1 //===-- Thumb1RegisterInfo.cpp - Thumb-1 Register Information -------------===//
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 //===----------------------------------------------------------------------===//
15 #include "Thumb1RegisterInfo.h"
16 #include "ARMBaseInstrInfo.h"
17 #include "ARMMachineFunctionInfo.h"
18 #include "ARMSubtarget.h"
19 #include "MCTargetDesc/ARMAddressingModes.h"
20 #include "llvm/CodeGen/MachineConstantPool.h"
21 #include "llvm/CodeGen/MachineFrameInfo.h"
22 #include "llvm/CodeGen/MachineFunction.h"
23 #include "llvm/CodeGen/MachineInstrBuilder.h"
24 #include "llvm/CodeGen/MachineRegisterInfo.h"
25 #include "llvm/CodeGen/RegisterScavenging.h"
26 #include "llvm/IR/Constants.h"
27 #include "llvm/IR/DerivedTypes.h"
28 #include "llvm/IR/Function.h"
29 #include "llvm/IR/LLVMContext.h"
30 #include "llvm/Support/CommandLine.h"
31 #include "llvm/Support/ErrorHandling.h"
32 #include "llvm/Target/TargetFrameLowering.h"
33 #include "llvm/Target/TargetMachine.h"
36 extern cl::opt<bool> ReuseFrameIndexVals;
41 Thumb1RegisterInfo::Thumb1RegisterInfo(const ARMSubtarget &sti)
42 : ARMBaseRegisterInfo(sti) {
45 const TargetRegisterClass*
46 Thumb1RegisterInfo::getLargestLegalSuperClass(const TargetRegisterClass *RC)
48 if (ARM::tGPRRegClass.hasSubClassEq(RC))
49 return &ARM::tGPRRegClass;
50 return ARMBaseRegisterInfo::getLargestLegalSuperClass(RC);
53 const TargetRegisterClass *
54 Thumb1RegisterInfo::getPointerRegClass(const MachineFunction &MF, unsigned Kind)
56 return &ARM::tGPRRegClass;
59 /// emitLoadConstPool - Emits a load from constpool to materialize the
60 /// specified immediate.
62 Thumb1RegisterInfo::emitLoadConstPool(MachineBasicBlock &MBB,
63 MachineBasicBlock::iterator &MBBI,
65 unsigned DestReg, unsigned SubIdx,
67 ARMCC::CondCodes Pred, unsigned PredReg,
68 unsigned MIFlags) const {
69 MachineFunction &MF = *MBB.getParent();
70 const TargetInstrInfo &TII = *MF.getSubtarget().getInstrInfo();
71 MachineConstantPool *ConstantPool = MF.getConstantPool();
72 const Constant *C = ConstantInt::get(
73 Type::getInt32Ty(MBB.getParent()->getFunction()->getContext()), Val);
74 unsigned Idx = ConstantPool->getConstantPoolIndex(C, 4);
76 BuildMI(MBB, MBBI, dl, TII.get(ARM::tLDRpci))
77 .addReg(DestReg, getDefRegState(true), SubIdx)
78 .addConstantPoolIndex(Idx).addImm(Pred).addReg(PredReg)
83 /// emitThumbRegPlusImmInReg - Emits a series of instructions to materialize
84 /// a destreg = basereg + immediate in Thumb code. Materialize the immediate
85 /// in a register using mov / mvn sequences or load the immediate from a
88 void emitThumbRegPlusImmInReg(MachineBasicBlock &MBB,
89 MachineBasicBlock::iterator &MBBI,
91 unsigned DestReg, unsigned BaseReg,
92 int NumBytes, bool CanChangeCC,
93 const TargetInstrInfo &TII,
94 const ARMBaseRegisterInfo& MRI,
95 unsigned MIFlags = MachineInstr::NoFlags) {
96 MachineFunction &MF = *MBB.getParent();
97 bool isHigh = !isARMLowRegister(DestReg) ||
98 (BaseReg != 0 && !isARMLowRegister(BaseReg));
100 // Subtract doesn't have high register version. Load the negative value
101 // if either base or dest register is a high register. Also, if do not
102 // issue sub as part of the sequence if condition register is to be
104 if (NumBytes < 0 && !isHigh && CanChangeCC) {
106 NumBytes = -NumBytes;
108 unsigned LdReg = DestReg;
109 if (DestReg == ARM::SP) {
110 assert(BaseReg == ARM::SP && "Unexpected!");
111 LdReg = MF.getRegInfo().createVirtualRegister(&ARM::tGPRRegClass);
114 if (NumBytes <= 255 && NumBytes >= 0)
115 AddDefaultT1CC(BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVi8), LdReg))
116 .addImm(NumBytes).setMIFlags(MIFlags);
117 else if (NumBytes < 0 && NumBytes >= -255) {
