1 //===- Thumb1RegisterInfo.cpp - Thumb-1 Register 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 Thumb-1 implementation of the TargetRegisterInfo
13 //===----------------------------------------------------------------------===//
16 #include "ARMAddressingModes.h"
17 #include "ARMBaseInstrInfo.h"
18 #include "ARMMachineFunctionInfo.h"
19 #include "ARMSubtarget.h"
20 #include "Thumb1InstrInfo.h"
21 #include "Thumb1RegisterInfo.h"
22 #include "llvm/Constants.h"
23 #include "llvm/DerivedTypes.h"
24 #include "llvm/Function.h"
25 #include "llvm/LLVMContext.h"
26 #include "llvm/CodeGen/MachineConstantPool.h"
27 #include "llvm/CodeGen/MachineFrameInfo.h"
28 #include "llvm/CodeGen/MachineFunction.h"
29 #include "llvm/CodeGen/MachineInstrBuilder.h"
30 #include "llvm/CodeGen/MachineLocation.h"
31 #include "llvm/CodeGen/MachineRegisterInfo.h"
32 #include "llvm/Target/TargetFrameLowering.h"
33 #include "llvm/Target/TargetMachine.h"
34 #include "llvm/Support/CommandLine.h"
35 #include "llvm/Support/ErrorHandling.h"
36 #include "llvm/Support/raw_ostream.h"
39 extern cl::opt<bool> ReuseFrameIndexVals;
44 Thumb1RegisterInfo::Thumb1RegisterInfo(const ARMBaseInstrInfo &tii,
45 const ARMSubtarget &sti)
46 : ARMBaseRegisterInfo(tii, sti) {
49 const TargetRegisterClass *
50 Thumb1RegisterInfo::getPointerRegClass(unsigned Kind) const {
51 return ARM::tGPRRegisterClass;
54 /// emitLoadConstPool - Emits a load from constpool to materialize the
55 /// specified immediate.
57 Thumb1RegisterInfo::emitLoadConstPool(MachineBasicBlock &MBB,
58 MachineBasicBlock::iterator &MBBI,
60 unsigned DestReg, unsigned SubIdx,
62 ARMCC::CondCodes Pred, unsigned PredReg,
63 unsigned MIFlags) const {
64 MachineFunction &MF = *MBB.getParent();
65 MachineConstantPool *ConstantPool = MF.getConstantPool();
66 const Constant *C = ConstantInt::get(
67 Type::getInt32Ty(MBB.getParent()->getFunction()->getContext()), Val);
68 unsigned Idx = ConstantPool->getConstantPoolIndex(C, 4);
70 BuildMI(MBB, MBBI, dl, TII.get(ARM::tLDRpci))
71 .addReg(DestReg, getDefRegState(true), SubIdx)
72 .addConstantPoolIndex(Idx).addImm(Pred).addReg(PredReg)
77 /// emitThumbRegPlusImmInReg - Emits a series of instructions to materialize
78 /// a destreg = basereg + immediate in Thumb code. Materialize the immediate
79 /// in a register using mov / mvn sequences or load the immediate from a
82 void emitThumbRegPlusImmInReg(MachineBasicBlock &MBB,
83 MachineBasicBlock::iterator &MBBI,
85 unsigned DestReg, unsigned BaseReg,
86 int NumBytes, bool CanChangeCC,
87 const TargetInstrInfo &TII,
88 const ARMBaseRegisterInfo& MRI,
89 unsigned MIFlags = MachineInstr::NoFlags) {
90 MachineFunction &MF = *MBB.getParent();
91 bool isHigh = !isARMLowRegister(DestReg) ||
92 (BaseReg != 0 && !isARMLowRegister(BaseReg));
94 // Subtract doesn't have high register version. Load the negative value
95 // if either base or dest register is a high register. Also, if do not
