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. This is "logically"
48 // a map from virtual register numbers to physical register numbers.
49 // Instead of using a map, however, which is slow, we use a vector. The
50 // index is the VREG number - FirstVirtualRegister. If the entry is zero,
51 // then it is logically "not in the map".
53 std::vector<unsigned> Virt2PhysRegMap;
55 unsigned &getVirt2PhysRegMapSlot(unsigned VirtReg) {
56 assert(VirtReg >= MRegisterInfo::FirstVirtualRegister &&"Illegal VREG #");
57 assert(VirtReg-MRegisterInfo::FirstVirtualRegister <Virt2PhysRegMap.size()
58 && "VirtReg not in map!");
59 return Virt2PhysRegMap[VirtReg-MRegisterInfo::FirstVirtualRegister];
61 unsigned &getOrInsertVirt2PhysRegMapSlot(unsigned VirtReg) {
62 assert(VirtReg >= MRegisterInfo::FirstVirtualRegister &&"Illegal VREG #");
63 if (VirtReg-MRegisterInfo::FirstVirtualRegister >= Virt2PhysRegMap.size())
64 Virt2PhysRegMap.resize(VirtReg-MRegisterInfo::FirstVirtualRegister+1);
65 return Virt2PhysRegMap[VirtReg-MRegisterInfo::FirstVirtualRegister];
68 // PhysRegsUsed - This array is effectively a map, containing entries for
69 // each physical register that currently has a value (ie, it is in
70 // Virt2PhysRegMap). The value mapped to is the virtual register
71 // corresponding to the physical register (the inverse of the
72 // Virt2PhysRegMap), or 0. The value is set to 0 if this register is pinned
73 // because it is used by a future instruction. If the entry for a physical
74 // register is -1, then the physical register is "not in the map".
76 int PhysRegsUsed[MRegisterInfo::FirstVirtualRegister];
78 // PhysRegsUseOrder - This contains a list of the physical registers that
79 // currently have a virtual register value in them. This list provides an
80 // ordering of registers, imposing a reallocation order. This list is only
81 // used if all registers are allocated and we have to spill one, in which
82 // case we spill the least recently used register. Entries at the front of
83 // the list are the least recently used registers, entries at the back are
84 // the most recently used.
86 std::vector<unsigned> PhysRegsUseOrder;
88 // VirtRegModified - This bitset contains information about which virtual
89 // registers need to be spilled back to memory when their registers are
90 // scavenged. If a virtual register has simply been rematerialized, there
91 // is no reason to spill it to memory when we need the register back.
93 std::vector<bool> VirtRegModified;
95 void markVirtRegModified(unsigned Reg, bool Val = true) {
96 assert(MRegisterInfo::isVirtualRegister(Reg) && "Illegal VirtReg!");
97 Reg -= MRegisterInfo::FirstVirtualRegister;
98 if (VirtRegModified.size() <= Reg) VirtRegModified.resize(Reg+1);
99 VirtRegModified[Reg] = Val;
102 bool isVirtRegModified(unsigned Reg) const {
103 assert(MRegisterInfo::isVirtualRegister(Reg) && "Illegal VirtReg!");
104 assert(Reg - MRegisterInfo::FirstVirtualRegister < VirtRegModified.size()
105 && "Illegal virtual register!");
106 return VirtRegModified[Reg - MRegisterInfo::FirstVirtualRegister];
109 void MarkPhysRegRecentlyUsed(unsigned Reg) {
110 assert(!PhysRegsUseOrder.empty() && "No registers used!");
111 if (PhysRegsUseOrder.back() == Reg) return; // Already most recently used
113 for (unsigned i = PhysRegsUseOrder.size(); i != 0; --i)
114 if (areRegsEqual(Reg, PhysRegsUseOrder[i-1])) {
115 unsigned RegMatch = PhysRegsUseOrder[i-1]; // remove from middle
116 PhysRegsUseOrder.erase(PhysRegsUseOrder.begin()+i-1);
117 // Add it to the end of the list
118 PhysRegsUseOrder.push_back(RegMatch);
120 return; // Found an exact match, exit early
125 virtual const char *getPassName() const {
126 return "Local Register Allocator";
129 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
131 AU.addRequired<LiveVariables>();
132 AU.addRequiredID(PHIEliminationID);
133 AU.addRequiredID(TwoAddressInstructionPassID);
134 MachineFunctionPass::getAnalysisUsage(AU);
138 /// runOnMachineFunction - Register allocate the whole function
139 bool runOnMachineFunction(MachineFunction &Fn);
141 /// AllocateBasicBlock - Register allocate the specified basic block.