118 AddDefaultT1CC(BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVi8), LdReg))
119 .addImm(NumBytes).setMIFlags(MIFlags);
120 AddDefaultT1CC(BuildMI(MBB, MBBI, dl, TII.get(ARM::tRSB), LdReg))
121 .addReg(LdReg, RegState::Kill).setMIFlags(MIFlags);
123 MRI.emitLoadConstPool(MBB, MBBI, dl, LdReg, 0, NumBytes,
124 ARMCC::AL, 0, MIFlags);
127 int Opc = (isSub) ? ARM::tSUBrr : (isHigh ? ARM::tADDhirr : ARM::tADDrr);
128 MachineInstrBuilder MIB =
129 BuildMI(MBB, MBBI, dl, TII.get(Opc), DestReg);
130 if (Opc != ARM::tADDhirr)
131 MIB = AddDefaultT1CC(MIB);
132 if (DestReg == ARM::SP || isSub)
133 MIB.addReg(BaseReg).addReg(LdReg, RegState::Kill);
135 MIB.addReg(LdReg).addReg(BaseReg, RegState::Kill);
139 /// calcNumMI - Returns the number of instructions required to materialize
140 /// the specific add / sub r, c instruction.
141 static unsigned calcNumMI(int Opc, int ExtraOpc, unsigned Bytes,
142 unsigned NumBits, unsigned Scale) {
144 unsigned Chunk = ((1 << NumBits) - 1) * Scale;
146 if (Opc == ARM::tADDrSPi) {
147 unsigned ThisVal = (Bytes > Chunk) ? Chunk : Bytes;
151 Scale = 1; // Followed by a number of tADDi8.
152 Chunk = ((1 << NumBits) - 1) * Scale;
155 NumMIs += Bytes / Chunk;
156 if ((Bytes % Chunk) != 0)
163 /// emitThumbRegPlusImmediate - Emits a series of instructions to materialize
164 /// a destreg = basereg + immediate in Thumb code.
165 void llvm::emitThumbRegPlusImmediate(MachineBasicBlock &MBB,
166 MachineBasicBlock::iterator &MBBI,
168 unsigned DestReg, unsigned BaseReg,
169 int NumBytes, const TargetInstrInfo &TII,
170 const ARMBaseRegisterInfo& MRI,
172 bool isSub = NumBytes < 0;
173 unsigned Bytes = (unsigned)NumBytes;
174 if (isSub) Bytes = -NumBytes;
175 bool isMul4 = (Bytes & 3) == 0;
176 bool isTwoAddr = false;
177 bool DstNotEqBase = false;
178 unsigned NumBits = 1;
184 if (DestReg == BaseReg && BaseReg == ARM::SP) {
185 assert(isMul4 && "Thumb sp inc / dec size must be multiple of 4!");
188 Opc = isSub ? ARM::tSUBspi : ARM::tADDspi;
190 } else if (!isSub && BaseReg == ARM::SP) {
193 // r1 = add sp, 100 * 4
197 ExtraOpc = ARM::tADDi3;
207 if (DestReg != BaseReg)
209 if (DestReg == ARM::SP) {
210 Opc = isSub ? ARM::tSUBspi : ARM::tADDspi;
211 assert(isMul4 && "Thumb sp inc / dec size must be multiple of 4!");
215 Opc = isSub ? ARM::tSUBi8 : ARM::tADDi8;
222 unsigned NumMIs = calcNumMI(Opc, ExtraOpc, Bytes, NumBits, Scale);
223 unsigned Threshold = (DestReg == ARM::SP) ? 3 : 2;
224 if (NumMIs > Threshold) {
225 // This will expand into too many instructions. Load the immediate from a
227 emitThumbRegPlusImmInReg(MBB, MBBI, dl,
228 DestReg, BaseReg, NumBytes, true,
234 if (isARMLowRegister(DestReg) && isARMLowRegister(BaseReg)) {
235 // If both are low registers, emit DestReg = add BaseReg, max(Imm, 7)
236 unsigned Chunk = (1 << 3) - 1;
237 unsigned ThisVal = (Bytes > Chunk) ? Chunk : Bytes;
239 const MCInstrDesc &MCID = TII.get(isSub ? ARM::tSUBi3 : ARM::tADDi3);
240 const MachineInstrBuilder MIB =
241 AddDefaultT1CC(BuildMI(MBB, MBBI, dl, MCID, DestReg)
242 .setMIFlags(MIFlags));
243 AddDefaultPred(MIB.addReg(BaseReg, RegState::Kill).addImm(ThisVal));
244 } else if (isARMLowRegister(DestReg) && BaseReg == ARM::SP && Bytes > 0) {
245 unsigned ThisVal = std::min(1020U, Bytes / 4 * 4);
247 AddDefaultPred(BuildMI(MBB, MBBI, dl, TII.get(ARM::tADDrSPi), DestReg)
248 .addReg(BaseReg, RegState::Kill).addImm(ThisVal / 4))
249 .setMIFlags(MIFlags);
251 AddDefaultPred(BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVr), DestReg)
252 .addReg(BaseReg, RegState::Kill))
253 .setMIFlags(MIFlags);
258 unsigned Chunk = ((1 << NumBits) - 1) * Scale;
260 unsigned ThisVal = (Bytes > Chunk) ? Chunk : Bytes;
263 // Build the new tADD / tSUB.
