LiveInterval::const_vni_iterator I = SavedLI->vni_begin(),
1687 E = SavedLI->vni_end(); I != E; ++I) {
1688 const VNInfo *ValNo = *I;
1689 VNInfo *NewValNo = RealInt.getNextValue(ValNo->def, ValNo->copy,
1690 false, // updated at *
1691 li_->getVNInfoAllocator());
1692 NewValNo->setFlags(ValNo->getFlags()); // * updated here.
1693 RealInt.addKills(NewValNo, ValNo->kills);
1694 RealInt.MergeValueInAsValue(*SavedLI, ValNo, NewValNo);
1696 RealInt.weight += SavedLI->weight;
1697 DstReg = RealDstReg ? RealDstReg : RealSrcReg;
1700 // Update the liveintervals of sub-registers.
1701 for (const unsigned *AS = tri_->getSubRegisters(DstReg); *AS; ++AS)
1702 li_->getOrCreateInterval(*AS).MergeInClobberRanges(*ResSrcInt,
1703 li_->getVNInfoAllocator());
1706 // If this is a EXTRACT_SUBREG, make sure the result of coalescing is the
1707 // larger super-register.
1708 if ((isExtSubReg || isInsSubReg || isSubRegToReg) &&
1709 !SrcIsPhys && !DstIsPhys) {
1710 if ((isExtSubReg && !Swapped) ||
1711 ((isInsSubReg || isSubRegToReg) && Swapped)) {
1712 ResSrcInt->Copy(*ResDstInt, mri_, li_->getVNInfoAllocator());
1713 std::swap(SrcReg, DstReg);
1714 std::swap(ResSrcInt, ResDstInt);
1718 // Coalescing to a virtual register that is of a sub-register class of the
1719 // other. Make sure the resulting register is set to the right register class.
1723 mri_->setRegClass(DstReg, NewRC);
1727 // Add all copies that define val# in the source interval into the queue.
1728 for (LiveInterval::const_vni_iterator i = ResSrcInt->vni_begin(),
1729 e = ResSrcInt->vni_end(); i != e; ++i) {
1730 const VNInfo *vni = *i;
1731 // FIXME: Do isPHIDef and isDefAccurate both need to be tested?
1732 if (!vni->def || vni->isUnused() || vni->isPHIDef() || !vni->isDefAccurate())
1734 MachineInstr *CopyMI = li_->getInstructionFromIndex(vni->def);
1735 unsigned NewSrcReg, NewDstReg, NewSrcSubIdx, NewDstSubIdx;
1737 JoinedCopies.count(CopyMI) == 0 &&
1738 tii_->isMoveInstr(*CopyMI, NewSrcReg, NewDstReg,
1739 NewSrcSubIdx, NewDstSubIdx)) {
1740 unsigned LoopDepth = loopInfo->getLoopDepth(CopyMBB);
1741 JoinQueue->push(CopyRec(CopyMI, LoopDepth,
1742 isBackEdgeCopy(CopyMI, DstReg)));
1747 // Remember to delete the copy instruction.
1748 JoinedCopies.insert(CopyMI);
1750 // Some live range has been lengthened due to colaescing, eliminate the
1751 // unnecessary kills.
1752 RemoveUnnecessaryKills(SrcReg, *ResDstInt);
1753 if (TargetRegisterInfo::isVirtualRegister(DstReg))
1754 RemoveUnnecessaryKills(DstReg, *ResDstInt);
1759 // r1024 = implicit_def
1762 RemoveDeadImpDef(DstReg, *ResDstInt);
1763 UpdateRegDefsUses(SrcReg, DstReg, SubIdx);
1765 // SrcReg is guarateed to be the register whose live interval that is
1767 li_->removeInterval(SrcReg);
1769 // Update regalloc hint.
1770 tri_->UpdateRegAllocHint(SrcReg, DstReg, *mf_);
1772 // Manually deleted the live interval copy.
1779 // Now the copy is being coalesced away, the val# previously defined
1780 // by the copy is being defined by an IMPLICIT_DEF which defines a zero
1781 // length interval. Remove the val#.
1782 unsigned CopyIdx = li_->getDefIndex(li_->getInstructionIndex(CopyMI));
1783 const LiveRange *LR = ResDstInt->getLiveRangeContaining(CopyIdx);
1784 VNInfo *ImpVal = LR->valno;
1785 assert(ImpVal->def == CopyIdx);
1786 unsigned NextDef = LR->end;
1787 TurnCopiesFromValNoToImpDefs(*ResDstInt, ImpVal);
1788 ResDstInt->removeValNo(ImpVal);
1789 LR = ResDstInt->FindLiveRangeContaining(NextDef);
1790 if (LR != ResDstInt->end() && LR->valno->def == NextDef) {
1791 // Special case: vr1024 = implicit_def
1792 // vr1024 = insert_subreg vr1024, vr1025, c
1793 // The insert_subreg becomes a "copy" that defines a val# which can itself
1794 // be coalesced away.
1795 MachineInstr *DefMI = li_->getInstructionFromIndex(NextDef);
1796 if (DefMI->getOpcode() == TargetInstrInfo::INSERT_SUBREG)
1797 LR->valno->copy = DefMI;
1801 // If resulting interval has a preference that no longer fits because of subreg
1802 // coalescing, just clear the preference.
1803 unsigned Preference = getRegAllocPreference(ResDstInt->reg, *mf_, mri_, tri_);
1804 if (Preference && (isExtSubReg || isInsSubReg || isSubRegToReg) &&
1805 TargetRegisterInfo::isVirtualRegister(ResDstInt->reg)) {
1806 const TargetRegisterClass *RC = mri_->getRegClass(ResDstInt->reg);
1807 if (!RC->contains(Preference))
1808 mri_->setRegAllocationHint(ResDstInt->reg, 0, 0);
1811 DOUT << "\n\t\tJoined. Result = "; ResDstInt->print(DOUT, tri_);
1818 /// ComputeUltimateVN - Assuming we are going to join two live intervals,
1819 /// compute what the resultant value numbers for each value in the input two
1820 /// ranges will be. This is complicated by copies between the two which can
1821 /// and will commonly cause multiple value numbers to be merged into one.
