1 //===-- llvm/CodeGen/VirtRegMap.cpp - Virtual Register Map ----------------===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the VirtRegMap class.
12 // It also contains implementations of the the Spiller interface, which, given a
13 // virtual register map and a machine function, eliminates all virtual
14 // references by replacing them with physical register references - adding spill
17 //===----------------------------------------------------------------------===//
19 #define DEBUG_TYPE "spiller"
20 #include "VirtRegMap.h"
21 #include "llvm/Function.h"
22 #include "llvm/CodeGen/MachineFrameInfo.h"
23 #include "llvm/CodeGen/MachineFunction.h"
24 #include "llvm/CodeGen/SSARegMap.h"
25 #include "llvm/Target/TargetMachine.h"
26 #include "llvm/Target/TargetInstrInfo.h"
27 #include "llvm/Support/CommandLine.h"
28 #include "llvm/Support/Debug.h"
29 #include "llvm/Support/Compiler.h"
30 #include "llvm/ADT/BitVector.h"
31 #include "llvm/ADT/Statistic.h"
32 #include "llvm/ADT/STLExtras.h"
33 #include "llvm/ADT/SmallSet.h"
37 STATISTIC(NumSpills, "Number of register spills");
38 STATISTIC(NumReMats, "Number of re-materialization");
39 STATISTIC(NumDRM , "Number of re-materializable defs elided");
40 STATISTIC(NumStores, "Number of stores added");
41 STATISTIC(NumLoads , "Number of loads added");
42 STATISTIC(NumReused, "Number of values reused");
43 STATISTIC(NumDSE , "Number of dead stores elided");
44 STATISTIC(NumDCE , "Number of copies elided");
47 enum SpillerName { simple, local };
49 static cl::opt<SpillerName>
51 cl::desc("Spiller to use: (default: local)"),
53 cl::values(clEnumVal(simple, " simple spiller"),
54 clEnumVal(local, " local spiller"),
59 //===----------------------------------------------------------------------===//
60 // VirtRegMap implementation
61 //===----------------------------------------------------------------------===//
63 VirtRegMap::VirtRegMap(MachineFunction &mf)
64 : TII(*mf.getTarget().getInstrInfo()), MF(mf),
65 Virt2PhysMap(NO_PHYS_REG), Virt2StackSlotMap(NO_STACK_SLOT),
66 Virt2ReMatIdMap(NO_STACK_SLOT), ReMatMap(NULL),
67 ReMatId(MAX_STACK_SLOT+1) {
71 void VirtRegMap::grow() {
72 unsigned LastVirtReg = MF.getSSARegMap()->getLastVirtReg();
73 Virt2PhysMap.grow(LastVirtReg);
74 Virt2StackSlotMap.grow(LastVirtReg);
75 Virt2ReMatIdMap.grow(LastVirtReg);
76 ReMatMap.grow(LastVirtReg);
79 int VirtRegMap::assignVirt2StackSlot(unsigned virtReg) {
80 assert(MRegisterInfo::isVirtualRegister(virtReg));
81 assert(Virt2StackSlotMap[virtReg] == NO_STACK_SLOT &&
82 "attempt to assign stack slot to already spilled register");
83 const TargetRegisterClass* RC = MF.getSSARegMap()->getRegClass(virtReg);
84 int frameIndex = MF.getFrameInfo()->CreateStackObject(RC->getSize(),
86 Virt2StackSlotMap[virtReg] = frameIndex;
91 void VirtRegMap::assignVirt2StackSlot(unsigned virtReg, int frameIndex) {
92 assert(MRegisterInfo::isVirtualRegister(virtReg));
93 assert(Virt2StackSlotMap[virtReg] == NO_STACK_SLOT &&
94 "attempt to assign stack slot to already spilled register");
95 assert((frameIndex >= 0 ||
96 (frameIndex >= MF.getFrameInfo()->getObjectIndexBegin())) &&
97 "illegal fixed frame index");
98 Virt2StackSlotMap[virtReg] = frameIndex;
101 int VirtRegMap::assignVirtReMatId(unsigned virtReg) {
102 assert(MRegisterInfo::isVirtualRegister(virtReg));
103 assert(Virt2ReMatIdMap[virtReg] == NO_STACK_SLOT &&
104 "attempt to assign re-mat id to already spilled register");
105 Virt2ReMatIdMap[virtReg] = ReMatId;
109 void VirtRegMap::assignVirtReMatId(unsigned virtReg, int id) {
110 assert(MRegisterInfo::isVirtualRegister(virtReg));
111 assert(Virt2ReMatIdMap[virtReg] == NO_STACK_SLOT &&
112 "attempt to assign re-mat id to already spilled register");
113 Virt2ReMatIdMap[virtReg] = id;
116 void VirtRegMap::virtFolded(unsigned VirtReg, MachineInstr *OldMI,
117 unsigned OpNo, MachineInstr *NewMI) {
118 // Move previous memory references folded to new instruction.
119 MI2VirtMapTy::iterator IP = MI2VirtMap.lower_bound(NewMI);
120 for (MI2VirtMapTy::iterator I = MI2VirtMap.lower_bound(OldMI),
121 E = MI2VirtMap.end(); I != E && I->first == OldMI; ) {
122 MI2VirtMap.insert(IP, std::make_pair(NewMI, I->second));
123 MI2VirtMap.erase(I++);
127 const TargetInstrDescriptor *TID = OldMI->getInstrDescriptor();
128 if (TID->getOperandConstraint(OpNo, TOI::TIED_TO) != -1 ||
129 TID->findTiedToSrcOperand(OpNo) != -1) {
130 // Folded a two-address operand.