142 void AllocateBasicBlock(MachineBasicBlock &MBB);
145 /// areRegsEqual - This method returns true if the specified registers are
146 /// related to each other. To do this, it checks to see if they are equal
147 /// or if the first register is in the alias set of the second register.
149 bool areRegsEqual(unsigned R1, unsigned R2) const {
150 if (R1 == R2) return true;
151 for (const unsigned *AliasSet = RegInfo->getAliasSet(R2);
152 *AliasSet; ++AliasSet) {
153 if (*AliasSet == R1) return true;
158 /// getStackSpaceFor - This returns the frame index of the specified virtual
159 /// register on the stack, allocating space if necessary.
160 int getStackSpaceFor(unsigned VirtReg, const TargetRegisterClass *RC);
162 /// removePhysReg - This method marks the specified physical register as no
163 /// longer being in use.
165 void removePhysReg(unsigned PhysReg);
167 /// spillVirtReg - This method spills the value specified by PhysReg into
168 /// the virtual register slot specified by VirtReg. It then updates the RA
169 /// data structures to indicate the fact that PhysReg is now available.
171 void spillVirtReg(MachineBasicBlock &MBB, MachineBasicBlock::iterator &I,
172 unsigned VirtReg, unsigned PhysReg);
174 /// spillPhysReg - This method spills the specified physical register into
175 /// the virtual register slot associated with it. If OnlyVirtRegs is set to
176 /// true, then the request is ignored if the physical register does not
177 /// contain a virtual register.
179 void spillPhysReg(MachineBasicBlock &MBB, MachineBasicBlock::iterator &I,
180 unsigned PhysReg, bool OnlyVirtRegs = false);
182 /// assignVirtToPhysReg - This method updates local state so that we know
183 /// that PhysReg is the proper container for VirtReg now. The physical
184 /// register must not be used for anything else when this is called.
186 void assignVirtToPhysReg(unsigned VirtReg, unsigned PhysReg);
188 /// liberatePhysReg - Make sure the specified physical register is available
189 /// for use. If there is currently a value in it, it is either moved out of
190 /// the way or spilled to memory.
192 void liberatePhysReg(MachineBasicBlock &MBB, MachineBasicBlock::iterator &I,
195 /// isPhysRegAvailable - Return true if the specified physical register is
196 /// free and available for use. This also includes checking to see if
197 /// aliased registers are all free...
199 bool isPhysRegAvailable(unsigned PhysReg) const;
201 /// getFreeReg - Look to see if there is a free register available in the
202 /// specified register class. If not, return 0.
204 unsigned getFreeReg(const TargetRegisterClass *RC);
206 /// getReg - Find a physical register to hold the specified virtual
207 /// register. If all compatible physical registers are used, this method
208 /// spills the last used virtual register to the stack, and uses that
211 unsigned getReg(MachineBasicBlock &MBB, MachineBasicBlock::iterator &I,
214 /// reloadVirtReg - This method loads the specified virtual register into a
215 /// physical register, returning the physical register chosen. This updates
216 /// the regalloc data structures to reflect the fact that the virtual reg is
217 /// now alive in a physical register, and the previous one isn't.
