1 //===-- RegAllocLocal.cpp - A BasicBlock generic register allocator -------===//
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 register allocator allocates registers to a basic block at a time,
11 // attempting to keep values in registers and reusing registers as appropriate.
13 //===----------------------------------------------------------------------===//
15 #define DEBUG_TYPE "regalloc"
16 #include "llvm/CodeGen/Passes.h"
17 #include "llvm/CodeGen/MachineFunctionPass.h"
18 #include "llvm/CodeGen/MachineInstr.h"
19 #include "llvm/CodeGen/SSARegMap.h"
20 #include "llvm/CodeGen/MachineFrameInfo.h"
21 #include "llvm/CodeGen/LiveVariables.h"
22 #include "llvm/Target/TargetInstrInfo.h"
23 #include "llvm/Target/TargetMachine.h"
24 #include "llvm/Support/CommandLine.h"
25 #include "llvm/Support/Debug.h"
26 #include "llvm/ADT/DenseMap.h"
27 #include "llvm/ADT/Statistic.h"
32 Statistic<> NumStores("ra-local", "Number of stores added");
33 Statistic<> NumLoads ("ra-local", "Number of loads added");
34 Statistic<> NumFolded("ra-local", "Number of loads/stores folded into "
36 class RA : public MachineFunctionPass {
37 const TargetMachine *TM;
39 const MRegisterInfo *RegInfo;
42 // StackSlotForVirtReg - Maps virtual regs to the frame index where these
43 // values are spilled.
44 std::map<unsigned, int> StackSlotForVirtReg;
46 // Virt2PhysRegMap - This map contains entries for each virtual register
47 // that is currently available in a physical register.
48 DenseMap<unsigned, VirtReg2IndexFunctor> Virt2PhysRegMap;
50 unsigned &getVirt2PhysRegMapSlot(unsigned VirtReg) {
51 return Virt2PhysRegMap[VirtReg];
54 // PhysRegsUsed - This array is effectively a map, containing entries for
55 // each physical register that currently has a value (ie, it is in
56 // Virt2PhysRegMap). The value mapped to is the virtual register
57 // corresponding to the physical register (the inverse of the
58 // Virt2PhysRegMap), or 0. The value is set to 0 if this register is pinned
59 // because it is used by a future instruction. If the entry for a physical
60 // register is -1, then the physical register is "not in the map".
62 std::vector<int> PhysRegsUsed;
64 // PhysRegsUseOrder - This contains a list of the physical registers that
65 // currently have a virtual register value in them. This list provides an
66 // ordering of registers, imposing a reallocation order. This list is only
67 // used if all registers are allocated and we have to spill one, in which
68 // case we spill the least recently used register. Entries at the front of
69 // the list are the least recently used registers, entries at the back are
70 // the most recently used.
72 std::vector<unsigned> PhysRegsUseOrder;
74 // VirtRegModified - This bitset contains information about which virtual
75 // registers need to be spilled back to memory when their registers are
76 // scavenged. If a virtual register has simply been rematerialized, there
77 // is no reason to spill it to memory when we need the register back.