132 } else if (OldMI->getOperand(OpNo).isDef()) {
138 // add new memory reference
139 MI2VirtMap.insert(IP, std::make_pair(NewMI, std::make_pair(VirtReg, MRInfo)));
142 void VirtRegMap::virtFolded(unsigned VirtReg, MachineInstr *MI, ModRef MRInfo) {
143 MI2VirtMapTy::iterator IP = MI2VirtMap.lower_bound(MI);
144 MI2VirtMap.insert(IP, std::make_pair(MI, std::make_pair(VirtReg, MRInfo)));
147 void VirtRegMap::print(std::ostream &OS) const {
148 const MRegisterInfo* MRI = MF.getTarget().getRegisterInfo();
150 OS << "********** REGISTER MAP **********\n";
151 for (unsigned i = MRegisterInfo::FirstVirtualRegister,
152 e = MF.getSSARegMap()->getLastVirtReg(); i <= e; ++i) {
153 if (Virt2PhysMap[i] != (unsigned)VirtRegMap::NO_PHYS_REG)
154 OS << "[reg" << i << " -> " << MRI->getName(Virt2PhysMap[i]) << "]\n";
158 for (unsigned i = MRegisterInfo::FirstVirtualRegister,
159 e = MF.getSSARegMap()->getLastVirtReg(); i <= e; ++i)
160 if (Virt2StackSlotMap[i] != VirtRegMap::NO_STACK_SLOT)
161 OS << "[reg" << i << " -> fi#" << Virt2StackSlotMap[i] << "]\n";
165 void VirtRegMap::dump() const {
170 //===----------------------------------------------------------------------===//
171 // Simple Spiller Implementation
172 //===----------------------------------------------------------------------===//
174 Spiller::~Spiller() {}
177 struct VISIBILITY_HIDDEN SimpleSpiller : public Spiller {
178 bool runOnMachineFunction(MachineFunction& mf, VirtRegMap &VRM);
182 bool SimpleSpiller::runOnMachineFunction(MachineFunction &MF, VirtRegMap &VRM) {
183 DOUT << "********** REWRITE MACHINE CODE **********\n";
184 DOUT << "********** Function: " << MF.getFunction()->getName() << '\n';
185 const TargetMachine &TM = MF.getTarget();
186 const MRegisterInfo &MRI = *TM.getRegisterInfo();
188 // LoadedRegs - Keep track of which vregs are loaded, so that we only load
189 // each vreg once (in the case where a spilled vreg is used by multiple
190 // operands). This is always smaller than the number of operands to the
191 // current machine instr, so it should be small.
192 std::vector<unsigned> LoadedRegs;
194 for (MachineFunction::iterator MBBI = MF.begin(), E = MF.end();
196 DOUT << MBBI->getBasicBlock()->getName() << ":\n";
197 MachineBasicBlock &MBB = *MBBI;
198 for (MachineBasicBlock::iterator MII = MBB.begin(),
199 E = MBB.end(); MII != E; ++MII) {
200 MachineInstr &MI = *MII;
201 for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
202 MachineOperand &MO = MI.getOperand(i);
203 if (MO.isRegister() && MO.getReg())
204 if (MRegisterInfo::isVirtualRegister(MO.getReg())) {
205 unsigned VirtReg = MO.getReg();
206 unsigned PhysReg = VRM.getPhys(VirtReg);
207 if (!VRM.isAssignedReg(VirtReg)) {
208 int StackSlot = VRM.getStackSlot(VirtReg);
209 const TargetRegisterClass* RC =
210 MF.getSSARegMap()->getRegClass(VirtReg);
213 std::find(LoadedRegs.begin(), LoadedRegs.end(), VirtReg)
214 == LoadedRegs.end()) {
215 MRI.loadRegFromStackSlot(MBB, &MI, PhysReg, StackSlot, RC);
216 LoadedRegs.push_back(VirtReg);
218 DOUT << '\t' << *prior(MII);
222 MRI.storeRegToStackSlot(MBB, next(MII), PhysReg, StackSlot, RC);
226 MF.setPhysRegUsed(PhysReg);
227 MI.getOperand(i).setReg(PhysReg);
229 MF.setPhysRegUsed(MO.getReg());
240 //===----------------------------------------------------------------------===//
241 // Local Spiller Implementation
242 //===----------------------------------------------------------------------===//
245 /// LocalSpiller - This spiller does a simple pass over the machine basic
246 /// block to attempt to keep spills in registers as much as possible for
247 /// blocks that have low register pressure (the vreg may be spilled due to
248 /// register pressure in other blocks).
249 class VISIBILITY_HIDDEN LocalSpiller : public Spiller {
251 const MRegisterInfo *MRI;
252 const TargetInstrInfo *TII;
254 bool runOnMachineFunction(MachineFunction &MF, VirtRegMap &VRM) {
255 RegMap = MF.getSSARegMap();
256 MRI = MF.getTarget().getRegisterInfo();
257 TII = MF.getTarget().getInstrInfo();
258 DOUT << "\n**** Local spiller rewriting function '"
259 << MF.getFunction()->getName() << "':\n";
260 DOUT << "**** Machine Instrs (NOTE! Does not include spills and reloads!) ****\n";
263 for (MachineFunction::iterator MBB = MF.begin(), E = MF.end();
265 RewriteMBB(*MBB, VRM);
267 DOUT << "**** Post Machine Instrs ****\n";
273 void RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM);
277 /// AvailableSpills - As the local spiller is scanning and rewriting an MBB from
278 /// top down, keep track of which spills slots or remat are available in each
281 /// Note that not all physregs are created equal here. In particular, some
282 /// physregs are reloads that we are allowed to clobber or ignore at any time.
283 /// Other physregs are values that the register allocated program is using that
284 /// we cannot CHANGE, but we can read if we like. We keep track of this on a
285 /// per-stack-slot / remat id basis as the low bit in the value of the
286 /// SpillSlotsAvailable entries. The predicate 'canClobberPhysReg()' checks
287 /// this bit and addAvailable sets it if.
289 class VISIBILITY_HIDDEN AvailableSpills {
290 const MRegisterInfo *MRI;
291 const TargetInstrInfo *TII;
293 // SpillSlotsOrReMatsAvailable - This map keeps track of all of the spilled
294 // or remat'ed virtual register values that are still available, due to being
295 // loaded or stored to, but not invalidated yet.
296 std::map<int, unsigned> SpillSlotsOrReMatsAvailable;
298 // PhysRegsAvailable - This is the inverse of SpillSlotsOrReMatsAvailable,
299 // indicating which stack slot values are currently held by a physreg. This
300 // is used to invalidate entries in SpillSlotsOrReMatsAvailable when a
301 // physreg is modified.
302 std::multimap<unsigned, int> PhysRegsAvailable;
304 void disallowClobberPhysRegOnly(unsigned PhysReg);
306 void ClobberPhysRegOnly(unsigned PhysReg);
308 AvailableSpills(const MRegisterInfo *mri, const TargetInstrInfo *tii)
309 : MRI(mri), TII(tii) {
312 const MRegisterInfo *getRegInfo() const { return MRI; }
314 /// getSpillSlotOrReMatPhysReg - If the specified stack slot or remat is
315 /// available in a physical register, return that PhysReg, otherwise
317 unsigned getSpillSlotOrReMatPhysReg(int Slot) const {
318 std::map<int, unsigned>::const_iterator I =
319 SpillSlotsOrReMatsAvailable.find(Slot);
320 if (I != SpillSlotsOrReMatsAvailable.end()) {
321 return I->second >> 1; // Remove the CanClobber bit.
