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);
63 static RegisterPass<SimpleRegisterCoalescing>
64 X("simple-register-coalescing", "Simple Register Coalescing");
66 // Declare that we implement the RegisterCoalescer interface
67 static RegisterAnalysisGroup<RegisterCoalescer, true/*The Default*/> V(X);
69 const PassInfo *const llvm::SimpleRegisterCoalescingID = &X;
71 void SimpleRegisterCoalescing::getAnalysisUsage(AnalysisUsage &AU) const {
72 AU.addRequired<LiveIntervals>();
73 AU.addPreserved<LiveIntervals>();
74 AU.addRequired<MachineLoopInfo>();
75 AU.addPreserved<MachineLoopInfo>();
76 AU.addPreservedID(MachineDominatorsID);
78 AU.addPreservedID(StrongPHIEliminationID);
80 AU.addPreservedID(PHIEliminationID);
81 AU.addPreservedID(TwoAddressInstructionPassID);
82 MachineFunctionPass::getAnalysisUsage(AU);
85 /// AdjustCopiesBackFrom - We found a non-trivially-coalescable copy with IntA
86 /// being the source and IntB being the dest, thus this defines a value number
87 /// in IntB. If the source value number (in IntA) is defined by a copy from B,
88 /// see if we can merge these two pieces of B into a single value number,
89 /// eliminating a copy. For example:
93 /// B1 = A3 <- this copy
95 /// In this case, B0 can be extended to where the B1 copy lives, allowing the B1
96 /// value number to be replaced with B0 (which simplifies the B liveinterval).
98 /// This returns true if an interval was modified.
100 bool SimpleRegisterCoalescing::AdjustCopiesBackFrom(LiveInterval &IntA,
102 MachineInstr *CopyMI) {
103 unsigned CopyIdx = li_->getDefIndex(li_->getInstructionIndex(CopyMI));
105 // BValNo is a value number in B that is defined by a copy from A. 'B3' in
106 // the example above.
107 LiveInterval::iterator BLR = IntB.FindLiveRangeContaining(CopyIdx);
108 assert(BLR != IntB.end() && "Live range not found!");
109 VNInfo *BValNo = BLR->valno;
111 // Get the location that B is defined at. Two options: either this value has
112 // an unknown definition point or it is defined at CopyIdx. If unknown, we
114 if (!BValNo->copy) return false;
115 assert(BValNo->def == CopyIdx && "Copy doesn't define the value?");
117 // AValNo is the value number in A that defines the copy, A3 in the example.
118 LiveInterval::iterator ALR = IntA.FindLiveRangeContaining(CopyIdx-1);
119 assert(ALR != IntA.end() && "Live range not found!");
120 VNInfo *AValNo = ALR->valno;
121 // If it's re-defined by an early clobber somewhere in the live range, then
122 // it's not safe to eliminate the copy. FIXME: This is a temporary workaround.
124 // 172 %ECX<def> = MOV32rr %reg1039<kill>
125 // 180 INLINEASM <es:subl $5,$1
126 // sbbl $3,$0>, 10, %EAX<def>, 14, %ECX<earlyclobber,def>, 9, %EAX<kill>,
127 // 36, <fi#0>, 1, %reg0, 0, 9, %ECX<kill>, 36, <fi#1>, 1, %reg0, 0
128 // 188 %EAX<def> = MOV32rr %EAX<kill>
129 // 196 %ECX<def> = MOV32rr %ECX<kill>
130 // 204 %ECX<def> = MOV32rr %ECX<kill>
131 // 212 %EAX<def> = MOV32rr %EAX<kill>
132 // 220 %EAX<def> = MOV32rr %EAX
133 // 228 %reg1039<def> = MOV32rr %ECX<kill>
134 // The early clobber operand ties ECX input to the ECX def.
136 // The live interval of ECX is represented as this:
137 // %reg20,inf = [46,47:1)[174,230:0) 0@174-(230) 1@46-(47)
138 // The coalescer has no idea there was a def in the middle of [174,230].
139 if (AValNo->redefByEC)
142 // If AValNo is defined as a copy from IntB, we can potentially process this.
143 // Get the instruction that defines this value number.
144 unsigned SrcReg = li_->getVNInfoSourceReg(AValNo);
145 if (!SrcReg) return false; // Not defined by a copy.
147 // If the value number is not defined by a copy instruction, ignore it.
149 // If the source register comes from an interval other than IntB, we can't
151 if (SrcReg != IntB.reg) return false;
153 // Get the LiveRange in IntB that this value number starts with.
154 LiveInterval::iterator ValLR = IntB.FindLiveRangeContaining(AValNo->def-1);
155 assert(ValLR != IntB.end() && "Live range not found!");
157 // Make sure that the end of the live range is inside the same block as
159 MachineInstr *ValLREndInst = li_->getInstructionFromIndex(ValLR->end-1);
161 ValLREndInst->getParent() != CopyMI->getParent()) return false;
163 // Okay, we now know that ValLR ends in the same block that the CopyMI
164 // live-range starts. If there are no intervening live ranges between them in
165 // IntB, we can merge them.
166 if (ValLR+1 != BLR) return false;
168 // If a live interval is a physical register, conservatively check if any
169 // of its sub-registers is overlapping the live interval of the virtual
170 // register. If so, do not coalesce.
171 if (TargetRegisterInfo::isPhysicalRegister(IntB.reg) &&
172 *tri_->getSubRegisters(IntB.reg)) {
173 for (const unsigned* SR = tri_->getSubRegisters(IntB.reg); *SR; ++SR)
174 if (li_->hasInterval(*SR) && IntA.overlaps(li_->getInterval(*SR))) {
175 DOUT << "Interfere with sub-register ";
176 DEBUG(li_->getInterval(*SR).print(DOUT, tri_));
181 DOUT << "\nExtending: "; IntB.print(DOUT, tri_);
183 unsigned FillerStart = ValLR->end, FillerEnd = BLR->start;
184 // We are about to delete CopyMI, so need to remove it as the 'instruction
185 // that defines this value #'. Update the the valnum with the new defining
187 BValNo->def = FillerStart;
190 // Okay, we can merge them. We need to insert a new liverange:
191 // [ValLR.end, BLR.begin) of either value number, then we merge the
192 // two value numbers.
193 IntB.addRange(LiveRange(FillerStart, FillerEnd, BValNo));
195 // If the IntB live range is assigned to a physical register, and if that
196 // physreg has aliases,
197 if (TargetRegisterInfo::isPhysicalRegister(IntB.reg)) {
198 // Update the liveintervals of sub-registers.
199 for (const unsigned *AS = tri_->getSubRegisters(IntB.reg); *AS; ++AS) {
200 LiveInterval &AliasLI = li_->getInterval(*AS);
201 AliasLI.addRange(LiveRange(FillerStart, FillerEnd,
202 AliasLI.getNextValue(FillerStart, 0, li_->getVNInfoAllocator())));
206 // Okay, merge "B1" into the same value number as "B0".
207 if (BValNo != ValLR->valno) {
208 IntB.addKills(ValLR->valno, BValNo->kills);
209 IntB.MergeValueNumberInto(BValNo, ValLR->valno);
211 DOUT << " result = "; IntB.print(DOUT, tri_);
214 // If the source instruction was killing the source register before the
215 // merge, unset the isKill marker given the live range has been extended.
216 int UIdx = ValLREndInst->findRegisterUseOperandIdx(IntB.reg, true);
218 ValLREndInst->getOperand(UIdx).setIsKill(false);
219 IntB.removeKill(ValLR->valno, FillerStart);
226 /// HasOtherReachingDefs - Return true if there are definitions of IntB
227 /// other than BValNo val# that can reach uses of AValno val# of IntA.
228 bool SimpleRegisterCoalescing::HasOtherReachingDefs(LiveInterval &IntA,
232 for (LiveInterval::iterator AI = IntA.begin(), AE = IntA.end();
234 if (AI->valno != AValNo) continue;
235 LiveInterval::Ranges::iterator BI =
236 std::upper_bound(IntB.ranges.begin(), IntB.ranges.end(), AI->start);
237 if (BI != IntB.ranges.begin())
239 for (; BI != IntB.ranges.end() && AI->end >= BI->start; ++BI) {
240 if (BI->valno == BValNo)
242 if (BI->start <= AI->start && BI->end > AI->start)
244 if (BI->start > AI->start && BI->start < AI->end)
251 /// RemoveCopyByCommutingDef - We found a non-trivially-coalescable copy with IntA
252 /// being the source and IntB being the dest, thus this defines a value number
253 /// in IntB. If the source value number (in IntA) is defined by a commutable
254 /// instruction and its other operand is coalesced to the copy dest register,
255 /// see if we can transform the copy into a noop by commuting the definition. For
258 /// A3 = op A2 B0<kill>
260 /// B1 = A3 <- this copy
262 /// = op A3 <- more uses
266 /// B2 = op B0 A2<kill>
268 /// B1 = B2 <- now an identify copy
270 /// = op B2 <- more uses
272 /// This returns true if an interval was modified.
274 bool SimpleRegisterCoalescing::RemoveCopyByCommutingDef(LiveInterval &IntA,
276 MachineInstr *CopyMI) {
277 unsigned CopyIdx = li_->getDefIndex(li_->getInstructionIndex(CopyMI));
279 // FIXME: For now, only eliminate the copy by commuting its def when the
280 // source register is a virtual register. We want to guard against cases
281 // where the copy is a back edge copy and commuting the def lengthen the
282 // live interval of the source register to the entire loop.
283 if (TargetRegisterInfo::isPhysicalRegister(IntA.reg))
286 // BValNo is a value number in B that is defined by a copy from A. 'B3' in
287 // the example above.
288 LiveInterval::iterator BLR = IntB.FindLiveRangeContaining(CopyIdx);
289 assert(BLR != IntB.end() && "Live range not found!");
290 VNInfo *BValNo = BLR->valno;
292 // Get the location that B is defined at. Two options: either this value has
293 // an unknown definition point or it is defined at CopyIdx. If unknown, we
295 if (!BValNo->copy) return false;
296 assert(BValNo->def == CopyIdx && "Copy doesn't define the value?");
298 // AValNo is the value number in A that defines the copy, A3 in the example.
299 LiveInterval::iterator ALR = IntA.FindLiveRangeContaining(CopyIdx-1);
300 assert(ALR != IntA.end() && "Live range not found!");
301 VNInfo *AValNo = ALR->valno;
302 // If other defs can reach uses of this def, then it's not safe to perform
304 if (AValNo->def == ~0U || AValNo->def == ~1U || AValNo->hasPHIKill)
306 MachineInstr *DefMI = li_->getInstructionFromIndex(AValNo->def);
307 const TargetInstrDesc &TID = DefMI->getDesc();
309 if (!TID.isCommutable() ||
310 !tii_->CommuteChangesDestination(DefMI, NewDstIdx))
313 MachineOperand &NewDstMO = DefMI->getOperand(NewDstIdx);
314 unsigned NewReg = NewDstMO.getReg();
315 if (NewReg != IntB.reg || !NewDstMO.isKill())
318 // Make sure there are no other definitions of IntB that would reach the
319 // uses which the new definition can reach.
320 if (HasOtherReachingDefs(IntA, IntB, AValNo, BValNo))
323 // If some of the uses of IntA.reg is already coalesced away, return false.
324 // It's not possible to determine whether it's safe to perform the coalescing.
325 for (MachineRegisterInfo::use_iterator UI = mri_->use_begin(IntA.reg),
326 UE = mri_->use_end(); UI != UE; ++UI) {
327 MachineInstr *UseMI = &*UI;
328 unsigned UseIdx = li_->getInstructionIndex(UseMI);
329 LiveInterval::iterator ULR = IntA.FindLiveRangeContaining(UseIdx);
330 if (ULR == IntA.end())
332 if (ULR->valno == AValNo && JoinedCopies.count(UseMI))
336 // At this point we have decided that it is legal to do this
337 // transformation. Start by commuting the instruction.
338 MachineBasicBlock *MBB = DefMI->getParent();
339 MachineInstr *NewMI = tii_->commuteInstruction(DefMI);
342 if (NewMI != DefMI) {
343 li_->ReplaceMachineInstrInMaps(DefMI, NewMI);
344 MBB->insert(DefMI, NewMI);
347 unsigned OpIdx = NewMI->findRegisterUseOperandIdx(IntA.reg, false);
348 NewMI->getOperand(OpIdx).setIsKill();
350 bool BHasPHIKill = BValNo->hasPHIKill;
351 SmallVector<VNInfo*, 4> BDeadValNos;
352 SmallVector<unsigned, 4> BKills;
353 std::map<unsigned, unsigned> BExtend;
355 // If ALR and BLR overlaps and end of BLR extends beyond end of ALR, e.g.
364 // then do not add kills of A to the newly created B interval.
365 bool Extended = BLR->end > ALR->end && ALR->end != ALR->start;
367 BExtend[ALR->end] = BLR->end;
369 // Update uses of IntA of the specific Val# with IntB.
