C++ ARMFunctionInfo::hasStackFrame方法代码示例

void Thumb1FrameLowering::emitEpilogue(MachineFunction &MF,
                                   MachineBasicBlock &MBB) const {
  MachineBasicBlock::iterator MBBI = MBB.getFirstTerminator();
  DebugLoc dl = MBBI != MBB.end() ? MBBI->getDebugLoc() : DebugLoc();
  MachineFrameInfo *MFI = MF.getFrameInfo();
  ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
  const ThumbRegisterInfo *RegInfo =
      static_cast<const ThumbRegisterInfo *>(STI.getRegisterInfo());
  const Thumb1InstrInfo &TII =
      *static_cast<const Thumb1InstrInfo *>(STI.getInstrInfo());

  unsigned ArgRegsSaveSize = AFI->getArgRegsSaveSize();
  int NumBytes = (int)MFI->getStackSize();
  assert((unsigned)NumBytes >= ArgRegsSaveSize &&
         "ArgRegsSaveSize is included in NumBytes");
  const MCPhysReg *CSRegs = RegInfo->getCalleeSavedRegs(&MF);
  unsigned FramePtr = RegInfo->getFrameRegister(MF);

  if (!AFI->hasStackFrame()) {
    if (NumBytes - ArgRegsSaveSize != 0)
      emitSPUpdate(MBB, MBBI, TII, dl, *RegInfo, NumBytes - ArgRegsSaveSize);
  } else {
    // Unwind MBBI to point to first LDR / VLDRD.
    if (MBBI != MBB.begin()) {
      do
        --MBBI;
      while (MBBI != MBB.begin() && isCSRestore(MBBI, CSRegs));
      if (!isCSRestore(MBBI, CSRegs))
        ++MBBI;
    }

    // Move SP to start of FP callee save spill area.
    NumBytes -= (AFI->getGPRCalleeSavedArea1Size() +
                 AFI->getGPRCalleeSavedArea2Size() +
                 AFI->getDPRCalleeSavedAreaSize() +
                 ArgRegsSaveSize);

    if (AFI->shouldRestoreSPFromFP()) {
      NumBytes = AFI->getFramePtrSpillOffset() - NumBytes;
      // Reset SP based on frame pointer only if the stack frame extends beyond
      // frame pointer stack slot, the target is ELF and the function has FP, or
      // the target uses var sized objects.
      if (NumBytes) {
        assert(!MFI->getPristineRegs(MF).test(ARM::R4) &&
               "No scratch register to restore SP from FP!");
        emitThumbRegPlusImmediate(MBB, MBBI, dl, ARM::R4, FramePtr, -NumBytes,
                                  TII, *RegInfo);
        AddDefaultPred(BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVr),
                               ARM::SP)
          .addReg(ARM::R4));
      } else
        AddDefaultPred(BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVr),
                               ARM::SP)
          .addReg(FramePtr));
    } else {
      if (MBBI != MBB.end() && MBBI->getOpcode() == ARM::tBX_RET &&
          &MBB.front() != MBBI && std::prev(MBBI)->getOpcode() == ARM::tPOP) {
        MachineBasicBlock::iterator PMBBI = std::prev(MBBI);
        if (!tryFoldSPUpdateIntoPushPop(STI, MF, PMBBI, NumBytes))
          emitSPUpdate(MBB, PMBBI, TII, dl, *RegInfo, NumBytes);
      } else if (!tryFoldSPUpdateIntoPushPop(STI, MF, MBBI, NumBytes))
        emitSPUpdate(MBB, MBBI, TII, dl, *RegInfo, NumBytes);
    }
  }

  if (needPopSpecialFixUp(MF)) {
    bool Done = emitPopSpecialFixUp(MBB, /* DoIt */ true);
    (void)Done;
    assert(Done && "Emission of the special fixup failed!?");
  }
}