326 /// addAvailable - Mark that the specified stack slot / remat is available in
327 /// the specified physreg. If CanClobber is true, the physreg can be modified
328 /// at any time without changing the semantics of the program.
329 void addAvailable(int SlotOrReMat, MachineInstr *MI, unsigned Reg,
330 bool CanClobber = true) {
331 // If this stack slot is thought to be available in some other physreg,
332 // remove its record.
333 ModifyStackSlotOrReMat(SlotOrReMat);
335 PhysRegsAvailable.insert(std::make_pair(Reg, SlotOrReMat));
336 SpillSlotsOrReMatsAvailable[SlotOrReMat]= (Reg << 1) | (unsigned)CanClobber;
338 if (SlotOrReMat > VirtRegMap::MAX_STACK_SLOT)
339 DOUT << "Remembering RM#" << SlotOrReMat-VirtRegMap::MAX_STACK_SLOT-1;
341 DOUT << "Remembering SS#" << SlotOrReMat;
342 DOUT << " in physreg " << MRI->getName(Reg) << "\n";
345 /// canClobberPhysReg - Return true if the spiller is allowed to change the
346 /// value of the specified stackslot register if it desires. The specified
347 /// stack slot must be available in a physreg for this query to make sense.
348 bool canClobberPhysReg(int SlotOrReMat) const {
349 assert(SpillSlotsOrReMatsAvailable.count(SlotOrReMat) &&
350 "Value not available!");
351 return SpillSlotsOrReMatsAvailable.find(SlotOrReMat)->second & 1;
354 /// disallowClobberPhysReg - Unset the CanClobber bit of the specified
355 /// stackslot register. The register is still available but is no longer
356 /// allowed to be modifed.
357 void disallowClobberPhysReg(unsigned PhysReg);
359 /// ClobberPhysReg - This is called when the specified physreg changes
360 /// value. We use this to invalidate any info about stuff we thing lives in
361 /// it and any of its aliases.
362 void ClobberPhysReg(unsigned PhysReg);
364 /// ModifyStackSlotOrReMat - This method is called when the value in a stack
365 /// slot changes. This removes information about which register the previous
366 /// value for this slot lives in (as the previous value is dead now).
367 void ModifyStackSlotOrReMat(int SlotOrReMat);
371 /// disallowClobberPhysRegOnly - Unset the CanClobber bit of the specified
372 /// stackslot register. The register is still available but is no longer
373 /// allowed to be modifed.
374 void AvailableSpills::disallowClobberPhysRegOnly(unsigned PhysReg) {
375 std::multimap<unsigned, int>::iterator I =
376 PhysRegsAvailable.lower_bound(PhysReg);
377 while (I != PhysRegsAvailable.end() && I->first == PhysReg) {
378 int SlotOrReMat = I->second;
380 assert((SpillSlotsOrReMatsAvailable[SlotOrReMat] >> 1) == PhysReg &&
381 "Bidirectional map mismatch!");
382 SpillSlotsOrReMatsAvailable[SlotOrReMat] &= ~1;
383 DOUT << "PhysReg " << MRI->getName(PhysReg)
384 << " copied, it is available for use but can no longer be modified\n";
388 /// disallowClobberPhysReg - Unset the CanClobber bit of the specified
389 /// stackslot register and its aliases. The register and its aliases may
390 /// still available but is no longer allowed to be modifed.
391 void AvailableSpills::disallowClobberPhysReg(unsigned PhysReg) {
392 for (const unsigned *AS = MRI->getAliasSet(PhysReg); *AS; ++AS)
393 disallowClobberPhysRegOnly(*AS);
394 disallowClobberPhysRegOnly(PhysReg);
397 /// ClobberPhysRegOnly - This is called when the specified physreg changes
398 /// value. We use this to invalidate any info about stuff we thing lives in it.
399 void AvailableSpills::ClobberPhysRegOnly(unsigned PhysReg) {
400 std::multimap<unsigned, int>::iterator I =
401 PhysRegsAvailable.lower_bound(PhysReg);
402 while (I != PhysRegsAvailable.end() && I->first == PhysReg) {
403 int SlotOrReMat = I->second;
404 PhysRegsAvailable.erase(I++);
405 assert((SpillSlotsOrReMatsAvailable[SlotOrReMat] >> 1) == PhysReg &&
406 "Bidirectional map mismatch!");
407 SpillSlotsOrReMatsAvailable.erase(SlotOrReMat);
408 DOUT << "PhysReg " << MRI->getName(PhysReg)
409 << " clobbered, invalidating ";
410 if (SlotOrReMat > VirtRegMap::MAX_STACK_SLOT)
411 DOUT << "RM#" << SlotOrReMat-VirtRegMap::MAX_STACK_SLOT-1 << "\n";
413 DOUT << "SS#" << SlotOrReMat << "\n";
417 /// ClobberPhysReg - This is called when the specified physreg changes
418 /// value. We use this to invalidate any info about stuff we thing lives in
419 /// it and any of its aliases.
420 void AvailableSpills::ClobberPhysReg(unsigned PhysReg) {
421 for (const unsigned *AS = MRI->getAliasSet(PhysReg); *AS; ++AS)
422 ClobberPhysRegOnly(*AS);
423 ClobberPhysRegOnly(PhysReg);
426 /// ModifyStackSlotOrReMat - This method is called when the value in a stack
427 /// slot changes. This removes information about which register the previous
428 /// value for this slot lives in (as the previous value is dead now).
429 void AvailableSpills::ModifyStackSlotOrReMat(int SlotOrReMat) {
430 std::map<int, unsigned>::iterator It =
431 SpillSlotsOrReMatsAvailable.find(SlotOrReMat);
432 if (It == SpillSlotsOrReMatsAvailable.end()) return;
433 unsigned Reg = It->second >> 1;
434 SpillSlotsOrReMatsAvailable.erase(It);
436 // This register may hold the value of multiple stack slots, only remove this
437 // stack slot from the set of values the register contains.
438 std::multimap<unsigned, int>::iterator I = PhysRegsAvailable.lower_bound(Reg);
440 assert(I != PhysRegsAvailable.end() && I->first == Reg &&
441 "Map inverse broken!");
442 if (I->second == SlotOrReMat) break;
444 PhysRegsAvailable.erase(I);
449 /// InvalidateKills - MI is going to be deleted. If any of its operands are
450 /// marked kill, then invalidate the information.