96 // issue sub as part of the sequence if condition register is to be
98 if (NumBytes < 0 && !isHigh && CanChangeCC) {
100 NumBytes = -NumBytes;
102 unsigned LdReg = DestReg;
103 if (DestReg == ARM::SP) {
104 assert(BaseReg == ARM::SP && "Unexpected!");
105 LdReg = MF.getRegInfo().createVirtualRegister(ARM::tGPRRegisterClass);
108 if (NumBytes <= 255 && NumBytes >= 0)
109 AddDefaultT1CC(BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVi8), LdReg))
110 .addImm(NumBytes).setMIFlags(MIFlags);
111 else if (NumBytes < 0 && NumBytes >= -255) {
112 AddDefaultT1CC(BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVi8), LdReg))
113 .addImm(NumBytes).setMIFlags(MIFlags);
114 AddDefaultT1CC(BuildMI(MBB, MBBI, dl, TII.get(ARM::tRSB), LdReg))
115 .addReg(LdReg, RegState::Kill).setMIFlags(MIFlags);
117 MRI.emitLoadConstPool(MBB, MBBI, dl, LdReg, 0, NumBytes,
118 ARMCC::AL, 0, MIFlags);
121 int Opc = (isSub) ? ARM::tSUBrr : (isHigh ? ARM::tADDhirr : ARM::tADDrr);
122 MachineInstrBuilder MIB =
123 BuildMI(MBB, MBBI, dl, TII.get(Opc), DestReg);
124 if (Opc != ARM::tADDhirr)
125 MIB = AddDefaultT1CC(MIB);
126 if (DestReg == ARM::SP || isSub)
127 MIB.addReg(BaseReg).addReg(LdReg, RegState::Kill);
129 MIB.addReg(LdReg).addReg(BaseReg, RegState::Kill);
133 /// calcNumMI - Returns the number of instructions required to materialize
134 /// the specific add / sub r, c instruction.
135 static unsigned calcNumMI(int Opc, int ExtraOpc, unsigned Bytes,
136 unsigned NumBits, unsigned Scale) {
138 unsigned Chunk = ((1 << NumBits) - 1) * Scale;
140 if (Opc == ARM::tADDrSPi) {
141 unsigned ThisVal = (Bytes > Chunk) ? Chunk : Bytes;
145 Scale = 1; // Followed by a number of tADDi8.
146 Chunk = ((1 << NumBits) - 1) * Scale;
149 NumMIs += Bytes / Chunk;
150 if ((Bytes % Chunk) != 0)
157 /// emitThumbRegPlusImmediate - Emits a series of instructions to materialize
158 /// a destreg = basereg + immediate in Thumb code.
159 void llvm::emitThumbRegPlusImmediate(MachineBasicBlock &MBB,
160 MachineBasicBlock::iterator &MBBI,
162 unsigned DestReg, unsigned BaseReg,
163 int NumBytes, const TargetInstrInfo &TII,
164 const ARMBaseRegisterInfo& MRI,
166 bool isSub = NumBytes < 0;
167 unsigned Bytes = (unsigned)NumBytes;
168 if (isSub) Bytes = -NumBytes;
169 bool isMul4 = (Bytes & 3) == 0;
170 bool isTwoAddr = false;
171 bool DstNotEqBase = false;
172 unsigned NumBits = 1;
177 bool NeedPred = false;
179 if (DestReg == BaseReg && BaseReg == ARM::SP) {
180 assert(isMul4 && "Thumb sp inc / dec size must be multiple of 4!");
183 Opc = isSub ? ARM::tSUBspi : ARM::tADDspi;
185 } else if (!isSub && BaseReg == ARM::SP) {
188 // r1 = add sp, 100 * 4
192 ExtraOpc = ARM::tADDi3;
201 if (DestReg != BaseReg)
204 if (DestReg == ARM::SP) {
205 Opc = isSub ? ARM::tSUBspi : ARM::tADDspi;
206 assert(isMul4 && "Thumb sp inc / dec size must be multiple of 4!");
210 Opc = isSub ? ARM::tSUBi8 : ARM::tADDi8;
