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 class AvailableSpills;
247 /// LocalSpiller - This spiller does a simple pass over the machine basic
248 /// block to attempt to keep spills in registers as much as possible for
249 /// blocks that have low register pressure (the vreg may be spilled due to
250 /// register pressure in other blocks).
251 class VISIBILITY_HIDDEN LocalSpiller : public Spiller {
253 const MRegisterInfo *MRI;
254 const TargetInstrInfo *TII;
256 bool runOnMachineFunction(MachineFunction &MF, VirtRegMap &VRM) {
257 RegMap = MF.getSSARegMap();
258 MRI = MF.getTarget().getRegisterInfo();
259 TII = MF.getTarget().getInstrInfo();
260 DOUT << "\n**** Local spiller rewriting function '"
261 << MF.getFunction()->getName() << "':\n";
262 DOUT << "**** Machine Instrs (NOTE! Does not include spills and reloads!) ****\n";
265 for (MachineFunction::iterator MBB = MF.begin(), E = MF.end();
267 RewriteMBB(*MBB, VRM);
269 DOUT << "**** Post Machine Instrs ****\n";
275 bool PrepForUnfoldOpti(MachineBasicBlock &MBB,
276 MachineBasicBlock::iterator &MII,
277 std::vector<MachineInstr*> &MaybeDeadStores,
278 AvailableSpills &Spills, BitVector &RegKills,
279 std::vector<MachineOperand*> &KillOps,
281 void RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM);
285 /// AvailableSpills - As the local spiller is scanning and rewriting an MBB from
286 /// top down, keep track of which spills slots or remat are available in each
289 /// Note that not all physregs are created equal here. In particular, some
290 /// physregs are reloads that we are allowed to clobber or ignore at any time.
291 /// Other physregs are values that the register allocated program is using that
292 /// we cannot CHANGE, but we can read if we like. We keep track of this on a
293 /// per-stack-slot / remat id basis as the low bit in the value of the
294 /// SpillSlotsAvailable entries. The predicate 'canClobberPhysReg()' checks
295 /// this bit and addAvailable sets it if.
297 class VISIBILITY_HIDDEN AvailableSpills {
298 const MRegisterInfo *MRI;
299 const TargetInstrInfo *TII;
301 // SpillSlotsOrReMatsAvailable - This map keeps track of all of the spilled
302 // or remat'ed virtual register values that are still available, due to being
303 // loaded or stored to, but not invalidated yet.
304 std::map<int, unsigned> SpillSlotsOrReMatsAvailable;
306 // PhysRegsAvailable - This is the inverse of SpillSlotsOrReMatsAvailable,
307 // indicating which stack slot values are currently held by a physreg. This
308 // is used to invalidate entries in SpillSlotsOrReMatsAvailable when a
309 // physreg is modified.
310 std::multimap<unsigned, int> PhysRegsAvailable;
312 void disallowClobberPhysRegOnly(unsigned PhysReg);
314 void ClobberPhysRegOnly(unsigned PhysReg);
316 AvailableSpills(const MRegisterInfo *mri, const TargetInstrInfo *tii)
317 : MRI(mri), TII(tii) {
320 const MRegisterInfo *getRegInfo() const { return MRI; }
322 /// getSpillSlotOrReMatPhysReg - If the specified stack slot or remat is
323 /// available in a physical register, return that PhysReg, otherwise
325 unsigned getSpillSlotOrReMatPhysReg(int Slot) const {
326 std::map<int, unsigned>::const_iterator I =
327 SpillSlotsOrReMatsAvailable.find(Slot);
328 if (I != SpillSlotsOrReMatsAvailable.end()) {
329 return I->second >> 1; // Remove the CanClobber bit.
334 /// addAvailable - Mark that the specified stack slot / remat is available in
335 /// the specified physreg. If CanClobber is true, the physreg can be modified
336 /// at any time without changing the semantics of the program.
337 void addAvailable(int SlotOrReMat, MachineInstr *MI, unsigned Reg,
338 bool CanClobber = true) {
339 // If this stack slot is thought to be available in some other physreg,
340 // remove its record.
341 ModifyStackSlotOrReMat(SlotOrReMat);
343 PhysRegsAvailable.insert(std::make_pair(Reg, SlotOrReMat));
344 SpillSlotsOrReMatsAvailable[SlotOrReMat]= (Reg << 1) | (unsigned)CanClobber;
346 if (SlotOrReMat > VirtRegMap::MAX_STACK_SLOT)
347 DOUT << "Remembering RM#" << SlotOrReMat-VirtRegMap::MAX_STACK_SLOT-1;
349 DOUT << "Remembering SS#" << SlotOrReMat;
350 DOUT << " in physreg " << MRI->getName(Reg) << "\n";
353 /// canClobberPhysReg - Return true if the spiller is allowed to change the
354 /// value of the specified stackslot register if it desires. The specified
355 /// stack slot must be available in a physreg for this query to make sense.
356 bool canClobberPhysReg(int SlotOrReMat) const {
357 assert(SpillSlotsOrReMatsAvailable.count(SlotOrReMat) &&
358 "Value not available!");
359 return SpillSlotsOrReMatsAvailable.find(SlotOrReMat)->second & 1;
362 /// disallowClobberPhysReg - Unset the CanClobber bit of the specified
363 /// stackslot register. The register is still available but is no longer
364 /// allowed to be modifed.
365 void disallowClobberPhysReg(unsigned PhysReg);
367 /// ClobberPhysReg - This is called when the specified physreg changes
368 /// value. We use this to invalidate any info about stuff that lives in
369 /// it and any of its aliases.
370 void ClobberPhysReg(unsigned PhysReg);
372 /// ModifyStackSlotOrReMat - This method is called when the value in a stack
373 /// slot changes. This removes information about which register the previous
374 /// value for this slot lives in (as the previous value is dead now).
375 void ModifyStackSlotOrReMat(int SlotOrReMat);
379 /// disallowClobberPhysRegOnly - Unset the CanClobber bit of the specified
380 /// stackslot register. The register is still available but is no longer
381 /// allowed to be modifed.