451 static void InvalidateKills(MachineInstr &MI, BitVector &RegKills,
452 std::vector<MachineOperand*> &KillOps,
453 SmallVector<unsigned, 1> *KillRegs = NULL) {
454 for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
455 MachineOperand &MO = MI.getOperand(i);
456 if (!MO.isRegister() || !MO.isUse() || !MO.isKill())
458 unsigned Reg = MO.getReg();
460 KillRegs->push_back(Reg);
461 if (KillOps[Reg] == &MO) {
468 /// InvalidateRegDef - If the def operand of the specified def MI is now dead
469 /// (since it's spill instruction is removed), mark it isDead. Also checks if
470 /// the def MI has other definition operands that are not dead. Returns it by
472 static bool InvalidateRegDef(MachineBasicBlock::iterator I,
473 MachineInstr &NewDef, unsigned Reg,
475 // Due to remat, it's possible this reg isn't being reused. That is,
476 // the def of this reg (by prev MI) is now dead.
477 MachineInstr *DefMI = I;
478 MachineOperand *DefOp = NULL;
479 for (unsigned i = 0, e = DefMI->getNumOperands(); i != e; ++i) {
480 MachineOperand &MO = DefMI->getOperand(i);
481 if (MO.isRegister() && MO.isDef()) {
482 if (MO.getReg() == Reg)
484 else if (!MO.isDead())
491 bool FoundUse = false, Done = false;
492 MachineBasicBlock::iterator E = NewDef;
494 for (; !Done && I != E; ++I) {
495 MachineInstr *NMI = I;
496 for (unsigned j = 0, ee = NMI->getNumOperands(); j != ee; ++j) {
497 MachineOperand &MO = NMI->getOperand(j);
498 if (!MO.isRegister() || MO.getReg() != Reg)
502 Done = true; // Stop after scanning all the operands of this MI.
513 /// UpdateKills - Track and update kill info. If a MI reads a register that is
514 /// marked kill, then it must be due to register reuse. Transfer the kill info
516 static void UpdateKills(MachineInstr &MI, BitVector &RegKills,
517 std::vector<MachineOperand*> &KillOps) {
518 const TargetInstrDescriptor *TID = MI.getInstrDescriptor();
519 for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
520 MachineOperand &MO = MI.getOperand(i);
521 if (!MO.isRegister() || !MO.isUse())
523 unsigned Reg = MO.getReg();
528 // That can't be right. Register is killed but not re-defined and it's
529 // being reused. Let's fix that.
530 KillOps[Reg]->unsetIsKill();
531 if (i < TID->numOperands &&
532 TID->getOperandConstraint(i, TOI::TIED_TO) == -1)
533 // Unless it's a two-address operand, this is the new kill.
543 for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
544 const MachineOperand &MO = MI.getOperand(i);
545 if (!MO.isRegister() || !MO.isDef())
547 unsigned Reg = MO.getReg();
554 // ReusedOp - For each reused operand, we keep track of a bit of information, in
555 // case we need to rollback upon processing a new operand. See comments below.
558 // The MachineInstr operand that reused an available value.
561 // StackSlotOrReMat - The spill slot or remat id of the value being reused.
562 unsigned StackSlotOrReMat;
564 // PhysRegReused - The physical register the value was available in.
565 unsigned PhysRegReused;
567 // AssignedPhysReg - The physreg that was assigned for use by the reload.
568 unsigned AssignedPhysReg;
570 // VirtReg - The virtual register itself.
573 ReusedOp(unsigned o, unsigned ss, unsigned prr, unsigned apr,
575 : Operand(o), StackSlotOrReMat(ss), PhysRegReused(prr),
576 AssignedPhysReg(apr), VirtReg(vreg) {}
579 /// ReuseInfo - This maintains a collection of ReuseOp's for each operand that
580 /// is reused instead of reloaded.
581 class VISIBILITY_HIDDEN ReuseInfo {
583 std::vector<ReusedOp> Reuses;
584 BitVector PhysRegsClobbered;
586 ReuseInfo(MachineInstr &mi, const MRegisterInfo *mri) : MI(mi) {
587 PhysRegsClobbered.resize(mri->getNumRegs());
590 bool hasReuses() const {
591 return !Reuses.empty();
594 /// addReuse - If we choose to reuse a virtual register that is already
595 /// available instead of reloading it, remember that we did so.
596 void addReuse(unsigned OpNo, unsigned StackSlotOrReMat,
597 unsigned PhysRegReused, unsigned AssignedPhysReg,
599 // If the reload is to the assigned register anyway, no undo will be
601 if (PhysRegReused == AssignedPhysReg) return;
603 // Otherwise, remember this.
604 Reuses.push_back(ReusedOp(OpNo, StackSlotOrReMat, PhysRegReused,
605 AssignedPhysReg, VirtReg));
608 void markClobbered(unsigned PhysReg) {
609 PhysRegsClobbered.set(PhysReg);
612 bool isClobbered(unsigned PhysReg) const {
613 return PhysRegsClobbered.test(PhysReg);
616 /// GetRegForReload - We are about to emit a reload into PhysReg. If there
617 /// is some other operand that is using the specified register, either pick
618 /// a new register to use, or evict the previous reload and use this reg.
619 unsigned GetRegForReload(unsigned PhysReg, MachineInstr *MI,
620 AvailableSpills &Spills,
621 std::vector<MachineInstr*> &MaybeDeadStores,
622 SmallSet<unsigned, 8> &Rejected,
624 std::vector<MachineOperand*> &KillOps,
626 if (Reuses.empty()) return PhysReg; // This is most often empty.
628 for (unsigned ro = 0, e = Reuses.size(); ro != e; ++ro) {
629 ReusedOp &Op = Reuses[ro];
630 // If we find some other reuse that was supposed to use this register
631 // exactly for its reload, we can change this reload to use ITS reload
632 // register. That is, unless its reload register has already been
633 // considered and subsequently rejected because it has also been reused
634 // by another operand.
635 if (Op.PhysRegReused == PhysReg &&
636 Rejected.count(Op.AssignedPhysReg) == 0) {
637 // Yup, use the reload register that we didn't use before.
638 unsigned NewReg = Op.AssignedPhysReg;
639 Rejected.insert(PhysReg);
640 return GetRegForReload(NewReg, MI, Spills, MaybeDeadStores, Rejected,
641 RegKills, KillOps, VRM);
643 // Otherwise, we might also have a problem if a previously reused
644 // value aliases the new register. If so, codegen the previous reload
646 unsigned PRRU = Op.PhysRegReused;
647 const MRegisterInfo *MRI = Spills.getRegInfo();
648 if (MRI->areAliases(PRRU, PhysReg)) {
649 // Okay, we found out that an alias of a reused register
650 // was used. This isn't good because it means we have
651 // to undo a previous reuse.