212 NeedPred = NeedCC = true;
217 unsigned NumMIs = calcNumMI(Opc, ExtraOpc, Bytes, NumBits, Scale);
218 unsigned Threshold = (DestReg == ARM::SP) ? 3 : 2;
219 if (NumMIs > Threshold) {
220 // This will expand into too many instructions. Load the immediate from a
222 emitThumbRegPlusImmInReg(MBB, MBBI, dl,
223 DestReg, BaseReg, NumBytes, true,
229 if (isARMLowRegister(DestReg) && isARMLowRegister(BaseReg)) {
230 // If both are low registers, emit DestReg = add BaseReg, max(Imm, 7)
231 unsigned Chunk = (1 << 3) - 1;
232 unsigned ThisVal = (Bytes > Chunk) ? Chunk : Bytes;
234 const TargetInstrDesc &TID = TII.get(isSub ? ARM::tSUBi3 : ARM::tADDi3);
235 const MachineInstrBuilder MIB =
236 AddDefaultT1CC(BuildMI(MBB, MBBI, dl, TID, DestReg).setMIFlags(MIFlags));
237 AddDefaultPred(MIB.addReg(BaseReg, RegState::Kill).addImm(ThisVal));
239 BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVr), DestReg)
240 .addReg(BaseReg, RegState::Kill)
241 .setMIFlags(MIFlags);
246 unsigned Chunk = ((1 << NumBits) - 1) * Scale;
248 unsigned ThisVal = (Bytes > Chunk) ? Chunk : Bytes;
251 // Build the new tADD / tSUB.
253 MachineInstrBuilder MIB = BuildMI(MBB, MBBI, dl, TII.get(Opc), DestReg);
255 MIB = AddDefaultT1CC(MIB);
256 MIB.addReg(DestReg).addImm(ThisVal);
258 MIB = AddDefaultPred(MIB);
259 MIB.setMIFlags(MIFlags);
262 bool isKill = BaseReg != ARM::SP;
263 MachineInstrBuilder MIB = BuildMI(MBB, MBBI, dl, TII.get(Opc), DestReg);
265 MIB = AddDefaultT1CC(MIB);
266 MIB.addReg(BaseReg, getKillRegState(isKill)).addImm(ThisVal);
268 MIB = AddDefaultPred(MIB);
269 MIB.setMIFlags(MIFlags);
272 if (Opc == ARM::tADDrSPi) {
278 Chunk = ((1 << NumBits) - 1) * Scale;
279 Opc = isSub ? ARM::tSUBi8 : ARM::tADDi8;
280 NeedPred = NeedCC = isTwoAddr = true;
286 const TargetInstrDesc &TID = TII.get(ExtraOpc);
287 AddDefaultPred(AddDefaultT1CC(BuildMI(MBB, MBBI, dl, TID, DestReg))
288 .addReg(DestReg, RegState::Kill)
289 .addImm(((unsigned)NumBytes) & 3)
290 .setMIFlags(MIFlags));
294 static void emitSPUpdate(MachineBasicBlock &MBB,
295 MachineBasicBlock::iterator &MBBI,
296 const TargetInstrInfo &TII, DebugLoc dl,
297 const Thumb1RegisterInfo &MRI,
299 emitThumbRegPlusImmediate(MBB, MBBI, dl, ARM::SP, ARM::SP, NumBytes, TII,
303 void Thumb1RegisterInfo::
304 eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
305 MachineBasicBlock::iterator I) const {
306 const TargetFrameLowering *TFI = MF.getTarget().getFrameLowering();
308 if (!TFI->hasReservedCallFrame(MF)) {
309 // If we have alloca, convert as follows:
310 // ADJCALLSTACKDOWN -> sub, sp, sp, amount
311 // ADJCALLSTACKUP -> add, sp, sp, amount
312 MachineInstr *Old = I;
313 DebugLoc dl = Old->getDebugLoc();
314 unsigned Amount = Old->getOperand(0).getImm();
316 // We need to keep the stack aligned properly. To do this, we round the
317 // amount of space needed for the outgoing arguments up to the next
318 // alignment boundary.