219 unsigned reloadVirtReg(MachineBasicBlock &MBB,
220 MachineBasicBlock::iterator &I, unsigned VirtReg);
222 void reloadPhysReg(MachineBasicBlock &MBB, MachineBasicBlock::iterator &I,
227 /// getStackSpaceFor - This allocates space for the specified virtual register
228 /// to be held on the stack.
229 int RA::getStackSpaceFor(unsigned VirtReg, const TargetRegisterClass *RC) {
230 // Find the location Reg would belong...
231 std::map<unsigned, int>::iterator I =StackSlotForVirtReg.lower_bound(VirtReg);
233 if (I != StackSlotForVirtReg.end() && I->first == VirtReg)
234 return I->second; // Already has space allocated?
236 // Allocate a new stack object for this spill location...
237 int FrameIdx = MF->getFrameInfo()->CreateStackObject(RC);
239 // Assign the slot...
240 StackSlotForVirtReg.insert(I, std::make_pair(VirtReg, FrameIdx));
245 /// removePhysReg - This method marks the specified physical register as no
246 /// longer being in use.
248 void RA::removePhysReg(unsigned PhysReg) {
249 PhysRegsUsed[PhysReg] = -1; // PhyReg no longer used
251 std::vector<unsigned>::iterator It =
252 std::find(PhysRegsUseOrder.begin(), PhysRegsUseOrder.end(), PhysReg);
253 if (It != PhysRegsUseOrder.end())
254 PhysRegsUseOrder.erase(It);
258 /// spillVirtReg - This method spills the value specified by PhysReg into the
259 /// virtual register slot specified by VirtReg. It then updates the RA data
260 /// structures to indicate the fact that PhysReg is now available.
262 void RA::spillVirtReg(MachineBasicBlock &MBB, MachineBasicBlock::iterator &I,
263 unsigned VirtReg, unsigned PhysReg) {
264 if (!VirtReg && DisableKill) return;
265 assert(VirtReg && "Spilling a physical register is illegal!"
266 " Must not have appropriate kill for the register or use exists beyond"
267 " the intended one.");
268 DEBUG(std::cerr << " Spilling register " << RegInfo->getName(PhysReg);
269 std::cerr << " containing %reg" << VirtReg;
270 if (!isVirtRegModified(VirtReg))
271 std::cerr << " which has not been modified, so no store necessary!");
273 // Otherwise, there is a virtual register corresponding to this physical
274 // register. We only need to spill it into its stack slot if it has been
276 if (isVirtRegModified(VirtReg)) {
277 const TargetRegisterClass *RC = MF->getSSARegMap()->getRegClass(VirtReg);
278 int FrameIndex = getStackSpaceFor(VirtReg, RC);
279 DEBUG(std::cerr << " to stack slot #" << FrameIndex);
280 RegInfo->storeRegToStackSlot(MBB, I, PhysReg, FrameIndex, RC);
281 ++NumSpilled; // Update statistics
284 getVirt2PhysRegMapSlot(VirtReg) = 0; // VirtReg no longer available
286 DEBUG(std::cerr << "\n");
287 removePhysReg(PhysReg);
291 /// spillPhysReg - This method spills the specified physical register into the
292 /// virtual register slot associated with it. If OnlyVirtRegs is set to true,
293 /// then the request is ignored if the physical register does not contain a
294 /// virtual register.
296 void RA::spillPhysReg(MachineBasicBlock &MBB, MachineBasicBlock::iterator &I,
297 unsigned PhysReg, bool OnlyVirtRegs) {
298 if (PhysRegsUsed[PhysReg] != -1) { // Only spill it if it's used!
299 if (PhysRegsUsed[PhysReg] || !OnlyVirtRegs)
300 spillVirtReg(MBB, I, PhysRegsUsed[PhysReg], PhysReg);
302 // If the selected register aliases any other registers, we must make
303 // sure that one of the aliases isn't alive...