1823 /// VN is the value number that we're trying to resolve. InstDefiningValue
1824 /// keeps track of the new InstDefiningValue assignment for the result
1825 /// LiveInterval. ThisFromOther/OtherFromThis are sets that keep track of
1826 /// whether a value in this or other is a copy from the opposite set.
1827 /// ThisValNoAssignments/OtherValNoAssignments keep track of value #'s that have
1828 /// already been assigned.
1830 /// ThisFromOther[x] - If x is defined as a copy from the other interval, this
1831 /// contains the value number the copy is from.
1833 static unsigned ComputeUltimateVN(VNInfo *VNI,
1834 SmallVector<VNInfo*, 16> &NewVNInfo,
1835 DenseMap<VNInfo*, VNInfo*> &ThisFromOther,
1836 DenseMap<VNInfo*, VNInfo*> &OtherFromThis,
1837 SmallVector<int, 16> &ThisValNoAssignments,
1838 SmallVector<int, 16> &OtherValNoAssignments) {
1839 unsigned VN = VNI->id;
1841 // If the VN has already been computed, just return it.
1842 if (ThisValNoAssignments[VN] >= 0)
1843 return ThisValNoAssignments[VN];
1844 // assert(ThisValNoAssignments[VN] != -2 && "Cyclic case?");
1846 // If this val is not a copy from the other val, then it must be a new value
1847 // number in the destination.
1848 DenseMap<VNInfo*, VNInfo*>::iterator I = ThisFromOther.find(VNI);
1849 if (I == ThisFromOther.end()) {
1850 NewVNInfo.push_back(VNI);
1851 return ThisValNoAssignments[VN] = NewVNInfo.size()-1;
1853 VNInfo *OtherValNo = I->second;
1855 // Otherwise, this *is* a copy from the RHS. If the other side has already
1856 // been computed, return it.
1857 if (OtherValNoAssignments[OtherValNo->id] >= 0)
1858 return ThisValNoAssignments[VN] = OtherValNoAssignments[OtherValNo->id];
1860 // Mark this value number as currently being computed, then ask what the
1861 // ultimate value # of the other value is.
1862 ThisValNoAssignments[VN] = -2;
1863 unsigned UltimateVN =
1864 ComputeUltimateVN(OtherValNo, NewVNInfo, OtherFromThis, ThisFromOther,
1865 OtherValNoAssignments, ThisValNoAssignments);
1866 return ThisValNoAssignments[VN] = UltimateVN;
1869 static bool InVector(VNInfo *Val, const SmallVector<VNInfo*, 8> &V) {
1870 return std::find(V.begin(), V.end(), Val) != V.end();
1873 /// RangeIsDefinedByCopyFromReg - Return true if the specified live range of
1874 /// the specified live interval is defined by a copy from the specified
1876 bool SimpleRegisterCoalescing::RangeIsDefinedByCopyFromReg(LiveInterval &li,
1879 unsigned SrcReg = li_->getVNInfoSourceReg(LR->valno);
1882 // FIXME: Do isPHIDef and isDefAccurate both need to be tested?
1883 if ((LR->valno->isPHIDef() || !LR->valno->isDefAccurate()) &&
1884 TargetRegisterInfo::isPhysicalRegister(li.reg) &&
1885 *tri_->getSuperRegisters(li.reg)) {
1886 // It's a sub-register live interval, we may not have precise information.
1888 MachineInstr *DefMI = li_->getInstructionFromIndex(LR->start);
1889 unsigned SrcReg, DstReg, SrcSubIdx, DstSubIdx;
1891 tii_->isMoveInstr(*DefMI, SrcReg, DstReg, SrcSubIdx, DstSubIdx) &&
1892 DstReg == li.reg && SrcReg == Reg) {
1893 // Cache computed info.
1894 LR->valno->def = LR->start;
1895 LR->valno->copy = DefMI;
1902 /// SimpleJoin - Attempt to joint the specified interval into this one. The
1903 /// caller of this method must guarantee that the RHS only contains a single
1904 /// value number and that the RHS is not defined by a copy from this
1905 /// interval. This returns false if the intervals are not joinable, or it
1906 /// joins them and returns true.
1907 bool SimpleRegisterCoalescing::SimpleJoin(LiveInterval &LHS, LiveInterval &RHS){
1908 assert(RHS.containsOneValue());
1910 // Some number (potentially more than one) value numbers in the current
1911 // interval may be defined as copies from the RHS. Scan the overlapping
1912 // portions of the LHS and RHS, keeping track of this and looking for
1913 // overlapping live ranges that are NOT defined as copies. If these exist, we
1916 LiveInterval::iterator LHSIt = LHS.begin(), LHSEnd = LHS.end();
1917 LiveInterval::iterator RHSIt = RHS.begin(), RHSEnd = RHS.end();
1919 if (LHSIt->start < RHSIt->start) {
1920 LHSIt = std::upper_bound(LHSIt, LHSEnd, RHSIt->start);
1921 if (LHSIt != LHS.begin()) --LHSIt;
1922 } else if (RHSIt->start < LHSIt->start) {
1923 RHSIt = std::upper_bound(RHSIt, RHSEnd, LHSIt->start);
1924 if (RHSIt != RHS.begin()) --RHSIt;
1927 SmallVector<VNInfo*, 8> EliminatedLHSVals;
1930 // Determine if these live intervals overlap.
1931 bool Overlaps = false;
1932 if (LHSIt->start <= RHSIt->start)
1933 Overlaps = LHSIt->end > RHSIt->start;
1935 Overlaps = RHSIt->end > LHSIt->start;
1937 // If the live intervals overlap, there are two interesting cases: if the
1938 // LHS interval is defined by a copy from the RHS, it's ok and we record
1939 // that the LHS value # is the same as the RHS. If it's not, then we cannot
1940 // coalesce these live ranges and we bail out.
1942 // If we haven't already recorded that this value # is safe, check it.
1943 if (!InVector(LHSIt->valno, EliminatedLHSVals)) {
1944 // Copy from the RHS?
1945 if (!RangeIsDefinedByCopyFromReg(LHS, LHSIt, RHS.reg))
1946 return false; // Nope, bail out.
1948 if (LHSIt->contains(RHSIt->valno->def))
1949 // Here is an interesting situation:
1951 // vr1025 = copy vr1024
1956 // Even though vr1025 is copied from vr1024, it's not safe to
1957 // coalesce them since the live range of vr1025 intersects the
1958 // def of vr1024. This happens because vr1025 is assigned the
1959 // value of the previous iteration of vr1024.