319 unsigned Align = TFI->getStackAlignment();
320 Amount = (Amount+Align-1)/Align*Align;
322 // Replace the pseudo instruction with a new instruction...
323 unsigned Opc = Old->getOpcode();
324 if (Opc == ARM::ADJCALLSTACKDOWN || Opc == ARM::tADJCALLSTACKDOWN) {
325 emitSPUpdate(MBB, I, TII, dl, *this, -Amount);
327 assert(Opc == ARM::ADJCALLSTACKUP || Opc == ARM::tADJCALLSTACKUP);
328 emitSPUpdate(MBB, I, TII, dl, *this, Amount);
335 /// emitThumbConstant - Emit a series of instructions to materialize a
337 static void emitThumbConstant(MachineBasicBlock &MBB,
338 MachineBasicBlock::iterator &MBBI,
339 unsigned DestReg, int Imm,
340 const TargetInstrInfo &TII,
341 const Thumb1RegisterInfo& MRI,
343 bool isSub = Imm < 0;
344 if (isSub) Imm = -Imm;
346 int Chunk = (1 << 8) - 1;
347 int ThisVal = (Imm > Chunk) ? Chunk : Imm;
349 AddDefaultPred(AddDefaultT1CC(BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVi8),
353 emitThumbRegPlusImmediate(MBB, MBBI, dl, DestReg, DestReg, Imm, TII, MRI);
355 const TargetInstrDesc &TID = TII.get(ARM::tRSB);
356 AddDefaultPred(AddDefaultT1CC(BuildMI(MBB, MBBI, dl, TID, DestReg))
357 .addReg(DestReg, RegState::Kill));
361 static void removeOperands(MachineInstr &MI, unsigned i) {
363 for (unsigned e = MI.getNumOperands(); i != e; ++i)
364 MI.RemoveOperand(Op);
367 /// convertToNonSPOpcode - Change the opcode to the non-SP version, because
368 /// we're replacing the frame index with a non-SP register.
369 static unsigned convertToNonSPOpcode(unsigned Opcode) {
372 case ARM::tRestore: // FIXME: Should this opcode be here?
376 case ARM::tSpill: // FIXME: Should this opcode be here?
383 bool Thumb1RegisterInfo::
384 rewriteFrameIndex(MachineBasicBlock::iterator II, unsigned FrameRegIdx,
385 unsigned FrameReg, int &Offset,
386 const ARMBaseInstrInfo &TII) const {
387 MachineInstr &MI = *II;
388 MachineBasicBlock &MBB = *MI.getParent();
389 DebugLoc dl = MI.getDebugLoc();
390 unsigned Opcode = MI.getOpcode();
391 const TargetInstrDesc &Desc = MI.getDesc();
392 unsigned AddrMode = (Desc.TSFlags & ARMII::AddrModeMask);
394 if (Opcode == ARM::tADDrSPi) {
395 Offset += MI.getOperand(FrameRegIdx+1).getImm();
397 // Can't use tADDrSPi if it's based off the frame pointer.
398 unsigned NumBits = 0;
400 if (FrameReg != ARM::SP) {
401 Opcode = ARM::tADDi3;
402 MI.setDesc(TII.get(Opcode));
407 assert((Offset & 3) == 0 &&
408 "Thumb add/sub sp, #imm immediate must be multiple of 4!");
412 if (Offset == 0 && getInstrPredicate(&MI, PredReg) == ARMCC::AL) {
413 // Turn it into a move.
414 MI.setDesc(TII.get(ARM::tMOVgpr2tgpr));
415 MI.getOperand(FrameRegIdx).ChangeToRegister(FrameReg, false);
416 // Remove offset and remaining explicit predicate operands.
