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"
31 Statistic<> NumSpilled ("ra-local", "Number of registers spilled");
32 Statistic<> NumReloaded("ra-local", "Number of registers reloaded");
33 cl::opt<bool> DisableKill("disable-kill", cl::Hidden,
34 cl::desc("Disable register kill in local-ra"));
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.
49 std::map<unsigned, unsigned> Virt2PhysRegMap;
51 // PhysRegsUsed - This array is effectively a map, containing entries for
52 // each physical register that currently has a value (ie, it is in
53 // Virt2PhysRegMap). The value mapped to is the virtual register
54 // corresponding to the physical register (the inverse of the
55 // Virt2PhysRegMap), or 0. The value is set to 0 if this register is pinned
56 // because it is used by a future instruction. If the entry for a physical
57 // register is -1, then the physical register is "not in the map".
59 int PhysRegsUsed[MRegisterInfo::FirstVirtualRegister];
61 // PhysRegsUseOrder - This contains a list of the physical registers that
62 // currently have a virtual register value in them. This list provides an
63 // ordering of registers, imposing a reallocation order. This list is only
64 // used if all registers are allocated and we have to spill one, in which
65 // case we spill the least recently used register. Entries at the front of
66 // the list are the least recently used registers, entries at the back are
67 // the most recently used.
69 std::vector<unsigned> PhysRegsUseOrder;
71 // VirtRegModified - This bitset contains information about which virtual
72 // registers need to be spilled back to memory when their registers are
73 // scavenged. If a virtual register has simply been rematerialized, there
74 // is no reason to spill it to memory when we need the register back.
76 std::vector<bool> VirtRegModified;
78 void markVirtRegModified(unsigned Reg, bool Val = true) {
79 assert(MRegisterInfo::isVirtualRegister(Reg) && "Illegal VirtReg!");
80 Reg -= MRegisterInfo::FirstVirtualRegister;
81 if (VirtRegModified.size() <= Reg) VirtRegModified.resize(Reg+1);
82 VirtRegModified[Reg] = Val;
85 bool isVirtRegModified(unsigned Reg) const {
86 assert(MRegisterInfo::isVirtualRegister(Reg) && "Illegal VirtReg!");
87 assert(Reg - MRegisterInfo::FirstVirtualRegister < VirtRegModified.size()
88 && "Illegal virtual register!");
89 return VirtRegModified[Reg - MRegisterInfo::FirstVirtualRegister];
92 void MarkPhysRegRecentlyUsed(unsigned Reg) {
93 assert(!PhysRegsUseOrder.empty() && "No registers used!");
94 if (PhysRegsUseOrder.back() == Reg) return; // Already most recently used
96 for (unsigned i = PhysRegsUseOrder.size(); i != 0; --i)
97 if (areRegsEqual(Reg, PhysRegsUseOrder[i-1])) {
98 unsigned RegMatch = PhysRegsUseOrder[i-1]; // remove from middle
99 PhysRegsUseOrder.erase(PhysRegsUseOrder.begin()+i-1);
100 // Add it to the end of the list
101 PhysRegsUseOrder.push_back(RegMatch);
103 return; // Found an exact match, exit early
108 virtual const char *getPassName() const {
109 return "Local Register Allocator";
112 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
114 AU.addRequired<LiveVariables>();
115 AU.addRequiredID(PHIEliminationID);
116 AU.addRequiredID(TwoAddressInstructionPassID);
117 MachineFunctionPass::getAnalysisUsage(AU);
121 /// runOnMachineFunction - Register allocate the whole function
122 bool runOnMachineFunction(MachineFunction &Fn);
124 /// AllocateBasicBlock - Register allocate the specified basic block.
125 void AllocateBasicBlock(MachineBasicBlock &MBB);
128 /// areRegsEqual - This method returns true if the specified registers are
129 /// related to each other. To do this, it checks to see if they are equal
130 /// or if the first register is in the alias set of the second register.