265 MachineInstrBuilder MIB = BuildMI(MBB, MBBI, dl, TII.get(Opc), DestReg);
267 MIB = AddDefaultT1CC(MIB);
268 MIB.addReg(DestReg).addImm(ThisVal);
269 MIB = AddDefaultPred(MIB);
270 MIB.setMIFlags(MIFlags);
272 bool isKill = BaseReg != ARM::SP;
273 MachineInstrBuilder MIB = BuildMI(MBB, MBBI, dl, TII.get(Opc), DestReg);
275 MIB = AddDefaultT1CC(MIB);
276 MIB.addReg(BaseReg, getKillRegState(isKill)).addImm(ThisVal);
277 MIB = AddDefaultPred(MIB);
278 MIB.setMIFlags(MIFlags);
281 if (Opc == ARM::tADDrSPi) {
287 Chunk = ((1 << NumBits) - 1) * Scale;
288 Opc = isSub ? ARM::tSUBi8 : ARM::tADDi8;
289 NeedCC = isTwoAddr = true;
295 const MCInstrDesc &MCID = TII.get(ExtraOpc);
296 AddDefaultPred(AddDefaultT1CC(BuildMI(MBB, MBBI, dl, MCID, DestReg))
297 .addReg(DestReg, RegState::Kill)
298 .addImm(((unsigned)NumBytes) & 3)
299 .setMIFlags(MIFlags));
303 static void removeOperands(MachineInstr &MI, unsigned i) {
305 for (unsigned e = MI.getNumOperands(); i != e; ++i)
306 MI.RemoveOperand(Op);
309 /// convertToNonSPOpcode - Change the opcode to the non-SP version, because
310 /// we're replacing the frame index with a non-SP register.
311 static unsigned convertToNonSPOpcode(unsigned Opcode) {
323 bool Thumb1RegisterInfo::
324 rewriteFrameIndex(MachineBasicBlock::iterator II, unsigned FrameRegIdx,
325 unsigned FrameReg, int &Offset,
326 const ARMBaseInstrInfo &TII) const {
327 MachineInstr &MI = *II;
328 MachineBasicBlock &MBB = *MI.getParent();
329 DebugLoc dl = MI.getDebugLoc();
330 MachineInstrBuilder MIB(*MBB.getParent(), &MI);
331 unsigned Opcode = MI.getOpcode();
332 const MCInstrDesc &Desc = MI.getDesc();
333 unsigned AddrMode = (Desc.TSFlags & ARMII::AddrModeMask);
335 if (Opcode == ARM::tADDframe) {
336 Offset += MI.getOperand(FrameRegIdx+1).getImm();
337 unsigned DestReg = MI.getOperand(0).getReg();
339 emitThumbRegPlusImmediate(MBB, II, dl, DestReg, FrameReg, Offset, TII,
344 if (AddrMode != ARMII::AddrModeT1_s)
345 llvm_unreachable("Unsupported addressing mode!");
347 unsigned ImmIdx = FrameRegIdx + 1;
348 int InstrOffs = MI.getOperand(ImmIdx).getImm();
349 unsigned NumBits = (FrameReg == ARM::SP) ? 8 : 5;
352 Offset += InstrOffs * Scale;
353 assert((Offset & (Scale - 1)) == 0 && "Can't encode this offset!");
355 // Common case: small offset, fits into instruction.