370 for (MachineRegisterInfo::use_iterator UI = mri_->use_begin(IntA.reg),
371 UE = mri_->use_end(); UI != UE;) {
372 MachineOperand &UseMO = UI.getOperand();
373 MachineInstr *UseMI = &*UI;
375 if (JoinedCopies.count(UseMI))
377 unsigned UseIdx = li_->getInstructionIndex(UseMI);
378 LiveInterval::iterator ULR = IntA.FindLiveRangeContaining(UseIdx);
379 if (ULR == IntA.end() || ULR->valno != AValNo)
381 UseMO.setReg(NewReg);
384 if (UseMO.isKill()) {
386 UseMO.setIsKill(false);
388 BKills.push_back(li_->getUseIndex(UseIdx)+1);
390 unsigned SrcReg, DstReg, SrcSubIdx, DstSubIdx;
391 if (!tii_->isMoveInstr(*UseMI, SrcReg, DstReg, SrcSubIdx, DstSubIdx))
393 if (DstReg == IntB.reg) {
394 // This copy will become a noop. If it's defining a new val#,
395 // remove that val# as well. However this live range is being
396 // extended to the end of the existing live range defined by the copy.
397 unsigned DefIdx = li_->getDefIndex(UseIdx);
398 const LiveRange *DLR = IntB.getLiveRangeContaining(DefIdx);
399 BHasPHIKill |= DLR->valno->hasPHIKill;
400 assert(DLR->valno->def == DefIdx);
401 BDeadValNos.push_back(DLR->valno);
402 BExtend[DLR->start] = DLR->end;
403 JoinedCopies.insert(UseMI);
404 // If this is a kill but it's going to be removed, the last use
405 // of the same val# is the new kill.
411 // We need to insert a new liverange: [ALR.start, LastUse). It may be we can
412 // simply extend BLR if CopyMI doesn't end the range.
413 DOUT << "\nExtending: "; IntB.print(DOUT, tri_);
415 // Remove val#'s defined by copies that will be coalesced away.
416 for (unsigned i = 0, e = BDeadValNos.size(); i != e; ++i)
417 IntB.removeValNo(BDeadValNos[i]);
419 // Extend BValNo by merging in IntA live ranges of AValNo. Val# definition
420 // is updated. Kills are also updated.
421 VNInfo *ValNo = BValNo;
422 ValNo->def = AValNo->def;
424 for (unsigned j = 0, ee = ValNo->kills.size(); j != ee; ++j) {
425 unsigned Kill = ValNo->kills[j];
426 if (Kill != BLR->end)
427 BKills.push_back(Kill);
429 ValNo->kills.clear();
430 for (LiveInterval::iterator AI = IntA.begin(), AE = IntA.end();
432 if (AI->valno != AValNo) continue;
433 unsigned End = AI->end;
434 std::map<unsigned, unsigned>::iterator EI = BExtend.find(End);
435 if (EI != BExtend.end())
437 IntB.addRange(LiveRange(AI->start, End, ValNo));
439 IntB.addKills(ValNo, BKills);
440 ValNo->hasPHIKill = BHasPHIKill;
442 DOUT << " result = "; IntB.print(DOUT, tri_);
445 DOUT << "\nShortening: "; IntA.print(DOUT, tri_);
446 IntA.removeValNo(AValNo);
447 DOUT << " result = "; IntA.print(DOUT, tri_);
454 /// isSameOrFallThroughBB - Return true if MBB == SuccMBB or MBB simply
455 /// fallthoughs to SuccMBB.
456 static bool isSameOrFallThroughBB(MachineBasicBlock *MBB,
457 MachineBasicBlock *SuccMBB,
458 const TargetInstrInfo *tii_) {
461 MachineBasicBlock *TBB = 0, *FBB = 0;
462 SmallVector<MachineOperand, 4> Cond;
463 return !tii_->AnalyzeBranch(*MBB, TBB, FBB, Cond) && !TBB && !FBB &&
464 MBB->isSuccessor(SuccMBB);
467 /// removeRange - Wrapper for LiveInterval::removeRange. This removes a range
468 /// from a physical register live interval as well as from the live intervals
469 /// of its sub-registers.
470 static void removeRange(LiveInterval &li, unsigned Start, unsigned End,
471 LiveIntervals *li_, const TargetRegisterInfo *tri_) {
472 li.removeRange(Start, End, true);
473 if (TargetRegisterInfo::isPhysicalRegister(li.reg)) {
474 for (const unsigned* SR = tri_->getSubRegisters(li.reg); *SR; ++SR) {
475 if (!li_->hasInterval(*SR))
477 LiveInterval &sli = li_->getInterval(*SR);
478 unsigned RemoveEnd = Start;
479 while (RemoveEnd != End) {
480 LiveInterval::iterator LR = sli.FindLiveRangeContaining(Start);
483 RemoveEnd = (LR->end < End) ? LR->end : End;
484 sli.removeRange(Start, RemoveEnd, true);
491 /// TrimLiveIntervalToLastUse - If there is a last use in the same basic block
492 /// as the copy instruction, trim the live interval to the last use and return
495 SimpleRegisterCoalescing::TrimLiveIntervalToLastUse(unsigned CopyIdx,
496 MachineBasicBlock *CopyMBB,
498 const LiveRange *LR) {
499 unsigned MBBStart = li_->getMBBStartIdx(CopyMBB);
501 MachineOperand *LastUse = lastRegisterUse(LR->start, CopyIdx-1, li.reg,
504 MachineInstr *LastUseMI = LastUse->getParent();
505 if (!isSameOrFallThroughBB(LastUseMI->getParent(), CopyMBB, tii_)) {
512 // r1025<dead> = r1024<kill>
513 if (MBBStart < LR->end)
514 removeRange(li, MBBStart, LR->end, li_, tri_);
518 // There are uses before the copy, just shorten the live range to the end
520 LastUse->setIsKill();
521 removeRange(li, li_->getDefIndex(LastUseIdx), LR->end, li_, tri_);
522 unsigned SrcReg, DstReg, SrcSubIdx, DstSubIdx;
523 if (tii_->isMoveInstr(*LastUseMI, SrcReg, DstReg, SrcSubIdx, DstSubIdx) &&
525 // Last use is itself an identity code.
526 int DeadIdx = LastUseMI->findRegisterDefOperandIdx(li.reg, false, tri_);
527 LastUseMI->getOperand(DeadIdx).setIsDead();
533 if (LR->start <= MBBStart && LR->end > MBBStart) {
534 if (LR->start == 0) {
535 assert(TargetRegisterInfo::isPhysicalRegister(li.reg));
536 // Live-in to the function but dead. Remove it from entry live-in set.
537 mf_->begin()->removeLiveIn(li.reg);
539 // FIXME: Shorten intervals in BBs that reaches this BB.
545 /// ReMaterializeTrivialDef - If the source of a copy is defined by a trivial
546 /// computation, replace the copy by rematerialize the definition.
547 bool SimpleRegisterCoalescing::ReMaterializeTrivialDef(LiveInterval &SrcInt,
549 MachineInstr *CopyMI) {
550 unsigned CopyIdx = li_->getUseIndex(li_->getInstructionIndex(CopyMI));
551 LiveInterval::iterator SrcLR = SrcInt.FindLiveRangeContaining(CopyIdx);
552 assert(SrcLR != SrcInt.end() && "Live range not found!");
553 VNInfo *ValNo = SrcLR->valno;
554 // If other defs can reach uses of this def, then it's not safe to perform
556 if (ValNo->def == ~0U || ValNo->def == ~1U || ValNo->hasPHIKill)
558 MachineInstr *DefMI = li_->getInstructionFromIndex(ValNo->def);
559 const TargetInstrDesc &TID = DefMI->getDesc();
560 if (!TID.isAsCheapAsAMove())
562 if (!DefMI->getDesc().isRematerializable() ||
563 !tii_->isTriviallyReMaterializable(DefMI))
565 bool SawStore = false;
566 if (!DefMI->isSafeToMove(tii_, SawStore))
569 unsigned DefIdx = li_->getDefIndex(CopyIdx);
570 const LiveRange *DLR= li_->getInterval(DstReg).getLiveRangeContaining(DefIdx);
571 DLR->valno->copy = NULL;
572 // Don't forget to update sub-register intervals.
573 if (TargetRegisterInfo::isPhysicalRegister(DstReg)) {
574 for (const unsigned* SR = tri_->getSubRegisters(DstReg); *SR; ++SR) {
575 if (!li_->hasInterval(*SR))
577 DLR = li_->getInterval(*SR).getLiveRangeContaining(DefIdx);
578 if (DLR && DLR->valno->copy == CopyMI)
579 DLR->valno->copy = NULL;
583 // If copy kills the source register, find the last use and propagate
585 MachineBasicBlock *MBB = CopyMI->getParent();
586 if (CopyMI->killsRegister(SrcInt.reg))
587 TrimLiveIntervalToLastUse(CopyIdx, MBB, SrcInt, SrcLR);
589 MachineBasicBlock::iterator MII = next(MachineBasicBlock::iterator(CopyMI));
590 CopyMI->removeFromParent();
591 tii_->reMaterialize(*MBB, MII, DstReg, DefMI);
592 MachineInstr *NewMI = prior(MII);
593 // CopyMI may have implicit operands, transfer them over to the newly
594 // rematerialized instruction. And update implicit def interval valnos.
595 for (unsigned i = CopyMI->getDesc().getNumOperands(),
596 e = CopyMI->getNumOperands(); i != e; ++i) {
597 MachineOperand &MO = CopyMI->getOperand(i);
598 if (MO.isReg() && MO.isImplicit())
599 NewMI->addOperand(MO);
600 if (MO.isDef() && li_->hasInterval(MO.getReg())) {
601 unsigned Reg = MO.getReg();
602 DLR = li_->getInterval(Reg).getLiveRangeContaining(DefIdx);
603 if (DLR && DLR->valno->copy == CopyMI)
604 DLR->valno->copy = NULL;
608 li_->ReplaceMachineInstrInMaps(CopyMI, NewMI);
609 MBB->getParent()->DeleteMachineInstr(CopyMI);
610 ReMatCopies.insert(CopyMI);
611 ReMatDefs.insert(DefMI);
616 /// isBackEdgeCopy - Returns true if CopyMI is a back edge copy.
618 bool SimpleRegisterCoalescing::isBackEdgeCopy(MachineInstr *CopyMI,
619 unsigned DstReg) const {
620 MachineBasicBlock *MBB = CopyMI->getParent();
621 const MachineLoop *L = loopInfo->getLoopFor(MBB);
624 if (MBB != L->getLoopLatch())
627 LiveInterval &LI = li_->getInterval(DstReg);
628 unsigned DefIdx = li_->getInstructionIndex(CopyMI);
629 LiveInterval::const_iterator DstLR =
630 LI.FindLiveRangeContaining(li_->getDefIndex(DefIdx));
631 if (DstLR == LI.end())
633 unsigned KillIdx = li_->getMBBEndIdx(MBB) + 1;
634 if (DstLR->valno->kills.size() == 1 &&
635 DstLR->valno->kills[0] == KillIdx && DstLR->valno->hasPHIKill)
640 /// UpdateRegDefsUses - Replace all defs and uses of SrcReg to DstReg and
641 /// update the subregister number if it is not zero. If DstReg is a
642 /// physical register and the existing subregister number of the def / use
643 /// being updated is not zero, make sure to set it to the correct physical
646 SimpleRegisterCoalescing::UpdateRegDefsUses(unsigned SrcReg, unsigned DstReg,
648 bool DstIsPhys = TargetRegisterInfo::isPhysicalRegister(DstReg);
649 if (DstIsPhys && SubIdx) {
650 // Figure out the real physical register we are updating with.
651 DstReg = tri_->getSubReg(DstReg, SubIdx);
655 for (MachineRegisterInfo::reg_iterator I = mri_->reg_begin(SrcReg),
656 E = mri_->reg_end(); I != E; ) {
657 MachineOperand &O = I.getOperand();
658 MachineInstr *UseMI = &*I;
660 unsigned OldSubIdx = O.getSubReg();
662 unsigned UseDstReg = DstReg;
664 UseDstReg = tri_->getSubReg(DstReg, OldSubIdx);
666 unsigned CopySrcReg, CopyDstReg, CopySrcSubIdx, CopyDstSubIdx;
667 if (tii_->isMoveInstr(*UseMI, CopySrcReg, CopyDstReg,
668 CopySrcSubIdx, CopyDstSubIdx) &&
669 CopySrcReg != CopyDstReg &&
670 CopySrcReg == SrcReg && CopyDstReg != UseDstReg) {
671 // If the use is a copy and it won't be coalesced away, and its source
672 // is defined by a trivial computation, try to rematerialize it instead.
673 if (ReMaterializeTrivialDef(li_->getInterval(SrcReg), CopyDstReg,UseMI))
682 // Sub-register indexes goes from small to large. e.g.
683 // RAX: 1 -> AL, 2 -> AX, 3 -> EAX
684 // EAX: 1 -> AL, 2 -> AX
685 // So RAX's sub-register 2 is AX, RAX's sub-regsiter 3 is EAX, whose
686 // sub-register 2 is also AX.
687 if (SubIdx && OldSubIdx && SubIdx != OldSubIdx)
688 assert(OldSubIdx < SubIdx && "Conflicting sub-register index!");
691 // Remove would-be duplicated kill marker.
692 if (O.isKill() && UseMI->killsRegister(DstReg))
696 // After updating the operand, check if the machine instruction has
697 // become a copy. If so, update its val# information.