304 for (const unsigned *AliasSet = RegInfo->getAliasSet(PhysReg);
305 *AliasSet; ++AliasSet)
306 if (PhysRegsUsed[*AliasSet] != -1) // Spill aliased register...
307 if (PhysRegsUsed[*AliasSet] || !OnlyVirtRegs)
308 spillVirtReg(MBB, I, PhysRegsUsed[*AliasSet], *AliasSet);
313 /// assignVirtToPhysReg - This method updates local state so that we know
314 /// that PhysReg is the proper container for VirtReg now. The physical
315 /// register must not be used for anything else when this is called.
317 void RA::assignVirtToPhysReg(unsigned VirtReg, unsigned PhysReg) {
318 assert(PhysRegsUsed[PhysReg] == -1 && "Phys reg already assigned!");
319 // Update information to note the fact that this register was just used, and
321 PhysRegsUsed[PhysReg] = VirtReg;
322 getOrInsertVirt2PhysRegMapSlot(VirtReg) = PhysReg;
323 PhysRegsUseOrder.push_back(PhysReg); // New use of PhysReg
327 /// isPhysRegAvailable - Return true if the specified physical register is free
328 /// and available for use. This also includes checking to see if aliased
329 /// registers are all free...
331 bool RA::isPhysRegAvailable(unsigned PhysReg) const {
332 if (PhysRegsUsed[PhysReg] != -1) return false;
334 // If the selected register aliases any other allocated registers, it is
336 for (const unsigned *AliasSet = RegInfo->getAliasSet(PhysReg);
337 *AliasSet; ++AliasSet)
338 if (PhysRegsUsed[*AliasSet] != -1) // Aliased register in use?
339 return false; // Can't use this reg then.
344 /// getFreeReg - Look to see if there is a free register available in the
345 /// specified register class. If not, return 0.
347 unsigned RA::getFreeReg(const TargetRegisterClass *RC) {
348 // Get iterators defining the range of registers that are valid to allocate in
349 // this class, which also specifies the preferred allocation order.
350 TargetRegisterClass::iterator RI = RC->allocation_order_begin(*MF);
351 TargetRegisterClass::iterator RE = RC->allocation_order_end(*MF);
353 for (; RI != RE; ++RI)
354 if (isPhysRegAvailable(*RI)) { // Is reg unused?
355 assert(*RI != 0 && "Cannot use register!");
356 return *RI; // Found an unused register!
362 /// liberatePhysReg - Make sure the specified physical register is available for
363 /// use. If there is currently a value in it, it is either moved out of the way
364 /// or spilled to memory.
366 void RA::liberatePhysReg(MachineBasicBlock &MBB, MachineBasicBlock::iterator &I,
368 // FIXME: This code checks to see if a register is available, but it really
369 // wants to know if a reg is available BEFORE the instruction executes. If
370 // called after killed operands are freed, it runs the risk of reallocating a
373 if (isPhysRegAvailable(PhysReg)) return; // Already available...
375 // Check to see if the register is directly used, not indirectly used through
376 // aliases. If aliased registers are the ones actually used, we cannot be
377 // sure that we will be able to save the whole thing if we do a reg-reg copy.
378 if (PhysRegsUsed[PhysReg] != -1) {
379 // The virtual register held...
380 unsigned VirtReg = PhysRegsUsed[PhysReg]->second;
382 // Check to see if there is a compatible register available. If so, we can
383 // move the value into the new register...
385 const TargetRegisterClass *RC = RegInfo->getRegClass(PhysReg);
386 if (unsigned NewReg = getFreeReg(RC)) {
387 // Emit the code to copy the value...
388 RegInfo->copyRegToReg(MBB, I, NewReg, PhysReg, RC);
390 // Update our internal state to indicate that PhysReg is available and Reg
392 getVirt2PhysRegMapSlot[VirtReg] = 0;
393 removePhysReg(PhysReg); // Free the physreg
395 // Move reference over to new register...
