1 //===- MipsInstrInfo.cpp - Mips Instruction Information ---------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file contains the Mips implementation of the TargetInstrInfo class.
12 //===----------------------------------------------------------------------===//
14 #include "MipsInstrInfo.h"
15 #include "MipsTargetMachine.h"
16 #include "MipsMachineFunction.h"
17 #include "llvm/ADT/STLExtras.h"
18 #include "llvm/CodeGen/MachineInstrBuilder.h"
19 #include "llvm/CodeGen/MachineRegisterInfo.h"
20 #include "llvm/Support/ErrorHandling.h"
21 #include "MipsGenInstrInfo.inc"
25 MipsInstrInfo::MipsInstrInfo(MipsTargetMachine &tm)
26 : TargetInstrInfoImpl(MipsInsts, array_lengthof(MipsInsts)),
27 TM(tm), RI(*TM.getSubtargetImpl(), *this) {}
29 static bool isZeroImm(const MachineOperand &op) {
30 return op.isImm() && op.getImm() == 0;
33 /// Return true if the instruction is a register to register move and
34 /// leave the source and dest operands in the passed parameters.
36 isMoveInstr(const MachineInstr &MI, unsigned &SrcReg, unsigned &DstReg,
37 unsigned &SrcSubIdx, unsigned &DstSubIdx) const
39 SrcSubIdx = DstSubIdx = 0; // No sub-registers.
41 // addu $dst, $src, $zero || addu $dst, $zero, $src
42 // or $dst, $src, $zero || or $dst, $zero, $src
43 if ((MI.getOpcode() == Mips::ADDu) || (MI.getOpcode() == Mips::OR)) {
44 if (MI.getOperand(1).getReg() == Mips::ZERO) {
45 DstReg = MI.getOperand(0).getReg();
46 SrcReg = MI.getOperand(2).getReg();
48 } else if (MI.getOperand(2).getReg() == Mips::ZERO) {
49 DstReg = MI.getOperand(0).getReg();
50 SrcReg = MI.getOperand(1).getReg();
58 if (MI.getOpcode() == Mips::FMOV_S32 ||
59 MI.getOpcode() == Mips::FMOV_D32 ||
60 MI.getOpcode() == Mips::MFC1 ||
61 MI.getOpcode() == Mips::MTC1 ||
62 MI.getOpcode() == Mips::MOVCCRToCCR) {
63 DstReg = MI.getOperand(0).getReg();
64 SrcReg = MI.getOperand(1).getReg();
68 // addiu $dst, $src, 0
69 if (MI.getOpcode() == Mips::ADDiu) {
70 if ((MI.getOperand(1).isReg()) && (isZeroImm(MI.getOperand(2)))) {
71 DstReg = MI.getOperand(0).getReg();
72 SrcReg = MI.getOperand(1).getReg();
80 /// isLoadFromStackSlot - If the specified machine instruction is a direct
81 /// load from a stack slot, return the virtual or physical register number of
82 /// the destination along with the FrameIndex of the loaded stack slot. If
83 /// not, return 0. This predicate must return 0 if the instruction has
84 /// any side effects other than loading from the stack slot.
85 unsigned MipsInstrInfo::
86 isLoadFromStackSlot(const MachineInstr *MI, int &FrameIndex) const
88 if ((MI->getOpcode() == Mips::LW) || (MI->getOpcode() == Mips::LWC1) ||
89 (MI->getOpcode() == Mips::LDC1)) {
90 if ((MI->getOperand(2).isFI()) && // is a stack slot
91 (MI->getOperand(1).isImm()) && // the imm is zero
92 (isZeroImm(MI->getOperand(1)))) {
93 FrameIndex = MI->getOperand(2).getIndex();
94 return MI->getOperand(0).getReg();
101 /// isStoreToStackSlot - If the specified machine instruction is a direct
102 /// store to a stack slot, return the virtual or physical register number of
103 /// the source reg along with the FrameIndex of the loaded stack slot. If
104 /// not, return 0. This predicate must return 0 if the instruction has
105 /// any side effects other than storing to the stack slot.