132 bool areRegsEqual(unsigned R1, unsigned R2) const {
133 if (R1 == R2) return true;
134 for (const unsigned *AliasSet = RegInfo->getAliasSet(R2);
135 *AliasSet; ++AliasSet) {
136 if (*AliasSet == R1) return true;
141 /// getStackSpaceFor - This returns the frame index of the specified virtual
142 /// register on the stack, allocating space if necessary.
143 int getStackSpaceFor(unsigned VirtReg, const TargetRegisterClass *RC);
145 /// removePhysReg - This method marks the specified physical register as no
146 /// longer being in use.
148 void removePhysReg(unsigned PhysReg);
150 /// spillVirtReg - This method spills the value specified by PhysReg into
151 /// the virtual register slot specified by VirtReg. It then updates the RA
152 /// data structures to indicate the fact that PhysReg is now available.
154 void spillVirtReg(MachineBasicBlock &MBB, MachineBasicBlock::iterator &I,
155 unsigned VirtReg, unsigned PhysReg);
157 /// spillPhysReg - This method spills the specified physical register into
158 /// the virtual register slot associated with it. If OnlyVirtRegs is set to
159 /// true, then the request is ignored if the physical register does not
160 /// contain a virtual register.
162 void spillPhysReg(MachineBasicBlock &MBB, MachineBasicBlock::iterator &I,
163 unsigned PhysReg, bool OnlyVirtRegs = false);
165 /// assignVirtToPhysReg - This method updates local state so that we know
166 /// that PhysReg is the proper container for VirtReg now. The physical
167 /// register must not be used for anything else when this is called.
169 void assignVirtToPhysReg(unsigned VirtReg, unsigned PhysReg);
171 /// liberatePhysReg - Make sure the specified physical register is available
172 /// for use. If there is currently a value in it, it is either moved out of
173 /// the way or spilled to memory.
175 void liberatePhysReg(MachineBasicBlock &MBB, MachineBasicBlock::iterator &I,
178 /// isPhysRegAvailable - Return true if the specified physical register is
179 /// free and available for use. This also includes checking to see if
180 /// aliased registers are all free...
182 bool isPhysRegAvailable(unsigned PhysReg) const;
184 /// getFreeReg - Look to see if there is a free register available in the
185 /// specified register class. If not, return 0.
187 unsigned getFreeReg(const TargetRegisterClass *RC);
189 /// getReg - Find a physical register to hold the specified virtual
190 /// register. If all compatible physical registers are used, this method
191 /// spills the last used virtual register to the stack, and uses that
194 unsigned getReg(MachineBasicBlock &MBB, MachineBasicBlock::iterator &I,
197 /// reloadVirtReg - This method loads the specified virtual register into a
198 /// physical register, returning the physical register chosen. This updates
199 /// the regalloc data structures to reflect the fact that the virtual reg is
200 /// now alive in a physical register, and the previous one isn't.
202 unsigned reloadVirtReg(MachineBasicBlock &MBB,
203 MachineBasicBlock::iterator &I, unsigned VirtReg);
205 void reloadPhysReg(MachineBasicBlock &MBB, MachineBasicBlock::iterator &I,
210 /// getStackSpaceFor - This allocates space for the specified virtual register
211 /// to be held on the stack.
212 int RA::getStackSpaceFor(unsigned VirtReg, const TargetRegisterClass *RC) {
213 // Find the location Reg would belong...
214 std::map<unsigned, int>::iterator I =StackSlotForVirtReg.lower_bound(VirtReg);
216 if (I != StackSlotForVirtReg.end() && I->first == VirtReg)
217 return I->second; // Already has space allocated?
219 // Allocate a new stack object for this spill location...
220 int FrameIdx = MF->getFrameInfo()->CreateStackObject(RC);
222 // Assign the slot...