79 std::vector<bool> VirtRegModified;
81 void markVirtRegModified(unsigned Reg, bool Val = true) {
82 assert(MRegisterInfo::isVirtualRegister(Reg) && "Illegal VirtReg!");
83 Reg -= MRegisterInfo::FirstVirtualRegister;
84 if (VirtRegModified.size() <= Reg) VirtRegModified.resize(Reg+1);
85 VirtRegModified[Reg] = Val;
88 bool isVirtRegModified(unsigned Reg) const {
89 assert(MRegisterInfo::isVirtualRegister(Reg) && "Illegal VirtReg!");
90 assert(Reg - MRegisterInfo::FirstVirtualRegister < VirtRegModified.size()
91 && "Illegal virtual register!");
92 return VirtRegModified[Reg - MRegisterInfo::FirstVirtualRegister];
95 void MarkPhysRegRecentlyUsed(unsigned Reg) {
96 if(PhysRegsUseOrder.empty() ||
97 PhysRegsUseOrder.back() == Reg) return; // Already most recently used
99 for (unsigned i = PhysRegsUseOrder.size(); i != 0; --i)
100 if (areRegsEqual(Reg, PhysRegsUseOrder[i-1])) {
101 unsigned RegMatch = PhysRegsUseOrder[i-1]; // remove from middle
102 PhysRegsUseOrder.erase(PhysRegsUseOrder.begin()+i-1);
103 // Add it to the end of the list
104 PhysRegsUseOrder.push_back(RegMatch);
106 return; // Found an exact match, exit early
111 virtual const char *getPassName() const {
112 return "Local Register Allocator";
115 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
116 AU.addRequired<LiveVariables>();
117 AU.addRequiredID(PHIEliminationID);
118 AU.addRequiredID(TwoAddressInstructionPassID);
119 MachineFunctionPass::getAnalysisUsage(AU);
123 /// runOnMachineFunction - Register allocate the whole function
124 bool runOnMachineFunction(MachineFunction &Fn);
126 /// AllocateBasicBlock - Register allocate the specified basic block.
127 void AllocateBasicBlock(MachineBasicBlock &MBB);
130 /// areRegsEqual - This method returns true if the specified registers are
131 /// related to each other. To do this, it checks to see if they are equal
132 /// or if the first register is in the alias set of the second register.
134 bool areRegsEqual(unsigned R1, unsigned R2) const {
135 if (R1 == R2) return true;
136 for (const unsigned *AliasSet = RegInfo->getAliasSet(R2);
137 *AliasSet; ++AliasSet) {
138 if (*AliasSet == R1) return true;
143 /// getStackSpaceFor - This returns the frame index of the specified virtual
144 /// register on the stack, allocating space if necessary.
145 int getStackSpaceFor(unsigned VirtReg, const TargetRegisterClass *RC);
147 /// removePhysReg - This method marks the specified physical register as no
148 /// longer being in use.
150 void removePhysReg(unsigned PhysReg);
152 /// spillVirtReg - This method spills the value specified by PhysReg into
153 /// the virtual register slot specified by VirtReg. It then updates the RA
154 /// data structures to indicate the fact that PhysReg is now available.
156 void spillVirtReg(MachineBasicBlock &MBB, MachineBasicBlock::iterator MI,
157 unsigned VirtReg, unsigned PhysReg);
159 /// spillPhysReg - This method spills the specified physical register into
160 /// the virtual register slot associated with it. If OnlyVirtRegs is set to
161 /// true, then the request is ignored if the physical register does not
162 /// contain a virtual register.
164 void spillPhysReg(MachineBasicBlock &MBB, MachineInstr *I,
165 unsigned PhysReg, bool OnlyVirtRegs = false);
167 /// assignVirtToPhysReg - This method updates local state so that we know
168 /// that PhysReg is the proper container for VirtReg now. The physical
169 /// register must not be used for anything else when this is called.
171 void assignVirtToPhysReg(unsigned VirtReg, unsigned PhysReg);
173 /// liberatePhysReg - Make sure the specified physical register is available
174 /// for use. If there is currently a value in it, it is either moved out of
175 /// the way or spilled to memory.
177 void liberatePhysReg(MachineBasicBlock &MBB, MachineBasicBlock::iterator &I,
180 /// isPhysRegAvailable - Return true if the specified physical register is
181 /// free and available for use. This also includes checking to see if
182 /// aliased registers are all free...
184 bool isPhysRegAvailable(unsigned PhysReg) const;
186 /// getFreeReg - Look to see if there is a free register available in the
187 /// specified register class. If not, return 0.