356 MachineOperand &ImmOp = MI.getOperand(ImmIdx);
357 int ImmedOffset = Offset / Scale;
358 unsigned Mask = (1 << NumBits) - 1;
360 if ((unsigned)Offset <= Mask * Scale) {
361 // Replace the FrameIndex with the frame register (e.g., sp).
362 MI.getOperand(FrameRegIdx).ChangeToRegister(FrameReg, false);
363 ImmOp.ChangeToImmediate(ImmedOffset);
365 // If we're using a register where sp was stored, convert the instruction
366 // to the non-SP version.
367 unsigned NewOpc = convertToNonSPOpcode(Opcode);
368 if (NewOpc != Opcode && FrameReg != ARM::SP)
369 MI.setDesc(TII.get(NewOpc));
375 Mask = (1 << NumBits) - 1;
377 // If this is a thumb spill / restore, we will be using a constpool load to
378 // materialize the offset.
379 if (Opcode == ARM::tLDRspi || Opcode == ARM::tSTRspi) {
380 ImmOp.ChangeToImmediate(0);
382 // Otherwise, it didn't fit. Pull in what we can to simplify the immed.
383 ImmedOffset = ImmedOffset & Mask;
384 ImmOp.ChangeToImmediate(ImmedOffset);
385 Offset &= ~(Mask * Scale);
392 void Thumb1RegisterInfo::resolveFrameIndex(MachineInstr &MI, unsigned BaseReg,
393 int64_t Offset) const {
394 const ARMBaseInstrInfo &TII =
395 *static_cast<const ARMBaseInstrInfo *>(MI.getParent()
400 int Off = Offset; // ARM doesn't need the general 64-bit offsets
403 while (!MI.getOperand(i).isFI()) {
405 assert(i < MI.getNumOperands() && "Instr doesn't have FrameIndex operand!");
407 bool Done = rewriteFrameIndex(MI, i, BaseReg, Off, TII);
408 assert (Done && "Unable to resolve frame index!");
412 /// saveScavengerRegister - Spill the register so it can be used by the
413 /// register scavenger. Return true.
415 Thumb1RegisterInfo::saveScavengerRegister(MachineBasicBlock &MBB,
416 MachineBasicBlock::iterator I,
417 MachineBasicBlock::iterator &UseMI,
418 const TargetRegisterClass *RC,
419 unsigned Reg) const {
420 // Thumb1 can't use the emergency spill slot on the stack because
421 // ldr/str immediate offsets must be positive, and if we're referencing
422 // off the frame pointer (if, for example, there are alloca() calls in
423 // the function, the offset will be negative. Use R12 instead since that's
424 // a call clobbered register that we know won't be used in Thumb1 mode.
425 const TargetInstrInfo &TII = *MBB.getParent()->getSubtarget().getInstrInfo();
427 AddDefaultPred(BuildMI(MBB, I, DL, TII.get(ARM::tMOVr))
428 .addReg(ARM::R12, RegState::Define)
429 .addReg(Reg, RegState::Kill));
431 // The UseMI is where we would like to restore the register. If there's
432 // interference with R12 before then, however, we'll need to restore it
433 // before that instead and adjust the UseMI.
435 for (MachineBasicBlock::iterator II = I; !done && II != UseMI ; ++II) {
436 if (II->isDebugValue())
438 // If this instruction affects R12, adjust our restore point.
439 for (unsigned i = 0, e = II->getNumOperands(); i != e; ++i) {
440 const MachineOperand &MO = II->getOperand(i);
441 if (MO.isRegMask() && MO.clobbersPhysReg(ARM::R12)) {
446 if (!MO.isReg() || MO.isUndef() || !MO.getReg() ||
447 TargetRegisterInfo::isVirtualRegister(MO.getReg()))
449 if (MO.getReg() == ARM::R12) {
456 // Restore the register from R12
457 AddDefaultPred(BuildMI(MBB, UseMI, DL, TII.get(ARM::tMOVr)).
458 addReg(Reg, RegState::Define).addReg(ARM::R12, RegState::Kill));
464 Thumb1RegisterInfo::eliminateFrameIndex(MachineBasicBlock::iterator II,
465 int SPAdj, unsigned FIOperandNum,
466 RegScavenger *RS) const {
468 MachineInstr &MI = *II;
469 MachineBasicBlock &MBB = *MI.getParent();
470 MachineFunction &MF = *MBB.getParent();
471 const ARMBaseInstrInfo &TII =
472 *static_cast<const ARMBaseInstrInfo *>(MF.getSubtarget().getInstrInfo());
473 ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
474 DebugLoc dl = MI.getDebugLoc();
475 MachineInstrBuilder MIB(*MBB.getParent(), &MI);
477 unsigned FrameReg = ARM::SP;
478 int FrameIndex = MI.getOperand(FIOperandNum).getIndex();
479 int Offset = MF.getFrameInfo()->getObjectOffset(FrameIndex) +
480 MF.getFrameInfo()->getStackSize() + SPAdj;
482 if (MF.getFrameInfo()->hasVarSizedObjects()) {
483 assert(SPAdj == 0 && MF.getSubtarget().getFrameLowering()->hasFP(MF) &&
485 // There are alloca()'s in this function, must reference off the frame
486 // pointer or base pointer instead.
