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 "Support/CommandLine.h"
25 #include "Support/Debug.h"
26 #include "Support/Statistic.h"
32 Statistic<> NumSpilled ("ra-local", "Number of registers spilled");
33 Statistic<> NumReloaded("ra-local", "Number of registers reloaded");
34 cl::opt<bool> DisableKill("disable-kill", cl::Hidden,
35 cl::desc("Disable register kill in local-ra"));
37 class RA : public MachineFunctionPass {
38 const TargetMachine *TM;
40 const MRegisterInfo *RegInfo;
43 // StackSlotForVirtReg - Maps virtual regs to the frame index where these
44 // values are spilled.
45 std::map<unsigned, int> StackSlotForVirtReg;
47 // Virt2PhysRegMap - This map contains entries for each virtual register
48 // that is currently available in a physical register.
50 std::map<unsigned, unsigned> Virt2PhysRegMap;
52 // PhysRegsUsed - This map contains entries for each physical register that
53 // currently has a value (ie, it is in Virt2PhysRegMap). The value mapped
54 // to is the virtual register corresponding to the physical register (the
55 // inverse of the Virt2PhysRegMap), or 0. The value is set to 0 if this
56 // register is pinned because it is used by a future instruction.
58 std::map<unsigned, unsigned> PhysRegsUsed;
60 // PhysRegsUseOrder - This contains a list of the physical registers that
61 // currently have a virtual register value in them. This list provides an
62 // ordering of registers, imposing a reallocation order. This list is only
63 // used if all registers are allocated and we have to spill one, in which
64 // case we spill the least recently used register. Entries at the front of
65 // the list are the least recently used registers, entries at the back are
66 // the most recently used.
68 std::vector<unsigned> PhysRegsUseOrder;
70 // VirtRegModified - This bitset contains information about which virtual
71 // registers need to be spilled back to memory when their registers are
72 // scavenged. If a virtual register has simply been rematerialized, there
73 // is no reason to spill it to memory when we need the register back.
75 std::vector<bool> VirtRegModified;
77 void markVirtRegModified(unsigned Reg, bool Val = true) {
78 assert(Reg >= MRegisterInfo::FirstVirtualRegister && "Illegal VirtReg!");
79 Reg -= MRegisterInfo::FirstVirtualRegister;
80 if (VirtRegModified.size() <= Reg) VirtRegModified.resize(Reg+1);
81 VirtRegModified[Reg] = Val;
84 bool isVirtRegModified(unsigned Reg) const {
85 assert(Reg >= MRegisterInfo::FirstVirtualRegister && "Illegal VirtReg!");
86 assert(Reg - MRegisterInfo::FirstVirtualRegister < VirtRegModified.size()
87 && "Illegal virtual register!");
88 return VirtRegModified[Reg - MRegisterInfo::FirstVirtualRegister];
91 void MarkPhysRegRecentlyUsed(unsigned Reg) {
92 assert(!PhysRegsUseOrder.empty() && "No registers used!");
93 if (PhysRegsUseOrder.back() == Reg) return; // Already most recently used
95 for (unsigned i = PhysRegsUseOrder.size(); i != 0; --i)
96 if (areRegsEqual(Reg, PhysRegsUseOrder[i-1])) {
97 unsigned RegMatch = PhysRegsUseOrder[i-1]; // remove from middle
98 PhysRegsUseOrder.erase(PhysRegsUseOrder.begin()+i-1);
99 // Add it to the end of the list
100 PhysRegsUseOrder.push_back(RegMatch);
102 return; // Found an exact match, exit early
107 virtual const char *getPassName() const {
108 return "Local Register Allocator";
111 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
113 AU.addRequired<LiveVariables>();
114 AU.addRequiredID(PHIEliminationID);
115 AU.addRequiredID(TwoAddressInstructionPassID);
116 MachineFunctionPass::getAnalysisUsage(AU);
120 /// runOnMachineFunction - Register allocate the whole function
121 bool runOnMachineFunction(MachineFunction &Fn);
123 /// AllocateBasicBlock - Register allocate the specified basic block.
124 void AllocateBasicBlock(MachineBasicBlock &MBB);
127 /// areRegsEqual - This method returns true if the specified registers are
128 /// related to each other. To do this, it checks to see if they are equal
129 /// or if the first register is in the alias set of the second register.