698 const TargetInstrDesc &TID = UseMI->getDesc();
699 unsigned CopySrcReg, CopyDstReg, CopySrcSubIdx, CopyDstSubIdx;
700 if (TID.getNumDefs() == 1 && TID.getNumOperands() > 2 &&
701 tii_->isMoveInstr(*UseMI, CopySrcReg, CopyDstReg,
702 CopySrcSubIdx, CopyDstSubIdx) &&
703 CopySrcReg != CopyDstReg &&
704 (TargetRegisterInfo::isVirtualRegister(CopyDstReg) ||
705 allocatableRegs_[CopyDstReg])) {
706 LiveInterval &LI = li_->getInterval(CopyDstReg);
707 unsigned DefIdx = li_->getDefIndex(li_->getInstructionIndex(UseMI));
708 const LiveRange *DLR = LI.getLiveRangeContaining(DefIdx);
709 if (DLR->valno->def == DefIdx)
710 DLR->valno->copy = UseMI;
715 /// RemoveDeadImpDef - Remove implicit_def instructions which are "re-defining"
716 /// registers due to insert_subreg coalescing. e.g.
718 /// r1025 = implicit_def
719 /// r1025 = insert_subreg r1025, r1024
723 /// r1025 = implicit_def
724 /// r1025 = insert_subreg r1025, r1025
727 SimpleRegisterCoalescing::RemoveDeadImpDef(unsigned Reg, LiveInterval &LI) {
728 for (MachineRegisterInfo::reg_iterator I = mri_->reg_begin(Reg),
729 E = mri_->reg_end(); I != E; ) {
730 MachineOperand &O = I.getOperand();
731 MachineInstr *DefMI = &*I;
735 if (DefMI->getOpcode() != TargetInstrInfo::IMPLICIT_DEF)
737 if (!LI.liveBeforeAndAt(li_->getInstructionIndex(DefMI)))
739 li_->RemoveMachineInstrFromMaps(DefMI);
740 DefMI->eraseFromParent();
744 /// RemoveUnnecessaryKills - Remove kill markers that are no longer accurate
745 /// due to live range lengthening as the result of coalescing.
746 void SimpleRegisterCoalescing::RemoveUnnecessaryKills(unsigned Reg,
748 for (MachineRegisterInfo::use_iterator UI = mri_->use_begin(Reg),
749 UE = mri_->use_end(); UI != UE; ++UI) {
750 MachineOperand &UseMO = UI.getOperand();
751 if (UseMO.isKill()) {
752 MachineInstr *UseMI = UseMO.getParent();
753 unsigned UseIdx = li_->getUseIndex(li_->getInstructionIndex(UseMI));
754 if (JoinedCopies.count(UseMI))
756 const LiveRange *UI = LI.getLiveRangeContaining(UseIdx);
757 if (!UI || !LI.isKill(UI->valno, UseIdx+1))
758 UseMO.setIsKill(false);
763 /// removeIntervalIfEmpty - Check if the live interval of a physical register
764 /// is empty, if so remove it and also remove the empty intervals of its
765 /// sub-registers. Return true if live interval is removed.
766 static bool removeIntervalIfEmpty(LiveInterval &li, LiveIntervals *li_,
767 const TargetRegisterInfo *tri_) {
769 if (TargetRegisterInfo::isPhysicalRegister(li.reg))
770 for (const unsigned* SR = tri_->getSubRegisters(li.reg); *SR; ++SR) {
771 if (!li_->hasInterval(*SR))
773 LiveInterval &sli = li_->getInterval(*SR);
775 li_->removeInterval(*SR);
777 li_->removeInterval(li.reg);
783 /// ShortenDeadCopyLiveRange - Shorten a live range defined by a dead copy.
784 /// Return true if live interval is removed.
785 bool SimpleRegisterCoalescing::ShortenDeadCopyLiveRange(LiveInterval &li,
786 MachineInstr *CopyMI) {
787 unsigned CopyIdx = li_->getInstructionIndex(CopyMI);
788 LiveInterval::iterator MLR =
789 li.FindLiveRangeContaining(li_->getDefIndex(CopyIdx));
791 return false; // Already removed by ShortenDeadCopySrcLiveRange.
792 unsigned RemoveStart = MLR->start;
793 unsigned RemoveEnd = MLR->end;
794 // Remove the liverange that's defined by this.
795 if (RemoveEnd == li_->getDefIndex(CopyIdx)+1) {
796 removeRange(li, RemoveStart, RemoveEnd, li_, tri_);
797 return removeIntervalIfEmpty(li, li_, tri_);
802 /// RemoveDeadDef - If a def of a live interval is now determined dead, remove
803 /// the val# it defines. If the live interval becomes empty, remove it as well.
804 bool SimpleRegisterCoalescing::RemoveDeadDef(LiveInterval &li,
805 MachineInstr *DefMI) {
806 unsigned DefIdx = li_->getDefIndex(li_->getInstructionIndex(DefMI));
807 LiveInterval::iterator MLR = li.FindLiveRangeContaining(DefIdx);
808 if (DefIdx != MLR->valno->def)
810 li.removeValNo(MLR->valno);
811 return removeIntervalIfEmpty(li, li_, tri_);
814 /// PropagateDeadness - Propagate the dead marker to the instruction which
815 /// defines the val#.
816 static void PropagateDeadness(LiveInterval &li, MachineInstr *CopyMI,
817 unsigned &LRStart, LiveIntervals *li_,
818 const TargetRegisterInfo* tri_) {
819 MachineInstr *DefMI =
820 li_->getInstructionFromIndex(li_->getDefIndex(LRStart));
821 if (DefMI && DefMI != CopyMI) {
822 int DeadIdx = DefMI->findRegisterDefOperandIdx(li.reg, false, tri_);
824 DefMI->getOperand(DeadIdx).setIsDead();
825 // A dead def should have a single cycle interval.
831 /// ShortenDeadCopySrcLiveRange - Shorten a live range as it's artificially
832 /// extended by a dead copy. Mark the last use (if any) of the val# as kill as
833 /// ends the live range there. If there isn't another use, then this live range
834 /// is dead. Return true if live interval is removed.
836 SimpleRegisterCoalescing::ShortenDeadCopySrcLiveRange(LiveInterval &li,
837 MachineInstr *CopyMI) {
838 unsigned CopyIdx = li_->getInstructionIndex(CopyMI);
840 // FIXME: special case: function live in. It can be a general case if the
841 // first instruction index starts at > 0 value.
842 assert(TargetRegisterInfo::isPhysicalRegister(li.reg));
843 // Live-in to the function but dead. Remove it from entry live-in set.
844 if (mf_->begin()->isLiveIn(li.reg))
845 mf_->begin()->removeLiveIn(li.reg);
846 const LiveRange *LR = li.getLiveRangeContaining(CopyIdx);
847 removeRange(li, LR->start, LR->end, li_, tri_);
848 return removeIntervalIfEmpty(li, li_, tri_);
851 LiveInterval::iterator LR = li.FindLiveRangeContaining(CopyIdx-1);
853 // Livein but defined by a phi.
856 unsigned RemoveStart = LR->start;
857 unsigned RemoveEnd = li_->getDefIndex(CopyIdx)+1;
858 if (LR->end > RemoveEnd)
859 // More uses past this copy? Nothing to do.
862 // If there is a last use in the same bb, we can't remove the live range.
863 // Shorten the live interval and return.
864 if (TrimLiveIntervalToLastUse(CopyIdx, CopyMI->getParent(), li, LR))
867 if (LR->valno->def == RemoveStart) {
868 // If the def MI defines the val# and this copy is the only kill of the
869 // val#, then propagate the dead marker.
870 if (!li.isOnlyLROfValNo(LR)) {
871 if (li.isKill(LR->valno, RemoveEnd))
872 li.removeKill(LR->valno, RemoveEnd);
874 PropagateDeadness(li, CopyMI, RemoveStart, li_, tri_);
879 removeRange(li, RemoveStart, LR->end, li_, tri_);
880 return removeIntervalIfEmpty(li, li_, tri_);
883 /// CanCoalesceWithImpDef - Returns true if the specified copy instruction
884 /// from an implicit def to another register can be coalesced away.
885 bool SimpleRegisterCoalescing::CanCoalesceWithImpDef(MachineInstr *CopyMI,
887 LiveInterval &ImpLi) const{
888 if (!CopyMI->killsRegister(ImpLi.reg))
890 unsigned CopyIdx = li_->getDefIndex(li_->getInstructionIndex(CopyMI));
891 LiveInterval::iterator LR = li.FindLiveRangeContaining(CopyIdx);
894 if (LR->valno->hasPHIKill)
896 if (LR->valno->def != CopyIdx)
898 // Make sure all of val# uses are copies.
899 for (MachineRegisterInfo::use_iterator UI = mri_->use_begin(li.reg),
900 UE = mri_->use_end(); UI != UE;) {
901 MachineInstr *UseMI = &*UI;
903 if (JoinedCopies.count(UseMI))
905 unsigned UseIdx = li_->getUseIndex(li_->getInstructionIndex(UseMI));
906 LiveInterval::iterator ULR = li.FindLiveRangeContaining(UseIdx);
907 if (ULR == li.end() || ULR->valno != LR->valno)
909 // If the use is not a use, then it's not safe to coalesce the move.
910 unsigned SrcReg, DstReg, SrcSubIdx, DstSubIdx;
911 if (!tii_->isMoveInstr(*UseMI, SrcReg, DstReg, SrcSubIdx, DstSubIdx)) {
912 if (UseMI->getOpcode() == TargetInstrInfo::INSERT_SUBREG &&
913 UseMI->getOperand(1).getReg() == li.reg)
922 /// RemoveCopiesFromValNo - The specified value# is defined by an implicit
923 /// def and it is being removed. Turn all copies from this value# into
924 /// identity copies so they will be removed.
925 void SimpleRegisterCoalescing::RemoveCopiesFromValNo(LiveInterval &li,
927 SmallVector<MachineInstr*, 4> ImpDefs;
928 MachineOperand *LastUse = NULL;
929 unsigned LastUseIdx = li_->getUseIndex(VNI->def);
930 for (MachineRegisterInfo::reg_iterator RI = mri_->reg_begin(li.reg),
931 RE = mri_->reg_end(); RI != RE;) {
932 MachineOperand *MO = &RI.getOperand();
933 MachineInstr *MI = &*RI;
936 if (MI->getOpcode() == TargetInstrInfo::IMPLICIT_DEF) {
937 ImpDefs.push_back(MI);
941 if (JoinedCopies.count(MI))
943 unsigned UseIdx = li_->getUseIndex(li_->getInstructionIndex(MI));
944 LiveInterval::iterator ULR = li.FindLiveRangeContaining(UseIdx);
945 if (ULR == li.end() || ULR->valno != VNI)
947 // If the use is a copy, turn it into an identity copy.
948 unsigned SrcReg, DstReg, SrcSubIdx, DstSubIdx;
949 if (tii_->isMoveInstr(*MI, SrcReg, DstReg, SrcSubIdx, DstSubIdx) &&
951 // Each use MI may have multiple uses of this register. Change them all.
952 for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
953 MachineOperand &MO = MI->getOperand(i);
954 if (MO.isReg() && MO.getReg() == li.reg)
957 JoinedCopies.insert(MI);
958 } else if (UseIdx > LastUseIdx) {
964 LastUse->setIsKill();
966 // Remove dead implicit_def's.
967 while (!ImpDefs.empty()) {
968 MachineInstr *ImpDef = ImpDefs.back();
970 li_->RemoveMachineInstrFromMaps(ImpDef);
971 ImpDef->eraseFromParent();
976 /// getMatchingSuperReg - Return a super-register of the specified register
977 /// Reg so its sub-register of index SubIdx is Reg.
978 static unsigned getMatchingSuperReg(unsigned Reg, unsigned SubIdx,
979 const TargetRegisterClass *RC,
980 const TargetRegisterInfo* TRI) {
981 for (const unsigned *SRs = TRI->getSuperRegisters(Reg);
982 unsigned SR = *SRs; ++SRs)
983 if (Reg == TRI->getSubReg(SR, SubIdx) && RC->contains(SR))
988 /// isWinToJoinCrossClass - Return true if it's profitable to coalesce
989 /// two virtual registers from different register classes.
991 SimpleRegisterCoalescing::isWinToJoinCrossClass(unsigned LargeReg,
993 unsigned Threshold) {
994 // Then make sure the intervals are *short*.
995 LiveInterval &LargeInt = li_->getInterval(LargeReg);
996 LiveInterval &SmallInt = li_->getInterval(SmallReg);
997 unsigned LargeSize = li_->getApproximateInstructionCount(LargeInt);
998 unsigned SmallSize = li_->getApproximateInstructionCount(SmallInt);
999 if (SmallSize > Threshold || LargeSize > Threshold)
1000 if ((float)std::distance(mri_->use_begin(SmallReg),
1001 mri_->use_end()) / SmallSize <
1002 (float)std::distance(mri_->use_begin(LargeReg),
1003 mri_->use_end()) / LargeSize)
1008 /// HasIncompatibleSubRegDefUse - If we are trying to coalesce a virtual
1009 /// register with a physical register, check if any of the virtual register
1010 /// operand is a sub-register use or def. If so, make sure it won't result
1011 /// in an illegal extract_subreg or insert_subreg instruction. e.g.
1012 /// vr1024 = extract_subreg vr1025, 1
1014 /// vr1024 = mov8rr AH
1015 /// If vr1024 is coalesced with AH, the extract_subreg is now illegal since
1016 /// AH does not have a super-reg whose sub-register 1 is AH.