106 unsigned MipsInstrInfo::
107 isStoreToStackSlot(const MachineInstr *MI, int &FrameIndex) const
109 if ((MI->getOpcode() == Mips::SW) || (MI->getOpcode() == Mips::SWC1) ||
110 (MI->getOpcode() == Mips::SDC1)) {
111 if ((MI->getOperand(2).isFI()) && // is a stack slot
112 (MI->getOperand(1).isImm()) && // the imm is zero
113 (isZeroImm(MI->getOperand(1)))) {
114 FrameIndex = MI->getOperand(2).getIndex();
115 return MI->getOperand(0).getReg();
121 /// insertNoop - If data hazard condition is found insert the target nop
124 insertNoop(MachineBasicBlock &MBB, MachineBasicBlock::iterator MI) const
127 BuildMI(MBB, MI, DL, get(Mips::NOP));
131 copyRegToReg(MachineBasicBlock &MBB, MachineBasicBlock::iterator I,
132 unsigned DestReg, unsigned SrcReg,
133 const TargetRegisterClass *DestRC,
134 const TargetRegisterClass *SrcRC,
137 if (DestRC != SrcRC) {
139 // Copy to/from FCR31 condition register
140 if ((DestRC == Mips::CPURegsRegisterClass) &&
141 (SrcRC == Mips::CCRRegisterClass))
142 BuildMI(MBB, I, DL, get(Mips::CFC1), DestReg).addReg(SrcReg);
143 else if ((DestRC == Mips::CCRRegisterClass) &&
144 (SrcRC == Mips::CPURegsRegisterClass))
145 BuildMI(MBB, I, DL, get(Mips::CTC1), DestReg).addReg(SrcReg);
147 // Moves between coprocessors and cpu
148 else if ((DestRC == Mips::CPURegsRegisterClass) &&
149 (SrcRC == Mips::FGR32RegisterClass))
150 BuildMI(MBB, I, DL, get(Mips::MFC1), DestReg).addReg(SrcReg);
151 else if ((DestRC == Mips::FGR32RegisterClass) &&
152 (SrcRC == Mips::CPURegsRegisterClass))
153 BuildMI(MBB, I, DL, get(Mips::MTC1), DestReg).addReg(SrcReg);
155 // Move from/to Hi/Lo registers
156 else if ((DestRC == Mips::HILORegisterClass) &&
157 (SrcRC == Mips::CPURegsRegisterClass)) {
158 unsigned Opc = (DestReg == Mips::HI) ? Mips::MTHI : Mips::MTLO;
159 BuildMI(MBB, I, DL, get(Opc), DestReg);
160 } else if ((SrcRC == Mips::HILORegisterClass) &&
161 (DestRC == Mips::CPURegsRegisterClass)) {
162 unsigned Opc = (SrcReg == Mips::HI) ? Mips::MFHI : Mips::MFLO;
163 BuildMI(MBB, I, DL, get(Opc), DestReg);
165 // Can't copy this register
171 if (DestRC == Mips::CPURegsRegisterClass)
172 BuildMI(MBB, I, DL, get(Mips::ADDu), DestReg).addReg(Mips::ZERO)
174 else if (DestRC == Mips::FGR32RegisterClass)
175 BuildMI(MBB, I, DL, get(Mips::FMOV_S32), DestReg).addReg(SrcReg);
176 else if (DestRC == Mips::AFGR64RegisterClass)
177 BuildMI(MBB, I, DL, get(Mips::FMOV_D32), DestReg).addReg(SrcReg);
178 else if (DestRC == Mips::CCRRegisterClass)
179 BuildMI(MBB, I, DL, get(Mips::MOVCCRToCCR), DestReg).addReg(SrcReg);
181 // Can't copy this register
188 storeRegToStackSlot(MachineBasicBlock &MBB, MachineBasicBlock::iterator I,
189 unsigned SrcReg, bool isKill, int FI,
190 const TargetRegisterClass *RC,
191 const TargetRegisterInfo *TRI) const {
193 if (I != MBB.end()) DL = I->getDebugLoc();
195 if (RC == Mips::CPURegsRegisterClass)
196 BuildMI(MBB, I, DL, get(Mips::SW)).addReg(SrcReg, getKillRegState(isKill))
197 .addImm(0).addFrameIndex(FI);
198 else if (RC == Mips::FGR32RegisterClass)
199 BuildMI(MBB, I, DL, get(Mips::SWC1)).addReg(SrcReg, getKillRegState(isKill))
200 .addImm(0).addFrameIndex(FI);
201 else if (RC == Mips::AFGR64RegisterClass) {