131 bool areRegsEqual(unsigned R1, unsigned R2) const {
132 if (R1 == R2) return true;
133 for (const unsigned *AliasSet = RegInfo->getAliasSet(R2);
134 *AliasSet; ++AliasSet) {
135 if (*AliasSet == R1) return true;
140 /// getStackSpaceFor - This returns the frame index of the specified virtual
141 /// register on the stack, allocating space if necessary.
142 int getStackSpaceFor(unsigned VirtReg, const TargetRegisterClass *RC);
144 /// removePhysReg - This method marks the specified physical register as no
145 /// longer being in use.
147 void removePhysReg(unsigned PhysReg);
149 /// spillVirtReg - This method spills the value specified by PhysReg into
150 /// the virtual register slot specified by VirtReg. It then updates the RA
151 /// data structures to indicate the fact that PhysReg is now available.
153 void spillVirtReg(MachineBasicBlock &MBB, MachineBasicBlock::iterator &I,
154 unsigned VirtReg, unsigned PhysReg);
156 /// spillPhysReg - This method spills the specified physical register into
157 /// the virtual register slot associated with it. If OnlyVirtRegs is set to
158 /// true, then the request is ignored if the physical register does not
159 /// contain a virtual register.
161 void spillPhysReg(MachineBasicBlock &MBB, MachineBasicBlock::iterator &I,
162 unsigned PhysReg, bool OnlyVirtRegs = false);
164 /// assignVirtToPhysReg - This method updates local state so that we know
165 /// that PhysReg is the proper container for VirtReg now. The physical
166 /// register must not be used for anything else when this is called.
168 void assignVirtToPhysReg(unsigned VirtReg, unsigned PhysReg);
170 /// liberatePhysReg - Make sure the specified physical register is available
171 /// for use. If there is currently a value in it, it is either moved out of
172 /// the way or spilled to memory.
174 void liberatePhysReg(MachineBasicBlock &MBB, MachineBasicBlock::iterator &I,
177 /// isPhysRegAvailable - Return true if the specified physical register is
178 /// free and available for use. This also includes checking to see if
179 /// aliased registers are all free...
181 bool isPhysRegAvailable(unsigned PhysReg) const;
183 /// getFreeReg - Look to see if there is a free register available in the
184 /// specified register class. If not, return 0.
186 unsigned getFreeReg(const TargetRegisterClass *RC);
188 /// getReg - Find a physical register to hold the specified virtual
189 /// register. If all compatible physical registers are used, this method
190 /// spills the last used virtual register to the stack, and uses that
193 unsigned getReg(MachineBasicBlock &MBB, MachineBasicBlock::iterator &I,
196 /// reloadVirtReg - This method loads the specified virtual register into a
197 /// physical register, returning the physical register chosen. This updates
198 /// the regalloc data structures to reflect the fact that the virtual reg is
199 /// now alive in a physical register, and the previous one isn't.
201 unsigned reloadVirtReg(MachineBasicBlock &MBB,
202 MachineBasicBlock::iterator &I, unsigned VirtReg);
204 void reloadPhysReg(MachineBasicBlock &MBB, MachineBasicBlock::iterator &I,
209 /// getStackSpaceFor - This allocates space for the specified virtual register
210 /// to be held on the stack.
211 int RA::getStackSpaceFor(unsigned VirtReg, const TargetRegisterClass *RC) {
212 // Find the location Reg would belong...
213 std::map<unsigned, int>::iterator I =StackSlotForVirtReg.lower_bound(VirtReg);
215 if (I != StackSlotForVirtReg.end() && I->first == VirtReg)
216 return I->second; // Already has space allocated?
218 // Allocate a new stack object for this spill location...
219 int FrameIdx = MF->getFrameInfo()->CreateStackObject(RC);
221 // Assign the slot...
222 StackSlotForVirtReg.insert(I, std::make_pair(VirtReg, FrameIdx));
227 /// removePhysReg - This method marks the specified physical register as no
228 /// longer being in use.