1961 EliminatedLHSVals.push_back(LHSIt->valno);
1964 // We know this entire LHS live range is okay, so skip it now.
1965 if (++LHSIt == LHSEnd) break;
1969 if (LHSIt->end < RHSIt->end) {
1970 if (++LHSIt == LHSEnd) break;
1972 // One interesting case to check here. It's possible that we have
1973 // something like "X3 = Y" which defines a new value number in the LHS,
1974 // and is the last use of this liverange of the RHS. In this case, we
1975 // want to notice this copy (so that it gets coalesced away) even though
1976 // the live ranges don't actually overlap.
1977 if (LHSIt->start == RHSIt->end) {
1978 if (InVector(LHSIt->valno, EliminatedLHSVals)) {
1979 // We already know that this value number is going to be merged in
1980 // if coalescing succeeds. Just skip the liverange.
1981 if (++LHSIt == LHSEnd) break;
1983 // Otherwise, if this is a copy from the RHS, mark it as being merged
1985 if (RangeIsDefinedByCopyFromReg(LHS, LHSIt, RHS.reg)) {
1986 if (LHSIt->contains(RHSIt->valno->def))
1987 // Here is an interesting situation:
1989 // vr1025 = copy vr1024
1994 // Even though vr1025 is copied from vr1024, it's not safe to
1995 // coalesced them since live range of vr1025 intersects the
1996 // def of vr1024. This happens because vr1025 is assigned the
1997 // value of the previous iteration of vr1024.
1999 EliminatedLHSVals.push_back(LHSIt->valno);
2001 // We know this entire LHS live range is okay, so skip it now.
2002 if (++LHSIt == LHSEnd) break;
2007 if (++RHSIt == RHSEnd) break;
2011 // If we got here, we know that the coalescing will be successful and that
2012 // the value numbers in EliminatedLHSVals will all be merged together. Since
2013 // the most common case is that EliminatedLHSVals has a single number, we
2014 // optimize for it: if there is more than one value, we merge them all into
2015 // the lowest numbered one, then handle the interval as if we were merging
2016 // with one value number.
2017 VNInfo *LHSValNo = NULL;
2018 if (EliminatedLHSVals.size() > 1) {
2019 // Loop through all the equal value numbers merging them into the smallest
2021 VNInfo *Smallest = EliminatedLHSVals[0];
2022 for (unsigned i = 1, e = EliminatedLHSVals.size(); i != e; ++i) {
2023 if (EliminatedLHSVals[i]->id < Smallest->id) {
2024 // Merge the current notion of the smallest into the smaller one.
2025 LHS.MergeValueNumberInto(Smallest, EliminatedLHSVals[i]);
2026 Smallest = EliminatedLHSVals[i];
2028 // Merge into the smallest.
2029 LHS.MergeValueNumberInto(EliminatedLHSVals[i], Smallest);
2032 LHSValNo = Smallest;
2033 } else if (EliminatedLHSVals.empty()) {
2034 if (TargetRegisterInfo::isPhysicalRegister(LHS.reg) &&
2035 *tri_->getSuperRegisters(LHS.reg))
2036 // Imprecise sub-register information. Can't handle it.
2038 assert(0 && "No copies from the RHS?");
2040 LHSValNo = EliminatedLHSVals[0];
2043 // Okay, now that there is a single LHS value number that we're merging the
2044 // RHS into, update the value number info for the LHS to indicate that the
2045 // value number is defined where the RHS value number was.
2046 const VNInfo *VNI = RHS.getValNumInfo(0);
2047 LHSValNo->def = VNI->def;
2048 LHSValNo->copy = VNI->copy;
2050 // Okay, the final step is to loop over the RHS live intervals, adding them to
2052 if (VNI->hasPHIKill())
2053 LHSValNo->setHasPHIKill(true);
2054 LHS.addKills(LHSValNo, VNI->kills);
2055 LHS.MergeRangesInAsValue(RHS, LHSValNo);
2056 LHS.weight += RHS.weight;
2058 // Update regalloc hint if both are virtual registers.
2059 if (TargetRegisterInfo::isVirtualRegister(LHS.reg) &&
2060 TargetRegisterInfo::isVirtualRegister(RHS.reg)) {
2061 std::pair<unsigned, unsigned> RHSPref = mri_->getRegAllocationHint(RHS.reg);
2062 std::pair<unsigned, unsigned> LHSPref = mri_->getRegAllocationHint(LHS.reg);
2063 if (RHSPref != LHSPref)
2064 mri_->setRegAllocationHint(LHS.reg, RHSPref.first, RHSPref.second);
2067 // Update the liveintervals of sub-registers.
2068 if (TargetRegisterInfo::isPhysicalRegister(LHS.reg))
2069 for (const unsigned *AS = tri_->getSubRegisters(LHS.reg); *AS; ++AS)
2070 li_->getOrCreateInterval(*AS).MergeInClobberRanges(LHS,
2071 li_->getVNInfoAllocator());
2076 /// JoinIntervals - Attempt to join these two intervals. On failure, this
2077 /// returns false. Otherwise, if one of the intervals being joined is a
2078 /// physreg, this method always canonicalizes LHS to be it. The output
2079 /// "RHS" will not have been modified, so we can use this information
2080 /// below to update aliases.
2082 SimpleRegisterCoalescing::JoinIntervals(LiveInterval &LHS, LiveInterval &RHS,
2084 // Compute the final value assignment, assuming that the live ranges can be
2086 SmallVector<int, 16> LHSValNoAssignments;
2087 SmallVector<int, 16> RHSValNoAssignments;
2088 DenseMap<VNInfo*, VNInfo*> LHSValsDefinedFromRHS;
2089 DenseMap<VNInfo*, VNInfo*> RHSValsDefinedFromLHS;
2090 SmallVector<VNInfo*, 16> NewVNInfo;
2092 // If a live interval is a physical register, conservatively check if any
2093 // of its sub-registers is overlapping the live interval of the virtual
2094 // register. If so, do not coalesce.
2095 if (TargetRegisterInfo::isPhysicalRegister(LHS.reg) &&
2096 *tri_->getSubRegisters(LHS.reg)) {
2097 // If it's coalescing a virtual register to a physical register, estimate
2098 // its live interval length. This is the *cost* of scanning an entire live
2099 // interval. If the cost is low, we'll do an exhaustive check instead.