189 unsigned getFreeReg(const TargetRegisterClass *RC);
191 /// getReg - Find a physical register to hold the specified virtual
192 /// register. If all compatible physical registers are used, this method
193 /// spills the last used virtual register to the stack, and uses that
196 unsigned getReg(MachineBasicBlock &MBB, MachineInstr *MI,
199 /// reloadVirtReg - This method transforms the specified specified virtual
200 /// register use to refer to a physical register. This method may do this
201 /// in one of several ways: if the register is available in a physical
202 /// register already, it uses that physical register. If the value is not
203 /// in a physical register, and if there are physical registers available,
204 /// it loads it into a register. If register pressure is high, and it is
205 /// possible, it tries to fold the load of the virtual register into the
206 /// instruction itself. It avoids doing this if register pressure is low to
207 /// improve the chance that subsequent instructions can use the reloaded
208 /// value. This method returns the modified instruction.
210 MachineInstr *reloadVirtReg(MachineBasicBlock &MBB, MachineInstr *MI,
214 void reloadPhysReg(MachineBasicBlock &MBB, MachineBasicBlock::iterator &I,
219 /// getStackSpaceFor - This allocates space for the specified virtual register
220 /// to be held on the stack.
221 int RA::getStackSpaceFor(unsigned VirtReg, const TargetRegisterClass *RC) {
222 // Find the location Reg would belong...
223 std::map<unsigned, int>::iterator I =StackSlotForVirtReg.lower_bound(VirtReg);
225 if (I != StackSlotForVirtReg.end() && I->first == VirtReg)
226 return I->second; // Already has space allocated?
228 // Allocate a new stack object for this spill location...
229 int FrameIdx = MF->getFrameInfo()->CreateStackObject(RC->getSize(),
232 // Assign the slot...
233 StackSlotForVirtReg.insert(I, std::make_pair(VirtReg, FrameIdx));
238 /// removePhysReg - This method marks the specified physical register as no
239 /// longer being in use.
241 void RA::removePhysReg(unsigned PhysReg) {
242 PhysRegsUsed[PhysReg] = -1; // PhyReg no longer used
244 std::vector<unsigned>::iterator It =
245 std::find(PhysRegsUseOrder.begin(), PhysRegsUseOrder.end(), PhysReg);
246 if (It != PhysRegsUseOrder.end())
247 PhysRegsUseOrder.erase(It);
251 /// spillVirtReg - This method spills the value specified by PhysReg into the
252 /// virtual register slot specified by VirtReg. It then updates the RA data
253 /// structures to indicate the fact that PhysReg is now available.
255 void RA::spillVirtReg(MachineBasicBlock &MBB, MachineBasicBlock::iterator I,
256 unsigned VirtReg, unsigned PhysReg) {
257 assert(VirtReg && "Spilling a physical register is illegal!"
258 " Must not have appropriate kill for the register or use exists beyond"
259 " the intended one.");
260 DEBUG(std::cerr << " Spilling register " << RegInfo->getName(PhysReg);
261 std::cerr << " containing %reg" << VirtReg;
262 if (!isVirtRegModified(VirtReg))
263 std::cerr << " which has not been modified, so no store necessary!");
265 // Otherwise, there is a virtual register corresponding to this physical
266 // register. We only need to spill it into its stack slot if it has been
268 if (isVirtRegModified(VirtReg)) {
269 const TargetRegisterClass *RC = MF->getSSARegMap()->getRegClass(VirtReg);
270 int FrameIndex = getStackSpaceFor(VirtReg, RC);
271 DEBUG(std::cerr << " to stack slot #" << FrameIndex);
272 RegInfo->storeRegToStackSlot(MBB, I, PhysReg, FrameIndex);
273 ++NumStores; // Update statistics
276 getVirt2PhysRegMapSlot(VirtReg) = 0; // VirtReg no longer available
278 DEBUG(std::cerr << "\n");
279 removePhysReg(PhysReg);
283 /// spillPhysReg - This method spills the specified physical register into the
284 /// virtual register slot associated with it. If OnlyVirtRegs is set to true,
285 /// then the request is ignored if the physical register does not contain a
286 /// virtual register.
288 void RA::spillPhysReg(MachineBasicBlock &MBB, MachineInstr *I,
289 unsigned PhysReg, bool OnlyVirtRegs) {
290 if (PhysRegsUsed[PhysReg] != -1) { // Only spill it if it's used!