396 assignVirtToPhysReg(VirtReg, NewReg);
401 spillPhysReg(MBB, I, PhysReg);
405 /// getReg - Find a physical register to hold the specified virtual
406 /// register. If all compatible physical registers are used, this method spills
407 /// the last used virtual register to the stack, and uses that register.
409 unsigned RA::getReg(MachineBasicBlock &MBB, MachineBasicBlock::iterator &I,
411 const TargetRegisterClass *RC = MF->getSSARegMap()->getRegClass(VirtReg);
413 // First check to see if we have a free register of the requested type...
414 unsigned PhysReg = getFreeReg(RC);
416 // If we didn't find an unused register, scavenge one now!
418 assert(!PhysRegsUseOrder.empty() && "No allocated registers??");
420 // Loop over all of the preallocated registers from the least recently used
421 // to the most recently used. When we find one that is capable of holding
422 // our register, use it.
423 for (unsigned i = 0; PhysReg == 0; ++i) {
424 assert(i != PhysRegsUseOrder.size() &&
425 "Couldn't find a register of the appropriate class!");
427 unsigned R = PhysRegsUseOrder[i];
429 // We can only use this register if it holds a virtual register (ie, it
430 // can be spilled). Do not use it if it is an explicitly allocated
431 // physical register!
432 assert(PhysRegsUsed[R] != -1 &&
433 "PhysReg in PhysRegsUseOrder, but is not allocated?");
434 if (PhysRegsUsed[R]) {
435 // If the current register is compatible, use it.
436 if (RegInfo->getRegClass(R) == RC) {
440 // If one of the registers aliased to the current register is
441 // compatible, use it.
442 for (const unsigned *AliasSet = RegInfo->getAliasSet(R);
443 *AliasSet; ++AliasSet) {
444 if (RegInfo->getRegClass(*AliasSet) == RC) {
445 PhysReg = *AliasSet; // Take an aliased register
453 assert(PhysReg && "Physical register not assigned!?!?");
455 // At this point PhysRegsUseOrder[i] is the least recently used register of
456 // compatible register class. Spill it to memory and reap its remains.
457 spillPhysReg(MBB, I, PhysReg);
460 // Now that we know which register we need to assign this to, do it now!
461 assignVirtToPhysReg(VirtReg, PhysReg);
466 /// reloadVirtReg - This method loads the specified virtual register into a
467 /// physical register, returning the physical register chosen. This updates the
468 /// regalloc data structures to reflect the fact that the virtual reg is now
469 /// alive in a physical register, and the previous one isn't.
471 unsigned RA::reloadVirtReg(MachineBasicBlock &MBB,
472 MachineBasicBlock::iterator &I,
474 if (unsigned PR = getOrInsertVirt2PhysRegMapSlot(VirtReg)) {
475 MarkPhysRegRecentlyUsed(PR);
476 return PR; // Already have this value available!
479 unsigned PhysReg = getReg(MBB, I, VirtReg);
481 const TargetRegisterClass *RC = MF->getSSARegMap()->getRegClass(VirtReg);
482 int FrameIndex = getStackSpaceFor(VirtReg, RC);
484 markVirtRegModified(VirtReg, false); // Note that this reg was just reloaded
486 DEBUG(std::cerr << " Reloading %reg" << VirtReg << " into "
487 << RegInfo->getName(PhysReg) << "\n");
489 // Add move instruction(s)
490 RegInfo->loadRegFromStackSlot(MBB, I, PhysReg, FrameIndex, RC);
491 ++NumReloaded; // Update statistics
497 void RA::AllocateBasicBlock(MachineBasicBlock &MBB) {
498 // loop over each instruction
499 MachineBasicBlock::iterator I = MBB.begin();
500 for (; I != MBB.end(); ++I) {
501 MachineInstr *MI = *I;
502 const TargetInstrDescriptor &TID = TM->getInstrInfo().get(MI->getOpcode());
503 DEBUG(std::cerr << "\nStarting RegAlloc of: " << *MI;
504 std::cerr << " Regs have values: ";
505 for (unsigned i = 0; i != RegInfo->getNumRegs(); ++i)
506 if (PhysRegsUsed[i] != -1)
507 std::cerr << "[" << RegInfo->getName(i)
508 << ",%reg" << PhysRegsUsed[i] << "] ";
511 // Loop over the implicit uses, making sure that they are at the head of the
512 // use order list, so they don't get reallocated.