417 do MI.RemoveOperand(FrameRegIdx+1);
418 while (MI.getNumOperands() > FrameRegIdx+1 &&
419 (!MI.getOperand(FrameRegIdx+1).isReg() ||
420 !MI.getOperand(FrameRegIdx+1).isImm()));
424 // Common case: small offset, fits into instruction.
425 unsigned Mask = (1 << NumBits) - 1;
426 if (((Offset / Scale) & ~Mask) == 0) {
427 // Replace the FrameIndex with sp / fp
428 if (Opcode == ARM::tADDi3) {
429 removeOperands(MI, FrameRegIdx);
430 MachineInstrBuilder MIB(&MI);
431 AddDefaultPred(AddDefaultT1CC(MIB).addReg(FrameReg)
432 .addImm(Offset / Scale));
434 MI.getOperand(FrameRegIdx).ChangeToRegister(FrameReg, false);
435 MI.getOperand(FrameRegIdx+1).ChangeToImmediate(Offset / Scale);
440 unsigned DestReg = MI.getOperand(0).getReg();
441 unsigned Bytes = (Offset > 0) ? Offset : -Offset;
442 unsigned NumMIs = calcNumMI(Opcode, 0, Bytes, NumBits, Scale);
443 // MI would expand into a large number of instructions. Don't try to
444 // simplify the immediate.
446 emitThumbRegPlusImmediate(MBB, II, dl, DestReg, FrameReg, Offset, TII,
453 // Translate r0 = add sp, imm to
454 // r0 = add sp, 255*4
455 // r0 = add r0, (imm - 255*4)
456 if (Opcode == ARM::tADDi3) {
457 removeOperands(MI, FrameRegIdx);
458 MachineInstrBuilder MIB(&MI);
459 AddDefaultPred(AddDefaultT1CC(MIB).addReg(FrameReg).addImm(Mask));
461 MI.getOperand(FrameRegIdx).ChangeToRegister(FrameReg, false);
462 MI.getOperand(FrameRegIdx+1).ChangeToImmediate(Mask);
464 Offset = (Offset - Mask * Scale);
465 MachineBasicBlock::iterator NII = llvm::next(II);
466 emitThumbRegPlusImmediate(MBB, NII, dl, DestReg, DestReg, Offset, TII,
469 // Translate r0 = add sp, -imm to
470 // r0 = -imm (this is then translated into a series of instructons)
472 emitThumbConstant(MBB, II, DestReg, Offset, TII, *this, dl);
474 MI.setDesc(TII.get(ARM::tADDhirr));
475 MI.getOperand(FrameRegIdx).ChangeToRegister(DestReg, false, false, true);
476 MI.getOperand(FrameRegIdx+1).ChangeToRegister(FrameReg, false);
477 if (Opcode == ARM::tADDi3) {
478 MachineInstrBuilder MIB(&MI);
484 if (AddrMode != ARMII::AddrModeT1_s)
485 llvm_unreachable("Unsupported addressing mode!");
487 unsigned ImmIdx = FrameRegIdx + 1;
488 int InstrOffs = MI.getOperand(ImmIdx).getImm();
489 unsigned NumBits = (FrameReg == ARM::SP) ? 8 : 5;
492 Offset += InstrOffs * Scale;
493 assert((Offset & (Scale - 1)) == 0 && "Can't encode this offset!");
495 // Common case: small offset, fits into instruction.
496 MachineOperand &ImmOp = MI.getOperand(ImmIdx);
497 int ImmedOffset = Offset / Scale;
498 unsigned Mask = (1 << NumBits) - 1;
500 if ((unsigned)Offset <= Mask * Scale) {
501 // Replace the FrameIndex with the frame register (e.g., sp).
502 MI.getOperand(FrameRegIdx).ChangeToRegister(FrameReg, false);
503 ImmOp.ChangeToImmediate(ImmedOffset);
505 // If we're using a register where sp was stored, convert the instruction
506 // to the non-SP version.