382 void AvailableSpills::disallowClobberPhysRegOnly(unsigned PhysReg) {
383 std::multimap<unsigned, int>::iterator I =
384 PhysRegsAvailable.lower_bound(PhysReg);
385 while (I != PhysRegsAvailable.end() && I->first == PhysReg) {
386 int SlotOrReMat = I->second;
388 assert((SpillSlotsOrReMatsAvailable[SlotOrReMat] >> 1) == PhysReg &&
389 "Bidirectional map mismatch!");
390 SpillSlotsOrReMatsAvailable[SlotOrReMat] &= ~1;
391 DOUT << "PhysReg " << MRI->getName(PhysReg)
392 << " copied, it is available for use but can no longer be modified\n";
396 /// disallowClobberPhysReg - Unset the CanClobber bit of the specified
397 /// stackslot register and its aliases. The register and its aliases may
398 /// still available but is no longer allowed to be modifed.
399 void AvailableSpills::disallowClobberPhysReg(unsigned PhysReg) {
400 for (const unsigned *AS = MRI->getAliasSet(PhysReg); *AS; ++AS)
401 disallowClobberPhysRegOnly(*AS);
402 disallowClobberPhysRegOnly(PhysReg);
405 /// ClobberPhysRegOnly - This is called when the specified physreg changes
406 /// value. We use this to invalidate any info about stuff we thing lives in it.
407 void AvailableSpills::ClobberPhysRegOnly(unsigned PhysReg) {
408 std::multimap<unsigned, int>::iterator I =
409 PhysRegsAvailable.lower_bound(PhysReg);
410 while (I != PhysRegsAvailable.end() && I->first == PhysReg) {
411 int SlotOrReMat = I->second;
412 PhysRegsAvailable.erase(I++);
413 assert((SpillSlotsOrReMatsAvailable[SlotOrReMat] >> 1) == PhysReg &&
414 "Bidirectional map mismatch!");
415 SpillSlotsOrReMatsAvailable.erase(SlotOrReMat);
416 DOUT << "PhysReg " << MRI->getName(PhysReg)
417 << " clobbered, invalidating ";
418 if (SlotOrReMat > VirtRegMap::MAX_STACK_SLOT)
419 DOUT << "RM#" << SlotOrReMat-VirtRegMap::MAX_STACK_SLOT-1 << "\n";
421 DOUT << "SS#" << SlotOrReMat << "\n";
425 /// ClobberPhysReg - This is called when the specified physreg changes
426 /// value. We use this to invalidate any info about stuff we thing lives in
427 /// it and any of its aliases.
428 void AvailableSpills::ClobberPhysReg(unsigned PhysReg) {
429 for (const unsigned *AS = MRI->getAliasSet(PhysReg); *AS; ++AS)
430 ClobberPhysRegOnly(*AS);
431 ClobberPhysRegOnly(PhysReg);
434 /// ModifyStackSlotOrReMat - This method is called when the value in a stack
435 /// slot changes. This removes information about which register the previous
436 /// value for this slot lives in (as the previous value is dead now).
437 void AvailableSpills::ModifyStackSlotOrReMat(int SlotOrReMat) {
438 std::map<int, unsigned>::iterator It =
439 SpillSlotsOrReMatsAvailable.find(SlotOrReMat);
440 if (It == SpillSlotsOrReMatsAvailable.end()) return;
441 unsigned Reg = It->second >> 1;
442 SpillSlotsOrReMatsAvailable.erase(It);
444 // This register may hold the value of multiple stack slots, only remove this
445 // stack slot from the set of values the register contains.
446 std::multimap<unsigned, int>::iterator I = PhysRegsAvailable.lower_bound(Reg);
448 assert(I != PhysRegsAvailable.end() && I->first == Reg &&
449 "Map inverse broken!");
450 if (I->second == SlotOrReMat) break;
452 PhysRegsAvailable.erase(I);
457 /// InvalidateKills - MI is going to be deleted. If any of its operands are
458 /// marked kill, then invalidate the information.
459 static void InvalidateKills(MachineInstr &MI, BitVector &RegKills,
460 std::vector<MachineOperand*> &KillOps,
461 SmallVector<unsigned, 2> *KillRegs = NULL) {
462 for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
463 MachineOperand &MO = MI.getOperand(i);
464 if (!MO.isRegister() || !MO.isUse() || !MO.isKill())
466 unsigned Reg = MO.getReg();
468 KillRegs->push_back(Reg);
469 if (KillOps[Reg] == &MO) {
476 /// InvalidateRegDef - If the def operand of the specified def MI is now dead
477 /// (since it's spill instruction is removed), mark it isDead. Also checks if
478 /// the def MI has other definition operands that are not dead. Returns it by
480 static bool InvalidateRegDef(MachineBasicBlock::iterator I,
481 MachineInstr &NewDef, unsigned Reg,
483 // Due to remat, it's possible this reg isn't being reused. That is,
484 // the def of this reg (by prev MI) is now dead.
485 MachineInstr *DefMI = I;
486 MachineOperand *DefOp = NULL;
487 for (unsigned i = 0, e = DefMI->getNumOperands(); i != e; ++i) {
488 MachineOperand &MO = DefMI->getOperand(i);
489 if (MO.isRegister() && MO.isDef()) {
490 if (MO.getReg() == Reg)
492 else if (!MO.isDead())
499 bool FoundUse = false, Done = false;
500 MachineBasicBlock::iterator E = NewDef;
502 for (; !Done && I != E; ++I) {
503 MachineInstr *NMI = I;
504 for (unsigned j = 0, ee = NMI->getNumOperands(); j != ee; ++j) {
505 MachineOperand &MO = NMI->getOperand(j);
506 if (!MO.isRegister() || MO.getReg() != Reg)
510 Done = true; // Stop after scanning all the operands of this MI.
521 /// UpdateKills - Track and update kill info. If a MI reads a register that is
522 /// marked kill, then it must be due to register reuse. Transfer the kill info
524 static void UpdateKills(MachineInstr &MI, BitVector &RegKills,
525 std::vector<MachineOperand*> &KillOps) {
526 const TargetInstrDescriptor *TID = MI.getInstrDescriptor();
527 for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
528 MachineOperand &MO = MI.getOperand(i);
529 if (!MO.isRegister() || !MO.isUse())
531 unsigned Reg = MO.getReg();
536 // That can't be right. Register is killed but not re-defined and it's
537 // being reused. Let's fix that.