230 void RA::removePhysReg(unsigned PhysReg) {
231 PhysRegsUsed.erase(PhysReg); // PhyReg no longer used
233 std::vector<unsigned>::iterator It =
234 std::find(PhysRegsUseOrder.begin(), PhysRegsUseOrder.end(), PhysReg);
235 assert(It != PhysRegsUseOrder.end() &&
236 "Spilled a physical register, but it was not in use list!");
237 PhysRegsUseOrder.erase(It);
241 /// spillVirtReg - This method spills the value specified by PhysReg into the
242 /// virtual register slot specified by VirtReg. It then updates the RA data
243 /// structures to indicate the fact that PhysReg is now available.
245 void RA::spillVirtReg(MachineBasicBlock &MBB, MachineBasicBlock::iterator &I,
246 unsigned VirtReg, unsigned PhysReg) {
247 if (!VirtReg && DisableKill) return;
248 assert(VirtReg && "Spilling a physical register is illegal!"
249 " Must not have appropriate kill for the register or use exists beyond"
250 " the intended one.");
251 DEBUG(std::cerr << " Spilling register " << RegInfo->getName(PhysReg);
252 std::cerr << " containing %reg" << VirtReg;
253 if (!isVirtRegModified(VirtReg))
254 std::cerr << " which has not been modified, so no store necessary!");
256 // Otherwise, there is a virtual register corresponding to this physical
257 // register. We only need to spill it into its stack slot if it has been
259 if (isVirtRegModified(VirtReg)) {
260 const TargetRegisterClass *RC = MF->getSSARegMap()->getRegClass(VirtReg);
261 int FrameIndex = getStackSpaceFor(VirtReg, RC);
262 DEBUG(std::cerr << " to stack slot #" << FrameIndex);
263 RegInfo->storeRegToStackSlot(MBB, I, PhysReg, FrameIndex, RC);
264 ++NumSpilled; // Update statistics
266 Virt2PhysRegMap.erase(VirtReg); // VirtReg no longer available
268 DEBUG(std::cerr << "\n");
269 removePhysReg(PhysReg);
273 /// spillPhysReg - This method spills the specified physical register into the
274 /// virtual register slot associated with it. If OnlyVirtRegs is set to true,
275 /// then the request is ignored if the physical register does not contain a
276 /// virtual register.
278 void RA::spillPhysReg(MachineBasicBlock &MBB, MachineBasicBlock::iterator &I,
279 unsigned PhysReg, bool OnlyVirtRegs) {
280 std::map<unsigned, unsigned>::iterator PI = PhysRegsUsed.find(PhysReg);
281 if (PI != PhysRegsUsed.end()) { // Only spill it if it's used!
282 if (PI->second || !OnlyVirtRegs)
283 spillVirtReg(MBB, I, PI->second, PhysReg);
285 // If the selected register aliases any other registers, we must make
286 // sure that one of the aliases isn't alive...
287 for (const unsigned *AliasSet = RegInfo->getAliasSet(PhysReg);
288 *AliasSet; ++AliasSet) {
289 PI = PhysRegsUsed.find(*AliasSet);
290 if (PI != PhysRegsUsed.end()) // Spill aliased register...
291 if (PI->second || !OnlyVirtRegs)
292 spillVirtReg(MBB, I, PI->second, *AliasSet);
298 /// assignVirtToPhysReg - This method updates local state so that we know
299 /// that PhysReg is the proper container for VirtReg now. The physical
300 /// register must not be used for anything else when this is called.
302 void RA::assignVirtToPhysReg(unsigned VirtReg, unsigned PhysReg) {
303 assert(PhysRegsUsed.find(PhysReg) == PhysRegsUsed.end() &&
304 "Phys reg already assigned!");
305 // Update information to note the fact that this register was just used, and
307 PhysRegsUsed[PhysReg] = VirtReg;
308 Virt2PhysRegMap[VirtReg] = PhysReg;
309 PhysRegsUseOrder.push_back(PhysReg); // New use of PhysReg
313 /// isPhysRegAvailable - Return true if the specified physical register is free
314 /// and available for use. This also includes checking to see if aliased
315 /// registers are all free...
317 bool RA::isPhysRegAvailable(unsigned PhysReg) const {
318 if (PhysRegsUsed.count(PhysReg)) return false;
320 // If the selected register aliases any other allocated registers, it is
322 for (const unsigned *AliasSet = RegInfo->getAliasSet(PhysReg);
323 *AliasSet; ++AliasSet)
324 if (PhysRegsUsed.count(*AliasSet)) // Aliased register in use?
325 return false; // Can't use this reg then.