507 unsigned NewOpc = convertToNonSPOpcode(Opcode);
508 if (NewOpc != Opcode && FrameReg != ARM::SP)
509 MI.setDesc(TII.get(NewOpc));
515 Mask = (1 << NumBits) - 1;
517 // If this is a thumb spill / restore, we will be using a constpool load to
518 // materialize the offset.
519 if (Opcode == ARM::tRestore || Opcode == ARM::tSpill) {
520 ImmOp.ChangeToImmediate(0);
522 // Otherwise, it didn't fit. Pull in what we can to simplify the immed.
523 ImmedOffset = ImmedOffset & Mask;
524 ImmOp.ChangeToImmediate(ImmedOffset);
525 Offset &= ~(Mask * Scale);
533 Thumb1RegisterInfo::resolveFrameIndex(MachineBasicBlock::iterator I,
534 unsigned BaseReg, int64_t Offset) const {
535 MachineInstr &MI = *I;
536 int Off = Offset; // ARM doesn't need the general 64-bit offsets
539 while (!MI.getOperand(i).isFI()) {
541 assert(i < MI.getNumOperands() && "Instr doesn't have FrameIndex operand!");
544 Done = rewriteFrameIndex(MI, i, BaseReg, Off, TII);
545 assert (Done && "Unable to resolve frame index!");
548 /// saveScavengerRegister - Spill the register so it can be used by the
549 /// register scavenger. Return true.
551 Thumb1RegisterInfo::saveScavengerRegister(MachineBasicBlock &MBB,
552 MachineBasicBlock::iterator I,
553 MachineBasicBlock::iterator &UseMI,
554 const TargetRegisterClass *RC,
555 unsigned Reg) const {
556 // Thumb1 can't use the emergency spill slot on the stack because
557 // ldr/str immediate offsets must be positive, and if we're referencing
558 // off the frame pointer (if, for example, there are alloca() calls in
559 // the function, the offset will be negative. Use R12 instead since that's
560 // a call clobbered register that we know won't be used in Thumb1 mode.
562 BuildMI(MBB, I, DL, TII.get(ARM::tMOVtgpr2gpr)).
563 addReg(ARM::R12, RegState::Define).addReg(Reg, RegState::Kill);
565 // The UseMI is where we would like to restore the register. If there's
566 // interference with R12 before then, however, we'll need to restore it
567 // before that instead and adjust the UseMI.
569 for (MachineBasicBlock::iterator II = I; !done && II != UseMI ; ++II) {
570 if (II->isDebugValue())
572 // If this instruction affects R12, adjust our restore point.
573 for (unsigned i = 0, e = II->getNumOperands(); i != e; ++i) {
574 const MachineOperand &MO = II->getOperand(i);
575 if (!MO.isReg() || MO.isUndef() || !MO.getReg() ||
576 TargetRegisterInfo::isVirtualRegister(MO.getReg()))
578 if (MO.getReg() == ARM::R12) {
585 // Restore the register from R12
586 BuildMI(MBB, UseMI, DL, TII.get(ARM::tMOVgpr2tgpr)).
587 addReg(Reg, RegState::Define).addReg(ARM::R12, RegState::Kill);
593 Thumb1RegisterInfo::eliminateFrameIndex(MachineBasicBlock::iterator II,
594 int SPAdj, RegScavenger *RS) const {
597 MachineInstr &MI = *II;
598 MachineBasicBlock &MBB = *MI.getParent();
599 MachineFunction &MF = *MBB.getParent();
600 ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
601 DebugLoc dl = MI.getDebugLoc();
603 while (!MI.getOperand(i).isFI()) {
605 assert(i < MI.getNumOperands() && "Instr doesn't have FrameIndex operand!");
608 unsigned FrameReg = ARM::SP;
609 int FrameIndex = MI.getOperand(i).getIndex();
610 int Offset = MF.getFrameInfo()->getObjectOffset(FrameIndex) +
611 MF.getFrameInfo()->getStackSize() + SPAdj;
613 if (AFI->isGPRCalleeSavedArea1Frame(FrameIndex))
614 Offset -= AFI->getGPRCalleeSavedArea1Offset();
615 else if (AFI->isGPRCalleeSavedArea2Frame(FrameIndex))
616 Offset -= AFI->getGPRCalleeSavedArea2Offset();
617 else if (MF.getFrameInfo()->hasVarSizedObjects()) {
618 assert(SPAdj == 0 && MF.getTarget().getFrameLowering()->hasFP(MF) &&
620 // There are alloca()'s in this function, must reference off the frame
621 // pointer or base pointer instead.