202 if (!TM.getSubtarget<MipsSubtarget>().isMips1()) {
203 BuildMI(MBB, I, DL, get(Mips::SDC1))
204 .addReg(SrcReg, getKillRegState(isKill))
205 .addImm(0).addFrameIndex(FI);
207 const TargetRegisterInfo *TRI =
208 MBB.getParent()->getTarget().getRegisterInfo();
209 const unsigned *SubSet = TRI->getSubRegisters(SrcReg);
210 BuildMI(MBB, I, DL, get(Mips::SWC1))
211 .addReg(SubSet[0], getKillRegState(isKill))
212 .addImm(0).addFrameIndex(FI);
213 BuildMI(MBB, I, DL, get(Mips::SWC1))
214 .addReg(SubSet[1], getKillRegState(isKill))
215 .addImm(4).addFrameIndex(FI);
218 llvm_unreachable("Register class not handled!");
222 loadRegFromStackSlot(MachineBasicBlock &MBB, MachineBasicBlock::iterator I,
223 unsigned DestReg, int FI,
224 const TargetRegisterClass *RC,
225 const TargetRegisterInfo *TRI) const
228 if (I != MBB.end()) DL = I->getDebugLoc();
230 if (RC == Mips::CPURegsRegisterClass)
231 BuildMI(MBB, I, DL, get(Mips::LW), DestReg).addImm(0).addFrameIndex(FI);
232 else if (RC == Mips::FGR32RegisterClass)
233 BuildMI(MBB, I, DL, get(Mips::LWC1), DestReg).addImm(0).addFrameIndex(FI);
234 else if (RC == Mips::AFGR64RegisterClass) {
235 if (!TM.getSubtarget<MipsSubtarget>().isMips1()) {
236 BuildMI(MBB, I, DL, get(Mips::LDC1), DestReg).addImm(0).addFrameIndex(FI);
238 const TargetRegisterInfo *TRI =
239 MBB.getParent()->getTarget().getRegisterInfo();
240 const unsigned *SubSet = TRI->getSubRegisters(DestReg);
241 BuildMI(MBB, I, DL, get(Mips::LWC1), SubSet[0])
242 .addImm(0).addFrameIndex(FI);
243 BuildMI(MBB, I, DL, get(Mips::LWC1), SubSet[1])
244 .addImm(4).addFrameIndex(FI);
247 llvm_unreachable("Register class not handled!");
250 MachineInstr *MipsInstrInfo::
251 foldMemoryOperandImpl(MachineFunction &MF,
253 const SmallVectorImpl<unsigned> &Ops, int FI) const
255 if (Ops.size() != 1) return NULL;
257 MachineInstr *NewMI = NULL;
259 switch (MI->getOpcode()) {
261 if ((MI->getOperand(0).isReg()) &&
262 (MI->getOperand(1).isReg()) &&
263 (MI->getOperand(1).getReg() == Mips::ZERO) &&
264 (MI->getOperand(2).isReg())) {
265 if (Ops[0] == 0) { // COPY -> STORE
266 unsigned SrcReg = MI->getOperand(2).getReg();
267 bool isKill = MI->getOperand(2).isKill();
268 bool isUndef = MI->getOperand(2).isUndef();
269 NewMI = BuildMI(MF, MI->getDebugLoc(), get(Mips::SW))
270 .addReg(SrcReg, getKillRegState(isKill) | getUndefRegState(isUndef))
271 .addImm(0).addFrameIndex(FI);
272 } else { // COPY -> LOAD
273 unsigned DstReg = MI->getOperand(0).getReg();
274 bool isDead = MI->getOperand(0).isDead();
275 bool isUndef = MI->getOperand(0).isUndef();
276 NewMI = BuildMI(MF, MI->getDebugLoc(), get(Mips::LW))
277 .addReg(DstReg, RegState::Define | getDeadRegState(isDead) |
278 getUndefRegState(isUndef))
279 .addImm(0).addFrameIndex(FI);
285 if ((MI->getOperand(0).isReg()) &&
286 (MI->getOperand(1).isReg())) {
287 const TargetRegisterClass
288 *RC = RI.getRegClass(MI->getOperand(0).getReg());
289 unsigned StoreOpc, LoadOpc;
290 bool IsMips1 = TM.getSubtarget<MipsSubtarget>().isMips1();
292 if (RC == Mips::FGR32RegisterClass) {
293 LoadOpc = Mips::LWC1; StoreOpc = Mips::SWC1;
295 assert(RC == Mips::AFGR64RegisterClass);
296 // Mips1 doesn't have ldc/sdc instructions.