223 StackSlotForVirtReg.insert(I, std::make_pair(VirtReg, FrameIdx));
228 /// removePhysReg - This method marks the specified physical register as no
229 /// longer being in use.
231 void RA::removePhysReg(unsigned PhysReg) {
232 PhysRegsUsed[PhysReg] = -1; // PhyReg no longer used
234 std::vector<unsigned>::iterator It =
235 std::find(PhysRegsUseOrder.begin(), PhysRegsUseOrder.end(), PhysReg);
236 if (It != PhysRegsUseOrder.end())
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 if (PhysRegsUsed[PhysReg] != -1) { // Only spill it if it's used!
281 if (PhysRegsUsed[PhysReg] || !OnlyVirtRegs)
282 spillVirtReg(MBB, I, PhysRegsUsed[PhysReg], PhysReg);
284 // If the selected register aliases any other registers, we must make
285 // sure that one of the aliases isn't alive...
286 for (const unsigned *AliasSet = RegInfo->getAliasSet(PhysReg);
287 *AliasSet; ++AliasSet)
288 if (PhysRegsUsed[*AliasSet] != -1) // Spill aliased register...
289 if (PhysRegsUsed[*AliasSet] || !OnlyVirtRegs)
290 spillVirtReg(MBB, I, PhysRegsUsed[*AliasSet], *AliasSet);
295 /// assignVirtToPhysReg - This method updates local state so that we know
296 /// that PhysReg is the proper container for VirtReg now. The physical
297 /// register must not be used for anything else when this is called.
299 void RA::assignVirtToPhysReg(unsigned VirtReg, unsigned PhysReg) {
300 assert(PhysRegsUsed[PhysReg] == -1 && "Phys reg already assigned!");
301 // Update information to note the fact that this register was just used, and
303 PhysRegsUsed[PhysReg] = VirtReg;
304 Virt2PhysRegMap[VirtReg] = PhysReg;
305 PhysRegsUseOrder.push_back(PhysReg); // New use of PhysReg
309 /// isPhysRegAvailable - Return true if the specified physical register is free
310 /// and available for use. This also includes checking to see if aliased
311 /// registers are all free...
313 bool RA::isPhysRegAvailable(unsigned PhysReg) const {
314 if (PhysRegsUsed[PhysReg] != -1) return false;
316 // If the selected register aliases any other allocated registers, it is
318 for (const unsigned *AliasSet = RegInfo->getAliasSet(PhysReg);
319 *AliasSet; ++AliasSet)
320 if (PhysRegsUsed[*AliasSet] != -1) // Aliased register in use?
321 return false; // Can't use this reg then.
326 /// getFreeReg - Look to see if there is a free register available in the
327 /// specified register class. If not, return 0.
329 unsigned RA::getFreeReg(const TargetRegisterClass *RC) {
330 // Get iterators defining the range of registers that are valid to allocate in
331 // this class, which also specifies the preferred allocation order.
332 TargetRegisterClass::iterator RI = RC->allocation_order_begin(*MF);
333 TargetRegisterClass::iterator RE = RC->allocation_order_end(*MF);
335 for (; RI != RE; ++RI)
336 if (isPhysRegAvailable(*RI)) { // Is reg unused?
337 assert(*RI != 0 && "Cannot use register!");
338 return *RI; // Found an unused register!
344 /// liberatePhysReg - Make sure the specified physical register is available for
345 /// use. If there is currently a value in it, it is either moved out of the way
346 /// or spilled to memory.
348 void RA::liberatePhysReg(MachineBasicBlock &MBB, MachineBasicBlock::iterator &I,
350 // FIXME: This code checks to see if a register is available, but it really
351 // wants to know if a reg is available BEFORE the instruction executes. If
352 // called after killed operands are freed, it runs the risk of reallocating a
355 if (isPhysRegAvailable(PhysReg)) return; // Already available...
357 // Check to see if the register is directly used, not indirectly used through
358 // aliases. If aliased registers are the ones actually used, we cannot be
359 // sure that we will be able to save the whole thing if we do a reg-reg copy.