291 if (PhysRegsUsed[PhysReg] || !OnlyVirtRegs)
292 spillVirtReg(MBB, I, PhysRegsUsed[PhysReg], PhysReg);
294 // If the selected register aliases any other registers, we must make
295 // sure that one of the aliases isn't alive...
296 for (const unsigned *AliasSet = RegInfo->getAliasSet(PhysReg);
297 *AliasSet; ++AliasSet)
298 if (PhysRegsUsed[*AliasSet] != -1) // Spill aliased register...
299 if (PhysRegsUsed[*AliasSet] || !OnlyVirtRegs)
300 spillVirtReg(MBB, I, PhysRegsUsed[*AliasSet], *AliasSet);
305 /// assignVirtToPhysReg - This method updates local state so that we know
306 /// that PhysReg is the proper container for VirtReg now. The physical
307 /// register must not be used for anything else when this is called.
309 void RA::assignVirtToPhysReg(unsigned VirtReg, unsigned PhysReg) {
310 assert(PhysRegsUsed[PhysReg] == -1 && "Phys reg already assigned!");
311 // Update information to note the fact that this register was just used, and
313 PhysRegsUsed[PhysReg] = VirtReg;
314 getVirt2PhysRegMapSlot(VirtReg) = PhysReg;
315 PhysRegsUseOrder.push_back(PhysReg); // New use of PhysReg
319 /// isPhysRegAvailable - Return true if the specified physical register is free
320 /// and available for use. This also includes checking to see if aliased
321 /// registers are all free...
323 bool RA::isPhysRegAvailable(unsigned PhysReg) const {
324 if (PhysRegsUsed[PhysReg] != -1) return false;
326 // If the selected register aliases any other allocated registers, it is
328 for (const unsigned *AliasSet = RegInfo->getAliasSet(PhysReg);
329 *AliasSet; ++AliasSet)
330 if (PhysRegsUsed[*AliasSet] != -1) // Aliased register in use?
331 return false; // Can't use this reg then.
336 /// getFreeReg - Look to see if there is a free register available in the
337 /// specified register class. If not, return 0.
339 unsigned RA::getFreeReg(const TargetRegisterClass *RC) {
340 // Get iterators defining the range of registers that are valid to allocate in
341 // this class, which also specifies the preferred allocation order.
342 TargetRegisterClass::iterator RI = RC->allocation_order_begin(*MF);
343 TargetRegisterClass::iterator RE = RC->allocation_order_end(*MF);
345 for (; RI != RE; ++RI)
346 if (isPhysRegAvailable(*RI)) { // Is reg unused?
347 assert(*RI != 0 && "Cannot use register!");
348 return *RI; // Found an unused register!
354 /// liberatePhysReg - Make sure the specified physical register is available for
355 /// use. If there is currently a value in it, it is either moved out of the way
356 /// or spilled to memory.
358 void RA::liberatePhysReg(MachineBasicBlock &MBB, MachineBasicBlock::iterator &I,
360 spillPhysReg(MBB, I, PhysReg);
364 /// getReg - Find a physical register to hold the specified virtual
365 /// register. If all compatible physical registers are used, this method spills
366 /// the last used virtual register to the stack, and uses that register.
368 unsigned RA::getReg(MachineBasicBlock &MBB, MachineInstr *I,
370 const TargetRegisterClass *RC = MF->getSSARegMap()->getRegClass(VirtReg);
372 // First check to see if we have a free register of the requested type...
373 unsigned PhysReg = getFreeReg(RC);
375 // If we didn't find an unused register, scavenge one now!
377 assert(!PhysRegsUseOrder.empty() && "No allocated registers??");
379 // Loop over all of the preallocated registers from the least recently used
380 // to the most recently used. When we find one that is capable of holding
381 // our register, use it.