void Thumb1FrameLowering::emitPrologue(MachineFunction &MF,
                                       MachineBasicBlock &MBB) const {
  MachineBasicBlock::iterator MBBI = MBB.begin();
  MachineFrameInfo  *MFI = MF.getFrameInfo();
  ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
  MachineModuleInfo &MMI = MF.getMMI();
  const MCRegisterInfo *MRI = MMI.getContext().getRegisterInfo();
  const ThumbRegisterInfo *RegInfo =
      static_cast<const ThumbRegisterInfo *>(STI.getRegisterInfo());
  const Thumb1InstrInfo &TII =
      *static_cast<const Thumb1InstrInfo *>(STI.getInstrInfo());

  unsigned ArgRegsSaveSize = AFI->getArgRegsSaveSize();
  unsigned NumBytes = MFI->getStackSize();
  assert(NumBytes >= ArgRegsSaveSize &&
         "ArgRegsSaveSize is included in NumBytes");
  const std::vector<CalleeSavedInfo> &CSI = MFI->getCalleeSavedInfo();

  // Debug location must be unknown since the first debug location is used
  // to determine the end of the prologue.
  DebugLoc dl;
  
  unsigned FramePtr = RegInfo->getFrameRegister(MF);
  unsigned BasePtr = RegInfo->getBaseRegister();
  int CFAOffset = 0;

  // Thumb add/sub sp, imm8 instructions implicitly multiply the offset by 4.
  NumBytes = (NumBytes + 3) & ~3;
  MFI->setStackSize(NumBytes);

  // Determine the sizes of each callee-save spill areas and record which frame
  // belongs to which callee-save spill areas.
  unsigned GPRCS1Size = 0, GPRCS2Size = 0, DPRCSSize = 0;
  int FramePtrSpillFI = 0;

  if (ArgRegsSaveSize) {
    emitSPUpdate(MBB, MBBI, TII, dl, *RegInfo, -ArgRegsSaveSize,
                 MachineInstr::FrameSetup);
    CFAOffset -= ArgRegsSaveSize;
    unsigned CFIIndex = MMI.addFrameInst(
        MCCFIInstruction::createDefCfaOffset(nullptr, CFAOffset));
    BuildMI(MBB, MBBI, dl, TII.get(TargetOpcode::CFI_INSTRUCTION))
        .addCFIIndex(CFIIndex)
        .setMIFlags(MachineInstr::FrameSetup);
  }

  if (!AFI->hasStackFrame()) {
    if (NumBytes - ArgRegsSaveSize != 0) {
      emitSPUpdate(MBB, MBBI, TII, dl, *RegInfo, -(NumBytes - ArgRegsSaveSize),
                   MachineInstr::FrameSetup);
      CFAOffset -= NumBytes - ArgRegsSaveSize;
      unsigned CFIIndex = MMI.addFrameInst(
          MCCFIInstruction::createDefCfaOffset(nullptr, CFAOffset));
      BuildMI(MBB, MBBI, dl, TII.get(TargetOpcode::CFI_INSTRUCTION))
          .addCFIIndex(CFIIndex)
          .setMIFlags(MachineInstr::FrameSetup);
    }
    return;
  }

  for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
    unsigned Reg = CSI[i].getReg();
    int FI = CSI[i].getFrameIdx();
    switch (Reg) {
    case ARM::R8:
    case ARM::R9:
    case ARM::R10:
    case ARM::R11:
      if (STI.isTargetMachO()) {
        GPRCS2Size += 4;
        break;
      }
      // fallthrough
    case ARM::R4:
    case ARM::R5:
    case ARM::R6:
    case ARM::R7:
    case ARM::LR:
      if (Reg == FramePtr)
        FramePtrSpillFI = FI;
      GPRCS1Size += 4;
      break;
    default:
      DPRCSSize += 8;
    }
  }

  if (MBBI != MBB.end() && MBBI->getOpcode() == ARM::tPUSH) {
    ++MBBI;
  }

  // Determine starting offsets of spill areas.
  unsigned DPRCSOffset  = NumBytes - ArgRegsSaveSize - (GPRCS1Size + GPRCS2Size + DPRCSSize);
  unsigned GPRCS2Offset = DPRCSOffset + DPRCSSize;
  unsigned GPRCS1Offset = GPRCS2Offset + GPRCS2Size;
  bool HasFP = hasFP(MF);
  if (HasFP)
    AFI->setFramePtrSpillOffset(MFI->getObjectOffset(FramePtrSpillFI) +
                                NumBytes);
  AFI->setGPRCalleeSavedArea1Offset(GPRCS1Offset);
//.........这里部分代码省略.........