360 if (PhysRegsUsed[PhysReg] != -1) {
361 // The virtual register held...
362 unsigned VirtReg = PhysRegsUsed[PhysReg]->second;
364 // Check to see if there is a compatible register available. If so, we can
365 // move the value into the new register...
367 const TargetRegisterClass *RC = RegInfo->getRegClass(PhysReg);
368 if (unsigned NewReg = getFreeReg(RC)) {
369 // Emit the code to copy the value...
370 RegInfo->copyRegToReg(MBB, I, NewReg, PhysReg, RC);
372 // Update our internal state to indicate that PhysReg is available and Reg
374 Virt2PhysRegMap.erase(VirtReg);
375 removePhysReg(PhysReg); // Free the physreg
377 // Move reference over to new register...
378 assignVirtToPhysReg(VirtReg, NewReg);
383 spillPhysReg(MBB, I, PhysReg);
387 /// getReg - Find a physical register to hold the specified virtual
388 /// register. If all compatible physical registers are used, this method spills
389 /// the last used virtual register to the stack, and uses that register.
391 unsigned RA::getReg(MachineBasicBlock &MBB, MachineBasicBlock::iterator &I,
393 const TargetRegisterClass *RC = MF->getSSARegMap()->getRegClass(VirtReg);
395 // First check to see if we have a free register of the requested type...
396 unsigned PhysReg = getFreeReg(RC);
398 // If we didn't find an unused register, scavenge one now!
400 assert(!PhysRegsUseOrder.empty() && "No allocated registers??");
402 // Loop over all of the preallocated registers from the least recently used
403 // to the most recently used. When we find one that is capable of holding
404 // our register, use it.
405 for (unsigned i = 0; PhysReg == 0; ++i) {
406 assert(i != PhysRegsUseOrder.size() &&
407 "Couldn't find a register of the appropriate class!");
409 unsigned R = PhysRegsUseOrder[i];
411 // We can only use this register if it holds a virtual register (ie, it
412 // can be spilled). Do not use it if it is an explicitly allocated
413 // physical register!
414 assert(PhysRegsUsed[R] != -1 &&
415 "PhysReg in PhysRegsUseOrder, but is not allocated?");
416 if (PhysRegsUsed[R]) {
417 // If the current register is compatible, use it.
418 if (RegInfo->getRegClass(R) == RC) {
422 // If one of the registers aliased to the current register is
423 // compatible, use it.
424 for (const unsigned *AliasSet = RegInfo->getAliasSet(R);
425 *AliasSet; ++AliasSet) {
426 if (RegInfo->getRegClass(*AliasSet) == RC) {
427 PhysReg = *AliasSet; // Take an aliased register
435 assert(PhysReg && "Physical register not assigned!?!?");
437 // At this point PhysRegsUseOrder[i] is the least recently used register of
438 // compatible register class. Spill it to memory and reap its remains.
439 spillPhysReg(MBB, I, PhysReg);
442 // Now that we know which register we need to assign this to, do it now!
443 assignVirtToPhysReg(VirtReg, PhysReg);
448 /// reloadVirtReg - This method loads the specified virtual register into a
449 /// physical register, returning the physical register chosen. This updates the
450 /// regalloc data structures to reflect the fact that the virtual reg is now
451 /// alive in a physical register, and the previous one isn't.
453 unsigned RA::reloadVirtReg(MachineBasicBlock &MBB,
454 MachineBasicBlock::iterator &I,
456 std::map<unsigned, unsigned>::iterator It = Virt2PhysRegMap.find(VirtReg);
457 if (It != Virt2PhysRegMap.end()) {
458 MarkPhysRegRecentlyUsed(It->second);
459 return It->second; // Already have this value available!