538 KillOps[Reg]->unsetIsKill();
539 if (i < TID->numOperands &&
540 TID->getOperandConstraint(i, TOI::TIED_TO) == -1)
541 // Unless it's a two-address operand, this is the new kill.
551 for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
552 const MachineOperand &MO = MI.getOperand(i);
553 if (!MO.isRegister() || !MO.isDef())
555 unsigned Reg = MO.getReg();
562 // ReusedOp - For each reused operand, we keep track of a bit of information, in
563 // case we need to rollback upon processing a new operand. See comments below.
566 // The MachineInstr operand that reused an available value.
569 // StackSlotOrReMat - The spill slot or remat id of the value being reused.
570 unsigned StackSlotOrReMat;
572 // PhysRegReused - The physical register the value was available in.
573 unsigned PhysRegReused;
575 // AssignedPhysReg - The physreg that was assigned for use by the reload.
576 unsigned AssignedPhysReg;
578 // VirtReg - The virtual register itself.
581 ReusedOp(unsigned o, unsigned ss, unsigned prr, unsigned apr,
583 : Operand(o), StackSlotOrReMat(ss), PhysRegReused(prr),
584 AssignedPhysReg(apr), VirtReg(vreg) {}
587 /// ReuseInfo - This maintains a collection of ReuseOp's for each operand that
588 /// is reused instead of reloaded.
589 class VISIBILITY_HIDDEN ReuseInfo {
591 std::vector<ReusedOp> Reuses;
592 BitVector PhysRegsClobbered;
594 ReuseInfo(MachineInstr &mi, const MRegisterInfo *mri) : MI(mi) {
595 PhysRegsClobbered.resize(mri->getNumRegs());
598 bool hasReuses() const {
599 return !Reuses.empty();
602 /// addReuse - If we choose to reuse a virtual register that is already
603 /// available instead of reloading it, remember that we did so.
604 void addReuse(unsigned OpNo, unsigned StackSlotOrReMat,
605 unsigned PhysRegReused, unsigned AssignedPhysReg,
607 // If the reload is to the assigned register anyway, no undo will be
609 if (PhysRegReused == AssignedPhysReg) return;
611 // Otherwise, remember this.
612 Reuses.push_back(ReusedOp(OpNo, StackSlotOrReMat, PhysRegReused,
613 AssignedPhysReg, VirtReg));
616 void markClobbered(unsigned PhysReg) {
617 PhysRegsClobbered.set(PhysReg);
620 bool isClobbered(unsigned PhysReg) const {
621 return PhysRegsClobbered.test(PhysReg);
624 /// GetRegForReload - We are about to emit a reload into PhysReg. If there
625 /// is some other operand that is using the specified register, either pick
626 /// a new register to use, or evict the previous reload and use this reg.
627 unsigned GetRegForReload(unsigned PhysReg, MachineInstr *MI,
628 AvailableSpills &Spills,
629 std::vector<MachineInstr*> &MaybeDeadStores,
630 SmallSet<unsigned, 8> &Rejected,
632 std::vector<MachineOperand*> &KillOps,
634 if (Reuses.empty()) return PhysReg; // This is most often empty.
636 for (unsigned ro = 0, e = Reuses.size(); ro != e; ++ro) {
637 ReusedOp &Op = Reuses[ro];
638 // If we find some other reuse that was supposed to use this register
639 // exactly for its reload, we can change this reload to use ITS reload
640 // register. That is, unless its reload register has already been
641 // considered and subsequently rejected because it has also been reused
642 // by another operand.
643 if (Op.PhysRegReused == PhysReg &&
644 Rejected.count(Op.AssignedPhysReg) == 0) {
645 // Yup, use the reload register that we didn't use before.
646 unsigned NewReg = Op.AssignedPhysReg;
647 Rejected.insert(PhysReg);
648 return GetRegForReload(NewReg, MI, Spills, MaybeDeadStores, Rejected,
649 RegKills, KillOps, VRM);
651 // Otherwise, we might also have a problem if a previously reused
652 // value aliases the new register. If so, codegen the previous reload
654 unsigned PRRU = Op.PhysRegReused;
655 const MRegisterInfo *MRI = Spills.getRegInfo();
656 if (MRI->areAliases(PRRU, PhysReg)) {
657 // Okay, we found out that an alias of a reused register
658 // was used. This isn't good because it means we have
659 // to undo a previous reuse.
660 MachineBasicBlock *MBB = MI->getParent();
661 const TargetRegisterClass *AliasRC =
662 MBB->getParent()->getSSARegMap()->getRegClass(Op.VirtReg);
664 // Copy Op out of the vector and remove it, we're going to insert an
665 // explicit load for it.
667 Reuses.erase(Reuses.begin()+ro);
669 // Ok, we're going to try to reload the assigned physreg into the
670 // slot that we were supposed to in the first place. However, that
671 // register could hold a reuse. Check to see if it conflicts or
672 // would prefer us to use a different register.
673 unsigned NewPhysReg = GetRegForReload(NewOp.AssignedPhysReg,
674 MI, Spills, MaybeDeadStores,
675 Rejected, RegKills, KillOps, VRM);
677 if (NewOp.StackSlotOrReMat > VirtRegMap::MAX_STACK_SLOT) {
678 MRI->reMaterialize(*MBB, MI, NewPhysReg,
679 VRM.getReMaterializedMI(NewOp.VirtReg));
682 MRI->loadRegFromStackSlot(*MBB, MI, NewPhysReg,
683 NewOp.StackSlotOrReMat, AliasRC);
684 // Any stores to this stack slot are not dead anymore.