void Thumb1FrameLowering::emitPrologue(MachineFunction &MF) const {
  MachineBasicBlock &MBB = MF.front();
  MachineBasicBlock::iterator MBBI = MBB.begin();
  MachineFrameInfo  *MFI = MF.getFrameInfo();
  ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
  const Thumb1RegisterInfo *RegInfo =
    static_cast<const Thumb1RegisterInfo*>(MF.getTarget().getRegisterInfo());
  const Thumb1InstrInfo &TII =
    *static_cast<const Thumb1InstrInfo*>(MF.getTarget().getInstrInfo());

  unsigned VARegSaveSize = AFI->getVarArgsRegSaveSize();
  unsigned NumBytes = MFI->getStackSize();
  const std::vector<CalleeSavedInfo> &CSI = MFI->getCalleeSavedInfo();
  DebugLoc dl = MBBI != MBB.end() ? MBBI->getDebugLoc() : DebugLoc();
  unsigned FramePtr = RegInfo->getFrameRegister(MF);
  unsigned BasePtr = RegInfo->getBaseRegister();

  // Thumb add/sub sp, imm8 instructions implicitly multiply the offset by 4.
  NumBytes = (NumBytes + 3) & ~3;
  MFI->setStackSize(NumBytes);

  // Determine the sizes of each callee-save spill areas and record which frame
  // belongs to which callee-save spill areas.
  unsigned GPRCS1Size = 0, GPRCS2Size = 0, DPRCSSize = 0;
  int FramePtrSpillFI = 0;

  if (VARegSaveSize)
    emitSPUpdate(MBB, MBBI, TII, dl, *RegInfo, -VARegSaveSize,
                 MachineInstr::FrameSetup);

  if (!AFI->hasStackFrame()) {
    if (NumBytes != 0)
      emitSPUpdate(MBB, MBBI, TII, dl, *RegInfo, -NumBytes,
                   MachineInstr::FrameSetup);
    return;
  }

  for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
    unsigned Reg = CSI[i].getReg();
    int FI = CSI[i].getFrameIdx();
    switch (Reg) {
    case ARM::R4:
    case ARM::R5:
    case ARM::R6:
    case ARM::R7:
    case ARM::LR:
      if (Reg == FramePtr)
        FramePtrSpillFI = FI;
      AFI->addGPRCalleeSavedArea1Frame(FI);
      GPRCS1Size += 4;
      break;
    case ARM::R8:
    case ARM::R9:
    case ARM::R10:
    case ARM::R11:
      if (Reg == FramePtr)
        FramePtrSpillFI = FI;
      if (STI.isTargetDarwin()) {
        AFI->addGPRCalleeSavedArea2Frame(FI);
        GPRCS2Size += 4;
      } else {
        AFI->addGPRCalleeSavedArea1Frame(FI);
        GPRCS1Size += 4;
      }
      break;
    default:
      AFI->addDPRCalleeSavedAreaFrame(FI);
      DPRCSSize += 8;
    }
  }

  if (MBBI != MBB.end() && MBBI->getOpcode() == ARM::tPUSH) {
    ++MBBI;
    if (MBBI != MBB.end())
      dl = MBBI->getDebugLoc();
  }

  // Determine starting offsets of spill areas.
  unsigned DPRCSOffset  = NumBytes - (GPRCS1Size + GPRCS2Size + DPRCSSize);
  unsigned GPRCS2Offset = DPRCSOffset + DPRCSSize;
  unsigned GPRCS1Offset = GPRCS2Offset + GPRCS2Size;
  AFI->setFramePtrSpillOffset(MFI->getObjectOffset(FramePtrSpillFI) + NumBytes);
  AFI->setGPRCalleeSavedArea1Offset(GPRCS1Offset);
  AFI->setGPRCalleeSavedArea2Offset(GPRCS2Offset);
  AFI->setDPRCalleeSavedAreaOffset(DPRCSOffset);
  NumBytes = DPRCSOffset;