382 for (unsigned i = 0; PhysReg == 0; ++i) {
383 assert(i != PhysRegsUseOrder.size() &&
384 "Couldn't find a register of the appropriate class!");
386 unsigned R = PhysRegsUseOrder[i];
388 // We can only use this register if it holds a virtual register (ie, it
389 // can be spilled). Do not use it if it is an explicitly allocated
390 // physical register!
391 assert(PhysRegsUsed[R] != -1 &&
392 "PhysReg in PhysRegsUseOrder, but is not allocated?");
393 if (PhysRegsUsed[R]) {
394 // If the current register is compatible, use it.
395 if (RC->contains(R)) {
399 // If one of the registers aliased to the current register is
400 // compatible, use it.
401 for (const unsigned *AliasSet = RegInfo->getAliasSet(R);
402 *AliasSet; ++AliasSet) {
403 if (RC->contains(*AliasSet)) {
404 PhysReg = *AliasSet; // Take an aliased register
412 assert(PhysReg && "Physical register not assigned!?!?");
414 // At this point PhysRegsUseOrder[i] is the least recently used register of
415 // compatible register class. Spill it to memory and reap its remains.
416 spillPhysReg(MBB, I, PhysReg);
419 // Now that we know which register we need to assign this to, do it now!
420 assignVirtToPhysReg(VirtReg, PhysReg);
425 /// reloadVirtReg - This method transforms the specified specified virtual
426 /// register use to refer to a physical register. This method may do this in
427 /// one of several ways: if the register is available in a physical register
428 /// already, it uses that physical register. If the value is not in a physical
429 /// register, and if there are physical registers available, it loads it into a
430 /// register. If register pressure is high, and it is possible, it tries to
431 /// fold the load of the virtual register into the instruction itself. It
432 /// avoids doing this if register pressure is low to improve the chance that
433 /// subsequent instructions can use the reloaded value. This method returns the
434 /// modified instruction.
436 MachineInstr *RA::reloadVirtReg(MachineBasicBlock &MBB, MachineInstr *MI,
438 unsigned VirtReg = MI->getOperand(OpNum).getReg();
440 // If the virtual register is already available, just update the instruction
442 if (unsigned PR = getVirt2PhysRegMapSlot(VirtReg)) {
443 MarkPhysRegRecentlyUsed(PR); // Already have this value available!
444 MI->SetMachineOperandReg(OpNum, PR); // Assign the input register
448 // Otherwise, we need to fold it into the current instruction, or reload it.
449 // If we have registers available to hold the value, use them.
450 const TargetRegisterClass *RC = MF->getSSARegMap()->getRegClass(VirtReg);
451 unsigned PhysReg = getFreeReg(RC);
452 int FrameIndex = getStackSpaceFor(VirtReg, RC);
454 if (PhysReg) { // Register is available, allocate it!
455 assignVirtToPhysReg(VirtReg, PhysReg);
456 } else { // No registers available.
457 // If we can fold this spill into this instruction, do so now.
458 if (MachineInstr* FMI = RegInfo->foldMemoryOperand(MI, OpNum, FrameIndex)){
460 // Since we changed the address of MI, make sure to update live variables
461 // to know that the new instruction has the properties of the old one.
462 LV->instructionChanged(MI, FMI);
463 return MBB.insert(MBB.erase(MI), FMI);
466 // It looks like we can't fold this virtual register load into this
467 // instruction. Force some poor hapless value out of the register file to
468 // make room for the new register, and reload it.