513 for (const unsigned *ImplicitUses = TID.ImplicitUses;
514 *ImplicitUses; ++ImplicitUses)
515 MarkPhysRegRecentlyUsed(*ImplicitUses);
517 // Get the used operands into registers. This has the potential to spill
518 // incoming values if we are out of registers. Note that we completely
519 // ignore physical register uses here. We assume that if an explicit
520 // physical register is referenced by the instruction, that it is guaranteed
521 // to be live-in, or the input is badly hosed.
523 for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i)
524 if (MI->getOperand(i).isUse() &&
525 !MI->getOperand(i).isDef() &&
526 MI->getOperand(i).isVirtualRegister()){
527 unsigned VirtSrcReg = MI->getOperand(i).getAllocatedRegNum();
528 unsigned PhysSrcReg = reloadVirtReg(MBB, I, VirtSrcReg);
529 MI->SetMachineOperandReg(i, PhysSrcReg); // Assign the input register
533 // If this instruction is the last user of anything in registers, kill the
534 // value, freeing the register being used, so it doesn't need to be
535 // spilled to memory.
537 for (LiveVariables::killed_iterator KI = LV->killed_begin(MI),
538 KE = LV->killed_end(MI); KI != KE; ++KI) {
539 unsigned VirtReg = KI->second;
540 unsigned PhysReg = VirtReg;
541 if (MRegisterInfo::isVirtualRegister(VirtReg)) {
542 unsigned &PhysRegSlot = getVirt2PhysRegMapSlot(VirtReg);
543 PhysReg = PhysRegSlot;
544 assert(PhysReg != 0);
549 DEBUG(std::cerr << " Last use of " << RegInfo->getName(PhysReg)
550 << "[%reg" << VirtReg <<"], removing it from live set\n");
551 removePhysReg(PhysReg);
556 // Loop over all of the operands of the instruction, spilling registers that
557 // are defined, and marking explicit destinations in the PhysRegsUsed map.
558 for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i)
559 if (MI->getOperand(i).isDef() && MI->getOperand(i).isRegister() &&
560 MRegisterInfo::isPhysicalRegister(MI->getOperand(i).getReg())) {
561 unsigned Reg = MI->getOperand(i).getAllocatedRegNum();
562 spillPhysReg(MBB, I, Reg, true); // Spill any existing value in the reg
563 PhysRegsUsed[Reg] = 0; // It is free and reserved now
564 PhysRegsUseOrder.push_back(Reg);
565 for (const unsigned *AliasSet = RegInfo->getAliasSet(Reg);
566 *AliasSet; ++AliasSet) {
567 PhysRegsUseOrder.push_back(*AliasSet);
568 PhysRegsUsed[*AliasSet] = 0; // It is free and reserved now
572 // Loop over the implicit defs, spilling them as well.
573 for (const unsigned *ImplicitDefs = TID.ImplicitDefs;
574 *ImplicitDefs; ++ImplicitDefs) {
575 unsigned Reg = *ImplicitDefs;
576 spillPhysReg(MBB, I, Reg);
577 PhysRegsUseOrder.push_back(Reg);
578 PhysRegsUsed[Reg] = 0; // It is free and reserved now
579 for (const unsigned *AliasSet = RegInfo->getAliasSet(Reg);
580 *AliasSet; ++AliasSet) {
581 PhysRegsUseOrder.push_back(*AliasSet);
582 PhysRegsUsed[*AliasSet] = 0; // It is free and reserved now
586 // Okay, we have allocated all of the source operands and spilled any values
587 // that would be destroyed by defs of this instruction. Loop over the
588 // implicit defs and assign them to a register, spilling incoming values if
589 // we need to scavenge a register.