1018 SimpleRegisterCoalescing::HasIncompatibleSubRegDefUse(MachineInstr *CopyMI,
1021 for (MachineRegisterInfo::reg_iterator I = mri_->reg_begin(VirtReg),
1022 E = mri_->reg_end(); I != E; ++I) {
1023 MachineOperand &O = I.getOperand();
1024 MachineInstr *MI = &*I;
1025 if (MI == CopyMI || JoinedCopies.count(MI))
1027 unsigned SubIdx = O.getSubReg();
1028 if (SubIdx && !tri_->getSubReg(PhysReg, SubIdx))
1030 if (MI->getOpcode() == TargetInstrInfo::EXTRACT_SUBREG) {
1031 SubIdx = MI->getOperand(2).getImm();
1032 if (O.isUse() && !tri_->getSubReg(PhysReg, SubIdx))
1035 unsigned SrcReg = MI->getOperand(1).getReg();
1036 const TargetRegisterClass *RC =
1037 TargetRegisterInfo::isPhysicalRegister(SrcReg)
1038 ? tri_->getPhysicalRegisterRegClass(SrcReg)
1039 : mri_->getRegClass(SrcReg);
1040 if (!getMatchingSuperReg(PhysReg, SubIdx, RC, tri_))
1044 if (MI->getOpcode() == TargetInstrInfo::INSERT_SUBREG) {
1045 SubIdx = MI->getOperand(3).getImm();
1046 if (VirtReg == MI->getOperand(0).getReg()) {
1047 if (!tri_->getSubReg(PhysReg, SubIdx))
1050 unsigned DstReg = MI->getOperand(0).getReg();
1051 const TargetRegisterClass *RC =
1052 TargetRegisterInfo::isPhysicalRegister(DstReg)
1053 ? tri_->getPhysicalRegisterRegClass(DstReg)
1054 : mri_->getRegClass(DstReg);
1055 if (!getMatchingSuperReg(PhysReg, SubIdx, RC, tri_))
1064 /// CanJoinExtractSubRegToPhysReg - Return true if it's possible to coalesce
1065 /// an extract_subreg where dst is a physical register, e.g.
1066 /// cl = EXTRACT_SUBREG reg1024, 1
1068 SimpleRegisterCoalescing::CanJoinExtractSubRegToPhysReg(unsigned DstReg,
1069 unsigned SrcReg, unsigned SubIdx,
1070 unsigned &RealDstReg) {
1071 const TargetRegisterClass *RC = mri_->getRegClass(SrcReg);
1072 RealDstReg = getMatchingSuperReg(DstReg, SubIdx, RC, tri_);
1073 assert(RealDstReg && "Invalid extract_subreg instruction!");
1075 // For this type of EXTRACT_SUBREG, conservatively
1076 // check if the live interval of the source register interfere with the
1077 // actual super physical register we are trying to coalesce with.
1078 LiveInterval &RHS = li_->getInterval(SrcReg);
1079 if (li_->hasInterval(RealDstReg) &&
1080 RHS.overlaps(li_->getInterval(RealDstReg))) {
1081 DOUT << "Interfere with register ";
1082 DEBUG(li_->getInterval(RealDstReg).print(DOUT, tri_));
1083 return false; // Not coalescable
1085 for (const unsigned* SR = tri_->getSubRegisters(RealDstReg); *SR; ++SR)
1086 if (li_->hasInterval(*SR) && RHS.overlaps(li_->getInterval(*SR))) {
1087 DOUT << "Interfere with sub-register ";
1088 DEBUG(li_->getInterval(*SR).print(DOUT, tri_));
1089 return false; // Not coalescable
1094 /// CanJoinInsertSubRegToPhysReg - Return true if it's possible to coalesce
1095 /// an insert_subreg where src is a physical register, e.g.
1096 /// reg1024 = INSERT_SUBREG reg1024, c1, 0
1098 SimpleRegisterCoalescing::CanJoinInsertSubRegToPhysReg(unsigned DstReg,
1099 unsigned SrcReg, unsigned SubIdx,
1100 unsigned &RealSrcReg) {
1101 const TargetRegisterClass *RC = mri_->getRegClass(DstReg);
1102 RealSrcReg = getMatchingSuperReg(SrcReg, SubIdx, RC, tri_);
1103 assert(RealSrcReg && "Invalid extract_subreg instruction!");
1105 LiveInterval &RHS = li_->getInterval(DstReg);
1106 if (li_->hasInterval(RealSrcReg) &&
1107 RHS.overlaps(li_->getInterval(RealSrcReg))) {
1108 DOUT << "Interfere with register ";
1109 DEBUG(li_->getInterval(RealSrcReg).print(DOUT, tri_));
1110 return false; // Not coalescable
1112 for (const unsigned* SR = tri_->getSubRegisters(RealSrcReg); *SR; ++SR)
1113 if (li_->hasInterval(*SR) && RHS.overlaps(li_->getInterval(*SR))) {
1114 DOUT << "Interfere with sub-register ";
1115 DEBUG(li_->getInterval(*SR).print(DOUT, tri_));
1116 return false; // Not coalescable
1121 /// JoinCopy - Attempt to join intervals corresponding to SrcReg/DstReg,
1122 /// which are the src/dst of the copy instruction CopyMI. This returns true
1123 /// if the copy was successfully coalesced away. If it is not currently
1124 /// possible to coalesce this interval, but it may be possible if other
1125 /// things get coalesced, then it returns true by reference in 'Again'.
1126 bool SimpleRegisterCoalescing::JoinCopy(CopyRec &TheCopy, bool &Again) {
1127 MachineInstr *CopyMI = TheCopy.MI;
1130 if (JoinedCopies.count(CopyMI) || ReMatCopies.count(CopyMI))
1131 return false; // Already done.
1133 DOUT << li_->getInstructionIndex(CopyMI) << '\t' << *CopyMI;
1135 unsigned SrcReg, DstReg, SrcSubIdx, DstSubIdx;
1136 bool isExtSubReg = CopyMI->getOpcode() == TargetInstrInfo::EXTRACT_SUBREG;
1137 bool isInsSubReg = CopyMI->getOpcode() == TargetInstrInfo::INSERT_SUBREG;
1138 unsigned SubIdx = 0;
1140 DstReg = CopyMI->getOperand(0).getReg();
1141 SrcReg = CopyMI->getOperand(1).getReg();
1142 } else if (isInsSubReg) {
1143 if (CopyMI->getOperand(2).getSubReg()) {
1144 DOUT << "\tSource of insert_subreg is already coalesced "
1145 << "to another register.\n";
1146 return false; // Not coalescable.
1148 DstReg = CopyMI->getOperand(0).getReg();
1149 SrcReg = CopyMI->getOperand(2).getReg();
1150 } else if (!tii_->isMoveInstr(*CopyMI, SrcReg, DstReg, SrcSubIdx, DstSubIdx)){
1151 assert(0 && "Unrecognized copy instruction!");
1155 // If they are already joined we continue.
1156 if (SrcReg == DstReg) {
1157 DOUT << "\tCopy already coalesced.\n";
1158 return false; // Not coalescable.
1161 bool SrcIsPhys = TargetRegisterInfo::isPhysicalRegister(SrcReg);
1162 bool DstIsPhys = TargetRegisterInfo::isPhysicalRegister(DstReg);
1164 // If they are both physical registers, we cannot join them.
1165 if (SrcIsPhys && DstIsPhys) {
1166 DOUT << "\tCan not coalesce physregs.\n";
1167 return false; // Not coalescable.
1170 // We only join virtual registers with allocatable physical registers.
1171 if (SrcIsPhys && !allocatableRegs_[SrcReg]) {
1172 DOUT << "\tSrc reg is unallocatable physreg.\n";
1173 return false; // Not coalescable.
1175 if (DstIsPhys && !allocatableRegs_[DstReg]) {
1176 DOUT << "\tDst reg is unallocatable physreg.\n";
1177 return false; // Not coalescable.
1180 // Should be non-null only when coalescing to a sub-register class.
1181 bool CrossRC = false;
1182 const TargetRegisterClass *NewRC = NULL;
1183 MachineBasicBlock *CopyMBB = CopyMI->getParent();
1184 unsigned RealDstReg = 0;
1185 unsigned RealSrcReg = 0;
1186 if (isExtSubReg || isInsSubReg) {
1187 SubIdx = CopyMI->getOperand(isExtSubReg ? 2 : 3).getImm();
1188 if (SrcIsPhys && isExtSubReg) {
1189 // r1024 = EXTRACT_SUBREG EAX, 0 then r1024 is really going to be
1190 // coalesced with AX.
1191 unsigned DstSubIdx = CopyMI->getOperand(0).getSubReg();
1193 // r1024<2> = EXTRACT_SUBREG EAX, 2. Then r1024 has already been
1194 // coalesced to a larger register so the subreg indices cancel out.
1195 if (DstSubIdx != SubIdx) {
1196 DOUT << "\t Sub-register indices mismatch.\n";
1197 return false; // Not coalescable.
1200 SrcReg = tri_->getSubReg(SrcReg, SubIdx);
1202 } else if (DstIsPhys && isInsSubReg) {
1203 // EAX = INSERT_SUBREG EAX, r1024, 0
1204 unsigned SrcSubIdx = CopyMI->getOperand(2).getSubReg();
1206 // EAX = INSERT_SUBREG EAX, r1024<2>, 2 Then r1024 has already been
1207 // coalesced to a larger register so the subreg indices cancel out.
1208 if (SrcSubIdx != SubIdx) {
1209 DOUT << "\t Sub-register indices mismatch.\n";
1210 return false; // Not coalescable.
1213 DstReg = tri_->getSubReg(DstReg, SubIdx);
1215 } else if ((DstIsPhys && isExtSubReg) || (SrcIsPhys && isInsSubReg)) {
1216 if (CopyMI->getOperand(1).getSubReg()) {
1217 DOUT << "\tSrc of extract_subreg already coalesced with reg"
1218 << " of a super-class.\n";
1219 return false; // Not coalescable.
1223 if (!CanJoinExtractSubRegToPhysReg(DstReg, SrcReg, SubIdx, RealDstReg))
1224 return false; // Not coalescable
1226 if (!CanJoinInsertSubRegToPhysReg(DstReg, SrcReg, SubIdx, RealSrcReg))
1227 return false; // Not coalescable
1231 unsigned OldSubIdx = isExtSubReg ? CopyMI->getOperand(0).getSubReg()
1232 : CopyMI->getOperand(2).getSubReg();
1234 if (OldSubIdx == SubIdx && !differingRegisterClasses(SrcReg, DstReg))
1235 // r1024<2> = EXTRACT_SUBREG r1025, 2. Then r1024 has already been
1236 // coalesced to a larger register so the subreg indices cancel out.
1237 // Also check if the other larger register is of the same register
1238 // class as the would be resulting register.
1241 DOUT << "\t Sub-register indices mismatch.\n";
1242 return false; // Not coalescable.
1246 unsigned LargeReg = isExtSubReg ? SrcReg : DstReg;
1247 unsigned SmallReg = isExtSubReg ? DstReg : SrcReg;
1248 unsigned Limit= allocatableRCRegs_[mri_->getRegClass(SmallReg)].count();
1249 if (!isWinToJoinCrossClass(LargeReg, SmallReg, Limit)) {
1250 Again = true; // May be possible to coalesce later.
1255 } else if (differingRegisterClasses(SrcReg, DstReg)) {
1256 if (!CrossClassJoin)
1260 // FIXME: What if the result of a EXTRACT_SUBREG is then coalesced
1261 // with another? If it's the resulting destination register, then
1262 // the subidx must be propagated to uses (but only those defined
1263 // by the EXTRACT_SUBREG). If it's being coalesced into another
1264 // register, it should be safe because register is assumed to have
1265 // the register class of the super-register.
1267 // Process moves where one of the registers have a sub-register index.
1268 MachineOperand *DstMO = CopyMI->findRegisterDefOperand(DstReg);
1269 if (DstMO->getSubReg())
1270 // FIXME: Can we handle this?
1272 MachineOperand *SrcMO = CopyMI->findRegisterUseOperand(SrcReg);
1273 SubIdx = SrcMO->getSubReg();
1275 // This is not a extract_subreg but it looks like one.
1276 // e.g. %cl = MOV16rr %reg1024:2
1279 if (!CanJoinExtractSubRegToPhysReg(DstReg, SrcReg, SubIdx,RealDstReg))
1280 return false; // Not coalescable
1285 const TargetRegisterClass *SrcRC= SrcIsPhys ? 0 : mri_->getRegClass(SrcReg);
1286 const TargetRegisterClass *DstRC= DstIsPhys ? 0 : mri_->getRegClass(DstReg);
1287 unsigned LargeReg = SrcReg;
1288 unsigned SmallReg = DstReg;
1291 // Now determine the register class of the joined register.
1293 if (SubIdx && DstRC && DstRC->isASubClass()) {
1294 // This is a move to a sub-register class. However, the source is a
1295 // sub-register of a larger register class. We don't know what should
1296 // the register class be. FIXME.
1300 Limit = allocatableRCRegs_[DstRC].count();
1301 } else if (!SrcIsPhys && !SrcIsPhys) {
1302 unsigned SrcSize = SrcRC->getSize();
1303 unsigned DstSize = DstRC->getSize();
1304 if (SrcSize < DstSize)
1305 // For example X86::MOVSD2PDrr copies from FR64 to VR128.
1307 else if (DstSize > SrcSize) {
1309 std::swap(LargeReg, SmallReg);
1311 unsigned SrcNumRegs = SrcRC->getNumRegs();
1312 unsigned DstNumRegs = DstRC->getNumRegs();
1313 if (DstNumRegs < SrcNumRegs)
1314 // Sub-register class?