469 PhysReg = getReg(MBB, MI, VirtReg);
472 markVirtRegModified(VirtReg, false); // Note that this reg was just reloaded
474 DEBUG(std::cerr << " Reloading %reg" << VirtReg << " into "
475 << RegInfo->getName(PhysReg) << "\n");
477 // Add move instruction(s)
478 RegInfo->loadRegFromStackSlot(MBB, MI, PhysReg, FrameIndex);
479 ++NumLoads; // Update statistics
481 MI->SetMachineOperandReg(OpNum, PhysReg); // Assign the input register
487 void RA::AllocateBasicBlock(MachineBasicBlock &MBB) {
488 // loop over each instruction
489 MachineBasicBlock::iterator MI = MBB.begin();
490 for (; MI != MBB.end(); ++MI) {
491 const TargetInstrDescriptor &TID = TM->getInstrInfo()->get(MI->getOpcode());
492 DEBUG(std::cerr << "\nStarting RegAlloc of: " << *MI;
493 std::cerr << " Regs have values: ";
494 for (unsigned i = 0; i != RegInfo->getNumRegs(); ++i)
495 if (PhysRegsUsed[i] != -1)
496 std::cerr << "[" << RegInfo->getName(i)
497 << ",%reg" << PhysRegsUsed[i] << "] ";
500 // Loop over the implicit uses, making sure that they are at the head of the
501 // use order list, so they don't get reallocated.
502 for (const unsigned *ImplicitUses = TID.ImplicitUses;
503 *ImplicitUses; ++ImplicitUses)
504 MarkPhysRegRecentlyUsed(*ImplicitUses);
506 // Get the used operands into registers. This has the potential to spill
507 // incoming values if we are out of registers. Note that we completely
508 // ignore physical register uses here. We assume that if an explicit
509 // physical register is referenced by the instruction, that it is guaranteed
510 // to be live-in, or the input is badly hosed.
512 for (unsigned i = 0; i != MI->getNumOperands(); ++i) {
513 MachineOperand& MO = MI->getOperand(i);
514 // here we are looking for only used operands (never def&use)
515 if (!MO.isDef() && MO.isRegister() && MO.getReg() &&
516 MRegisterInfo::isVirtualRegister(MO.getReg()))
517 MI = reloadVirtReg(MBB, MI, i);
520 // If this instruction is the last user of anything in registers, kill the
521 // value, freeing the register being used, so it doesn't need to be
522 // spilled to memory.
524 for (LiveVariables::killed_iterator KI = LV->killed_begin(MI),
525 KE = LV->killed_end(MI); KI != KE; ++KI) {
526 unsigned VirtReg = KI->second;
527 unsigned PhysReg = VirtReg;
528 if (MRegisterInfo::isVirtualRegister(VirtReg)) {
529 // If the virtual register was never materialized into a register, it
530 // might not be in the map, but it won't hurt to zero it out anyway.
531 unsigned &PhysRegSlot = getVirt2PhysRegMapSlot(VirtReg);
532 PhysReg = PhysRegSlot;
537 DEBUG(std::cerr << " Last use of " << RegInfo->getName(PhysReg)
538 << "[%reg" << VirtReg <<"], removing it from live set\n");
539 removePhysReg(PhysReg);
543 // Loop over all of the operands of the instruction, spilling registers that
544 // are defined, and marking explicit destinations in the PhysRegsUsed map.
545 for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
546 MachineOperand& MO = MI->getOperand(i);
547 if (MO.isDef() && MO.isRegister() && MO.getReg() &&
548 MRegisterInfo::isPhysicalRegister(MO.getReg())) {
549 unsigned Reg = MO.getReg();
550 spillPhysReg(MBB, MI, Reg, true); // Spill any existing value in the reg
551 PhysRegsUsed[Reg] = 0; // It is free and reserved now
552 PhysRegsUseOrder.push_back(Reg);
553 for (const unsigned *AliasSet = RegInfo->getAliasSet(Reg);
554 *AliasSet; ++AliasSet) {
555 PhysRegsUseOrder.push_back(*AliasSet);
556 PhysRegsUsed[*AliasSet] = 0; // It is free and reserved now
561 // Loop over the implicit defs, spilling them as well.