2101 // If this is something like this:
2109 // That is, the live interval of v1024 crosses a bb. Then we can't rely on
2110 // less conservative check. It's possible a sub-register is defined before
2111 // v1024 (or live in) and live out of BB1.
2112 if (RHS.containsOneValue() &&
2113 li_->intervalIsInOneMBB(RHS) &&
2114 li_->getApproximateInstructionCount(RHS) <= 10) {
2115 // Perform a more exhaustive check for some common cases.
2116 if (li_->conflictsWithPhysRegRef(RHS, LHS.reg, true, JoinedCopies))
2119 for (const unsigned* SR = tri_->getSubRegisters(LHS.reg); *SR; ++SR)
2120 if (li_->hasInterval(*SR) && RHS.overlaps(li_->getInterval(*SR))) {
2121 DOUT << "Interfere with sub-register ";
2122 DEBUG(li_->getInterval(*SR).print(DOUT, tri_));
2126 } else if (TargetRegisterInfo::isPhysicalRegister(RHS.reg) &&
2127 *tri_->getSubRegisters(RHS.reg)) {
2128 if (LHS.containsOneValue() &&
2129 li_->getApproximateInstructionCount(LHS) <= 10) {
2130 // Perform a more exhaustive check for some common cases.
2131 if (li_->conflictsWithPhysRegRef(LHS, RHS.reg, false, JoinedCopies))
2134 for (const unsigned* SR = tri_->getSubRegisters(RHS.reg); *SR; ++SR)
2135 if (li_->hasInterval(*SR) && LHS.overlaps(li_->getInterval(*SR))) {
2136 DOUT << "Interfere with sub-register ";
2137 DEBUG(li_->getInterval(*SR).print(DOUT, tri_));
2143 // Compute ultimate value numbers for the LHS and RHS values.
2144 if (RHS.containsOneValue()) {
2145 // Copies from a liveinterval with a single value are simple to handle and
2146 // very common, handle the special case here. This is important, because
2147 // often RHS is small and LHS is large (e.g. a physreg).
2149 // Find out if the RHS is defined as a copy from some value in the LHS.
2150 int RHSVal0DefinedFromLHS = -1;
2152 VNInfo *RHSValNoInfo = NULL;
2153 VNInfo *RHSValNoInfo0 = RHS.getValNumInfo(0);
2154 unsigned RHSSrcReg = li_->getVNInfoSourceReg(RHSValNoInfo0);
2155 if (RHSSrcReg == 0 || RHSSrcReg != LHS.reg) {
2156 // If RHS is not defined as a copy from the LHS, we can use simpler and
2157 // faster checks to see if the live ranges are coalescable. This joiner
2158 // can't swap the LHS/RHS intervals though.
2159 if (!TargetRegisterInfo::isPhysicalRegister(RHS.reg)) {
2160 return SimpleJoin(LHS, RHS);
2162 RHSValNoInfo = RHSValNoInfo0;
2165 // It was defined as a copy from the LHS, find out what value # it is.
2166 RHSValNoInfo = LHS.getLiveRangeContaining(RHSValNoInfo0->def-1)->valno;
2167 RHSValID = RHSValNoInfo->id;
2168 RHSVal0DefinedFromLHS = RHSValID;
2171 LHSValNoAssignments.resize(LHS.getNumValNums(), -1);
2172 RHSValNoAssignments.resize(RHS.getNumValNums(), -1);
2173 NewVNInfo.resize(LHS.getNumValNums(), NULL);
2175 // Okay, *all* of the values in LHS that are defined as a copy from RHS
2176 // should now get updated.
2177 for (LiveInterval::vni_iterator i = LHS.vni_begin(), e = LHS.vni_end();
2180 unsigned VN = VNI->id;
2181 if (unsigned LHSSrcReg = li_->getVNInfoSourceReg(VNI)) {
2182 if (LHSSrcReg != RHS.reg) {
2183 // If this is not a copy from the RHS, its value number will be
2184 // unmodified by the coalescing.
2185 NewVNInfo[VN] = VNI;
2186 LHSValNoAssignments[VN] = VN;
2187 } else if (RHSValID == -1) {
2188 // Otherwise, it is a copy from the RHS, and we don't already have a
2189 // value# for it. Keep the current value number, but remember it.
2190 LHSValNoAssignments[VN] = RHSValID = VN;
2191 NewVNInfo[VN] = RHSValNoInfo;
2192 LHSValsDefinedFromRHS[VNI] = RHSValNoInfo0;
2194 // Otherwise, use the specified value #.
2195 LHSValNoAssignments[VN] = RHSValID;
2196 if (VN == (unsigned)RHSValID) { // Else this val# is dead.
2197 NewVNInfo[VN] = RHSValNoInfo;
2198 LHSValsDefinedFromRHS[VNI] = RHSValNoInfo0;
2202 NewVNInfo[VN] = VNI;
2203 LHSValNoAssignments[VN] = VN;
2207 assert(RHSValID != -1 && "Didn't find value #?");
2208 RHSValNoAssignments[0] = RHSValID;
2209 if (RHSVal0DefinedFromLHS != -1) {
2210 // This path doesn't go through ComputeUltimateVN so just set
2212 RHSValsDefinedFromLHS[RHSValNoInfo0] = (VNInfo*)1;
2215 // Loop over the value numbers of the LHS, seeing if any are defined from
2217 for (LiveInterval::vni_iterator i = LHS.vni_begin(), e = LHS.vni_end();
2220 if (VNI->isUnused() || VNI->copy == 0) // Src not defined by a copy?
2223 // DstReg is known to be a register in the LHS interval. If the src is
2224 // from the RHS interval, we can use its value #.
2225 if (li_->getVNInfoSourceReg(VNI) != RHS.reg)
2228 // Figure out the value # from the RHS.
2229 LHSValsDefinedFromRHS[VNI]=RHS.getLiveRangeContaining(VNI->def-1)->valno;
2232 // Loop over the value numbers of the RHS, seeing if any are defined from
2234 for (LiveInterval::vni_iterator i = RHS.vni_begin(), e = RHS.vni_end();
2237 if (VNI->isUnused() || VNI->copy == 0) // Src not defined by a copy?