330 /// getFreeReg - Look to see if there is a free register available in the
331 /// specified register class. If not, return 0.
333 unsigned RA::getFreeReg(const TargetRegisterClass *RC) {
334 // Get iterators defining the range of registers that are valid to allocate in
335 // this class, which also specifies the preferred allocation order.
336 TargetRegisterClass::iterator RI = RC->allocation_order_begin(*MF);
337 TargetRegisterClass::iterator RE = RC->allocation_order_end(*MF);
339 for (; RI != RE; ++RI)
340 if (isPhysRegAvailable(*RI)) { // Is reg unused?
341 assert(*RI != 0 && "Cannot use register!");
342 return *RI; // Found an unused register!
348 /// liberatePhysReg - Make sure the specified physical register is available for
349 /// use. If there is currently a value in it, it is either moved out of the way
350 /// or spilled to memory.
352 void RA::liberatePhysReg(MachineBasicBlock &MBB, MachineBasicBlock::iterator &I,
354 // FIXME: This code checks to see if a register is available, but it really
355 // wants to know if a reg is available BEFORE the instruction executes. If
356 // called after killed operands are freed, it runs the risk of reallocating a
359 if (isPhysRegAvailable(PhysReg)) return; // Already available...
361 // Check to see if the register is directly used, not indirectly used through
362 // aliases. If aliased registers are the ones actually used, we cannot be
363 // sure that we will be able to save the whole thing if we do a reg-reg copy.
364 std::map<unsigned, unsigned>::iterator PRUI = PhysRegsUsed.find(PhysReg);
365 if (PRUI != PhysRegsUsed.end()) {
366 unsigned VirtReg = PRUI->second; // The virtual register held...
368 // Check to see if there is a compatible register available. If so, we can
369 // move the value into the new register...
371 const TargetRegisterClass *RC = RegInfo->getRegClass(PhysReg);
372 if (unsigned NewReg = getFreeReg(RC)) {
373 // Emit the code to copy the value...
374 RegInfo->copyRegToReg(MBB, I, NewReg, PhysReg, RC);
376 // Update our internal state to indicate that PhysReg is available and Reg
378 Virt2PhysRegMap.erase(VirtReg);
379 removePhysReg(PhysReg); // Free the physreg
381 // Move reference over to new register...
382 assignVirtToPhysReg(VirtReg, NewReg);
387 spillPhysReg(MBB, I, PhysReg);
391 /// getReg - Find a physical register to hold the specified virtual
392 /// register. If all compatible physical registers are used, this method spills
393 /// the last used virtual register to the stack, and uses that register.
395 unsigned RA::getReg(MachineBasicBlock &MBB, MachineBasicBlock::iterator &I,
397 const TargetRegisterClass *RC = MF->getSSARegMap()->getRegClass(VirtReg);
399 // First check to see if we have a free register of the requested type...
400 unsigned PhysReg = getFreeReg(RC);
402 // If we didn't find an unused register, scavenge one now!
404 assert(!PhysRegsUseOrder.empty() && "No allocated registers??");
406 // Loop over all of the preallocated registers from the least recently used
407 // to the most recently used. When we find one that is capable of holding
408 // our register, use it.
409 for (unsigned i = 0; PhysReg == 0; ++i) {
410 assert(i != PhysRegsUseOrder.size() &&
411 "Couldn't find a register of the appropriate class!");
413 unsigned R = PhysRegsUseOrder[i];
415 // We can only use this register if it holds a virtual register (ie, it
416 // can be spilled). Do not use it if it is an explicitly allocated
417 // physical register!
418 assert(PhysRegsUsed.count(R) &&
419 "PhysReg in PhysRegsUseOrder, but is not allocated?");
420 if (PhysRegsUsed[R]) {
421 // If the current register is compatible, use it.
422 if (RegInfo->getRegClass(R) == RC) {
426 // If one of the registers aliased to the current register is
427 // compatible, use it.
428 for (const unsigned *AliasSet = RegInfo->getAliasSet(R);
429 *AliasSet; ++AliasSet) {
430 if (RegInfo->getRegClass(*AliasSet) == RC) {
431 PhysReg = *AliasSet; // Take an aliased register
439 assert(PhysReg && "Physical register not assigned!?!?");
441 // At this point PhysRegsUseOrder[i] is the least recently used register of
442 // compatible register class. Spill it to memory and reap its remains.