652 MachineBasicBlock *MBB = MI->getParent();
653 const TargetRegisterClass *AliasRC =
654 MBB->getParent()->getSSARegMap()->getRegClass(Op.VirtReg);
656 // Copy Op out of the vector and remove it, we're going to insert an
657 // explicit load for it.
659 Reuses.erase(Reuses.begin()+ro);
661 // Ok, we're going to try to reload the assigned physreg into the
662 // slot that we were supposed to in the first place. However, that
663 // register could hold a reuse. Check to see if it conflicts or
664 // would prefer us to use a different register.
665 unsigned NewPhysReg = GetRegForReload(NewOp.AssignedPhysReg,
666 MI, Spills, MaybeDeadStores,
667 Rejected, RegKills, KillOps, VRM);
669 if (NewOp.StackSlotOrReMat > VirtRegMap::MAX_STACK_SLOT) {
670 MRI->reMaterialize(*MBB, MI, NewPhysReg,
671 VRM.getReMaterializedMI(NewOp.VirtReg));
674 MRI->loadRegFromStackSlot(*MBB, MI, NewPhysReg,
675 NewOp.StackSlotOrReMat, AliasRC);
676 // Any stores to this stack slot are not dead anymore.
677 MaybeDeadStores[NewOp.StackSlotOrReMat] = NULL;
680 Spills.ClobberPhysReg(NewPhysReg);
681 Spills.ClobberPhysReg(NewOp.PhysRegReused);
683 MI->getOperand(NewOp.Operand).setReg(NewPhysReg);
685 Spills.addAvailable(NewOp.StackSlotOrReMat, MI, NewPhysReg);
686 MachineBasicBlock::iterator MII = MI;
688 UpdateKills(*MII, RegKills, KillOps);
689 DOUT << '\t' << *MII;
691 DOUT << "Reuse undone!\n";
694 // Finally, PhysReg is now available, go ahead and use it.
702 /// GetRegForReload - Helper for the above GetRegForReload(). Add a
703 /// 'Rejected' set to remember which registers have been considered and
704 /// rejected for the reload. This avoids infinite looping in case like
707 /// t2 <- assigned r0 for use by the reload but ended up reuse r1
708 /// t3 <- assigned r1 for use by the reload but ended up reuse r0
710 /// sees r1 is taken by t2, tries t2's reload register r0
711 /// sees r0 is taken by t3, tries t3's reload register r1
712 /// sees r1 is taken by t2, tries t2's reload register r0 ...
713 unsigned GetRegForReload(unsigned PhysReg, MachineInstr *MI,
714 AvailableSpills &Spills,
715 std::vector<MachineInstr*> &MaybeDeadStores,
717 std::vector<MachineOperand*> &KillOps,
719 SmallSet<unsigned, 8> Rejected;
720 return GetRegForReload(PhysReg, MI, Spills, MaybeDeadStores, Rejected,
721 RegKills, KillOps, VRM);
727 /// rewriteMBB - Keep track of which spills are available even after the
728 /// register allocator is done with them. If possible, avoid reloading vregs.
729 void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM) {
730 DOUT << MBB.getBasicBlock()->getName() << ":\n";
732 MachineFunction &MF = *MBB.getParent();
734 // Spills - Keep track of which spilled values are available in physregs so
735 // that we can choose to reuse the physregs instead of emitting reloads.
736 AvailableSpills Spills(MRI, TII);
738 // MaybeDeadStores - When we need to write a value back into a stack slot,
739 // keep track of the inserted store. If the stack slot value is never read
740 // (because the value was used from some available register, for example), and
741 // subsequently stored to, the original store is dead. This map keeps track
742 // of inserted stores that are not used. If we see a subsequent store to the
743 // same stack slot, the original store is deleted.
744 std::vector<MachineInstr*> MaybeDeadStores;
745 MaybeDeadStores.resize(MF.getFrameInfo()->getObjectIndexEnd(), NULL);
747 // ReMatDefs - These are rematerializable def MIs which are not deleted.
748 SmallSet<MachineInstr*, 4> ReMatDefs;
750 // Keep track of kill information.
751 BitVector RegKills(MRI->getNumRegs());
752 std::vector<MachineOperand*> KillOps;
753 KillOps.resize(MRI->getNumRegs(), NULL);
755 for (MachineBasicBlock::iterator MII = MBB.begin(), E = MBB.end();
757 MachineInstr &MI = *MII;
758 MachineBasicBlock::iterator NextMII = MII; ++NextMII;
759 VirtRegMap::MI2VirtMapTy::const_iterator I, End;
762 bool BackTracked = false;
764 /// ReusedOperands - Keep track of operand reuse in case we need to undo
766 ReuseInfo ReusedOperands(MI, MRI);
768 // Loop over all of the implicit defs, clearing them from our available
770 const TargetInstrDescriptor *TID = MI.getInstrDescriptor();
771 if (TID->ImplicitDefs) {
772 const unsigned *ImpDef = TID->ImplicitDefs;
773 for ( ; *ImpDef; ++ImpDef) {
774 MF.setPhysRegUsed(*ImpDef);
775 ReusedOperands.markClobbered(*ImpDef);
776 Spills.ClobberPhysReg(*ImpDef);
780 // Process all of the spilled uses and all non spilled reg references.
781 for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
782 MachineOperand &MO = MI.getOperand(i);
783 if (!MO.isRegister() || MO.getReg() == 0)
784 continue; // Ignore non-register operands.
786 unsigned VirtReg = MO.getReg();
787 if (MRegisterInfo::isPhysicalRegister(VirtReg)) {
788 // Ignore physregs for spilling, but remember that it is used by this
790 MF.setPhysRegUsed(VirtReg);
791 ReusedOperands.markClobbered(VirtReg);
795 assert(MRegisterInfo::isVirtualRegister(VirtReg) &&
796 "Not a virtual or a physical register?");
799 bool isSubReg = RegMap->isSubRegister(VirtReg);
801 SubIdx = RegMap->getSubRegisterIndex(VirtReg);
802 VirtReg = RegMap->getSuperRegister(VirtReg);
805 if (VRM.isAssignedReg(VirtReg)) {
806 // This virtual register was assigned a physreg!
807 unsigned Phys = VRM.getPhys(VirtReg);
808 MF.setPhysRegUsed(Phys);
810 ReusedOperands.markClobbered(Phys);
811 unsigned RReg = isSubReg ? MRI->getSubReg(Phys, SubIdx) : Phys;
812 MI.getOperand(i).setReg(RReg);
816 // This virtual register is now known to be a spilled value.