591 for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i)
592 if (MI->getOperand(i).isDef() &&
593 MI->getOperand(i).isVirtualRegister()) {
594 unsigned DestVirtReg = MI->getOperand(i).getAllocatedRegNum();
595 unsigned DestPhysReg;
597 // If DestVirtReg already has a value, use it.
598 if (!(DestPhysReg = getOrInsertVirt2PhysRegMapSlot(DestVirtReg)))
599 DestPhysReg = getReg(MBB, I, DestVirtReg);
600 markVirtRegModified(DestVirtReg);
601 MI->SetMachineOperandReg(i, DestPhysReg); // Assign the output register
605 // If this instruction defines any registers that are immediately dead,
608 for (LiveVariables::killed_iterator KI = LV->dead_begin(MI),
609 KE = LV->dead_end(MI); KI != KE; ++KI) {
610 unsigned VirtReg = KI->second;
611 unsigned PhysReg = VirtReg;
612 if (MRegisterInfo::isVirtualRegister(VirtReg)) {
613 unsigned &PhysRegSlot = getVirt2PhysRegMapSlot(VirtReg);
614 PhysReg = PhysRegSlot;
615 assert(PhysReg != 0);
620 DEBUG(std::cerr << " Register " << RegInfo->getName(PhysReg)
621 << " [%reg" << VirtReg
622 << "] is never used, removing it frame live list\n");
623 removePhysReg(PhysReg);
629 // Rewind the iterator to point to the first flow control instruction...
630 const TargetInstrInfo &TII = TM->getInstrInfo();
632 while (I != MBB.begin() && TII.isTerminatorInstr((*(I-1))->getOpcode()))
635 // Spill all physical registers holding virtual registers now.
636 for (unsigned i = 0, e = RegInfo->getNumRegs(); i != e; ++i)
637 if (PhysRegsUsed[i] != -1)
638 if (unsigned VirtReg = PhysRegsUsed[i])
639 spillVirtReg(MBB, I, VirtReg, i);
645 for (unsigned i = 0, e = Virt2PhysRegMap.size(); i != e; ++i)
646 if (unsigned PR = Virt2PhysRegMap[i]) {
647 std::cerr << "Register still mapped: " << i << " -> " << PR << "\n";
650 assert(AllOk && "Virtual registers still in phys regs?");
653 // Clear any physical register which appear live at the end of the basic
654 // block, but which do not hold any virtual registers. e.g., the stack
656 PhysRegsUseOrder.clear();
660 /// runOnMachineFunction - Register allocate the whole function
662 bool RA::runOnMachineFunction(MachineFunction &Fn) {
663 DEBUG(std::cerr << "Machine Function " << "\n");
665 TM = &Fn.getTarget();
666 RegInfo = TM->getRegisterInfo();
668 memset(PhysRegsUsed, -1, RegInfo->getNumRegs()*sizeof(unsigned));
670 // Reserve some space for a moderate number of registers. If we know what the
671 // max virtual register number was we could use that instead and save some
672 // runtime overhead...
673 Virt2PhysRegMap.resize(1024);
676 LV = &getAnalysis<LiveVariables>();
678 // Loop over all of the basic blocks, eliminating virtual register references
679 for (MachineFunction::iterator MBB = Fn.begin(), MBBe = Fn.end();
681 AllocateBasicBlock(*MBB);
683 StackSlotForVirtReg.clear();
684 VirtRegModified.clear();
685 Virt2PhysRegMap.clear();
689 FunctionPass *llvm::createLocalRegisterAllocator() {