2240 // DstReg is known to be a register in the RHS interval. If the src is
2241 // from the LHS interval, we can use its value #.
2242 if (li_->getVNInfoSourceReg(VNI) != LHS.reg)
2245 // Figure out the value # from the LHS.
2246 RHSValsDefinedFromLHS[VNI]=LHS.getLiveRangeContaining(VNI->def-1)->valno;
2249 LHSValNoAssignments.resize(LHS.getNumValNums(), -1);
2250 RHSValNoAssignments.resize(RHS.getNumValNums(), -1);
2251 NewVNInfo.reserve(LHS.getNumValNums() + RHS.getNumValNums());
2253 for (LiveInterval::vni_iterator i = LHS.vni_begin(), e = LHS.vni_end();
2256 unsigned VN = VNI->id;
2257 if (LHSValNoAssignments[VN] >= 0 || VNI->isUnused())
2259 ComputeUltimateVN(VNI, NewVNInfo,
2260 LHSValsDefinedFromRHS, RHSValsDefinedFromLHS,
2261 LHSValNoAssignments, RHSValNoAssignments);
2263 for (LiveInterval::vni_iterator i = RHS.vni_begin(), e = RHS.vni_end();
2266 unsigned VN = VNI->id;
2267 if (RHSValNoAssignments[VN] >= 0 || VNI->isUnused())
2269 // If this value number isn't a copy from the LHS, it's a new number.
2270 if (RHSValsDefinedFromLHS.find(VNI) == RHSValsDefinedFromLHS.end()) {
2271 NewVNInfo.push_back(VNI);
2272 RHSValNoAssignments[VN] = NewVNInfo.size()-1;
2276 ComputeUltimateVN(VNI, NewVNInfo,
2277 RHSValsDefinedFromLHS, LHSValsDefinedFromRHS,
2278 RHSValNoAssignments, LHSValNoAssignments);
2282 // Armed with the mappings of LHS/RHS values to ultimate values, walk the
2283 // interval lists to see if these intervals are coalescable.
2284 LiveInterval::const_iterator I = LHS.begin();
2285 LiveInterval::const_iterator IE = LHS.end();
2286 LiveInterval::const_iterator J = RHS.begin();
2287 LiveInterval::const_iterator JE = RHS.end();
2289 // Skip ahead until the first place of potential sharing.
2290 if (I->start < J->start) {
2291 I = std::upper_bound(I, IE, J->start);
2292 if (I != LHS.begin()) --I;
2293 } else if (J->start < I->start) {
2294 J = std::upper_bound(J, JE, I->start);
2295 if (J != RHS.begin()) --J;
2299 // Determine if these two live ranges overlap.
2301 if (I->start < J->start) {
2302 Overlaps = I->end > J->start;
2304 Overlaps = J->end > I->start;
2307 // If so, check value # info to determine if they are really different.
2309 // If the live range overlap will map to the same value number in the
2310 // result liverange, we can still coalesce them. If not, we can't.
2311 if (LHSValNoAssignments[I->valno->id] !=
2312 RHSValNoAssignments[J->valno->id])
2316 if (I->end < J->end) {
2325 // Update kill info. Some live ranges are extended due to copy coalescing.
2326 for (DenseMap<VNInfo*, VNInfo*>::iterator I = LHSValsDefinedFromRHS.begin(),
2327 E = LHSValsDefinedFromRHS.end(); I != E; ++I) {
2328 VNInfo *VNI = I->first;
2329 unsigned LHSValID = LHSValNoAssignments[VNI->id];
2330 LiveInterval::removeKill(NewVNInfo[LHSValID], VNI->def);
2331 if (VNI->hasPHIKill())
2332 NewVNInfo[LHSValID]->setHasPHIKill(true);
2333 RHS.addKills(NewVNInfo[LHSValID], VNI->kills);
2336 // Update kill info. Some live ranges are extended due to copy coalescing.
2337 for (DenseMap<VNInfo*, VNInfo*>::iterator I = RHSValsDefinedFromLHS.begin(),
2338 E = RHSValsDefinedFromLHS.end(); I != E; ++I) {
2339 VNInfo *VNI = I->first;
2340 unsigned RHSValID = RHSValNoAssignments[VNI->id];
2341 LiveInterval::removeKill(NewVNInfo[RHSValID], VNI->def);
2342 if (VNI->hasPHIKill())
2343 NewVNInfo[RHSValID]->setHasPHIKill(true);
2344 LHS.addKills(NewVNInfo[RHSValID], VNI->kills);
2347 // If we get here, we know that we can coalesce the live ranges. Ask the
2348 // intervals to coalesce themselves now.
2349 if ((RHS.ranges.size() > LHS.ranges.size() &&
2350 TargetRegisterInfo::isVirtualRegister(LHS.reg)) ||
2351 TargetRegisterInfo::isPhysicalRegister(RHS.reg)) {
2352 RHS.join(LHS, &RHSValNoAssignments[0], &LHSValNoAssignments[0], NewVNInfo,
2356 LHS.join(RHS, &LHSValNoAssignments[0], &RHSValNoAssignments[0], NewVNInfo,
2364 // DepthMBBCompare - Comparison predicate that sort first based on the loop
2365 // depth of the basic block (the unsigned), and then on the MBB number.
2366 struct DepthMBBCompare {
2367 typedef std::pair<unsigned, MachineBasicBlock*> DepthMBBPair;
2368 bool operator()(const DepthMBBPair &LHS, const DepthMBBPair &RHS) const {
2369 if (LHS.first > RHS.first) return true; // Deeper loops first
2370 return LHS.first == RHS.first &&
2371 LHS.second->getNumber() < RHS.second->getNumber();
2376 /// getRepIntervalSize - Returns the size of the interval that represents the
2377 /// specified register.
2379 unsigned JoinPriorityQueue<SF>::getRepIntervalSize(unsigned Reg) {
2380 return Rc->getRepIntervalSize(Reg);
2383 /// CopyRecSort::operator - Join priority queue sorting function.
2385 bool CopyRecSort::operator()(CopyRec left, CopyRec right) const {
2386 // Inner loops first.