298 LoadOpc = Mips::LDC1; StoreOpc = Mips::SDC1;
301 if (Ops[0] == 0) { // COPY -> STORE
302 unsigned SrcReg = MI->getOperand(1).getReg();
303 bool isKill = MI->getOperand(1).isKill();
304 bool isUndef = MI->getOperand(2).isUndef();
305 NewMI = BuildMI(MF, MI->getDebugLoc(), get(StoreOpc))
306 .addReg(SrcReg, getKillRegState(isKill) | getUndefRegState(isUndef))
307 .addImm(0).addFrameIndex(FI) ;
308 } else { // COPY -> LOAD
309 unsigned DstReg = MI->getOperand(0).getReg();
310 bool isDead = MI->getOperand(0).isDead();
311 bool isUndef = MI->getOperand(0).isUndef();
312 NewMI = BuildMI(MF, MI->getDebugLoc(), get(LoadOpc))
313 .addReg(DstReg, RegState::Define | getDeadRegState(isDead) |
314 getUndefRegState(isUndef))
315 .addImm(0).addFrameIndex(FI);
324 //===----------------------------------------------------------------------===//
326 //===----------------------------------------------------------------------===//
328 /// GetCondFromBranchOpc - Return the Mips CC that matches
329 /// the correspondent Branch instruction opcode.
330 static Mips::CondCode GetCondFromBranchOpc(unsigned BrOpc)
333 default: return Mips::COND_INVALID;
334 case Mips::BEQ : return Mips::COND_E;
335 case Mips::BNE : return Mips::COND_NE;
336 case Mips::BGTZ : return Mips::COND_GZ;
337 case Mips::BGEZ : return Mips::COND_GEZ;
338 case Mips::BLTZ : return Mips::COND_LZ;
339 case Mips::BLEZ : return Mips::COND_LEZ;
341 // We dont do fp branch analysis yet!
343 case Mips::BC1F : return Mips::COND_INVALID;
347 /// GetCondBranchFromCond - Return the Branch instruction
348 /// opcode that matches the cc.
349 unsigned Mips::GetCondBranchFromCond(Mips::CondCode CC)
352 default: llvm_unreachable("Illegal condition code!");
353 case Mips::COND_E : return Mips::BEQ;
354 case Mips::COND_NE : return Mips::BNE;
355 case Mips::COND_GZ : return Mips::BGTZ;
356 case Mips::COND_GEZ : return Mips::BGEZ;
357 case Mips::COND_LZ : return Mips::BLTZ;
358 case Mips::COND_LEZ : return Mips::BLEZ;
363 case Mips::FCOND_UEQ:
364 case Mips::FCOND_OLT:
365 case Mips::FCOND_ULT:
366 case Mips::FCOND_OLE:
367 case Mips::FCOND_ULE:
369 case Mips::FCOND_NGLE:
370 case Mips::FCOND_SEQ:
371 case Mips::FCOND_NGL:
373 case Mips::FCOND_NGE:
375 case Mips::FCOND_NGT: return Mips::BC1T;
379 case Mips::FCOND_NEQ:
380 case Mips::FCOND_OGL:
381 case Mips::FCOND_UGE:
382 case Mips::FCOND_OGE:
383 case Mips::FCOND_UGT:
384 case Mips::FCOND_OGT:
386 case Mips::FCOND_GLE:
387 case Mips::FCOND_SNE:
389 case Mips::FCOND_NLT:
391 case Mips::FCOND_NLE:
392 case Mips::FCOND_GT: return Mips::BC1F;
396 /// GetOppositeBranchCondition - Return the inverse of the specified
397 /// condition, e.g. turning COND_E to COND_NE.