685 MaybeDeadStores[NewOp.StackSlotOrReMat] = NULL;
688 Spills.ClobberPhysReg(NewPhysReg);
689 Spills.ClobberPhysReg(NewOp.PhysRegReused);
691 MI->getOperand(NewOp.Operand).setReg(NewPhysReg);
693 Spills.addAvailable(NewOp.StackSlotOrReMat, MI, NewPhysReg);
694 MachineBasicBlock::iterator MII = MI;
696 UpdateKills(*MII, RegKills, KillOps);
697 DOUT << '\t' << *MII;
699 DOUT << "Reuse undone!\n";
702 // Finally, PhysReg is now available, go ahead and use it.
710 /// GetRegForReload - Helper for the above GetRegForReload(). Add a
711 /// 'Rejected' set to remember which registers have been considered and
712 /// rejected for the reload. This avoids infinite looping in case like
715 /// t2 <- assigned r0 for use by the reload but ended up reuse r1
716 /// t3 <- assigned r1 for use by the reload but ended up reuse r0
718 /// sees r1 is taken by t2, tries t2's reload register r0
719 /// sees r0 is taken by t3, tries t3's reload register r1
720 /// sees r1 is taken by t2, tries t2's reload register r0 ...
721 unsigned GetRegForReload(unsigned PhysReg, MachineInstr *MI,
722 AvailableSpills &Spills,
723 std::vector<MachineInstr*> &MaybeDeadStores,
725 std::vector<MachineOperand*> &KillOps,
727 SmallSet<unsigned, 8> Rejected;
728 return GetRegForReload(PhysReg, MI, Spills, MaybeDeadStores, Rejected,
729 RegKills, KillOps, VRM);
734 /// PrepForUnfoldOpti - Turn a store folding instruction into a load folding
735 /// instruction. e.g.
737 /// movl %eax, -32(%ebp)
738 /// movl -36(%ebp), %eax
739 /// orl %eax, -32(%ebp)
742 /// orl -36(%ebp), %eax
743 /// mov %eax, -32(%ebp)
744 /// This enables unfolding optimization for a subsequent instruction which will
745 /// also eliminate the newly introduced store instruction.
746 bool LocalSpiller::PrepForUnfoldOpti(MachineBasicBlock &MBB,
747 MachineBasicBlock::iterator &MII,
748 std::vector<MachineInstr*> &MaybeDeadStores,
749 AvailableSpills &Spills,
751 std::vector<MachineOperand*> &KillOps,
753 MachineFunction &MF = *MBB.getParent();
754 MachineInstr &MI = *MII;
755 unsigned UnfoldedOpc = 0;
756 unsigned UnfoldPR = 0;
757 unsigned UnfoldVR = 0;
758 int FoldedSS = VirtRegMap::NO_STACK_SLOT;
759 VirtRegMap::MI2VirtMapTy::const_iterator I, End;
760 for (tie(I, End) = VRM.getFoldedVirts(&MI); I != End; ++I) {
761 // Only transform a MI that folds a single register.
764 UnfoldVR = I->second.first;
765 VirtRegMap::ModRef MR = I->second.second;
766 if (VRM.isAssignedReg(UnfoldVR))
768 // If this reference is not a use, any previous store is now dead.
769 // Otherwise, the store to this stack slot is not dead anymore.
770 FoldedSS = VRM.getStackSlot(UnfoldVR);
771 MachineInstr* DeadStore = MaybeDeadStores[FoldedSS];
772 if (DeadStore && (MR & VirtRegMap::isModRef)) {
773 unsigned PhysReg = Spills.getSpillSlotOrReMatPhysReg(FoldedSS);
775 DeadStore->findRegisterUseOperandIdx(PhysReg, true) == -1)
778 UnfoldedOpc = MRI->getOpcodeAfterMemoryUnfold(MI.getOpcode(),
786 for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
787 MachineOperand &MO = MI.getOperand(i);
788 if (!MO.isRegister() || MO.getReg() == 0 || !MO.isUse())
790 unsigned VirtReg = MO.getReg();
791 if (MRegisterInfo::isPhysicalRegister(VirtReg) ||
792 RegMap->isSubRegister(VirtReg))
794 if (VRM.isAssignedReg(VirtReg)) {
795 unsigned PhysReg = VRM.getPhys(VirtReg);
796 if (PhysReg && MRI->regsOverlap(PhysReg, UnfoldPR))
798 } else if (VRM.isReMaterialized(VirtReg))
800 int SS = VRM.getStackSlot(VirtReg);
801 unsigned PhysReg = Spills.getSpillSlotOrReMatPhysReg(SS);
803 if (MRI->regsOverlap(PhysReg, UnfoldPR))
807 PhysReg = VRM.getPhys(VirtReg);
808 if (!MRI->regsOverlap(PhysReg, UnfoldPR))
811 // Ok, we'll need to reload the value into a register which makes
812 // it impossible to perform the store unfolding optimization later.
813 // Let's see if it is possible to fold the load if the store is
814 // unfolded. This allows us to perform the store unfolding
816 SmallVector<MachineInstr*, 4> NewMIs;
817 if (MRI->unfoldMemoryOperand(MF, &MI, UnfoldVR, false, false, NewMIs)) {
818 assert(NewMIs.size() == 1);
819 MachineInstr *NewMI = NewMIs.back();
821 unsigned Idx = NewMI->findRegisterUseOperandIdx(VirtReg);
822 MachineInstr *FoldedMI = MRI->foldMemoryOperand(NewMI, Idx, SS);
824 if (!VRM.hasPhys(UnfoldVR))
825 VRM.assignVirt2Phys(UnfoldVR, UnfoldPR);
826 VRM.virtFolded(VirtReg, FoldedMI, VirtRegMap::isRef);
827 MII = MBB.insert(MII, FoldedMI);
828 VRM.RemoveFromFoldedVirtMap(&MI);
838 /// findSuperReg - Find the SubReg's super-register of given register class
839 /// where its SubIdx sub-register is SubReg.