2387 if (left.LoopDepth > right.LoopDepth)
2389 else if (left.LoopDepth == right.LoopDepth)
2390 if (left.isBackEdge && !right.isBackEdge)
2395 void SimpleRegisterCoalescing::CopyCoalesceInMBB(MachineBasicBlock *MBB,
2396 std::vector<CopyRec> &TryAgain) {
2397 DOUT << ((Value*)MBB->getBasicBlock())->getName() << ":\n";
2399 std::vector<CopyRec> VirtCopies;
2400 std::vector<CopyRec> PhysCopies;
2401 std::vector<CopyRec> ImpDefCopies;
2402 unsigned LoopDepth = loopInfo->getLoopDepth(MBB);
2403 for (MachineBasicBlock::iterator MII = MBB->begin(), E = MBB->end();
2405 MachineInstr *Inst = MII++;
2407 // If this isn't a copy nor a extract_subreg, we can't join intervals.
2408 unsigned SrcReg, DstReg, SrcSubIdx, DstSubIdx;
2409 if (Inst->getOpcode() == TargetInstrInfo::EXTRACT_SUBREG) {
2410 DstReg = Inst->getOperand(0).getReg();
2411 SrcReg = Inst->getOperand(1).getReg();
2412 } else if (Inst->getOpcode() == TargetInstrInfo::INSERT_SUBREG ||
2413 Inst->getOpcode() == TargetInstrInfo::SUBREG_TO_REG) {
2414 DstReg = Inst->getOperand(0).getReg();
2415 SrcReg = Inst->getOperand(2).getReg();
2416 } else if (!tii_->isMoveInstr(*Inst, SrcReg, DstReg, SrcSubIdx, DstSubIdx))
2419 bool SrcIsPhys = TargetRegisterInfo::isPhysicalRegister(SrcReg);
2420 bool DstIsPhys = TargetRegisterInfo::isPhysicalRegister(DstReg);
2422 JoinQueue->push(CopyRec(Inst, LoopDepth, isBackEdgeCopy(Inst, DstReg)));
2424 if (li_->hasInterval(SrcReg) && li_->getInterval(SrcReg).empty())
2425 ImpDefCopies.push_back(CopyRec(Inst, 0, false));
2426 else if (SrcIsPhys || DstIsPhys)
2427 PhysCopies.push_back(CopyRec(Inst, 0, false));
2429 VirtCopies.push_back(CopyRec(Inst, 0, false));
2436 // Try coalescing implicit copies first, followed by copies to / from
2437 // physical registers, then finally copies from virtual registers to
2438 // virtual registers.
2439 for (unsigned i = 0, e = ImpDefCopies.size(); i != e; ++i) {
2440 CopyRec &TheCopy = ImpDefCopies[i];
2442 if (!JoinCopy(TheCopy, Again))
2444 TryAgain.push_back(TheCopy);
2446 for (unsigned i = 0, e = PhysCopies.size(); i != e; ++i) {
2447 CopyRec &TheCopy = PhysCopies[i];
2449 if (!JoinCopy(TheCopy, Again))
2451 TryAgain.push_back(TheCopy);
2453 for (unsigned i = 0, e = VirtCopies.size(); i != e; ++i) {
2454 CopyRec &TheCopy = VirtCopies[i];
2456 if (!JoinCopy(TheCopy, Again))
2458 TryAgain.push_back(TheCopy);
2462 void SimpleRegisterCoalescing::joinIntervals() {
2463 DOUT << "********** JOINING INTERVALS ***********\n";
2466 JoinQueue = new JoinPriorityQueue<CopyRecSort>(this);
2468 std::vector<CopyRec> TryAgainList;
2469 if (loopInfo->empty()) {
2470 // If there are no loops in the function, join intervals in function order.
2471 for (MachineFunction::iterator I = mf_->begin(), E = mf_->end();
2473 CopyCoalesceInMBB(I, TryAgainList);
2475 // Otherwise, join intervals in inner loops before other intervals.
2476 // Unfortunately we can't just iterate over loop hierarchy here because
2477 // there may be more MBB's than BB's. Collect MBB's for sorting.
2479 // Join intervals in the function prolog first. We want to join physical
2480 // registers with virtual registers before the intervals got too long.
2481 std::vector<std::pair<unsigned, MachineBasicBlock*> > MBBs;
2482 for (MachineFunction::iterator I = mf_->begin(), E = mf_->end();I != E;++I){
2483 MachineBasicBlock *MBB = I;
2484 MBBs.push_back(std::make_pair(loopInfo->getLoopDepth(MBB), I));
2487 // Sort by loop depth.
2488 std::sort(MBBs.begin(), MBBs.end(), DepthMBBCompare());
2490 // Finally, join intervals in loop nest order.
2491 for (unsigned i = 0, e = MBBs.size(); i != e; ++i)
2492 CopyCoalesceInMBB(MBBs[i].second, TryAgainList);
2495 // Joining intervals can allow other intervals to be joined. Iteratively join
2496 // until we make no progress.
2498 SmallVector<CopyRec, 16> TryAgain;
2499 bool ProgressMade = true;
2500 while (ProgressMade) {
2501 ProgressMade = false;
2502 while (!JoinQueue->empty()) {
2503 CopyRec R = JoinQueue->pop();
2505 bool Success = JoinCopy(R, Again);
2507 ProgressMade = true;
2509 TryAgain.push_back(R);
2513 while (!TryAgain.empty()) {
2514 JoinQueue->push(TryAgain.back());
2515 TryAgain.pop_back();
2520 bool ProgressMade = true;
2521 while (ProgressMade) {
2522 ProgressMade = false;
2524 for (unsigned i = 0, e = TryAgainList.size(); i != e; ++i) {
2525 CopyRec &TheCopy = TryAgainList[i];
2528 bool Success = JoinCopy(TheCopy, Again);
2529 if (Success || !Again) {
2530 TheCopy.MI = 0; // Mark this one as done.
2531 ProgressMade = true;
2542 /// Return true if the two specified registers belong to different register
2543 /// classes. The registers may be either phys or virt regs.
2545 SimpleRegisterCoalescing::differingRegisterClasses(unsigned RegA,
2546 unsigned RegB) const {
2547 // Get the register classes for the first reg.
2548 if (TargetRegisterInfo::isPhysicalRegister(RegA)) {
2549 assert(TargetRegisterInfo::isVirtualRegister(RegB) &&
2550 "Shouldn't consider two physregs!");
2551 return !mri_->getRegClass(RegB)->contains(RegA);
2554 // Compare against the regclass for the second reg.