1316 else if (SrcNumRegs < DstNumRegs) {
1318 std::swap(LargeReg, SmallReg);
1320 // No idea what's the right register class to use.
1325 // If we are joining two virtual registers and the resulting register
1326 // class is more restrictive (fewer register, smaller size). Check if it's
1327 // worth doing the merge.
1328 if (!SrcIsPhys && !DstIsPhys &&
1329 (isExtSubReg || DstRC->isASubClass()) &&
1330 !isWinToJoinCrossClass(LargeReg, SmallReg,
1331 allocatableRCRegs_[NewRC].count())) {
1332 DOUT << "\tSrc/Dest are different register classes.\n";
1333 // Allow the coalescer to try again in case either side gets coalesced to
1334 // a physical register that's compatible with the other side. e.g.
1335 // r1024 = MOV32to32_ r1025
1336 // But later r1024 is assigned EAX then r1025 may be coalesced with EAX.
1337 Again = true; // May be possible to coalesce later.
1342 // Will it create illegal extract_subreg / insert_subreg?
1343 if (SrcIsPhys && HasIncompatibleSubRegDefUse(CopyMI, DstReg, SrcReg))
1345 if (DstIsPhys && HasIncompatibleSubRegDefUse(CopyMI, SrcReg, DstReg))
1348 LiveInterval &SrcInt = li_->getInterval(SrcReg);
1349 LiveInterval &DstInt = li_->getInterval(DstReg);
1350 assert(SrcInt.reg == SrcReg && DstInt.reg == DstReg &&
1351 "Register mapping is horribly broken!");
1353 DOUT << "\t\tInspecting "; SrcInt.print(DOUT, tri_);
1354 DOUT << " and "; DstInt.print(DOUT, tri_);
1357 // Save a copy of the virtual register live interval. We'll manually
1358 // merge this into the "real" physical register live interval this is
1360 LiveInterval *SavedLI = 0;
1362 SavedLI = li_->dupInterval(&SrcInt);
1363 else if (RealSrcReg)
1364 SavedLI = li_->dupInterval(&DstInt);
1366 // Check if it is necessary to propagate "isDead" property.
1367 if (!isExtSubReg && !isInsSubReg) {
1368 MachineOperand *mopd = CopyMI->findRegisterDefOperand(DstReg, false);
1369 bool isDead = mopd->isDead();
1371 // We need to be careful about coalescing a source physical register with a
1372 // virtual register. Once the coalescing is done, it cannot be broken and
1373 // these are not spillable! If the destination interval uses are far away,
1374 // think twice about coalescing them!
1375 if (!isDead && (SrcIsPhys || DstIsPhys)) {
1376 LiveInterval &JoinVInt = SrcIsPhys ? DstInt : SrcInt;
1377 unsigned JoinVReg = SrcIsPhys ? DstReg : SrcReg;
1378 unsigned JoinPReg = SrcIsPhys ? SrcReg : DstReg;
1379 const TargetRegisterClass *RC = mri_->getRegClass(JoinVReg);
1380 unsigned Threshold = allocatableRCRegs_[RC].count() * 2;
1381 if (TheCopy.isBackEdge)
1382 Threshold *= 2; // Favors back edge copies.
1384 // If the virtual register live interval is long but it has low use desity,
1385 // do not join them, instead mark the physical register as its allocation
1387 unsigned Length = li_->getApproximateInstructionCount(JoinVInt);
1388 if (Length > Threshold &&
1389 (((float)std::distance(mri_->use_begin(JoinVReg), mri_->use_end())
1390 / Length) < (1.0 / Threshold))) {
1391 JoinVInt.preference = JoinPReg;
1393 DOUT << "\tMay tie down a physical register, abort!\n";
1394 Again = true; // May be possible to coalesce later.
1400 // Okay, attempt to join these two intervals. On failure, this returns false.
1401 // Otherwise, if one of the intervals being joined is a physreg, this method
1402 // always canonicalizes DstInt to be it. The output "SrcInt" will not have
1403 // been modified, so we can use this information below to update aliases.
1404 bool Swapped = false;
1405 // If SrcInt is implicitly defined, it's safe to coalesce.
1406 bool isEmpty = SrcInt.empty();
1407 if (isEmpty && !CanCoalesceWithImpDef(CopyMI, DstInt, SrcInt)) {
1408 // Only coalesce an empty interval (defined by implicit_def) with
1409 // another interval which has a valno defined by the CopyMI and the CopyMI
1410 // is a kill of the implicit def.
1411 DOUT << "Not profitable!\n";
1415 if (!isEmpty && !JoinIntervals(DstInt, SrcInt, Swapped)) {
1416 // Coalescing failed.
1418 // If definition of source is defined by trivial computation, try
1419 // rematerializing it.
1420 if (!isExtSubReg && !isInsSubReg &&
1421 ReMaterializeTrivialDef(SrcInt, DstInt.reg, CopyMI))
1424 // If we can eliminate the copy without merging the live ranges, do so now.
1425 if (!isExtSubReg && !isInsSubReg &&
1426 (AdjustCopiesBackFrom(SrcInt, DstInt, CopyMI) ||
1427 RemoveCopyByCommutingDef(SrcInt, DstInt, CopyMI))) {
1428 JoinedCopies.insert(CopyMI);
1432 // Otherwise, we are unable to join the intervals.
1433 DOUT << "Interference!\n";
1434 Again = true; // May be possible to coalesce later.
1438 LiveInterval *ResSrcInt = &SrcInt;
1439 LiveInterval *ResDstInt = &DstInt;
1441 std::swap(SrcReg, DstReg);
1442 std::swap(ResSrcInt, ResDstInt);
1444 assert(TargetRegisterInfo::isVirtualRegister(SrcReg) &&
1445 "LiveInterval::join didn't work right!");
1447 // If we're about to merge live ranges into a physical register live interval,
1448 // we have to update any aliased register's live ranges to indicate that they
1449 // have clobbered values for this range.
1450 if (TargetRegisterInfo::isPhysicalRegister(DstReg)) {
1451 // If this is a extract_subreg where dst is a physical register, e.g.
1452 // cl = EXTRACT_SUBREG reg1024, 1
1453 // then create and update the actual physical register allocated to RHS.
1454 if (RealDstReg || RealSrcReg) {
1455 LiveInterval &RealInt =
1456 li_->getOrCreateInterval(RealDstReg ? RealDstReg : RealSrcReg);
1457 for (LiveInterval::const_vni_iterator I = SavedLI->vni_begin(),
1458 E = SavedLI->vni_end(); I != E; ++I) {
1459 const VNInfo *ValNo = *I;
1460 VNInfo *NewValNo = RealInt.getNextValue(ValNo->def, ValNo->copy,
1461 li_->getVNInfoAllocator());
1462 NewValNo->hasPHIKill = ValNo->hasPHIKill;
1463 NewValNo->redefByEC = ValNo->redefByEC;
1464 RealInt.addKills(NewValNo, ValNo->kills);
1465 RealInt.MergeValueInAsValue(*SavedLI, ValNo, NewValNo);
1467 RealInt.weight += SavedLI->weight;
1468 DstReg = RealDstReg ? RealDstReg : RealSrcReg;
1471 // Update the liveintervals of sub-registers.
1472 for (const unsigned *AS = tri_->getSubRegisters(DstReg); *AS; ++AS)
1473 li_->getOrCreateInterval(*AS).MergeInClobberRanges(*ResSrcInt,
1474 li_->getVNInfoAllocator());
1477 // If this is a EXTRACT_SUBREG, make sure the result of coalescing is the
1478 // larger super-register.
1479 if ((isExtSubReg || isInsSubReg) && !SrcIsPhys && !DstIsPhys) {
1480 if ((isExtSubReg && !Swapped) || (isInsSubReg && Swapped)) {
1481 ResSrcInt->Copy(*ResDstInt, li_->getVNInfoAllocator());
1482 std::swap(SrcReg, DstReg);
1483 std::swap(ResSrcInt, ResDstInt);
1487 // Coalescing to a virtual register that is of a sub-register class of the
1488 // other. Make sure the resulting register is set to the right register class.
1492 mri_->setRegClass(DstReg, NewRC);
1496 // Add all copies that define val# in the source interval into the queue.
1497 for (LiveInterval::const_vni_iterator i = ResSrcInt->vni_begin(),
1498 e = ResSrcInt->vni_end(); i != e; ++i) {
1499 const VNInfo *vni = *i;
1500 if (!vni->def || vni->def == ~1U || vni->def == ~0U)
1502 MachineInstr *CopyMI = li_->getInstructionFromIndex(vni->def);
1503 unsigned NewSrcReg, NewDstReg, NewSrcSubIdx, NewDstSubIdx;
1505 JoinedCopies.count(CopyMI) == 0 &&
1506 tii_->isMoveInstr(*CopyMI, NewSrcReg, NewDstReg,
1507 NewSrcSubIdx, NewDstSubIdx)) {
1508 unsigned LoopDepth = loopInfo->getLoopDepth(CopyMBB);
1509 JoinQueue->push(CopyRec(CopyMI, LoopDepth,
1510 isBackEdgeCopy(CopyMI, DstReg)));
1515 // Remember to delete the copy instruction.
1516 JoinedCopies.insert(CopyMI);
1518 // Some live range has been lengthened due to colaescing, eliminate the
1519 // unnecessary kills.
1520 RemoveUnnecessaryKills(SrcReg, *ResDstInt);
1521 if (TargetRegisterInfo::isVirtualRegister(DstReg))
1522 RemoveUnnecessaryKills(DstReg, *ResDstInt);
1527 // r1024 = implicit_def
1530 RemoveDeadImpDef(DstReg, *ResDstInt);
1531 UpdateRegDefsUses(SrcReg, DstReg, SubIdx);
1533 // SrcReg is guarateed to be the register whose live interval that is
1535 li_->removeInterval(SrcReg);
1537 // Manually deleted the live interval copy.
1544 // Now the copy is being coalesced away, the val# previously defined
1545 // by the copy is being defined by an IMPLICIT_DEF which defines a zero
1546 // length interval. Remove the val#.
1547 unsigned CopyIdx = li_->getDefIndex(li_->getInstructionIndex(CopyMI));
1548 const LiveRange *LR = ResDstInt->getLiveRangeContaining(CopyIdx);
1549 VNInfo *ImpVal = LR->valno;
1550 assert(ImpVal->def == CopyIdx);
1551 unsigned NextDef = LR->end;
1552 RemoveCopiesFromValNo(*ResDstInt, ImpVal);
1553 ResDstInt->removeValNo(ImpVal);
1554 LR = ResDstInt->FindLiveRangeContaining(NextDef);
1555 if (LR != ResDstInt->end() && LR->valno->def == NextDef) {
1556 // Special case: vr1024 = implicit_def
1557 // vr1024 = insert_subreg vr1024, vr1025, c
1558 // The insert_subreg becomes a "copy" that defines a val# which can itself
1559 // be coalesced away.
1560 MachineInstr *DefMI = li_->getInstructionFromIndex(NextDef);
1561 if (DefMI->getOpcode() == TargetInstrInfo::INSERT_SUBREG)
1562 LR->valno->copy = DefMI;
1566 // If resulting interval has a preference that no longer fits because of subreg
1567 // coalescing, just clear the preference.
1568 if (ResDstInt->preference && (isExtSubReg || isInsSubReg) &&
1569 TargetRegisterInfo::isVirtualRegister(ResDstInt->reg)) {
1570 const TargetRegisterClass *RC = mri_->getRegClass(ResDstInt->reg);
1571 if (!RC->contains(ResDstInt->preference))
1572 ResDstInt->preference = 0;
1575 DOUT << "\n\t\tJoined. Result = "; ResDstInt->print(DOUT, tri_);
1582 /// ComputeUltimateVN - Assuming we are going to join two live intervals,
1583 /// compute what the resultant value numbers for each value in the input two
1584 /// ranges will be. This is complicated by copies between the two which can
1585 /// and will commonly cause multiple value numbers to be merged into one.
1587 /// VN is the value number that we're trying to resolve. InstDefiningValue
1588 /// keeps track of the new InstDefiningValue assignment for the result
1589 /// LiveInterval. ThisFromOther/OtherFromThis are sets that keep track of
1590 /// whether a value in this or other is a copy from the opposite set.
1591 /// ThisValNoAssignments/OtherValNoAssignments keep track of value #'s that have
1592 /// already been assigned.
1594 /// ThisFromOther[x] - If x is defined as a copy from the other interval, this
1595 /// contains the value number the copy is from.
1597 static unsigned ComputeUltimateVN(VNInfo *VNI,
1598 SmallVector<VNInfo*, 16> &NewVNInfo,
1599 DenseMap<VNInfo*, VNInfo*> &ThisFromOther,
1600 DenseMap<VNInfo*, VNInfo*> &OtherFromThis,
1601 SmallVector<int, 16> &ThisValNoAssignments,
1602 SmallVector<int, 16> &OtherValNoAssignments) {
1603 unsigned VN = VNI->id;
1605 // If the VN has already been computed, just return it.
1606 if (ThisValNoAssignments[VN] >= 0)
1607 return ThisValNoAssignments[VN];
1608 // assert(ThisValNoAssignments[VN] != -2 && "Cyclic case?");
1610 // If this val is not a copy from the other val, then it must be a new value
1611 // number in the destination.