840 static unsigned findSuperReg(const TargetRegisterClass *RC, unsigned SubReg,
841 unsigned SubIdx, const MRegisterInfo *MRI) {
842 for (TargetRegisterClass::iterator I = RC->begin(), E = RC->end();
845 if (MRI->getSubReg(Reg, SubIdx) == SubReg)
851 /// rewriteMBB - Keep track of which spills are available even after the
852 /// register allocator is done with them. If possible, avoid reloading vregs.
853 void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM) {
854 DOUT << MBB.getBasicBlock()->getName() << ":\n";
856 MachineFunction &MF = *MBB.getParent();
858 // Spills - Keep track of which spilled values are available in physregs so
859 // that we can choose to reuse the physregs instead of emitting reloads.
860 AvailableSpills Spills(MRI, TII);
862 // MaybeDeadStores - When we need to write a value back into a stack slot,
863 // keep track of the inserted store. If the stack slot value is never read
864 // (because the value was used from some available register, for example), and
865 // subsequently stored to, the original store is dead. This map keeps track
866 // of inserted stores that are not used. If we see a subsequent store to the
867 // same stack slot, the original store is deleted.
868 std::vector<MachineInstr*> MaybeDeadStores;
869 MaybeDeadStores.resize(MF.getFrameInfo()->getObjectIndexEnd(), NULL);
871 // ReMatDefs - These are rematerializable def MIs which are not deleted.
872 SmallSet<MachineInstr*, 4> ReMatDefs;
874 // Keep track of kill information.
875 BitVector RegKills(MRI->getNumRegs());
876 std::vector<MachineOperand*> KillOps;
877 KillOps.resize(MRI->getNumRegs(), NULL);
879 for (MachineBasicBlock::iterator MII = MBB.begin(), E = MBB.end();
881 MachineBasicBlock::iterator NextMII = MII; ++NextMII;
883 VirtRegMap::MI2VirtMapTy::const_iterator I, End;
885 bool BackTracked = false;
886 if (PrepForUnfoldOpti(MBB, MII,
887 MaybeDeadStores, Spills, RegKills, KillOps, VRM))
890 /// ReusedOperands - Keep track of operand reuse in case we need to undo
892 MachineInstr &MI = *MII;
893 ReuseInfo ReusedOperands(MI, MRI);
895 const TargetInstrDescriptor *TID = MI.getInstrDescriptor();
897 // Process all of the spilled uses and all non spilled reg references.
898 for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
899 MachineOperand &MO = MI.getOperand(i);
900 if (!MO.isRegister() || MO.getReg() == 0)
901 continue; // Ignore non-register operands.
903 unsigned VirtReg = MO.getReg();
904 if (MRegisterInfo::isPhysicalRegister(VirtReg)) {
905 // Ignore physregs for spilling, but remember that it is used by this
907 MF.setPhysRegUsed(VirtReg);
911 assert(MRegisterInfo::isVirtualRegister(VirtReg) &&
912 "Not a virtual or a physical register?");
915 bool isSubReg = RegMap->isSubRegister(VirtReg);
917 SubIdx = RegMap->getSubRegisterIndex(VirtReg);
918 VirtReg = RegMap->getSuperRegister(VirtReg);
921 if (VRM.isAssignedReg(VirtReg)) {
922 // This virtual register was assigned a physreg!
923 unsigned Phys = VRM.getPhys(VirtReg);
924 MF.setPhysRegUsed(Phys);
926 ReusedOperands.markClobbered(Phys);
927 unsigned RReg = isSubReg ? MRI->getSubReg(Phys, SubIdx) : Phys;
928 MI.getOperand(i).setReg(RReg);
932 // This virtual register is now known to be a spilled value.
934 continue; // Handle defs in the loop below (handle use&def here though)
936 bool DoReMat = VRM.isReMaterialized(VirtReg);
937 int SSorRMId = DoReMat
938 ? VRM.getReMatId(VirtReg) : VRM.getStackSlot(VirtReg);
939 int ReuseSlot = SSorRMId;
941 // Check to see if this stack slot is available.
942 unsigned PhysReg = Spills.getSpillSlotOrReMatPhysReg(SSorRMId);
943 if (!PhysReg && DoReMat) {
944 // This use is rematerializable. But perhaps the value is available in
945 // a register if the definition is not deleted. If so, check if we can
947 ReuseSlot = VRM.getStackSlot(VirtReg);
948 if (ReuseSlot != VirtRegMap::NO_STACK_SLOT)
949 PhysReg = Spills.getSpillSlotOrReMatPhysReg(ReuseSlot);
952 // If this is a sub-register use, make sure the reuse register is in the
953 // right register class. For example, for x86 not all of the 32-bit
954 // registers have accessible sub-registers.
955 // Similarly so for EXTRACT_SUBREG. Consider this:
957 // MOV32_mr fi#1, EDI
959 // = EXTRACT_SUBREG fi#1
960 // fi#1 is available in EDI, but it cannot be reused because it's not in
961 // the right register file.
963 (isSubReg || MI.getOpcode() == TargetInstrInfo::EXTRACT_SUBREG)) {
964 const TargetRegisterClass* RC = RegMap->getRegClass(VirtReg);
965 if (!RC->contains(PhysReg))
970 // This spilled operand might be part of a two-address operand. If this
971 // is the case, then changing it will necessarily require changing the
972 // def part of the instruction as well. However, in some cases, we
973 // aren't allowed to modify the reused register. If none of these cases
975 bool CanReuse = true;
976 int ti = TID->getOperandConstraint(i, TOI::TIED_TO);
978 MI.getOperand(ti).isRegister() &&
979 MI.getOperand(ti).getReg() == VirtReg) {
980 // Okay, we have a two address operand. We can reuse this physreg as
981 // long as we are allowed to clobber the value and there isn't an
982 // earlier def that has already clobbered the physreg.
983 CanReuse = Spills.canClobberPhysReg(ReuseSlot) &&
984 !ReusedOperands.isClobbered(PhysReg);
988 // If this stack slot value is already available, reuse it!