818 continue; // Handle defs in the loop below (handle use&def here though)
820 bool DoReMat = VRM.isReMaterialized(VirtReg);
821 int SSorRMId = DoReMat
822 ? VRM.getReMatId(VirtReg) : VRM.getStackSlot(VirtReg);
823 int ReuseSlot = SSorRMId;
825 // Check to see if this stack slot is available.
826 unsigned PhysReg = Spills.getSpillSlotOrReMatPhysReg(SSorRMId);
827 if (!PhysReg && DoReMat) {
828 // This use is rematerializable. But perhaps the value is available in
829 // stack if the definition is not deleted. If so, check if we can
831 ReuseSlot = VRM.getStackSlot(VirtReg);
832 if (ReuseSlot != VirtRegMap::NO_STACK_SLOT)
833 PhysReg = Spills.getSpillSlotOrReMatPhysReg(ReuseSlot);
836 // If this is a sub-register use, make sure the reuse register is in the
837 // right register class. For example, for x86 not all of the 32-bit
838 // registers have accessible sub-registers.
839 // Similarly so for EXTRACT_SUBREG. Consider this:
841 // MOV32_mr fi#1, EDI
843 // = EXTRACT_SUBREG fi#1
844 // fi#1 is available in EDI, but it cannot be reused because it's not in
845 // the right register file.
847 (isSubReg || MI.getOpcode() == TargetInstrInfo::EXTRACT_SUBREG)) {
848 const TargetRegisterClass* RC = RegMap->getRegClass(VirtReg);
849 if (!RC->contains(PhysReg))
854 // This spilled operand might be part of a two-address operand. If this
855 // is the case, then changing it will necessarily require changing the
856 // def part of the instruction as well. However, in some cases, we
857 // aren't allowed to modify the reused register. If none of these cases
859 bool CanReuse = true;
861 int ti = TID->getOperandConstraint(i, TOI::TIED_TO);
863 MI.getOperand(ti).isRegister() &&
864 MI.getOperand(ti).getReg() == VirtReg) {
865 // Okay, we have a two address operand. We can reuse this physreg as
866 // long as we are allowed to clobber the value and there isn't an
867 // earlier def that has already clobbered the physreg.
868 CanReuse = Spills.canClobberPhysReg(ReuseSlot) &&
869 !ReusedOperands.isClobbered(PhysReg);
873 // If this stack slot value is already available, reuse it!
874 if (ReuseSlot > VirtRegMap::MAX_STACK_SLOT)
875 DOUT << "Reusing RM#" << ReuseSlot-VirtRegMap::MAX_STACK_SLOT-1;
877 DOUT << "Reusing SS#" << ReuseSlot;
878 DOUT << " from physreg "
879 << MRI->getName(PhysReg) << " for vreg"
880 << VirtReg <<" instead of reloading into physreg "
881 << MRI->getName(VRM.getPhys(VirtReg)) << "\n";
882 unsigned RReg = isSubReg ? MRI->getSubReg(PhysReg, SubIdx) : PhysReg;
883 MI.getOperand(i).setReg(RReg);
885 // The only technical detail we have is that we don't know that
886 // PhysReg won't be clobbered by a reloaded stack slot that occurs
887 // later in the instruction. In particular, consider 'op V1, V2'.
888 // If V1 is available in physreg R0, we would choose to reuse it
889 // here, instead of reloading it into the register the allocator
890 // indicated (say R1). However, V2 might have to be reloaded
891 // later, and it might indicate that it needs to live in R0. When
892 // this occurs, we need to have information available that
893 // indicates it is safe to use R1 for the reload instead of R0.
895 // To further complicate matters, we might conflict with an alias,
896 // or R0 and R1 might not be compatible with each other. In this
897 // case, we actually insert a reload for V1 in R1, ensuring that
898 // we can get at R0 or its alias.
899 ReusedOperands.addReuse(i, ReuseSlot, PhysReg,
900 VRM.getPhys(VirtReg), VirtReg);
902 // Only mark it clobbered if this is a use&def operand.
903 ReusedOperands.markClobbered(PhysReg);
906 if (MI.getOperand(i).isKill() &&
907 ReuseSlot <= VirtRegMap::MAX_STACK_SLOT) {
908 // This was the last use and the spilled value is still available
909 // for reuse. That means the spill was unnecessary!
910 MachineInstr* DeadStore = MaybeDeadStores[ReuseSlot];
912 DOUT << "Removed dead store:\t" << *DeadStore;
913 InvalidateKills(*DeadStore, RegKills, KillOps);
914 MBB.erase(DeadStore);
915 VRM.RemoveFromFoldedVirtMap(DeadStore);
916 MaybeDeadStores[ReuseSlot] = NULL;
923 // Otherwise we have a situation where we have a two-address instruction
924 // whose mod/ref operand needs to be reloaded. This reload is already
925 // available in some register "PhysReg", but if we used PhysReg as the
926 // operand to our 2-addr instruction, the instruction would modify
927 // PhysReg. This isn't cool if something later uses PhysReg and expects
928 // to get its initial value.
930 // To avoid this problem, and to avoid doing a load right after a store,
931 // we emit a copy from PhysReg into the designated register for this
933 unsigned DesignatedReg = VRM.getPhys(VirtReg);
934 assert(DesignatedReg && "Must map virtreg to physreg!");
936 // Note that, if we reused a register for a previous operand, the
937 // register we want to reload into might not actually be
938 // available. If this occurs, use the register indicated by the
940 if (ReusedOperands.hasReuses())
941 DesignatedReg = ReusedOperands.GetRegForReload(DesignatedReg, &MI,
942 Spills, MaybeDeadStores, RegKills, KillOps, VRM);
944 // If the mapped designated register is actually the physreg we have
945 // incoming, we don't need to inserted a dead copy.
946 if (DesignatedReg == PhysReg) {
947 // If this stack slot value is already available, reuse it!
948 if (ReuseSlot > VirtRegMap::MAX_STACK_SLOT)
949 DOUT << "Reusing RM#" << ReuseSlot-VirtRegMap::MAX_STACK_SLOT-1;
951 DOUT << "Reusing SS#" << ReuseSlot;
952 DOUT << " from physreg " << MRI->getName(PhysReg) << " for vreg"
954 << " instead of reloading into same physreg.\n";
955 unsigned RReg = isSubReg ? MRI->getSubReg(PhysReg, SubIdx) : PhysReg;
956 MI.getOperand(i).setReg(RReg);
957 ReusedOperands.markClobbered(PhysReg);
962 const TargetRegisterClass* RC = RegMap->getRegClass(VirtReg);
963 MF.setPhysRegUsed(DesignatedReg);
964 ReusedOperands.markClobbered(DesignatedReg);
965 MRI->copyRegToReg(MBB, &MI, DesignatedReg, PhysReg, RC, RC);
967 MachineInstr *CopyMI = prior(MII);
968 UpdateKills(*CopyMI, RegKills, KillOps);
970 // This invalidates DesignatedReg.