398 Mips::CondCode Mips::GetOppositeBranchCondition(Mips::CondCode CC)
401 default: llvm_unreachable("Illegal condition code!");
402 case Mips::COND_E : return Mips::COND_NE;
403 case Mips::COND_NE : return Mips::COND_E;
404 case Mips::COND_GZ : return Mips::COND_LEZ;
405 case Mips::COND_GEZ : return Mips::COND_LZ;
406 case Mips::COND_LZ : return Mips::COND_GEZ;
407 case Mips::COND_LEZ : return Mips::COND_GZ;
408 case Mips::FCOND_F : return Mips::FCOND_T;
409 case Mips::FCOND_UN : return Mips::FCOND_OR;
410 case Mips::FCOND_EQ : return Mips::FCOND_NEQ;
411 case Mips::FCOND_UEQ: return Mips::FCOND_OGL;
412 case Mips::FCOND_OLT: return Mips::FCOND_UGE;
413 case Mips::FCOND_ULT: return Mips::FCOND_OGE;
414 case Mips::FCOND_OLE: return Mips::FCOND_UGT;
415 case Mips::FCOND_ULE: return Mips::FCOND_OGT;
416 case Mips::FCOND_SF: return Mips::FCOND_ST;
417 case Mips::FCOND_NGLE:return Mips::FCOND_GLE;
418 case Mips::FCOND_SEQ: return Mips::FCOND_SNE;
419 case Mips::FCOND_NGL: return Mips::FCOND_GL;
420 case Mips::FCOND_LT: return Mips::FCOND_NLT;
421 case Mips::FCOND_NGE: return Mips::FCOND_GE;
422 case Mips::FCOND_LE: return Mips::FCOND_NLE;
423 case Mips::FCOND_NGT: return Mips::FCOND_GT;
427 bool MipsInstrInfo::AnalyzeBranch(MachineBasicBlock &MBB,
428 MachineBasicBlock *&TBB,
429 MachineBasicBlock *&FBB,
430 SmallVectorImpl<MachineOperand> &Cond,
431 bool AllowModify) const
433 // If the block has no terminators, it just falls into the block after it.
434 MachineBasicBlock::iterator I = MBB.end();
435 if (I == MBB.begin())
438 while (I->isDebugValue()) {
439 if (I == MBB.begin())
443 if (!isUnpredicatedTerminator(I))
446 // Get the last instruction in the block.
447 MachineInstr *LastInst = I;
449 // If there is only one terminator instruction, process it.
450 unsigned LastOpc = LastInst->getOpcode();
451 if (I == MBB.begin() || !isUnpredicatedTerminator(--I)) {
452 if (!LastInst->getDesc().isBranch())
455 // Unconditional branch
456 if (LastOpc == Mips::J) {
457 TBB = LastInst->getOperand(0).getMBB();
461 Mips::CondCode BranchCode = GetCondFromBranchOpc(LastInst->getOpcode());
462 if (BranchCode == Mips::COND_INVALID)
463 return true; // Can't handle indirect branch.
465 // Conditional branch
466 // Block ends with fall-through condbranch.
467 if (LastOpc != Mips::COND_INVALID) {
468 int LastNumOp = LastInst->getNumOperands();
470 TBB = LastInst->getOperand(LastNumOp-1).getMBB();
471 Cond.push_back(MachineOperand::CreateImm(BranchCode));
473 for (int i=0; i<LastNumOp-1; i++) {
474 Cond.push_back(LastInst->getOperand(i));
481 // Get the instruction before it if it is a terminator.
482 MachineInstr *SecondLastInst = I;
484 // If there are three terminators, we don't know what sort of block this is.
485 if (SecondLastInst && I != MBB.begin() && isUnpredicatedTerminator(--I))
488 // If the block ends with Mips::J and a Mips::BNE/Mips::BEQ, handle it.
489 unsigned SecondLastOpc = SecondLastInst->getOpcode();
490 Mips::CondCode BranchCode = GetCondFromBranchOpc(SecondLastOpc);
492 if (BranchCode != Mips::COND_INVALID && LastOpc == Mips::J) {
493 int SecondNumOp = SecondLastInst->getNumOperands();
495 TBB = SecondLastInst->getOperand(SecondNumOp-1).getMBB();
496 Cond.push_back(MachineOperand::CreateImm(BranchCode));
498 for (int i=0; i<SecondNumOp-1; i++) {
499 Cond.push_back(SecondLastInst->getOperand(i));
502 FBB = LastInst->getOperand(0).getMBB();
506 // If the block ends with two unconditional branches, handle it. The last
507 // one is not executed, so remove it.