1612 DenseMap<VNInfo*, VNInfo*>::iterator I = ThisFromOther.find(VNI);
1613 if (I == ThisFromOther.end()) {
1614 NewVNInfo.push_back(VNI);
1615 return ThisValNoAssignments[VN] = NewVNInfo.size()-1;
1617 VNInfo *OtherValNo = I->second;
1619 // Otherwise, this *is* a copy from the RHS. If the other side has already
1620 // been computed, return it.
1621 if (OtherValNoAssignments[OtherValNo->id] >= 0)
1622 return ThisValNoAssignments[VN] = OtherValNoAssignments[OtherValNo->id];
1624 // Mark this value number as currently being computed, then ask what the
1625 // ultimate value # of the other value is.
1626 ThisValNoAssignments[VN] = -2;
1627 unsigned UltimateVN =
1628 ComputeUltimateVN(OtherValNo, NewVNInfo, OtherFromThis, ThisFromOther,
1629 OtherValNoAssignments, ThisValNoAssignments);
1630 return ThisValNoAssignments[VN] = UltimateVN;
1633 static bool InVector(VNInfo *Val, const SmallVector<VNInfo*, 8> &V) {
1634 return std::find(V.begin(), V.end(), Val) != V.end();
1637 /// RangeIsDefinedByCopyFromReg - Return true if the specified live range of
1638 /// the specified live interval is defined by a copy from the specified
1640 bool SimpleRegisterCoalescing::RangeIsDefinedByCopyFromReg(LiveInterval &li,
1643 unsigned SrcReg = li_->getVNInfoSourceReg(LR->valno);
1646 if (LR->valno->def == ~0U &&
1647 TargetRegisterInfo::isPhysicalRegister(li.reg) &&
1648 *tri_->getSuperRegisters(li.reg)) {
1649 // It's a sub-register live interval, we may not have precise information.
1651 MachineInstr *DefMI = li_->getInstructionFromIndex(LR->start);
1652 unsigned SrcReg, DstReg, SrcSubIdx, DstSubIdx;
1654 tii_->isMoveInstr(*DefMI, SrcReg, DstReg, SrcSubIdx, DstSubIdx) &&
1655 DstReg == li.reg && SrcReg == Reg) {
1656 // Cache computed info.
1657 LR->valno->def = LR->start;
1658 LR->valno->copy = DefMI;
1665 /// SimpleJoin - Attempt to joint the specified interval into this one. The
1666 /// caller of this method must guarantee that the RHS only contains a single
1667 /// value number and that the RHS is not defined by a copy from this
1668 /// interval. This returns false if the intervals are not joinable, or it
1669 /// joins them and returns true.
1670 bool SimpleRegisterCoalescing::SimpleJoin(LiveInterval &LHS, LiveInterval &RHS){
1671 assert(RHS.containsOneValue());
1673 // Some number (potentially more than one) value numbers in the current
1674 // interval may be defined as copies from the RHS. Scan the overlapping
1675 // portions of the LHS and RHS, keeping track of this and looking for
1676 // overlapping live ranges that are NOT defined as copies. If these exist, we
1679 LiveInterval::iterator LHSIt = LHS.begin(), LHSEnd = LHS.end();
1680 LiveInterval::iterator RHSIt = RHS.begin(), RHSEnd = RHS.end();
1682 if (LHSIt->start < RHSIt->start) {
1683 LHSIt = std::upper_bound(LHSIt, LHSEnd, RHSIt->start);
1684 if (LHSIt != LHS.begin()) --LHSIt;
1685 } else if (RHSIt->start < LHSIt->start) {
1686 RHSIt = std::upper_bound(RHSIt, RHSEnd, LHSIt->start);
1687 if (RHSIt != RHS.begin()) --RHSIt;
1690 SmallVector<VNInfo*, 8> EliminatedLHSVals;
1693 // Determine if these live intervals overlap.
1694 bool Overlaps = false;
1695 if (LHSIt->start <= RHSIt->start)
1696 Overlaps = LHSIt->end > RHSIt->start;
1698 Overlaps = RHSIt->end > LHSIt->start;
1700 // If the live intervals overlap, there are two interesting cases: if the
1701 // LHS interval is defined by a copy from the RHS, it's ok and we record
1702 // that the LHS value # is the same as the RHS. If it's not, then we cannot
1703 // coalesce these live ranges and we bail out.
1705 // If we haven't already recorded that this value # is safe, check it.
1706 if (!InVector(LHSIt->valno, EliminatedLHSVals)) {
1707 // Copy from the RHS?
1708 if (!RangeIsDefinedByCopyFromReg(LHS, LHSIt, RHS.reg))
1709 return false; // Nope, bail out.
1711 if (LHSIt->contains(RHSIt->valno->def))
1712 // Here is an interesting situation:
1714 // vr1025 = copy vr1024
1719 // Even though vr1025 is copied from vr1024, it's not safe to
1720 // coalesced them since live range of vr1025 intersects the
1721 // def of vr1024. This happens because vr1025 is assigned the
1722 // value of the previous iteration of vr1024.
1724 EliminatedLHSVals.push_back(LHSIt->valno);
1727 // We know this entire LHS live range is okay, so skip it now.
1728 if (++LHSIt == LHSEnd) break;
1732 if (LHSIt->end < RHSIt->end) {
1733 if (++LHSIt == LHSEnd) break;
1735 // One interesting case to check here. It's possible that we have
1736 // something like "X3 = Y" which defines a new value number in the LHS,
1737 // and is the last use of this liverange of the RHS. In this case, we
1738 // want to notice this copy (so that it gets coalesced away) even though
1739 // the live ranges don't actually overlap.
1740 if (LHSIt->start == RHSIt->end) {
1741 if (InVector(LHSIt->valno, EliminatedLHSVals)) {
1742 // We already know that this value number is going to be merged in
1743 // if coalescing succeeds. Just skip the liverange.
1744 if (++LHSIt == LHSEnd) break;
1746 // Otherwise, if this is a copy from the RHS, mark it as being merged
1748 if (RangeIsDefinedByCopyFromReg(LHS, LHSIt, RHS.reg)) {
1749 if (LHSIt->contains(RHSIt->valno->def))
1750 // Here is an interesting situation:
1752 // vr1025 = copy vr1024
1757 // Even though vr1025 is copied from vr1024, it's not safe to
1758 // coalesced them since live range of vr1025 intersects the
1759 // def of vr1024. This happens because vr1025 is assigned the
1760 // value of the previous iteration of vr1024.
1762 EliminatedLHSVals.push_back(LHSIt->valno);
1764 // We know this entire LHS live range is okay, so skip it now.
1765 if (++LHSIt == LHSEnd) break;
1770 if (++RHSIt == RHSEnd) break;
1774 // If we got here, we know that the coalescing will be successful and that
1775 // the value numbers in EliminatedLHSVals will all be merged together. Since
1776 // the most common case is that EliminatedLHSVals has a single number, we
1777 // optimize for it: if there is more than one value, we merge them all into
1778 // the lowest numbered one, then handle the interval as if we were merging
1779 // with one value number.
1780 VNInfo *LHSValNo = NULL;
1781 if (EliminatedLHSVals.size() > 1) {
1782 // Loop through all the equal value numbers merging them into the smallest
1784 VNInfo *Smallest = EliminatedLHSVals[0];
1785 for (unsigned i = 1, e = EliminatedLHSVals.size(); i != e; ++i) {
1786 if (EliminatedLHSVals[i]->id < Smallest->id) {
1787 // Merge the current notion of the smallest into the smaller one.
1788 LHS.MergeValueNumberInto(Smallest, EliminatedLHSVals[i]);
1789 Smallest = EliminatedLHSVals[i];
1791 // Merge into the smallest.
1792 LHS.MergeValueNumberInto(EliminatedLHSVals[i], Smallest);
1795 LHSValNo = Smallest;
1796 } else if (EliminatedLHSVals.empty()) {
1797 if (TargetRegisterInfo::isPhysicalRegister(LHS.reg) &&
1798 *tri_->getSuperRegisters(LHS.reg))
1799 // Imprecise sub-register information. Can't handle it.
1801 assert(0 && "No copies from the RHS?");
1803 LHSValNo = EliminatedLHSVals[0];
1806 // Okay, now that there is a single LHS value number that we're merging the
1807 // RHS into, update the value number info for the LHS to indicate that the
1808 // value number is defined where the RHS value number was.
1809 const VNInfo *VNI = RHS.getValNumInfo(0);
1810 LHSValNo->def = VNI->def;
1811 LHSValNo->copy = VNI->copy;
1813 // Okay, the final step is to loop over the RHS live intervals, adding them to
1815 LHSValNo->hasPHIKill |= VNI->hasPHIKill;
1816 LHS.addKills(LHSValNo, VNI->kills);
1817 LHS.MergeRangesInAsValue(RHS, LHSValNo);
1818 LHS.weight += RHS.weight;
1819 if (RHS.preference && !LHS.preference)
1820 LHS.preference = RHS.preference;
1825 /// JoinIntervals - Attempt to join these two intervals. On failure, this
1826 /// returns false. Otherwise, if one of the intervals being joined is a
1827 /// physreg, this method always canonicalizes LHS to be it. The output
1828 /// "RHS" will not have been modified, so we can use this information
1829 /// below to update aliases.
1831 SimpleRegisterCoalescing::JoinIntervals(LiveInterval &LHS, LiveInterval &RHS,
1833 // Compute the final value assignment, assuming that the live ranges can be
1835 SmallVector<int, 16> LHSValNoAssignments;
1836 SmallVector<int, 16> RHSValNoAssignments;
1837 DenseMap<VNInfo*, VNInfo*> LHSValsDefinedFromRHS;
1838 DenseMap<VNInfo*, VNInfo*> RHSValsDefinedFromLHS;
1839 SmallVector<VNInfo*, 16> NewVNInfo;
1841 // If a live interval is a physical register, conservatively check if any
1842 // of its sub-registers is overlapping the live interval of the virtual
1843 // register. If so, do not coalesce.
1844 if (TargetRegisterInfo::isPhysicalRegister(LHS.reg) &&
1845 *tri_->getSubRegisters(LHS.reg)) {
1846 // If it's coalescing a virtual register to a physical register, estimate
1847 // its live interval length. This is the *cost* of scanning an entire live
1848 // interval. If the cost is low, we'll do an exhaustive check instead.
1850 // If this is something like this:
1858 // That is, the live interval of v1024 crosses a bb. Then we can't rely on
1859 // less conservative check. It's possible a sub-register is defined before
1860 // v1024 (or live in) and live out of BB1.
1861 if (RHS.containsOneValue() &&
1862 li_->intervalIsInOneMBB(RHS) &&
1863 li_->getApproximateInstructionCount(RHS) <= 10) {
1864 // Perform a more exhaustive check for some common cases.
1865 if (li_->conflictsWithPhysRegRef(RHS, LHS.reg, true, JoinedCopies))
1868 for (const unsigned* SR = tri_->getSubRegisters(LHS.reg); *SR; ++SR)
1869 if (li_->hasInterval(*SR) && RHS.overlaps(li_->getInterval(*SR))) {
1870 DOUT << "Interfere with sub-register ";
1871 DEBUG(li_->getInterval(*SR).print(DOUT, tri_));
1875 } else if (TargetRegisterInfo::isPhysicalRegister(RHS.reg) &&
1876 *tri_->getSubRegisters(RHS.reg)) {
1877 if (LHS.containsOneValue() &&
1878 li_->getApproximateInstructionCount(LHS) <= 10) {
1879 // Perform a more exhaustive check for some common cases.
1880 if (li_->conflictsWithPhysRegRef(LHS, RHS.reg, false, JoinedCopies))
1883 for (const unsigned* SR = tri_->getSubRegisters(RHS.reg); *SR; ++SR)
1884 if (li_->hasInterval(*SR) && LHS.overlaps(li_->getInterval(*SR))) {
1885 DOUT << "Interfere with sub-register ";
1886 DEBUG(li_->getInterval(*SR).print(DOUT, tri_));
1892 // Compute ultimate value numbers for the LHS and RHS values.
1893 if (RHS.containsOneValue()) {
1894 // Copies from a liveinterval with a single value are simple to handle and
1895 // very common, handle the special case here. This is important, because
1896 // often RHS is small and LHS is large (e.g. a physreg).
1898 // Find out if the RHS is defined as a copy from some value in the LHS.
1899 int RHSVal0DefinedFromLHS = -1;
1901 VNInfo *RHSValNoInfo = NULL;
1902 VNInfo *RHSValNoInfo0 = RHS.getValNumInfo(0);
1903 unsigned RHSSrcReg = li_->getVNInfoSourceReg(RHSValNoInfo0);
1904 if (RHSSrcReg == 0 || RHSSrcReg != LHS.reg) {
1905 // If RHS is not defined as a copy from the LHS, we can use simpler and
1906 // faster checks to see if the live ranges are coalescable. This joiner
1907 // can't swap the LHS/RHS intervals though.
1908 if (!TargetRegisterInfo::isPhysicalRegister(RHS.reg)) {
1909 return SimpleJoin(LHS, RHS);
1911 RHSValNoInfo = RHSValNoInfo0;
1914 // It was defined as a copy from the LHS, find out what value # it is.
1915 RHSValNoInfo = LHS.getLiveRangeContaining(RHSValNoInfo0->def-1)->valno;
1916 RHSValID = RHSValNoInfo->id;
1917 RHSVal0DefinedFromLHS = RHSValID;
1920 LHSValNoAssignments.resize(LHS.getNumValNums(), -1);
1921 RHSValNoAssignments.resize(RHS.getNumValNums(), -1);
1922 NewVNInfo.resize(LHS.getNumValNums(), NULL);
1924 // Okay, *all* of the values in LHS that are defined as a copy from RHS
1925 // should now get updated.