443 spillPhysReg(MBB, I, PhysReg);
446 // Now that we know which register we need to assign this to, do it now!
447 assignVirtToPhysReg(VirtReg, PhysReg);
452 /// reloadVirtReg - This method loads the specified virtual register into a
453 /// physical register, returning the physical register chosen. This updates the
454 /// regalloc data structures to reflect the fact that the virtual reg is now
455 /// alive in a physical register, and the previous one isn't.
457 unsigned RA::reloadVirtReg(MachineBasicBlock &MBB,
458 MachineBasicBlock::iterator &I,
460 std::map<unsigned, unsigned>::iterator It = Virt2PhysRegMap.find(VirtReg);
461 if (It != Virt2PhysRegMap.end()) {
462 MarkPhysRegRecentlyUsed(It->second);
463 return It->second; // Already have this value available!
466 unsigned PhysReg = getReg(MBB, I, VirtReg);
468 const TargetRegisterClass *RC = MF->getSSARegMap()->getRegClass(VirtReg);
469 int FrameIndex = getStackSpaceFor(VirtReg, RC);
471 markVirtRegModified(VirtReg, false); // Note that this reg was just reloaded
473 DEBUG(std::cerr << " Reloading %reg" << VirtReg << " into "
474 << RegInfo->getName(PhysReg) << "\n");
476 // Add move instruction(s)
477 RegInfo->loadRegFromStackSlot(MBB, I, PhysReg, FrameIndex, RC);
478 ++NumReloaded; // Update statistics
484 void RA::AllocateBasicBlock(MachineBasicBlock &MBB) {
485 // loop over each instruction
486 MachineBasicBlock::iterator I = MBB.begin();
487 for (; I != MBB.end(); ++I) {
488 MachineInstr *MI = *I;
489 const TargetInstrDescriptor &TID = TM->getInstrInfo().get(MI->getOpcode());
490 DEBUG(std::cerr << "\nStarting RegAlloc of: " << *MI;
491 std::cerr << " Regs have values: ";
492 for (std::map<unsigned, unsigned>::const_iterator
493 I = PhysRegsUsed.begin(), E = PhysRegsUsed.end(); I != E; ++I)
494 std::cerr << "[" << RegInfo->getName(I->first)
495 << ",%reg" << I->second << "] ";
498 // Loop over the implicit uses, making sure that they are at the head of the
499 // use order list, so they don't get reallocated.
500 for (const unsigned *ImplicitUses = TID.ImplicitUses;
501 *ImplicitUses; ++ImplicitUses)
502 MarkPhysRegRecentlyUsed(*ImplicitUses);
504 // Get the used operands into registers. This has the potential to spill
505 // incoming values if we are out of registers. Note that we completely
506 // ignore physical register uses here. We assume that if an explicit
507 // physical register is referenced by the instruction, that it is guaranteed
508 // to be live-in, or the input is badly hosed.
510 for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i)
511 if (MI->getOperand(i).isUse() &&
512 !MI->getOperand(i).isDef() &&
513 MI->getOperand(i).isVirtualRegister()){
514 unsigned VirtSrcReg = MI->getOperand(i).getAllocatedRegNum();
515 unsigned PhysSrcReg = reloadVirtReg(MBB, I, VirtSrcReg);
516 MI->SetMachineOperandReg(i, PhysSrcReg); // Assign the input register
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 (VirtReg >= MRegisterInfo::FirstVirtualRegister) {
529 std::map<unsigned, unsigned>::iterator I =
530 Virt2PhysRegMap.find(VirtReg);
531 assert(I != Virt2PhysRegMap.end());
533 Virt2PhysRegMap.erase(I);
537 DEBUG(std::cerr << " Last use of " << RegInfo->getName(PhysReg)
538 << "[%reg" << VirtReg <<"], removing it from live set\n");
539 removePhysReg(PhysReg);
544 // Loop over all of the operands of the instruction, spilling registers that
545 // are defined, and marking explicit destinations in the PhysRegsUsed map.