989 if (ReuseSlot > VirtRegMap::MAX_STACK_SLOT)
990 DOUT << "Reusing RM#" << ReuseSlot-VirtRegMap::MAX_STACK_SLOT-1;
992 DOUT << "Reusing SS#" << ReuseSlot;
993 DOUT << " from physreg "
994 << MRI->getName(PhysReg) << " for vreg"
995 << VirtReg <<" instead of reloading into physreg "
996 << MRI->getName(VRM.getPhys(VirtReg)) << "\n";
997 unsigned RReg = isSubReg ? MRI->getSubReg(PhysReg, SubIdx) : PhysReg;
998 MI.getOperand(i).setReg(RReg);
1000 // The only technical detail we have is that we don't know that
1001 // PhysReg won't be clobbered by a reloaded stack slot that occurs
1002 // later in the instruction. In particular, consider 'op V1, V2'.
1003 // If V1 is available in physreg R0, we would choose to reuse it
1004 // here, instead of reloading it into the register the allocator
1005 // indicated (say R1). However, V2 might have to be reloaded
1006 // later, and it might indicate that it needs to live in R0. When
1007 // this occurs, we need to have information available that
1008 // indicates it is safe to use R1 for the reload instead of R0.
1010 // To further complicate matters, we might conflict with an alias,
1011 // or R0 and R1 might not be compatible with each other. In this
1012 // case, we actually insert a reload for V1 in R1, ensuring that
1013 // we can get at R0 or its alias.
1014 ReusedOperands.addReuse(i, ReuseSlot, PhysReg,
1015 VRM.getPhys(VirtReg), VirtReg);
1017 // Only mark it clobbered if this is a use&def operand.
1018 ReusedOperands.markClobbered(PhysReg);
1021 if (MI.getOperand(i).isKill() &&
1022 ReuseSlot <= VirtRegMap::MAX_STACK_SLOT) {
1023 // This was the last use and the spilled value is still available
1024 // for reuse. That means the spill was unnecessary!
1025 MachineInstr* DeadStore = MaybeDeadStores[ReuseSlot];
1027 DOUT << "Removed dead store:\t" << *DeadStore;
1028 InvalidateKills(*DeadStore, RegKills, KillOps);
1029 VRM.RemoveFromFoldedVirtMap(DeadStore);
1030 MBB.erase(DeadStore);
1031 MaybeDeadStores[ReuseSlot] = NULL;
1038 // Otherwise we have a situation where we have a two-address instruction
1039 // whose mod/ref operand needs to be reloaded. This reload is already
1040 // available in some register "PhysReg", but if we used PhysReg as the
1041 // operand to our 2-addr instruction, the instruction would modify
1042 // PhysReg. This isn't cool if something later uses PhysReg and expects
1043 // to get its initial value.
1045 // To avoid this problem, and to avoid doing a load right after a store,
1046 // we emit a copy from PhysReg into the designated register for this
1048 unsigned DesignatedReg = VRM.getPhys(VirtReg);
1049 assert(DesignatedReg && "Must map virtreg to physreg!");
1051 // Note that, if we reused a register for a previous operand, the
1052 // register we want to reload into might not actually be
1053 // available. If this occurs, use the register indicated by the
1055 if (ReusedOperands.hasReuses())
1056 DesignatedReg = ReusedOperands.GetRegForReload(DesignatedReg, &MI,
1057 Spills, MaybeDeadStores, RegKills, KillOps, VRM);
1059 // If the mapped designated register is actually the physreg we have
1060 // incoming, we don't need to inserted a dead copy.
1061 if (DesignatedReg == PhysReg) {
1062 // If this stack slot value is already available, reuse it!
1063 if (ReuseSlot > VirtRegMap::MAX_STACK_SLOT)
1064 DOUT << "Reusing RM#" << ReuseSlot-VirtRegMap::MAX_STACK_SLOT-1;
1066 DOUT << "Reusing SS#" << ReuseSlot;
1067 DOUT << " from physreg " << MRI->getName(PhysReg) << " for vreg"
1069 << " instead of reloading into same physreg.\n";
1070 unsigned RReg = isSubReg ? MRI->getSubReg(PhysReg, SubIdx) : PhysReg;
1071 MI.getOperand(i).setReg(RReg);
1072 ReusedOperands.markClobbered(RReg);
1077 const TargetRegisterClass* RC = RegMap->getRegClass(VirtReg);
1078 MF.setPhysRegUsed(DesignatedReg);
1079 ReusedOperands.markClobbered(DesignatedReg);
1080 MRI->copyRegToReg(MBB, &MI, DesignatedReg, PhysReg, RC, RC);
1082 MachineInstr *CopyMI = prior(MII);
1083 UpdateKills(*CopyMI, RegKills, KillOps);
1085 // This invalidates DesignatedReg.
1086 Spills.ClobberPhysReg(DesignatedReg);
1088 Spills.addAvailable(ReuseSlot, &MI, DesignatedReg);
1090 isSubReg ? MRI->getSubReg(DesignatedReg, SubIdx) : DesignatedReg;
1091 MI.getOperand(i).setReg(RReg);
1092 DOUT << '\t' << *prior(MII);
1097 // Otherwise, reload it and remember that we have it.
1098 PhysReg = VRM.getPhys(VirtReg);
1099 assert(PhysReg && "Must map virtreg to physreg!");
1101 // Note that, if we reused a register for a previous operand, the
1102 // register we want to reload into might not actually be
1103 // available. If this occurs, use the register indicated by the
1105 if (ReusedOperands.hasReuses())
1106 PhysReg = ReusedOperands.GetRegForReload(PhysReg, &MI,
1107 Spills, MaybeDeadStores, RegKills, KillOps, VRM);
1109 MF.setPhysRegUsed(PhysReg);
1110 ReusedOperands.markClobbered(PhysReg);
1112 MRI->reMaterialize(MBB, &MI, PhysReg, VRM.getReMaterializedMI(VirtReg));
1115 const TargetRegisterClass* RC = RegMap->getRegClass(VirtReg);
1116 MRI->loadRegFromStackSlot(MBB, &MI, PhysReg, SSorRMId, RC);
1119 // This invalidates PhysReg.
1120 Spills.ClobberPhysReg(PhysReg);
1122 // Any stores to this stack slot are not dead anymore.