1926 for (LiveInterval::vni_iterator i = LHS.vni_begin(), e = LHS.vni_end();
1929 unsigned VN = VNI->id;
1930 if (unsigned LHSSrcReg = li_->getVNInfoSourceReg(VNI)) {
1931 if (LHSSrcReg != RHS.reg) {
1932 // If this is not a copy from the RHS, its value number will be
1933 // unmodified by the coalescing.
1934 NewVNInfo[VN] = VNI;
1935 LHSValNoAssignments[VN] = VN;
1936 } else if (RHSValID == -1) {
1937 // Otherwise, it is a copy from the RHS, and we don't already have a
1938 // value# for it. Keep the current value number, but remember it.
1939 LHSValNoAssignments[VN] = RHSValID = VN;
1940 NewVNInfo[VN] = RHSValNoInfo;
1941 LHSValsDefinedFromRHS[VNI] = RHSValNoInfo0;
1943 // Otherwise, use the specified value #.
1944 LHSValNoAssignments[VN] = RHSValID;
1945 if (VN == (unsigned)RHSValID) { // Else this val# is dead.
1946 NewVNInfo[VN] = RHSValNoInfo;
1947 LHSValsDefinedFromRHS[VNI] = RHSValNoInfo0;
1951 NewVNInfo[VN] = VNI;
1952 LHSValNoAssignments[VN] = VN;
1956 assert(RHSValID != -1 && "Didn't find value #?");
1957 RHSValNoAssignments[0] = RHSValID;
1958 if (RHSVal0DefinedFromLHS != -1) {
1959 // This path doesn't go through ComputeUltimateVN so just set
1961 RHSValsDefinedFromLHS[RHSValNoInfo0] = (VNInfo*)1;
1964 // Loop over the value numbers of the LHS, seeing if any are defined from
1966 for (LiveInterval::vni_iterator i = LHS.vni_begin(), e = LHS.vni_end();
1969 if (VNI->def == ~1U || VNI->copy == 0) // Src not defined by a copy?
1972 // DstReg is known to be a register in the LHS interval. If the src is
1973 // from the RHS interval, we can use its value #.
1974 if (li_->getVNInfoSourceReg(VNI) != RHS.reg)
1977 // Figure out the value # from the RHS.
1978 LHSValsDefinedFromRHS[VNI]=RHS.getLiveRangeContaining(VNI->def-1)->valno;
1981 // Loop over the value numbers of the RHS, seeing if any are defined from
1983 for (LiveInterval::vni_iterator i = RHS.vni_begin(), e = RHS.vni_end();
1986 if (VNI->def == ~1U || VNI->copy == 0) // Src not defined by a copy?
1989 // DstReg is known to be a register in the RHS interval. If the src is
1990 // from the LHS interval, we can use its value #.
1991 if (li_->getVNInfoSourceReg(VNI) != LHS.reg)
1994 // Figure out the value # from the LHS.
1995 RHSValsDefinedFromLHS[VNI]=LHS.getLiveRangeContaining(VNI->def-1)->valno;
1998 LHSValNoAssignments.resize(LHS.getNumValNums(), -1);
1999 RHSValNoAssignments.resize(RHS.getNumValNums(), -1);
2000 NewVNInfo.reserve(LHS.getNumValNums() + RHS.getNumValNums());
2002 for (LiveInterval::vni_iterator i = LHS.vni_begin(), e = LHS.vni_end();
2005 unsigned VN = VNI->id;
2006 if (LHSValNoAssignments[VN] >= 0 || VNI->def == ~1U)
2008 ComputeUltimateVN(VNI, NewVNInfo,
2009 LHSValsDefinedFromRHS, RHSValsDefinedFromLHS,
2010 LHSValNoAssignments, RHSValNoAssignments);
2012 for (LiveInterval::vni_iterator i = RHS.vni_begin(), e = RHS.vni_end();
2015 unsigned VN = VNI->id;
2016 if (RHSValNoAssignments[VN] >= 0 || VNI->def == ~1U)
2018 // If this value number isn't a copy from the LHS, it's a new number.
2019 if (RHSValsDefinedFromLHS.find(VNI) == RHSValsDefinedFromLHS.end()) {
2020 NewVNInfo.push_back(VNI);
2021 RHSValNoAssignments[VN] = NewVNInfo.size()-1;
2025 ComputeUltimateVN(VNI, NewVNInfo,
2026 RHSValsDefinedFromLHS, LHSValsDefinedFromRHS,
2027 RHSValNoAssignments, LHSValNoAssignments);
2031 // Armed with the mappings of LHS/RHS values to ultimate values, walk the
2032 // interval lists to see if these intervals are coalescable.
2033 LiveInterval::const_iterator I = LHS.begin();
2034 LiveInterval::const_iterator IE = LHS.end();
2035 LiveInterval::const_iterator J = RHS.begin();
2036 LiveInterval::const_iterator JE = RHS.end();
2038 // Skip ahead until the first place of potential sharing.
2039 if (I->start < J->start) {
2040 I = std::upper_bound(I, IE, J->start);
2041 if (I != LHS.begin()) --I;
2042 } else if (J->start < I->start) {
2043 J = std::upper_bound(J, JE, I->start);
2044 if (J != RHS.begin()) --J;
2048 // Determine if these two live ranges overlap.
2050 if (I->start < J->start) {
2051 Overlaps = I->end > J->start;
2053 Overlaps = J->end > I->start;
2056 // If so, check value # info to determine if they are really different.
2058 // If the live range overlap will map to the same value number in the
2059 // result liverange, we can still coalesce them. If not, we can't.
2060 if (LHSValNoAssignments[I->valno->id] !=
2061 RHSValNoAssignments[J->valno->id])
2065 if (I->end < J->end) {
2074 // Update kill info. Some live ranges are extended due to copy coalescing.
2075 for (DenseMap<VNInfo*, VNInfo*>::iterator I = LHSValsDefinedFromRHS.begin(),
2076 E = LHSValsDefinedFromRHS.end(); I != E; ++I) {
2077 VNInfo *VNI = I->first;
2078 unsigned LHSValID = LHSValNoAssignments[VNI->id];
2079 LiveInterval::removeKill(NewVNInfo[LHSValID], VNI->def);
2080 NewVNInfo[LHSValID]->hasPHIKill |= VNI->hasPHIKill;
2081 RHS.addKills(NewVNInfo[LHSValID], VNI->kills);
2084 // Update kill info. Some live ranges are extended due to copy coalescing.
2085 for (DenseMap<VNInfo*, VNInfo*>::iterator I = RHSValsDefinedFromLHS.begin(),
2086 E = RHSValsDefinedFromLHS.end(); I != E; ++I) {
2087 VNInfo *VNI = I->first;
2088 unsigned RHSValID = RHSValNoAssignments[VNI->id];
2089 LiveInterval::removeKill(NewVNInfo[RHSValID], VNI->def);
2090 NewVNInfo[RHSValID]->hasPHIKill |= VNI->hasPHIKill;
2091 LHS.addKills(NewVNInfo[RHSValID], VNI->kills);
2094 // If we get here, we know that we can coalesce the live ranges. Ask the
2095 // intervals to coalesce themselves now.
2096 if ((RHS.ranges.size() > LHS.ranges.size() &&
2097 TargetRegisterInfo::isVirtualRegister(LHS.reg)) ||
2098 TargetRegisterInfo::isPhysicalRegister(RHS.reg)) {
2099 RHS.join(LHS, &RHSValNoAssignments[0], &LHSValNoAssignments[0], NewVNInfo);
2102 LHS.join(RHS, &LHSValNoAssignments[0], &RHSValNoAssignments[0], NewVNInfo);
2109 // DepthMBBCompare - Comparison predicate that sort first based on the loop
2110 // depth of the basic block (the unsigned), and then on the MBB number.
2111 struct DepthMBBCompare {
2112 typedef std::pair<unsigned, MachineBasicBlock*> DepthMBBPair;
2113 bool operator()(const DepthMBBPair &LHS, const DepthMBBPair &RHS) const {
2114 if (LHS.first > RHS.first) return true; // Deeper loops first
2115 return LHS.first == RHS.first &&
2116 LHS.second->getNumber() < RHS.second->getNumber();
2121 /// getRepIntervalSize - Returns the size of the interval that represents the
2122 /// specified register.
2124 unsigned JoinPriorityQueue<SF>::getRepIntervalSize(unsigned Reg) {
2125 return Rc->getRepIntervalSize(Reg);
2128 /// CopyRecSort::operator - Join priority queue sorting function.
2130 bool CopyRecSort::operator()(CopyRec left, CopyRec right) const {
2131 // Inner loops first.
2132 if (left.LoopDepth > right.LoopDepth)
2134 else if (left.LoopDepth == right.LoopDepth)
2135 if (left.isBackEdge && !right.isBackEdge)
2140 void SimpleRegisterCoalescing::CopyCoalesceInMBB(MachineBasicBlock *MBB,
2141 std::vector<CopyRec> &TryAgain) {
2142 DOUT << ((Value*)MBB->getBasicBlock())->getName() << ":\n";
2144 std::vector<CopyRec> VirtCopies;
2145 std::vector<CopyRec> PhysCopies;
2146 std::vector<CopyRec> ImpDefCopies;
2147 unsigned LoopDepth = loopInfo->getLoopDepth(MBB);
2148 for (MachineBasicBlock::iterator MII = MBB->begin(), E = MBB->end();
2150 MachineInstr *Inst = MII++;
2152 // If this isn't a copy nor a extract_subreg, we can't join intervals.
2153 unsigned SrcReg, DstReg, SrcSubIdx, DstSubIdx;
2154 if (Inst->getOpcode() == TargetInstrInfo::EXTRACT_SUBREG) {
2155 DstReg = Inst->getOperand(0).getReg();
2156 SrcReg = Inst->getOperand(1).getReg();
2157 } else if (Inst->getOpcode() == TargetInstrInfo::INSERT_SUBREG) {
2158 DstReg = Inst->getOperand(0).getReg();
2159 SrcReg = Inst->getOperand(2).getReg();
2160 } else if (!tii_->isMoveInstr(*Inst, SrcReg, DstReg, SrcSubIdx, DstSubIdx))
2163 bool SrcIsPhys = TargetRegisterInfo::isPhysicalRegister(SrcReg);
2164 bool DstIsPhys = TargetRegisterInfo::isPhysicalRegister(DstReg);
2166 JoinQueue->push(CopyRec(Inst, LoopDepth, isBackEdgeCopy(Inst, DstReg)));
2168 if (li_->hasInterval(SrcReg) && li_->getInterval(SrcReg).empty())
2169 ImpDefCopies.push_back(CopyRec(Inst, 0, false));
2170 else if (SrcIsPhys || DstIsPhys)
2171 PhysCopies.push_back(CopyRec(Inst, 0, false));
2173 VirtCopies.push_back(CopyRec(Inst, 0, false));
2180 // Try coalescing implicit copies first, followed by copies to / from
2181 // physical registers, then finally copies from virtual registers to
2182 // virtual registers.
2183 for (unsigned i = 0, e = ImpDefCopies.size(); i != e; ++i) {
2184 CopyRec &TheCopy = ImpDefCopies[i];
2186 if (!JoinCopy(TheCopy, Again))
2188 TryAgain.push_back(TheCopy);
2190 for (unsigned i = 0, e = PhysCopies.size(); i != e; ++i) {
2191 CopyRec &TheCopy = PhysCopies[i];
2193 if (!JoinCopy(TheCopy, Again))
2195 TryAgain.push_back(TheCopy);
2197 for (unsigned i = 0, e = VirtCopies.size(); i != e; ++i) {
2198 CopyRec &TheCopy = VirtCopies[i];
2200 if (!JoinCopy(TheCopy, Again))
2202 TryAgain.push_back(TheCopy);
2206 void SimpleRegisterCoalescing::joinIntervals() {
2207 DOUT << "********** JOINING INTERVALS ***********\n";
2210 JoinQueue = new JoinPriorityQueue<CopyRecSort>(this);
2212 std::vector<CopyRec> TryAgainList;
2213 if (loopInfo->empty()) {
2214 // If there are no loops in the function, join intervals in function order.
2215 for (MachineFunction::iterator I = mf_->begin(), E = mf_->end();
2217 CopyCoalesceInMBB(I, TryAgainList);
2219 // Otherwise, join intervals in inner loops before other intervals.
2220 // Unfortunately we can't just iterate over loop hierarchy here because
2221 // there may be more MBB's than BB's. Collect MBB's for sorting.
2223 // Join intervals in the function prolog first. We want to join physical
2224 // registers with virtual registers before the intervals got too long.
2225 std::vector<std::pair<unsigned, MachineBasicBlock*> > MBBs;
2226 for (MachineFunction::iterator I = mf_->begin(), E = mf_->end();I != E;++I){
2227 MachineBasicBlock *MBB = I;
2228 MBBs.push_back(std::make_pair(loopInfo->getLoopDepth(MBB), I));
2231 // Sort by loop depth.
2232 std::sort(MBBs.begin(), MBBs.end(), DepthMBBCompare());
2234 // Finally, join intervals in loop nest order.
2235 for (unsigned i = 0, e = MBBs.size(); i != e; ++i)
2236 CopyCoalesceInMBB(MBBs[i].second, TryAgainList);
2239 // Joining intervals can allow other intervals to be joined. Iteratively join
2240 // until we make no progress.