462 unsigned PhysReg = getReg(MBB, I, VirtReg);
464 const TargetRegisterClass *RC = MF->getSSARegMap()->getRegClass(VirtReg);
465 int FrameIndex = getStackSpaceFor(VirtReg, RC);
467 markVirtRegModified(VirtReg, false); // Note that this reg was just reloaded
469 DEBUG(std::cerr << " Reloading %reg" << VirtReg << " into "
470 << RegInfo->getName(PhysReg) << "\n");
472 // Add move instruction(s)
473 RegInfo->loadRegFromStackSlot(MBB, I, PhysReg, FrameIndex, RC);
474 ++NumReloaded; // Update statistics
480 void RA::AllocateBasicBlock(MachineBasicBlock &MBB) {
481 // loop over each instruction
482 MachineBasicBlock::iterator I = MBB.begin();
483 for (; I != MBB.end(); ++I) {
484 MachineInstr *MI = *I;
485 const TargetInstrDescriptor &TID = TM->getInstrInfo().get(MI->getOpcode());
486 DEBUG(std::cerr << "\nStarting RegAlloc of: " << *MI;
487 std::cerr << " Regs have values: ";
488 for (unsigned i = 0; i != RegInfo->getNumRegs(); ++i)
489 if (PhysRegsUsed[i] != -1)
490 std::cerr << "[" << RegInfo->getName(i)
491 << ",%reg" << PhysRegsUsed[i] << "] ";
494 // Loop over the implicit uses, making sure that they are at the head of the
495 // use order list, so they don't get reallocated.
496 for (const unsigned *ImplicitUses = TID.ImplicitUses;
497 *ImplicitUses; ++ImplicitUses)
498 MarkPhysRegRecentlyUsed(*ImplicitUses);
500 // Get the used operands into registers. This has the potential to spill
501 // incoming values if we are out of registers. Note that we completely
502 // ignore physical register uses here. We assume that if an explicit
503 // physical register is referenced by the instruction, that it is guaranteed
504 // to be live-in, or the input is badly hosed.
506 for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i)
507 if (MI->getOperand(i).isUse() &&
508 !MI->getOperand(i).isDef() &&
509 MI->getOperand(i).isVirtualRegister()){
510 unsigned VirtSrcReg = MI->getOperand(i).getAllocatedRegNum();
511 unsigned PhysSrcReg = reloadVirtReg(MBB, I, VirtSrcReg);
512 MI->SetMachineOperandReg(i, PhysSrcReg); // Assign the input register
516 // If this instruction is the last user of anything in registers, kill the
517 // value, freeing the register being used, so it doesn't need to be
518 // spilled to memory.
520 for (LiveVariables::killed_iterator KI = LV->killed_begin(MI),
521 KE = LV->killed_end(MI); KI != KE; ++KI) {
522 unsigned VirtReg = KI->second;
523 unsigned PhysReg = VirtReg;
524 if (MRegisterInfo::isVirtualRegister(VirtReg)) {
525 std::map<unsigned, unsigned>::iterator I =
526 Virt2PhysRegMap.find(VirtReg);
527 assert(I != Virt2PhysRegMap.end());
529 Virt2PhysRegMap.erase(I);
533 DEBUG(std::cerr << " Last use of " << RegInfo->getName(PhysReg)
534 << "[%reg" << VirtReg <<"], removing it from live set\n");
535 removePhysReg(PhysReg);
540 // Loop over all of the operands of the instruction, spilling registers that
541 // are defined, and marking explicit destinations in the PhysRegsUsed map.
542 for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i)
543 if (MI->getOperand(i).isDef() &&
544 MI->getOperand(i).isPhysicalRegister()) {
545 unsigned Reg = MI->getOperand(i).getAllocatedRegNum();
546 spillPhysReg(MBB, I, Reg, true); // Spill any existing value in the reg
547 PhysRegsUsed[Reg] = 0; // It is free and reserved now
548 PhysRegsUseOrder.push_back(Reg);
549 for (const unsigned *AliasSet = RegInfo->getAliasSet(Reg);
550 *AliasSet; ++AliasSet) {
551 PhysRegsUseOrder.push_back(*AliasSet);
552 PhysRegsUsed[*AliasSet] = 0; // It is free and reserved now
556 // Loop over the implicit defs, spilling them as well.