1124 MaybeDeadStores[SSorRMId] = NULL;
1125 Spills.addAvailable(SSorRMId, &MI, PhysReg);
1126 // Assumes this is the last use. IsKill will be unset if reg is reused
1127 // unless it's a two-address operand.
1128 if (TID->getOperandConstraint(i, TOI::TIED_TO) == -1)
1129 MI.getOperand(i).setIsKill();
1130 unsigned RReg = isSubReg ? MRI->getSubReg(PhysReg, SubIdx) : PhysReg;
1131 MI.getOperand(i).setReg(RReg);
1132 UpdateKills(*prior(MII), RegKills, KillOps);
1133 DOUT << '\t' << *prior(MII);
1138 // If we have folded references to memory operands, make sure we clear all
1139 // physical registers that may contain the value of the spilled virtual
1141 SmallSet<int, 2> FoldedSS;
1142 for (tie(I, End) = VRM.getFoldedVirts(&MI); I != End; ++I) {
1143 unsigned VirtReg = I->second.first;
1144 VirtRegMap::ModRef MR = I->second.second;
1145 DOUT << "Folded vreg: " << VirtReg << " MR: " << MR;
1146 if (VRM.isAssignedReg(VirtReg)) {
1147 DOUT << ": No stack slot!\n";
1150 int SS = VRM.getStackSlot(VirtReg);
1151 FoldedSS.insert(SS);
1152 DOUT << " - StackSlot: " << SS << "\n";
1154 // If this folded instruction is just a use, check to see if it's a
1155 // straight load from the virt reg slot.
1156 if ((MR & VirtRegMap::isRef) && !(MR & VirtRegMap::isMod)) {
1158 unsigned DestReg = TII->isLoadFromStackSlot(&MI, FrameIdx);
1159 if (DestReg && FrameIdx == SS) {
1160 // If this spill slot is available, turn it into a copy (or nothing)
1161 // instead of leaving it as a load!
1162 if (unsigned InReg = Spills.getSpillSlotOrReMatPhysReg(SS)) {
1163 DOUT << "Promoted Load To Copy: " << MI;
1164 if (DestReg != InReg) {
1165 const TargetRegisterClass *RC = RegMap->getRegClass(VirtReg);
1166 MRI->copyRegToReg(MBB, &MI, DestReg, InReg, RC, RC);
1167 // Revisit the copy so we make sure to notice the effects of the
1168 // operation on the destreg (either needing to RA it if it's
1169 // virtual or needing to clobber any values if it's physical).
1171 --NextMII; // backtrack to the copy.
1174 DOUT << "Removing now-noop copy: " << MI;
1176 VRM.RemoveFromFoldedVirtMap(&MI);
1179 goto ProcessNextInst;
1182 unsigned PhysReg = Spills.getSpillSlotOrReMatPhysReg(SS);
1183 SmallVector<MachineInstr*, 4> NewMIs;
1185 MRI->unfoldMemoryOperand(MF, &MI, PhysReg, false, false, NewMIs)) {
1186 MBB.insert(MII, NewMIs[0]);
1187 VRM.RemoveFromFoldedVirtMap(&MI);
1190 --NextMII; // backtrack to the unfolded instruction.
1192 goto ProcessNextInst;
1197 // If this reference is not a use, any previous store is now dead.
1198 // Otherwise, the store to this stack slot is not dead anymore.
1199 MachineInstr* DeadStore = MaybeDeadStores[SS];
1201 bool isDead = !(MR & VirtRegMap::isRef);
1202 MachineInstr *NewStore = NULL;
1203 if (MR & VirtRegMap::isModRef) {
1204 unsigned PhysReg = Spills.getSpillSlotOrReMatPhysReg(SS);
1205 SmallVector<MachineInstr*, 4> NewMIs;
1207 DeadStore->findRegisterUseOperandIdx(PhysReg, true) != -1 &&
1208 MRI->unfoldMemoryOperand(MF, &MI, PhysReg, false, true, NewMIs)) {
1209 MBB.insert(MII, NewMIs[0]);
1210 NewStore = NewMIs[1];
1211 MBB.insert(MII, NewStore);
1212 VRM.RemoveFromFoldedVirtMap(&MI);
1216 --NextMII; // backtrack to the unfolded instruction.
1222 if (isDead) { // Previous store is dead.
1223 // If we get here, the store is dead, nuke it now.
1224 DOUT << "Removed dead store:\t" << *DeadStore;
1225 InvalidateKills(*DeadStore, RegKills, KillOps);
1226 VRM.RemoveFromFoldedVirtMap(DeadStore);
1227 MBB.erase(DeadStore);
1232 MaybeDeadStores[SS] = NULL;
1234 // Treat this store as a spill merged into a copy. That makes the
1235 // stack slot value available.
1236 VRM.virtFolded(VirtReg, NewStore, VirtRegMap::isMod);
1237 goto ProcessNextInst;
1241 // If the spill slot value is available, and this is a new definition of
1242 // the value, the value is not available anymore.
1243 if (MR & VirtRegMap::isMod) {
1244 // Notice that the value in this stack slot has been modified.
1245 Spills.ModifyStackSlotOrReMat(SS);
1247 // If this is *just* a mod of the value, check to see if this is just a
1248 // store to the spill slot (i.e. the spill got merged into the copy). If
1249 // so, realize that the vreg is available now, and add the store to the
1250 // MaybeDeadStore info.
1252 if (!(MR & VirtRegMap::isRef)) {
1253 if (unsigned SrcReg = TII->isStoreToStackSlot(&MI, StackSlot)) {
1254 assert(MRegisterInfo::isPhysicalRegister(SrcReg) &&
1255 "Src hasn't been allocated yet?");
1256 // Okay, this is certainly a store of SrcReg to [StackSlot]. Mark
1257 // this as a potentially dead store in case there is a subsequent
1258 // store into the stack slot without a read from it.
1259 MaybeDeadStores[StackSlot] = &MI;
1261 // If the stack slot value was previously available in some other
1262 // register, change it now. Otherwise, make the register available,
1264 Spills.addAvailable(StackSlot, &MI, SrcReg, false/*don't clobber*/);
1270 // Process all of the spilled defs.