2555 const TargetRegisterClass *RegClassA = mri_->getRegClass(RegA);
2556 if (TargetRegisterInfo::isVirtualRegister(RegB)) {
2557 const TargetRegisterClass *RegClassB = mri_->getRegClass(RegB);
2558 return RegClassA != RegClassB;
2560 return !RegClassA->contains(RegB);
2563 /// lastRegisterUse - Returns the last use of the specific register between
2564 /// cycles Start and End or NULL if there are no uses.
2566 SimpleRegisterCoalescing::lastRegisterUse(unsigned Start, unsigned End,
2567 unsigned Reg, unsigned &UseIdx) const{
2569 if (TargetRegisterInfo::isVirtualRegister(Reg)) {
2570 MachineOperand *LastUse = NULL;
2571 for (MachineRegisterInfo::use_iterator I = mri_->use_begin(Reg),
2572 E = mri_->use_end(); I != E; ++I) {
2573 MachineOperand &Use = I.getOperand();
2574 MachineInstr *UseMI = Use.getParent();
2575 unsigned SrcReg, DstReg, SrcSubIdx, DstSubIdx;
2576 if (tii_->isMoveInstr(*UseMI, SrcReg, DstReg, SrcSubIdx, DstSubIdx) &&
2578 // Ignore identity copies.
2580 unsigned Idx = li_->getInstructionIndex(UseMI);
2581 if (Idx >= Start && Idx < End && Idx >= UseIdx) {
2583 UseIdx = li_->getUseIndex(Idx);
2589 int e = (End-1) / InstrSlots::NUM * InstrSlots::NUM;
2592 // Skip deleted instructions
2593 MachineInstr *MI = li_->getInstructionFromIndex(e);
2594 while ((e - InstrSlots::NUM) >= s && !MI) {
2595 e -= InstrSlots::NUM;
2596 MI = li_->getInstructionFromIndex(e);
2598 if (e < s || MI == NULL)
2601 // Ignore identity copies.
2602 unsigned SrcReg, DstReg, SrcSubIdx, DstSubIdx;
2603 if (!(tii_->isMoveInstr(*MI, SrcReg, DstReg, SrcSubIdx, DstSubIdx) &&
2605 for (unsigned i = 0, NumOps = MI->getNumOperands(); i != NumOps; ++i) {
2606 MachineOperand &Use = MI->getOperand(i);
2607 if (Use.isReg() && Use.isUse() && Use.getReg() &&
2608 tri_->regsOverlap(Use.getReg(), Reg)) {
2609 UseIdx = li_->getUseIndex(e);
2614 e -= InstrSlots::NUM;
2621 void SimpleRegisterCoalescing::printRegName(unsigned reg) const {
2622 if (TargetRegisterInfo::isPhysicalRegister(reg))
2623 cerr << tri_->getName(reg);
2625 cerr << "%reg" << reg;
2628 void SimpleRegisterCoalescing::releaseMemory() {
2629 JoinedCopies.clear();
2630 ReMatCopies.clear();
2634 static bool isZeroLengthInterval(LiveInterval *li) {
2635 for (LiveInterval::Ranges::const_iterator
2636 i = li->ranges.begin(), e = li->ranges.end(); i != e; ++i)
2637 if (i->end - i->start > LiveInterval::InstrSlots::NUM)
2642 /// TurnCopyIntoImpDef - If source of the specified copy is an implicit def,
2643 /// turn the copy into an implicit def.
2645 SimpleRegisterCoalescing::TurnCopyIntoImpDef(MachineBasicBlock::iterator &I,
2646 MachineBasicBlock *MBB,
2647 unsigned DstReg, unsigned SrcReg) {
2648 MachineInstr *CopyMI = &*I;
2649 unsigned CopyIdx = li_->getDefIndex(li_->getInstructionIndex(CopyMI));
2650 if (!li_->hasInterval(SrcReg))
2652 LiveInterval &SrcInt = li_->getInterval(SrcReg);
2653 if (!SrcInt.empty())
2655 if (!li_->hasInterval(DstReg))
2657 LiveInterval &DstInt = li_->getInterval(DstReg);
2658 const LiveRange *DstLR = DstInt.getLiveRangeContaining(CopyIdx);
2659 // If the valno extends beyond this basic block, then it's not safe to delete
2660 // the val# or else livein information won't be correct.
2661 MachineBasicBlock *EndMBB = li_->getMBBFromIndex(DstLR->end);
2664 DstInt.removeValNo(DstLR->valno);
2665 CopyMI->setDesc(tii_->get(TargetInstrInfo::IMPLICIT_DEF));
2666 for (int i = CopyMI->getNumOperands() - 1, e = 0; i > e; --i)
2667 CopyMI->RemoveOperand(i);
2668 bool NoUse = mri_->use_empty(SrcReg);
2670 for (MachineRegisterInfo::reg_iterator I = mri_->reg_begin(SrcReg),
2671 E = mri_->reg_end(); I != E; ) {
2672 assert(I.getOperand().isDef());
2673 MachineInstr *DefMI = &*I;
2675 // The implicit_def source has no other uses, delete it.
2676 assert(DefMI->getOpcode() == TargetInstrInfo::IMPLICIT_DEF);
2677 li_->RemoveMachineInstrFromMaps(DefMI);
2678 DefMI->eraseFromParent();
2686 bool SimpleRegisterCoalescing::runOnMachineFunction(MachineFunction &fn) {
2688 mri_ = &fn.getRegInfo();
2689 tm_ = &fn.getTarget();
2690 tri_ = tm_->getRegisterInfo();
2691 tii_ = tm_->getInstrInfo();
2692 li_ = &getAnalysis<LiveIntervals>();
2693 loopInfo = &getAnalysis<MachineLoopInfo>();
2695 DOUT << "********** SIMPLE REGISTER COALESCING **********\n"
2696 << "********** Function: "
2697 << ((Value*)mf_->getFunction())->getName() << '\n';
2699 allocatableRegs_ = tri_->getAllocatableSet(fn);
2700 for (TargetRegisterInfo::regclass_iterator I = tri_->regclass_begin(),
2701 E = tri_->regclass_end(); I != E; ++I)
2702 allocatableRCRegs_.insert(std::make_pair(*I,
2703 tri_->getAllocatableSet(fn, *I)));
2705 // Join (coalesce) intervals if requested.