557 for (const unsigned *ImplicitDefs = TID.ImplicitDefs;
558 *ImplicitDefs; ++ImplicitDefs) {
559 unsigned Reg = *ImplicitDefs;
560 spillPhysReg(MBB, I, Reg);
561 PhysRegsUseOrder.push_back(Reg);
562 PhysRegsUsed[Reg] = 0; // It is free and reserved now
563 for (const unsigned *AliasSet = RegInfo->getAliasSet(Reg);
564 *AliasSet; ++AliasSet) {
565 PhysRegsUseOrder.push_back(*AliasSet);
566 PhysRegsUsed[*AliasSet] = 0; // It is free and reserved now
570 // Okay, we have allocated all of the source operands and spilled any values
571 // that would be destroyed by defs of this instruction. Loop over the
572 // implicit defs and assign them to a register, spilling incoming values if
573 // we need to scavenge a register.
575 for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i)
576 if (MI->getOperand(i).isDef() &&
577 MI->getOperand(i).isVirtualRegister()) {
578 unsigned DestVirtReg = MI->getOperand(i).getAllocatedRegNum();
579 unsigned DestPhysReg;
581 // If DestVirtReg already has a value, use it.
582 std::map<unsigned, unsigned>::iterator DestI =
583 Virt2PhysRegMap.find(DestVirtReg);
584 if (DestI != Virt2PhysRegMap.end()) {
585 DestPhysReg = DestI->second;
588 DestPhysReg = getReg(MBB, I, 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 std::map<unsigned, unsigned>::iterator I =
604 Virt2PhysRegMap.find(VirtReg);
605 assert(I != Virt2PhysRegMap.end());
607 Virt2PhysRegMap.erase(I);
611 DEBUG(std::cerr << " Register " << RegInfo->getName(PhysReg)
612 << " [%reg" << VirtReg
613 << "] is never used, removing it frame live list\n");
614 removePhysReg(PhysReg);
620 // Rewind the iterator to point to the first flow control instruction...
621 const TargetInstrInfo &TII = TM->getInstrInfo();
623 while (I != MBB.begin() && TII.isTerminatorInstr((*(I-1))->getOpcode()))
626 // Spill all physical registers holding virtual registers now.
627 for (unsigned i = 0, e = RegInfo->getNumRegs(); i != e; ++i)
628 if (PhysRegsUsed[i] != -1)
629 if (unsigned VirtReg = PhysRegsUsed[i])
630 spillVirtReg(MBB, I, VirtReg, i);
634 for (std::map<unsigned, unsigned>::iterator I = Virt2PhysRegMap.begin(),
635 E = Virt2PhysRegMap.end(); I != E; ++I)
636 std::cerr << "Register still mapped: " << I->first << " -> "
637 << I->second << "\n";
639 assert(Virt2PhysRegMap.empty() && "Virtual registers still in phys regs?");
641 // Clear any physical register which appear live at the end of the basic
642 // block, but which do not hold any virtual registers. e.g., the stack
644 PhysRegsUseOrder.clear();
648 /// runOnMachineFunction - Register allocate the whole function
650 bool RA::runOnMachineFunction(MachineFunction &Fn) {
651 DEBUG(std::cerr << "Machine Function " << "\n");
653 TM = &Fn.getTarget();
654 RegInfo = TM->getRegisterInfo();
656 memset(PhysRegsUsed, -1, RegInfo->getNumRegs()*sizeof(unsigned));
659 LV = &getAnalysis<LiveVariables>();
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 VirtRegModified.clear();
671 FunctionPass *llvm::createLocalRegisterAllocator() {