508 if ((SecondLastOpc == Mips::J) && (LastOpc == Mips::J)) {
509 TBB = SecondLastInst->getOperand(0).getMBB();
512 I->eraseFromParent();
516 // Otherwise, can't handle this.
520 unsigned MipsInstrInfo::
521 InsertBranch(MachineBasicBlock &MBB, MachineBasicBlock *TBB,
522 MachineBasicBlock *FBB,
523 const SmallVectorImpl<MachineOperand> &Cond,
525 // Shouldn't be a fall through.
526 assert(TBB && "InsertBranch must not be told to insert a fallthrough");
527 assert((Cond.size() == 3 || Cond.size() == 2 || Cond.size() == 0) &&
528 "Mips branch conditions can have two|three components!");
530 if (FBB == 0) { // One way branch.
532 // Unconditional branch?
533 BuildMI(&MBB, DL, get(Mips::J)).addMBB(TBB);
535 // Conditional branch.
536 unsigned Opc = GetCondBranchFromCond((Mips::CondCode)Cond[0].getImm());
537 const TargetInstrDesc &TID = get(Opc);
539 if (TID.getNumOperands() == 3)
540 BuildMI(&MBB, DL, TID).addReg(Cond[1].getReg())
541 .addReg(Cond[2].getReg())
544 BuildMI(&MBB, DL, TID).addReg(Cond[1].getReg())
551 // Two-way Conditional branch.
552 unsigned Opc = GetCondBranchFromCond((Mips::CondCode)Cond[0].getImm());
553 const TargetInstrDesc &TID = get(Opc);
555 if (TID.getNumOperands() == 3)
556 BuildMI(&MBB, DL, TID).addReg(Cond[1].getReg()).addReg(Cond[2].getReg())
559 BuildMI(&MBB, DL, TID).addReg(Cond[1].getReg()).addMBB(TBB);
561 BuildMI(&MBB, DL, get(Mips::J)).addMBB(FBB);
565 unsigned MipsInstrInfo::
566 RemoveBranch(MachineBasicBlock &MBB) const
568 MachineBasicBlock::iterator I = MBB.end();
569 if (I == MBB.begin()) return 0;
571 while (I->isDebugValue()) {
572 if (I == MBB.begin())
576 if (I->getOpcode() != Mips::J &&
577 GetCondFromBranchOpc(I->getOpcode()) == Mips::COND_INVALID)
580 // Remove the branch.
581 I->eraseFromParent();
585 if (I == MBB.begin()) return 1;
587 if (GetCondFromBranchOpc(I->getOpcode()) == Mips::COND_INVALID)
590 // Remove the branch.
591 I->eraseFromParent();
595 /// ReverseBranchCondition - Return the inverse opcode of the
596 /// specified Branch instruction.
598 ReverseBranchCondition(SmallVectorImpl<MachineOperand> &Cond) const
600 assert( (Cond.size() == 3 || Cond.size() == 2) &&
601 "Invalid Mips branch condition!");
602 Cond[0].setImm(GetOppositeBranchCondition((Mips::CondCode)Cond[0].getImm()));
606 /// getGlobalBaseReg - Return a virtual register initialized with the
607 /// the global base register value. Output instructions required to
608 /// initialize the register in the function entry block, if necessary.
610 unsigned MipsInstrInfo::getGlobalBaseReg(MachineFunction *MF) const {
611 MipsFunctionInfo *MipsFI = MF->getInfo<MipsFunctionInfo>();
612 unsigned GlobalBaseReg = MipsFI->getGlobalBaseReg();
613 if (GlobalBaseReg != 0)
614 return GlobalBaseReg;
616 // Insert the set of GlobalBaseReg into the first MBB of the function
617 MachineBasicBlock &FirstMBB = MF->front();
618 MachineBasicBlock::iterator MBBI = FirstMBB.begin();
619 MachineRegisterInfo &RegInfo = MF->getRegInfo();
620 const TargetInstrInfo *TII = MF->getTarget().getInstrInfo();
622 GlobalBaseReg = RegInfo.createVirtualRegister(Mips::CPURegsRegisterClass);
623 BuildMI(FirstMBB, MBBI, DebugLoc(), TII->get(TargetOpcode::COPY),
624 GlobalBaseReg).addReg(Mips::GP);
625 RegInfo.addLiveIn(Mips::GP);
627 MipsFI->setGlobalBaseReg(GlobalBaseReg);
628 return GlobalBaseReg;