2706 if (EnableJoining) {
2709 DOUT << "********** INTERVALS POST JOINING **********\n";
2710 for (LiveIntervals::iterator I = li_->begin(), E = li_->end(); I != E; ++I){
2711 I->second->print(DOUT, tri_);
2717 // Perform a final pass over the instructions and compute spill weights
2718 // and remove identity moves.
2719 SmallVector<unsigned, 4> DeadDefs;
2720 for (MachineFunction::iterator mbbi = mf_->begin(), mbbe = mf_->end();
2721 mbbi != mbbe; ++mbbi) {
2722 MachineBasicBlock* mbb = mbbi;
2723 unsigned loopDepth = loopInfo->getLoopDepth(mbb);
2725 for (MachineBasicBlock::iterator mii = mbb->begin(), mie = mbb->end();
2727 MachineInstr *MI = mii;
2728 unsigned SrcReg, DstReg, SrcSubIdx, DstSubIdx;
2729 if (JoinedCopies.count(MI)) {
2730 // Delete all coalesced copies.
2731 if (!tii_->isMoveInstr(*MI, SrcReg, DstReg, SrcSubIdx, DstSubIdx)) {
2732 assert((MI->getOpcode() == TargetInstrInfo::EXTRACT_SUBREG ||
2733 MI->getOpcode() == TargetInstrInfo::INSERT_SUBREG ||
2734 MI->getOpcode() == TargetInstrInfo::SUBREG_TO_REG) &&
2735 "Unrecognized copy instruction");
2736 DstReg = MI->getOperand(0).getReg();
2738 if (MI->registerDefIsDead(DstReg)) {
2739 LiveInterval &li = li_->getInterval(DstReg);
2740 if (!ShortenDeadCopySrcLiveRange(li, MI))
2741 ShortenDeadCopyLiveRange(li, MI);
2743 li_->RemoveMachineInstrFromMaps(MI);
2744 mii = mbbi->erase(mii);
2749 // Now check if this is a remat'ed def instruction which is now dead.
2750 if (ReMatDefs.count(MI)) {
2752 for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
2753 const MachineOperand &MO = MI->getOperand(i);
2756 unsigned Reg = MO.getReg();
2759 if (TargetRegisterInfo::isVirtualRegister(Reg))
2760 DeadDefs.push_back(Reg);
2763 if (TargetRegisterInfo::isPhysicalRegister(Reg) ||
2764 !mri_->use_empty(Reg)) {
2770 while (!DeadDefs.empty()) {
2771 unsigned DeadDef = DeadDefs.back();
2772 DeadDefs.pop_back();
2773 RemoveDeadDef(li_->getInterval(DeadDef), MI);
2775 li_->RemoveMachineInstrFromMaps(mii);
2776 mii = mbbi->erase(mii);
2782 // If the move will be an identity move delete it
2783 bool isMove= tii_->isMoveInstr(*MI, SrcReg, DstReg, SrcSubIdx, DstSubIdx);
2784 if (isMove && SrcReg == DstReg) {
2785 if (li_->hasInterval(SrcReg)) {
2786 LiveInterval &RegInt = li_->getInterval(SrcReg);
2787 // If def of this move instruction is dead, remove its live range
2788 // from the dstination register's live interval.
2789 if (MI->registerDefIsDead(DstReg)) {
2790 if (!ShortenDeadCopySrcLiveRange(RegInt, MI))
2791 ShortenDeadCopyLiveRange(RegInt, MI);
2794 li_->RemoveMachineInstrFromMaps(MI);
2795 mii = mbbi->erase(mii);
2797 } else if (!isMove || !TurnCopyIntoImpDef(mii, mbb, DstReg, SrcReg)) {
2798 SmallSet<unsigned, 4> UniqueUses;
2799 for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
2800 const MachineOperand &mop = MI->getOperand(i);
2801 if (mop.isReg() && mop.getReg() &&
2802 TargetRegisterInfo::isVirtualRegister(mop.getReg())) {
2803 unsigned reg = mop.getReg();
2804 // Multiple uses of reg by the same instruction. It should not
2805 // contribute to spill weight again.
2806 if (UniqueUses.count(reg) != 0)
2808 LiveInterval &RegInt = li_->getInterval(reg);
2810 li_->getSpillWeight(mop.isDef(), mop.isUse(), loopDepth);
2811 UniqueUses.insert(reg);
2819 for (LiveIntervals::iterator I = li_->begin(), E = li_->end(); I != E; ++I) {
2820 LiveInterval &LI = *I->second;
2821 if (TargetRegisterInfo::isVirtualRegister(LI.reg)) {
2822 // If the live interval length is essentially zero, i.e. in every live
2823 // range the use follows def immediately, it doesn't make sense to spill
2824 // it and hope it will be easier to allocate for this li.
2825 if (isZeroLengthInterval(&LI))
2826 LI.weight = HUGE_VALF;
2828 bool isLoad = false;
2829 SmallVector<LiveInterval*, 4> SpillIs;
2830 if (li_->isReMaterializable(LI, SpillIs, isLoad)) {
2831 // If all of the definitions of the interval are re-materializable,
2832 // it is a preferred candidate for spilling. If non of the defs are
2833 // loads, then it's potentially very cheap to re-materialize.
2834 // FIXME: this gets much more complicated once we support non-trivial
2835 // re-materialization.
2843 // Slightly prefer live interval that has been assigned a preferred reg.
2844 std::pair<unsigned, unsigned> Hint = mri_->getRegAllocationHint(LI.reg);
2845 if (Hint.first || Hint.second)
2848 // Divide the weight of the interval by its size. This encourages
2849 // spilling of intervals that are large and have few uses, and
2850 // discourages spilling of small intervals with many uses.
2851 LI.weight /= li_->getApproximateInstructionCount(LI) * InstrSlots::NUM;
2859 /// print - Implement the dump method.
2860 void SimpleRegisterCoalescing::print(std::ostream &O, const Module* m) const {
2864 RegisterCoalescer* llvm::createSimpleRegisterCoalescer() {
2865 return new SimpleRegisterCoalescing();
2868 // Make sure that anything that uses RegisterCoalescer pulls in this file...
2869 DEFINING_FILE_FOR(SimpleRegisterCoalescing)