487 if (!hasBasePointer(MF)) {
488 FrameReg = getFrameRegister(MF);
489 Offset -= AFI->getFramePtrSpillOffset();
494 // PEI::scavengeFrameVirtualRegs() cannot accurately track SPAdj because the
495 // call frame setup/destroy instructions have already been eliminated. That
496 // means the stack pointer cannot be used to access the emergency spill slot
497 // when !hasReservedCallFrame().
499 if (RS && FrameReg == ARM::SP && RS->isScavengingFrameIndex(FrameIndex)){
500 assert(MF.getTarget()
503 ->hasReservedCallFrame(MF) &&
504 "Cannot use SP to access the emergency spill slot in "
505 "functions without a reserved call frame");
506 assert(!MF.getFrameInfo()->hasVarSizedObjects() &&
507 "Cannot use SP to access the emergency spill slot in "
508 "functions with variable sized frame objects");
512 // Special handling of dbg_value instructions.
513 if (MI.isDebugValue()) {
514 MI.getOperand(FIOperandNum). ChangeToRegister(FrameReg, false /*isDef*/);
515 MI.getOperand(FIOperandNum+1).ChangeToImmediate(Offset);
519 // Modify MI as necessary to handle as much of 'Offset' as possible
520 assert(AFI->isThumbFunction() &&
521 "This eliminateFrameIndex only supports Thumb1!");
522 if (rewriteFrameIndex(MI, FIOperandNum, FrameReg, Offset, TII))
525 // If we get here, the immediate doesn't fit into the instruction. We folded
526 // as much as possible above, handle the rest, providing a register that is
528 assert(Offset && "This code isn't needed if offset already handled!");
530 unsigned Opcode = MI.getOpcode();
532 // Remove predicate first.
533 int PIdx = MI.findFirstPredOperandIdx();
535 removeOperands(MI, PIdx);
538 // Use the destination register to materialize sp + offset.
539 unsigned TmpReg = MI.getOperand(0).getReg();
541 if (Opcode == ARM::tLDRspi) {
542 if (FrameReg == ARM::SP)
543 emitThumbRegPlusImmInReg(MBB, II, dl, TmpReg, FrameReg,
544 Offset, false, TII, *this);
546 emitLoadConstPool(MBB, II, dl, TmpReg, 0, Offset);
550 emitThumbRegPlusImmediate(MBB, II, dl, TmpReg, FrameReg, Offset, TII,
554 MI.setDesc(TII.get(UseRR ? ARM::tLDRr : ARM::tLDRi));
555 MI.getOperand(FIOperandNum).ChangeToRegister(TmpReg, false, false, true);
557 // Use [reg, reg] addrmode. Replace the immediate operand w/ the frame
558 // register. The offset is already handled in the vreg value.
559 MI.getOperand(FIOperandNum+1).ChangeToRegister(FrameReg, false, false,
561 } else if (MI.mayStore()) {
562 VReg = MF.getRegInfo().createVirtualRegister(&ARM::tGPRRegClass);
565 if (Opcode == ARM::tSTRspi) {
566 if (FrameReg == ARM::SP)
567 emitThumbRegPlusImmInReg(MBB, II, dl, VReg, FrameReg,
568 Offset, false, TII, *this);
570 emitLoadConstPool(MBB, II, dl, VReg, 0, Offset);
574 emitThumbRegPlusImmediate(MBB, II, dl, VReg, FrameReg, Offset, TII,
576 MI.setDesc(TII.get(UseRR ? ARM::tSTRr : ARM::tSTRi));
577 MI.getOperand(FIOperandNum).ChangeToRegister(VReg, false, false, true);
579 // Use [reg, reg] addrmode. Replace the immediate operand w/ the frame
580 // register. The offset is already handled in the vreg value.
581 MI.getOperand(FIOperandNum+1).ChangeToRegister(FrameReg, false, false,
584 llvm_unreachable("Unexpected opcode!");
587 // Add predicate back if it's needed.
588 if (MI.isPredicable())