546 for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i)
547 if (MI->getOperand(i).isDef() &&
548 MI->getOperand(i).isPhysicalRegister()) {
549 unsigned Reg = MI->getOperand(i).getAllocatedRegNum();
550 spillPhysReg(MBB, I, Reg, true); // Spill any existing value in the reg
551 PhysRegsUsed[Reg] = 0; // It is free and reserved now
552 PhysRegsUseOrder.push_back(Reg);
555 // Loop over the implicit defs, spilling them as well.
556 for (const unsigned *ImplicitDefs = TID.ImplicitDefs;
557 *ImplicitDefs; ++ImplicitDefs) {
558 unsigned Reg = *ImplicitDefs;
559 spillPhysReg(MBB, I, Reg);
560 PhysRegsUseOrder.push_back(Reg);
561 PhysRegsUsed[Reg] = 0; // It is free and reserved now
564 // Okay, we have allocated all of the source operands and spilled any values
565 // that would be destroyed by defs of this instruction. Loop over the
566 // implicit defs and assign them to a register, spilling incoming values if
567 // we need to scavenge a register.
569 for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i)
570 if (MI->getOperand(i).isDef() &&
571 MI->getOperand(i).isVirtualRegister()) {
572 unsigned DestVirtReg = MI->getOperand(i).getAllocatedRegNum();
573 unsigned DestPhysReg;
575 // If DestVirtReg already has a value, use it.
576 std::map<unsigned, unsigned>::iterator DestI =
577 Virt2PhysRegMap.find(DestVirtReg);
578 if (DestI != Virt2PhysRegMap.end()) {
579 DestPhysReg = DestI->second;
582 DestPhysReg = getReg(MBB, I, DestVirtReg);
584 markVirtRegModified(DestVirtReg);
585 MI->SetMachineOperandReg(i, DestPhysReg); // Assign the output register
589 // If this instruction defines any registers that are immediately dead,
592 for (LiveVariables::killed_iterator KI = LV->dead_begin(MI),
593 KE = LV->dead_end(MI); KI != KE; ++KI) {
594 unsigned VirtReg = KI->second;
595 unsigned PhysReg = VirtReg;
596 if (VirtReg >= MRegisterInfo::FirstVirtualRegister) {
597 std::map<unsigned, unsigned>::iterator I =
598 Virt2PhysRegMap.find(VirtReg);
599 assert(I != Virt2PhysRegMap.end());
601 Virt2PhysRegMap.erase(I);
605 DEBUG(std::cerr << " Register " << RegInfo->getName(PhysReg)
606 << " [%reg" << VirtReg
607 << "] is never used, removing it frame live list\n");
608 removePhysReg(PhysReg);
614 // Rewind the iterator to point to the first flow control instruction...
615 const TargetInstrInfo &TII = TM->getInstrInfo();
617 while (I != MBB.begin() && TII.isTerminatorInstr((*(I-1))->getOpcode()))
620 // Spill all physical registers holding virtual registers now.
621 while (!PhysRegsUsed.empty())
622 if (unsigned VirtReg = PhysRegsUsed.begin()->second)
623 spillVirtReg(MBB, I, VirtReg, PhysRegsUsed.begin()->first);
625 removePhysReg(PhysRegsUsed.begin()->first);
627 for (std::map<unsigned, unsigned>::iterator I = Virt2PhysRegMap.begin(),
628 E = Virt2PhysRegMap.end(); I != E; ++I)
629 std::cerr << "Register still mapped: " << I->first << " -> "
630 << I->second << "\n";
632 assert(Virt2PhysRegMap.empty() && "Virtual registers still in phys regs?");
634 // Clear any physical register which appear live at the end of the basic
635 // block, but which do not hold any virtual registers. e.g., the stack
637 PhysRegsUseOrder.clear();
641 /// runOnMachineFunction - Register allocate the whole function
643 bool RA::runOnMachineFunction(MachineFunction &Fn) {
644 DEBUG(std::cerr << "Machine Function " << "\n");
646 TM = &Fn.getTarget();
647 RegInfo = TM->getRegisterInfo();
650 LV = &getAnalysis<LiveVariables>();
652 // Loop over all of the basic blocks, eliminating virtual register references
653 for (MachineFunction::iterator MBB = Fn.begin(), MBBe = Fn.end();
655 AllocateBasicBlock(*MBB);
657 StackSlotForVirtReg.clear();
658 VirtRegModified.clear();
662 FunctionPass *createLocalRegisterAllocator() {
666 } // End llvm namespace