971 Spills.ClobberPhysReg(DesignatedReg);
973 Spills.addAvailable(ReuseSlot, &MI, DesignatedReg);
975 isSubReg ? MRI->getSubReg(DesignatedReg, SubIdx) : DesignatedReg;
976 MI.getOperand(i).setReg(RReg);
977 DOUT << '\t' << *prior(MII);
982 // Otherwise, reload it and remember that we have it.
983 PhysReg = VRM.getPhys(VirtReg);
984 assert(PhysReg && "Must map virtreg to physreg!");
986 // Note that, if we reused a register for a previous operand, the
987 // register we want to reload into might not actually be
988 // available. If this occurs, use the register indicated by the
990 if (ReusedOperands.hasReuses())
991 PhysReg = ReusedOperands.GetRegForReload(PhysReg, &MI,
992 Spills, MaybeDeadStores, RegKills, KillOps, VRM);
994 MF.setPhysRegUsed(PhysReg);
995 ReusedOperands.markClobbered(PhysReg);
997 MRI->reMaterialize(MBB, &MI, PhysReg, VRM.getReMaterializedMI(VirtReg));
1000 const TargetRegisterClass* RC = RegMap->getRegClass(VirtReg);
1001 MRI->loadRegFromStackSlot(MBB, &MI, PhysReg, SSorRMId, RC);
1004 // This invalidates PhysReg.
1005 Spills.ClobberPhysReg(PhysReg);
1007 // Any stores to this stack slot are not dead anymore.
1009 MaybeDeadStores[SSorRMId] = NULL;
1010 Spills.addAvailable(SSorRMId, &MI, PhysReg);
1011 // Assumes this is the last use. IsKill will be unset if reg is reused
1012 // unless it's a two-address operand.
1013 if (TID->getOperandConstraint(i, TOI::TIED_TO) == -1)
1014 MI.getOperand(i).setIsKill();
1015 unsigned RReg = isSubReg ? MRI->getSubReg(PhysReg, SubIdx) : PhysReg;
1016 MI.getOperand(i).setReg(RReg);
1017 UpdateKills(*prior(MII), RegKills, KillOps);
1018 DOUT << '\t' << *prior(MII);
1023 // If we have folded references to memory operands, make sure we clear all
1024 // physical registers that may contain the value of the spilled virtual
1026 SmallSet<int, 1> FoldedSS;
1027 for (tie(I, End) = VRM.getFoldedVirts(&MI); I != End; ++I) {
1028 DOUT << "Folded vreg: " << I->second.first << " MR: "
1029 << I->second.second;
1030 unsigned VirtReg = I->second.first;
1031 VirtRegMap::ModRef MR = I->second.second;
1032 if (VRM.isAssignedReg(VirtReg)) {
1033 DOUT << ": No stack slot!\n";
1036 int SS = VRM.getStackSlot(VirtReg);
1037 FoldedSS.insert(SS);
1038 DOUT << " - StackSlot: " << SS << "\n";
1040 // If this folded instruction is just a use, check to see if it's a
1041 // straight load from the virt reg slot.
1042 if ((MR & VirtRegMap::isRef) && !(MR & VirtRegMap::isMod)) {
1044 unsigned DestReg = TII->isLoadFromStackSlot(&MI, FrameIdx);
1045 if (DestReg && FrameIdx == SS) {
1046 // If this spill slot is available, turn it into a copy (or nothing)
1047 // instead of leaving it as a load!
1048 if (unsigned InReg = Spills.getSpillSlotOrReMatPhysReg(SS)) {
1049 DOUT << "Promoted Load To Copy: " << MI;
1050 if (DestReg != InReg) {
1051 const TargetRegisterClass *RC = RegMap->getRegClass(VirtReg);
1052 MRI->copyRegToReg(MBB, &MI, DestReg, InReg, RC, RC);
1053 // Revisit the copy so we make sure to notice the effects of the
1054 // operation on the destreg (either needing to RA it if it's
1055 // virtual or needing to clobber any values if it's physical).
1057 --NextMII; // backtrack to the copy.
1060 DOUT << "Removing now-noop copy: " << MI;
1062 VRM.RemoveFromFoldedVirtMap(&MI);
1065 goto ProcessNextInst;
1068 unsigned PhysReg = Spills.getSpillSlotOrReMatPhysReg(SS);
1069 SmallVector<MachineInstr*, 4> NewMIs;
1071 MRI->unfoldMemoryOperand(MF, &MI, PhysReg, false, false, NewMIs)) {
1072 MBB.insert(MII, NewMIs[0]);
1073 VRM.RemoveFromFoldedVirtMap(&MI);
1076 --NextMII; // backtrack to the unfolded instruction.
1078 goto ProcessNextInst;
1083 // If this reference is not a use, any previous store is now dead.
1084 // Otherwise, the store to this stack slot is not dead anymore.
1085 MachineInstr* DeadStore = MaybeDeadStores[SS];
1088 MachineInstr *NewStore = NULL;
1089 if (MR & VirtRegMap::isRef) {
1090 unsigned PhysReg = Spills.getSpillSlotOrReMatPhysReg(SS);
1091 SmallVector<MachineInstr*, 4> NewMIs;
1093 DeadStore->findRegisterUseOperandIdx(PhysReg, true) != -1 &&
1094 MRI->unfoldMemoryOperand(MF, &MI, PhysReg, false, true, NewMIs)) {
1095 MBB.insert(MII, NewMIs[0]);
1096 NewStore = NewMIs[1];
1097 MBB.insert(MII, NewStore);
1098 VRM.RemoveFromFoldedVirtMap(&MI);
1102 --NextMII; // backtrack to the unfolded instruction.
1108 if (isDead) { // Previous store is dead.
1109 // If we get here, the store is dead, nuke it now.
1110 DOUT << "Removed dead store:\t" << *DeadStore;
1111 InvalidateKills(*DeadStore, RegKills, KillOps);
1112 VRM.RemoveFromFoldedVirtMap(DeadStore);
1113 MBB.erase(DeadStore);
1118 MaybeDeadStores[SS] = NULL;
1120 // Treat this store as a spill merged into a copy. That makes the
1121 // stack slot value available.
1122 VRM.virtFolded(VirtReg, NewStore, VirtRegMap::isMod);
1123 goto ProcessNextInst;
1127 // If the spill slot value is available, and this is a new definition of
1128 // the value, the value is not available anymore.