622 if (!hasBasePointer(MF)) {
623 FrameReg = getFrameRegister(MF);
624 Offset -= AFI->getFramePtrSpillOffset();
629 // Special handling of dbg_value instructions.
630 if (MI.isDebugValue()) {
631 MI.getOperand(i). ChangeToRegister(FrameReg, false /*isDef*/);
632 MI.getOperand(i+1).ChangeToImmediate(Offset);
636 // Modify MI as necessary to handle as much of 'Offset' as possible
637 assert(AFI->isThumbFunction() &&
638 "This eliminateFrameIndex only supports Thumb1!");
639 if (rewriteFrameIndex(MI, i, FrameReg, Offset, TII))
642 // If we get here, the immediate doesn't fit into the instruction. We folded
643 // as much as possible above, handle the rest, providing a register that is
645 assert(Offset && "This code isn't needed if offset already handled!");
647 unsigned Opcode = MI.getOpcode();
648 const TargetInstrDesc &Desc = MI.getDesc();
650 // Remove predicate first.
651 int PIdx = MI.findFirstPredOperandIdx();
653 removeOperands(MI, PIdx);
655 if (Desc.mayLoad()) {
656 // Use the destination register to materialize sp + offset.
657 unsigned TmpReg = MI.getOperand(0).getReg();
659 if (Opcode == ARM::tRestore) {
660 if (FrameReg == ARM::SP)
661 emitThumbRegPlusImmInReg(MBB, II, dl, TmpReg, FrameReg,
662 Offset, false, TII, *this);
664 emitLoadConstPool(MBB, II, dl, TmpReg, 0, Offset);
668 emitThumbRegPlusImmediate(MBB, II, dl, TmpReg, FrameReg, Offset, TII,
672 MI.setDesc(TII.get(UseRR ? ARM::tLDRr : ARM::tLDRi));
673 MI.getOperand(i).ChangeToRegister(TmpReg, false, false, true);
675 // Use [reg, reg] addrmode. Replace the immediate operand w/ the frame
676 // register. The offset is already handled in the vreg value.
677 MI.getOperand(i+1).ChangeToRegister(FrameReg, false, false, false);
678 } else if (Desc.mayStore()) {
679 VReg = MF.getRegInfo().createVirtualRegister(ARM::tGPRRegisterClass);
682 if (Opcode == ARM::tSpill) {
683 if (FrameReg == ARM::SP)
684 emitThumbRegPlusImmInReg(MBB, II, dl, VReg, FrameReg,
685 Offset, false, TII, *this);
687 emitLoadConstPool(MBB, II, dl, VReg, 0, Offset);
691 emitThumbRegPlusImmediate(MBB, II, dl, VReg, FrameReg, Offset, TII,
693 MI.setDesc(TII.get(UseRR ? ARM::tSTRr : ARM::tSTRi));
694 MI.getOperand(i).ChangeToRegister(VReg, false, false, true);
696 // Use [reg, reg] addrmode. Replace the immediate operand w/ the frame
697 // register. The offset is already handled in the vreg value.
698 MI.getOperand(i+1).ChangeToRegister(FrameReg, false, false, false);
700 assert(false && "Unexpected opcode!");
703 // Add predicate back if it's needed.
704 if (MI.getDesc().isPredicable()) {
705 MachineInstrBuilder MIB(&MI);