1271 for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
1272 MachineOperand &MO = MI.getOperand(i);
1273 if (!(MO.isRegister() && MO.getReg() && MO.isDef()))
1276 unsigned VirtReg = MO.getReg();
1277 if (!MRegisterInfo::isVirtualRegister(VirtReg)) {
1278 // Check to see if this is a noop copy. If so, eliminate the
1279 // instruction before considering the dest reg to be changed.
1281 if (TII->isMoveInstr(MI, Src, Dst) && Src == Dst) {
1283 DOUT << "Removing now-noop copy: " << MI;
1286 VRM.RemoveFromFoldedVirtMap(&MI);
1287 Spills.disallowClobberPhysReg(VirtReg);
1288 goto ProcessNextInst;
1291 // If it's not a no-op copy, it clobbers the value in the destreg.
1292 Spills.ClobberPhysReg(VirtReg);
1293 ReusedOperands.markClobbered(VirtReg);
1295 // Check to see if this instruction is a load from a stack slot into
1296 // a register. If so, this provides the stack slot value in the reg.
1298 if (unsigned DestReg = TII->isLoadFromStackSlot(&MI, FrameIdx)) {
1299 assert(DestReg == VirtReg && "Unknown load situation!");
1301 // If it is a folded reference, then it's not safe to clobber.
1302 bool Folded = FoldedSS.count(FrameIdx);
1303 // Otherwise, if it wasn't available, remember that it is now!
1304 Spills.addAvailable(FrameIdx, &MI, DestReg, !Folded);
1305 goto ProcessNextInst;
1311 unsigned SubIdx = 0;
1312 bool isSubReg = RegMap->isSubRegister(VirtReg);
1314 SubIdx = RegMap->getSubRegisterIndex(VirtReg);
1315 VirtReg = RegMap->getSuperRegister(VirtReg);
1318 bool DoReMat = VRM.isReMaterialized(VirtReg);
1320 ReMatDefs.insert(&MI);
1322 // The only vregs left are stack slot definitions.
1323 int StackSlot = VRM.getStackSlot(VirtReg);
1324 const TargetRegisterClass *RC = RegMap->getRegClass(VirtReg);
1326 // If this def is part of a two-address operand, make sure to execute
1327 // the store from the correct physical register.
1329 int TiedOp = MI.getInstrDescriptor()->findTiedToSrcOperand(i);
1331 PhysReg = MI.getOperand(TiedOp).getReg();
1333 unsigned SuperReg = findSuperReg(RC, PhysReg, SubIdx, MRI);
1334 assert(SuperReg && MRI->getSubReg(SuperReg, SubIdx) == PhysReg &&
1335 "Can't find corresponding super-register!");
1339 PhysReg = VRM.getPhys(VirtReg);
1340 if (ReusedOperands.isClobbered(PhysReg)) {
1341 // Another def has taken the assigned physreg. It must have been a
1342 // use&def which got it due to reuse. Undo the reuse!
1343 PhysReg = ReusedOperands.GetRegForReload(PhysReg, &MI,
1344 Spills, MaybeDeadStores, RegKills, KillOps, VRM);
1348 MF.setPhysRegUsed(PhysReg);
1349 unsigned RReg = isSubReg ? MRI->getSubReg(PhysReg, SubIdx) : PhysReg;
1350 ReusedOperands.markClobbered(RReg);
1351 MI.getOperand(i).setReg(RReg);
1354 MRI->storeRegToStackSlot(MBB, next(MII), PhysReg, StackSlot, RC);
1355 DOUT << "Store:\t" << *next(MII);
1357 // If there is a dead store to this stack slot, nuke it now.
1358 MachineInstr *&LastStore = MaybeDeadStores[StackSlot];
1360 DOUT << "Removed dead store:\t" << *LastStore;
1362 SmallVector<unsigned, 2> KillRegs;
1363 InvalidateKills(*LastStore, RegKills, KillOps, &KillRegs);
1364 MachineBasicBlock::iterator PrevMII = LastStore;
1365 bool CheckDef = PrevMII != MBB.begin();
1368 MBB.erase(LastStore);
1369 VRM.RemoveFromFoldedVirtMap(LastStore);
1371 // Look at defs of killed registers on the store. Mark the defs
1372 // as dead since the store has been deleted and they aren't
1374 for (unsigned j = 0, ee = KillRegs.size(); j != ee; ++j) {
1375 bool HasOtherDef = false;
1376 if (InvalidateRegDef(PrevMII, MI, KillRegs[j], HasOtherDef)) {
1377 MachineInstr *DeadDef = PrevMII;
1378 if (ReMatDefs.count(DeadDef) && !HasOtherDef) {
1379 // FIXME: This assumes a remat def does not have side
1382 VRM.RemoveFromFoldedVirtMap(DeadDef);
1389 LastStore = next(MII);
1391 // If the stack slot value was previously available in some other
1392 // register, change it now. Otherwise, make the register available,
1394 Spills.ModifyStackSlotOrReMat(StackSlot);
1395 Spills.ClobberPhysReg(PhysReg);
1396 Spills.addAvailable(StackSlot, LastStore, PhysReg);
1399 // Check to see if this is a noop copy. If so, eliminate the
1400 // instruction before considering the dest reg to be changed.
1403 if (TII->isMoveInstr(MI, Src, Dst) && Src == Dst) {
1405 DOUT << "Removing now-noop copy: " << MI;
1408 VRM.RemoveFromFoldedVirtMap(&MI);
1409 UpdateKills(*LastStore, RegKills, KillOps);
1410 goto ProcessNextInst;
1416 if (!Erased && !BackTracked)
1417 for (MachineBasicBlock::iterator II = MI; II != NextMII; ++II)
1418 UpdateKills(*II, RegKills, KillOps);
1424 llvm::Spiller* llvm::createSpiller() {
1425 switch (SpillerOpt) {
1426 default: assert(0 && "Unreachable!");
1428 return new LocalSpiller();
1430 return new SimpleSpiller();