1129 if (MR & VirtRegMap::isMod) {
1130 // Notice that the value in this stack slot has been modified.
1131 Spills.ModifyStackSlotOrReMat(SS);
1133 // If this is *just* a mod of the value, check to see if this is just a
1134 // store to the spill slot (i.e. the spill got merged into the copy). If
1135 // so, realize that the vreg is available now, and add the store to the
1136 // MaybeDeadStore info.
1138 if (!(MR & VirtRegMap::isRef)) {
1139 if (unsigned SrcReg = TII->isStoreToStackSlot(&MI, StackSlot)) {
1140 assert(MRegisterInfo::isPhysicalRegister(SrcReg) &&
1141 "Src hasn't been allocated yet?");
1142 // Okay, this is certainly a store of SrcReg to [StackSlot]. Mark
1143 // this as a potentially dead store in case there is a subsequent
1144 // store into the stack slot without a read from it.
1145 MaybeDeadStores[StackSlot] = &MI;
1147 // If the stack slot value was previously available in some other
1148 // register, change it now. Otherwise, make the register available,
1150 Spills.addAvailable(StackSlot, &MI, SrcReg, false/*don't clobber*/);
1156 // Process all of the spilled defs.
1157 for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
1158 MachineOperand &MO = MI.getOperand(i);
1159 if (MO.isRegister() && MO.getReg() && MO.isDef()) {
1160 unsigned VirtReg = MO.getReg();
1162 if (!MRegisterInfo::isVirtualRegister(VirtReg)) {
1163 // Check to see if this is a noop copy. If so, eliminate the
1164 // instruction before considering the dest reg to be changed.
1166 if (TII->isMoveInstr(MI, Src, Dst) && Src == Dst) {
1168 DOUT << "Removing now-noop copy: " << MI;
1171 VRM.RemoveFromFoldedVirtMap(&MI);
1172 Spills.disallowClobberPhysReg(VirtReg);
1173 goto ProcessNextInst;
1176 // If it's not a no-op copy, it clobbers the value in the destreg.
1177 Spills.ClobberPhysReg(VirtReg);
1178 ReusedOperands.markClobbered(VirtReg);
1180 // Check to see if this instruction is a load from a stack slot into
1181 // a register. If so, this provides the stack slot value in the reg.
1183 if (unsigned DestReg = TII->isLoadFromStackSlot(&MI, FrameIdx)) {
1184 assert(DestReg == VirtReg && "Unknown load situation!");
1186 // If it is a folded reference, then it's not safe to clobber.
1187 bool Folded = FoldedSS.count(FrameIdx);
1188 // Otherwise, if it wasn't available, remember that it is now!
1189 Spills.addAvailable(FrameIdx, &MI, DestReg, !Folded);
1190 goto ProcessNextInst;
1196 bool DoReMat = VRM.isReMaterialized(VirtReg);
1198 ReMatDefs.insert(&MI);
1200 // The only vregs left are stack slot definitions.
1201 int StackSlot = VRM.getStackSlot(VirtReg);
1202 const TargetRegisterClass *RC = RegMap->getRegClass(VirtReg);
1204 // If this def is part of a two-address operand, make sure to execute
1205 // the store from the correct physical register.
1207 int TiedOp = MI.getInstrDescriptor()->findTiedToSrcOperand(i);
1209 PhysReg = MI.getOperand(TiedOp).getReg();
1211 PhysReg = VRM.getPhys(VirtReg);
1212 if (ReusedOperands.isClobbered(PhysReg)) {
1213 // Another def has taken the assigned physreg. It must have been a
1214 // use&def which got it due to reuse. Undo the reuse!
1215 PhysReg = ReusedOperands.GetRegForReload(PhysReg, &MI,
1216 Spills, MaybeDeadStores, RegKills, KillOps, VRM);
1220 MF.setPhysRegUsed(PhysReg);
1221 ReusedOperands.markClobbered(PhysReg);
1222 MI.getOperand(i).setReg(PhysReg);
1224 MRI->storeRegToStackSlot(MBB, next(MII), PhysReg, StackSlot, RC);
1225 DOUT << "Store:\t" << *next(MII);
1227 // If there is a dead store to this stack slot, nuke it now.
1228 MachineInstr *&LastStore = MaybeDeadStores[StackSlot];
1230 DOUT << "Removed dead store:\t" << *LastStore;
1232 SmallVector<unsigned, 1> KillRegs;
1233 InvalidateKills(*LastStore, RegKills, KillOps, &KillRegs);
1234 MachineBasicBlock::iterator PrevMII = LastStore;
1235 bool CheckDef = PrevMII != MBB.begin();
1238 MBB.erase(LastStore);
1239 VRM.RemoveFromFoldedVirtMap(LastStore);
1241 // Look at defs of killed registers on the store. Mark the defs
1242 // as dead since the store has been deleted and they aren't
1244 for (unsigned j = 0, ee = KillRegs.size(); j != ee; ++j) {
1245 bool HasOtherDef = false;
1246 if (InvalidateRegDef(PrevMII, MI, KillRegs[j], HasOtherDef)) {
1247 MachineInstr *DeadDef = PrevMII;
1248 if (ReMatDefs.count(DeadDef) && !HasOtherDef) {
1249 // FIXME: This assumes a remat def does not have side
1252 VRM.RemoveFromFoldedVirtMap(DeadDef);
1259 LastStore = next(MII);
1261 // If the stack slot value was previously available in some other
1262 // register, change it now. Otherwise, make the register available,
1264 Spills.ModifyStackSlotOrReMat(StackSlot);
1265 Spills.ClobberPhysReg(PhysReg);
1266 Spills.addAvailable(StackSlot, LastStore, PhysReg);
1269 // Check to see if this is a noop copy. If so, eliminate the
1270 // instruction before considering the dest reg to be changed.
1273 if (TII->isMoveInstr(MI, Src, Dst) && Src == Dst) {
1275 DOUT << "Removing now-noop copy: " << MI;
1278 VRM.RemoveFromFoldedVirtMap(&MI);
1279 UpdateKills(*LastStore, RegKills, KillOps);
1280 goto ProcessNextInst;
1287 if (!Erased && !BackTracked)
1288 for (MachineBasicBlock::iterator II = MI; II != NextMII; ++II)
1289 UpdateKills(*II, RegKills, KillOps);
1295 llvm::Spiller* llvm::createSpiller() {
1296 switch (SpillerOpt) {
1297 default: assert(0 && "Unreachable!");
1299 return new LocalSpiller();
1301 return new SimpleSpiller();