562 for (const unsigned *ImplicitDefs = TID.ImplicitDefs;
563 *ImplicitDefs; ++ImplicitDefs) {
564 unsigned Reg = *ImplicitDefs;
565 spillPhysReg(MBB, MI, Reg, true);
566 PhysRegsUseOrder.push_back(Reg);
567 PhysRegsUsed[Reg] = 0; // It is free and reserved now
568 for (const unsigned *AliasSet = RegInfo->getAliasSet(Reg);
569 *AliasSet; ++AliasSet) {
570 PhysRegsUseOrder.push_back(*AliasSet);
571 PhysRegsUsed[*AliasSet] = 0; // It is free and reserved now
575 // Okay, we have allocated all of the source operands and spilled any values
576 // that would be destroyed by defs of this instruction. Loop over the
577 // implicit defs and assign them to a register, spilling incoming values if
578 // we need to scavenge a register.
580 for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
581 MachineOperand& MO = MI->getOperand(i);
582 if (MO.isDef() && MO.isRegister() && MO.getReg() &&
583 MRegisterInfo::isVirtualRegister(MO.getReg())) {
584 unsigned DestVirtReg = MO.getReg();
585 unsigned DestPhysReg;
587 // If DestVirtReg already has a value, use it.
588 if (!(DestPhysReg = getVirt2PhysRegMapSlot(DestVirtReg)))
589 DestPhysReg = getReg(MBB, MI, DestVirtReg);
590 markVirtRegModified(DestVirtReg);
591 MI->SetMachineOperandReg(i, DestPhysReg); // Assign the output register
595 // If this instruction defines any registers that are immediately dead,
598 for (LiveVariables::killed_iterator KI = LV->dead_begin(MI),
599 KE = LV->dead_end(MI); KI != KE; ++KI) {
600 unsigned VirtReg = KI->second;
601 unsigned PhysReg = VirtReg;
602 if (MRegisterInfo::isVirtualRegister(VirtReg)) {
603 unsigned &PhysRegSlot = getVirt2PhysRegMapSlot(VirtReg);
604 PhysReg = PhysRegSlot;
605 assert(PhysReg != 0);
610 DEBUG(std::cerr << " Register " << RegInfo->getName(PhysReg)
611 << " [%reg" << VirtReg
612 << "] is never used, removing it frame live list\n");
613 removePhysReg(PhysReg);
618 MI = MBB.getFirstTerminator();
620 // Spill all physical registers holding virtual registers now.
621 for (unsigned i = 0, e = RegInfo->getNumRegs(); i != e; ++i)
622 if (PhysRegsUsed[i] != -1)
623 if (unsigned VirtReg = PhysRegsUsed[i])
624 spillVirtReg(MBB, MI, VirtReg, i);
630 for (unsigned i = MRegisterInfo::FirstVirtualRegister,
631 e = MF->getSSARegMap()->getLastVirtReg(); i <= e; ++i)
632 if (unsigned PR = Virt2PhysRegMap[i]) {
633 std::cerr << "Register still mapped: " << i << " -> " << PR << "\n";
636 assert(AllOk && "Virtual registers still in phys regs?");
639 // Clear any physical register which appear live at the end of the basic
640 // block, but which do not hold any virtual registers. e.g., the stack
642 PhysRegsUseOrder.clear();
646 /// runOnMachineFunction - Register allocate the whole function
648 bool RA::runOnMachineFunction(MachineFunction &Fn) {
649 DEBUG(std::cerr << "Machine Function " << "\n");
651 TM = &Fn.getTarget();
652 RegInfo = TM->getRegisterInfo();
653 LV = &getAnalysis<LiveVariables>();
655 PhysRegsUsed.assign(RegInfo->getNumRegs(), -1);
657 // initialize the virtual->physical register map to have a 'null'
658 // mapping for all virtual registers
659 Virt2PhysRegMap.grow(MF->getSSARegMap()->getLastVirtReg());
661 // Loop over all of the basic blocks, eliminating virtual register references
662 for (MachineFunction::iterator MBB = Fn.begin(), MBBe = Fn.end();
664 AllocateBasicBlock(*MBB);
666 StackSlotForVirtReg.clear();
667 PhysRegsUsed.clear();
668 VirtRegModified.clear();
669 Virt2PhysRegMap.clear();
673 FunctionPass *llvm::createLocalRegisterAllocator() {