2242 SmallVector<CopyRec, 16> TryAgain;
2243 bool ProgressMade = true;
2244 while (ProgressMade) {
2245 ProgressMade = false;
2246 while (!JoinQueue->empty()) {
2247 CopyRec R = JoinQueue->pop();
2249 bool Success = JoinCopy(R, Again);
2251 ProgressMade = true;
2253 TryAgain.push_back(R);
2257 while (!TryAgain.empty()) {
2258 JoinQueue->push(TryAgain.back());
2259 TryAgain.pop_back();
2264 bool ProgressMade = true;
2265 while (ProgressMade) {
2266 ProgressMade = false;
2268 for (unsigned i = 0, e = TryAgainList.size(); i != e; ++i) {
2269 CopyRec &TheCopy = TryAgainList[i];
2272 bool Success = JoinCopy(TheCopy, Again);
2273 if (Success || !Again) {
2274 TheCopy.MI = 0; // Mark this one as done.
2275 ProgressMade = true;
2286 /// Return true if the two specified registers belong to different register
2287 /// classes. The registers may be either phys or virt regs.
2289 SimpleRegisterCoalescing::differingRegisterClasses(unsigned RegA,
2290 unsigned RegB) const {
2291 // Get the register classes for the first reg.
2292 if (TargetRegisterInfo::isPhysicalRegister(RegA)) {
2293 assert(TargetRegisterInfo::isVirtualRegister(RegB) &&
2294 "Shouldn't consider two physregs!");
2295 return !mri_->getRegClass(RegB)->contains(RegA);
2298 // Compare against the regclass for the second reg.
2299 const TargetRegisterClass *RegClassA = mri_->getRegClass(RegA);
2300 if (TargetRegisterInfo::isVirtualRegister(RegB)) {
2301 const TargetRegisterClass *RegClassB = mri_->getRegClass(RegB);
2302 return RegClassA != RegClassB;
2304 return !RegClassA->contains(RegB);
2307 /// lastRegisterUse - Returns the last use of the specific register between
2308 /// cycles Start and End or NULL if there are no uses.
2310 SimpleRegisterCoalescing::lastRegisterUse(unsigned Start, unsigned End,
2311 unsigned Reg, unsigned &UseIdx) const{
2313 if (TargetRegisterInfo::isVirtualRegister(Reg)) {
2314 MachineOperand *LastUse = NULL;
2315 for (MachineRegisterInfo::use_iterator I = mri_->use_begin(Reg),
2316 E = mri_->use_end(); I != E; ++I) {
2317 MachineOperand &Use = I.getOperand();
2318 MachineInstr *UseMI = Use.getParent();
2319 unsigned SrcReg, DstReg, SrcSubIdx, DstSubIdx;
2320 if (tii_->isMoveInstr(*UseMI, SrcReg, DstReg, SrcSubIdx, DstSubIdx) &&
2322 // Ignore identity copies.
2324 unsigned Idx = li_->getInstructionIndex(UseMI);
2325 if (Idx >= Start && Idx < End && Idx >= UseIdx) {
2333 int e = (End-1) / InstrSlots::NUM * InstrSlots::NUM;
2336 // Skip deleted instructions
2337 MachineInstr *MI = li_->getInstructionFromIndex(e);
2338 while ((e - InstrSlots::NUM) >= s && !MI) {
2339 e -= InstrSlots::NUM;
2340 MI = li_->getInstructionFromIndex(e);
2342 if (e < s || MI == NULL)
2345 // Ignore identity copies.
2346 unsigned SrcReg, DstReg, SrcSubIdx, DstSubIdx;
2347 if (!(tii_->isMoveInstr(*MI, SrcReg, DstReg, SrcSubIdx, DstSubIdx) &&
2349 for (unsigned i = 0, NumOps = MI->getNumOperands(); i != NumOps; ++i) {
2350 MachineOperand &Use = MI->getOperand(i);
2351 if (Use.isReg() && Use.isUse() && Use.getReg() &&
2352 tri_->regsOverlap(Use.getReg(), Reg)) {
2358 e -= InstrSlots::NUM;
2365 void SimpleRegisterCoalescing::printRegName(unsigned reg) const {
2366 if (TargetRegisterInfo::isPhysicalRegister(reg))
2367 cerr << tri_->getName(reg);
2369 cerr << "%reg" << reg;
2372 void SimpleRegisterCoalescing::releaseMemory() {
2373 JoinedCopies.clear();
2374 ReMatCopies.clear();
2378 static bool isZeroLengthInterval(LiveInterval *li) {
2379 for (LiveInterval::Ranges::const_iterator
2380 i = li->ranges.begin(), e = li->ranges.end(); i != e; ++i)
2381 if (i->end - i->start > LiveIntervals::InstrSlots::NUM)
2386 /// TurnCopyIntoImpDef - If source of the specified copy is an implicit def,
2387 /// turn the copy into an implicit def.
2389 SimpleRegisterCoalescing::TurnCopyIntoImpDef(MachineBasicBlock::iterator &I,
2390 MachineBasicBlock *MBB,
2391 unsigned DstReg, unsigned SrcReg) {
2392 MachineInstr *CopyMI = &*I;
2393 unsigned CopyIdx = li_->getDefIndex(li_->getInstructionIndex(CopyMI));
2394 if (!li_->hasInterval(SrcReg))
2396 LiveInterval &SrcInt = li_->getInterval(SrcReg);
2397 if (!SrcInt.empty())
2399 if (!li_->hasInterval(DstReg))
2401 LiveInterval &DstInt = li_->getInterval(DstReg);
2402 const LiveRange *DstLR = DstInt.getLiveRangeContaining(CopyIdx);
2403 DstInt.removeValNo(DstLR->valno);
2404 CopyMI->setDesc(tii_->get(TargetInstrInfo::IMPLICIT_DEF));
2405 for (int i = CopyMI->getNumOperands() - 1, e = 0; i > e; --i)
2406 CopyMI->RemoveOperand(i);
2407 bool NoUse = mri_->use_empty(SrcReg);
2409 for (MachineRegisterInfo::reg_iterator I = mri_->reg_begin(SrcReg),
2410 E = mri_->reg_end(); I != E; ) {
2411 assert(I.getOperand().isDef());
2412 MachineInstr *DefMI = &*I;
2414 // The implicit_def source has no other uses, delete it.
2415 assert(DefMI->getOpcode() == TargetInstrInfo::IMPLICIT_DEF);
2416 li_->RemoveMachineInstrFromMaps(DefMI);
2417 DefMI->eraseFromParent();
2425 bool SimpleRegisterCoalescing::runOnMachineFunction(MachineFunction &fn) {
2427 mri_ = &fn.getRegInfo();
2428 tm_ = &fn.getTarget();
2429 tri_ = tm_->getRegisterInfo();
2430 tii_ = tm_->getInstrInfo();
2431 li_ = &getAnalysis<LiveIntervals>();
2432 loopInfo = &getAnalysis<MachineLoopInfo>();
2434 DOUT << "********** SIMPLE REGISTER COALESCING **********\n"
2435 << "********** Function: "
2436 << ((Value*)mf_->getFunction())->getName() << '\n';
2438 allocatableRegs_ = tri_->getAllocatableSet(fn);
2439 for (TargetRegisterInfo::regclass_iterator I = tri_->regclass_begin(),
2440 E = tri_->regclass_end(); I != E; ++I)
2441 allocatableRCRegs_.insert(std::make_pair(*I,
2442 tri_->getAllocatableSet(fn, *I)));
2444 // Join (coalesce) intervals if requested.
2445 if (EnableJoining) {
2448 DOUT << "********** INTERVALS POST JOINING **********\n";
2449 for (LiveIntervals::iterator I = li_->begin(), E = li_->end(); I != E; ++I){
2450 I->second->print(DOUT, tri_);
2456 // Perform a final pass over the instructions and compute spill weights
2457 // and remove identity moves.
2458 SmallVector<unsigned, 4> DeadDefs;
2459 for (MachineFunction::iterator mbbi = mf_->begin(), mbbe = mf_->end();
2460 mbbi != mbbe; ++mbbi) {
2461 MachineBasicBlock* mbb = mbbi;
2462 unsigned loopDepth = loopInfo->getLoopDepth(mbb);
2464 for (MachineBasicBlock::iterator mii = mbb->begin(), mie = mbb->end();
2466 MachineInstr *MI = mii;
2467 unsigned SrcReg, DstReg, SrcSubIdx, DstSubIdx;
2468 if (JoinedCopies.count(MI)) {
2469 // Delete all coalesced copies.
2470 if (!tii_->isMoveInstr(*MI, SrcReg, DstReg, SrcSubIdx, DstSubIdx)) {
2471 assert((MI->getOpcode() == TargetInstrInfo::EXTRACT_SUBREG ||
2472 MI->getOpcode() == TargetInstrInfo::INSERT_SUBREG) &&
2473 "Unrecognized copy instruction");
2474 DstReg = MI->getOperand(0).getReg();
2476 if (MI->registerDefIsDead(DstReg)) {
2477 LiveInterval &li = li_->getInterval(DstReg);
2478 if (!ShortenDeadCopySrcLiveRange(li, MI))
2479 ShortenDeadCopyLiveRange(li, MI);
2481 li_->RemoveMachineInstrFromMaps(MI);
2482 mii = mbbi->erase(mii);
2487 // Now check if this is a remat'ed def instruction which is now dead.
2488 if (ReMatDefs.count(MI)) {
2490 for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
2491 const MachineOperand &MO = MI->getOperand(i);
2494 unsigned Reg = MO.getReg();
2497 if (TargetRegisterInfo::isVirtualRegister(Reg))
2498 DeadDefs.push_back(Reg);
2501 if (TargetRegisterInfo::isPhysicalRegister(Reg) ||
2502 !mri_->use_empty(Reg)) {
2508 while (!DeadDefs.empty()) {
2509 unsigned DeadDef = DeadDefs.back();
2510 DeadDefs.pop_back();
2511 RemoveDeadDef(li_->getInterval(DeadDef), MI);
2513 li_->RemoveMachineInstrFromMaps(mii);
2514 mii = mbbi->erase(mii);
2520 // If the move will be an identity move delete it
2521 bool isMove= tii_->isMoveInstr(*MI, SrcReg, DstReg, SrcSubIdx, DstSubIdx);
2522 if (isMove && SrcReg == DstReg) {
2523 if (li_->hasInterval(SrcReg)) {
2524 LiveInterval &RegInt = li_->getInterval(SrcReg);
2525 // If def of this move instruction is dead, remove its live range
2526 // from the dstination register's live interval.
2527 if (MI->registerDefIsDead(DstReg)) {
2528 if (!ShortenDeadCopySrcLiveRange(RegInt, MI))
2529 ShortenDeadCopyLiveRange(RegInt, MI);
2532 li_->RemoveMachineInstrFromMaps(MI);
2533 mii = mbbi->erase(mii);
2535 } else if (!isMove || !TurnCopyIntoImpDef(mii, mbb, DstReg, SrcReg)) {
2536 SmallSet<unsigned, 4> UniqueUses;
2537 for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
2538 const MachineOperand &mop = MI->getOperand(i);
2539 if (mop.isReg() && mop.getReg() &&
2540 TargetRegisterInfo::isVirtualRegister(mop.getReg())) {
2541 unsigned reg = mop.getReg();
2542 // Multiple uses of reg by the same instruction. It should not
2543 // contribute to spill weight again.
2544 if (UniqueUses.count(reg) != 0)
2546 LiveInterval &RegInt = li_->getInterval(reg);
2548 li_->getSpillWeight(mop.isDef(), mop.isUse(), loopDepth);
2549 UniqueUses.insert(reg);
2557 for (LiveIntervals::iterator I = li_->begin(), E = li_->end(); I != E; ++I) {
2558 LiveInterval &LI = *I->second;
2559 if (TargetRegisterInfo::isVirtualRegister(LI.reg)) {
2560 // If the live interval length is essentially zero, i.e. in every live
2561 // range the use follows def immediately, it doesn't make sense to spill
2562 // it and hope it will be easier to allocate for this li.
2563 if (isZeroLengthInterval(&LI))
2564 LI.weight = HUGE_VALF;
2566 bool isLoad = false;
2567 SmallVector<LiveInterval*, 4> SpillIs;
2568 if (li_->isReMaterializable(LI, SpillIs, isLoad)) {
2569 // If all of the definitions of the interval are re-materializable,
2570 // it is a preferred candidate for spilling. If non of the defs are
2571 // loads, then it's potentially very cheap to re-materialize.
2572 // FIXME: this gets much more complicated once we support non-trivial
2573 // re-materialization.
2581 // Slightly prefer live interval that has been assigned a preferred reg.
2585 // Divide the weight of the interval by its size. This encourages
2586 // spilling of intervals that are large and have few uses, and
2587 // discourages spilling of small intervals with many uses.
2588 LI.weight /= li_->getApproximateInstructionCount(LI) * InstrSlots::NUM;
2596 /// print - Implement the dump method.
2597 void SimpleRegisterCoalescing::print(std::ostream &O, const Module* m) const {
2601 RegisterCoalescer* llvm::createSimpleRegisterCoalescer() {
2602 return new SimpleRegisterCoalescing();
2605 // Make sure that anything that uses RegisterCoalescer pulls in this file...
2606 DEFINING_FILE_FOR(SimpleRegisterCoalescing)