  // Adjust FP so it point to the stack slot that contains the previous FP.
  if (hasFP(MF)) {
    AddDefaultPred(BuildMI(MBB, MBBI, dl, TII.get(ARM::tADDrSPi), FramePtr)
      .addFrameIndex(FramePtrSpillFI).addImm(0)
      .setMIFlags(MachineInstr::FrameSetup));
    if (NumBytes > 508)
      // If offset is > 508 then sp cannot be adjusted in a single instruction,
      // try restoring from fp instead.
      AFI->setShouldRestoreSPFromFP(true);
  }

  if (NumBytes)
    // Insert it after all the callee-save spills.
//.........这里部分代码省略.........

void Thumb1FrameLowering::emitPrologue(MachineFunction &MF,
                                       MachineBasicBlock &MBB) const {
  MachineBasicBlock::iterator MBBI = MBB.begin();
  MachineFrameInfo &MFI = MF.getFrameInfo();
  ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
  MachineModuleInfo &MMI = MF.getMMI();
  const MCRegisterInfo *MRI = MMI.getContext().getRegisterInfo();
  const ThumbRegisterInfo *RegInfo =
      static_cast<const ThumbRegisterInfo *>(STI.getRegisterInfo());
  const Thumb1InstrInfo &TII =
      *static_cast<const Thumb1InstrInfo *>(STI.getInstrInfo());

  unsigned ArgRegsSaveSize = AFI->getArgRegsSaveSize();
  unsigned NumBytes = MFI.getStackSize();
  assert(NumBytes >= ArgRegsSaveSize &&
         "ArgRegsSaveSize is included in NumBytes");
  const std::vector<CalleeSavedInfo> &CSI = MFI.getCalleeSavedInfo();

  // Debug location must be unknown since the first debug location is used
  // to determine the end of the prologue.
  DebugLoc dl;
  
  unsigned FramePtr = RegInfo->getFrameRegister(MF);
  unsigned BasePtr = RegInfo->getBaseRegister();
  int CFAOffset = 0;

  // Thumb add/sub sp, imm8 instructions implicitly multiply the offset by 4.
  NumBytes = (NumBytes + 3) & ~3;
  MFI.setStackSize(NumBytes);

  // Determine the sizes of each callee-save spill areas and record which frame
  // belongs to which callee-save spill areas.
  unsigned GPRCS1Size = 0, GPRCS2Size = 0, DPRCSSize = 0;
  int FramePtrSpillFI = 0;

  if (ArgRegsSaveSize) {
    emitSPUpdate(MBB, MBBI, TII, dl, *RegInfo, -ArgRegsSaveSize,
                 MachineInstr::FrameSetup);
    CFAOffset -= ArgRegsSaveSize;
    unsigned CFIIndex = MF.addFrameInst(
        MCCFIInstruction::createDefCfaOffset(nullptr, CFAOffset));
    BuildMI(MBB, MBBI, dl, TII.get(TargetOpcode::CFI_INSTRUCTION))
        .addCFIIndex(CFIIndex)
        .setMIFlags(MachineInstr::FrameSetup);
  }

  if (!AFI->hasStackFrame()) {
    if (NumBytes - ArgRegsSaveSize != 0) {
      emitSPUpdate(MBB, MBBI, TII, dl, *RegInfo, -(NumBytes - ArgRegsSaveSize),
                   MachineInstr::FrameSetup);
      CFAOffset -= NumBytes - ArgRegsSaveSize;
      unsigned CFIIndex = MF.addFrameInst(
          MCCFIInstruction::createDefCfaOffset(nullptr, CFAOffset));
      BuildMI(MBB, MBBI, dl, TII.get(TargetOpcode::CFI_INSTRUCTION))
          .addCFIIndex(CFIIndex)
          .setMIFlags(MachineInstr::FrameSetup);
    }
    return;
  }

  for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
    unsigned Reg = CSI[i].getReg();
    int FI = CSI[i].getFrameIdx();
    switch (Reg) {
    case ARM::R8:
    case ARM::R9:
    case ARM::R10:
    case ARM::R11:
      if (STI.splitFramePushPop(MF)) {
        GPRCS2Size += 4;
        break;
      }
      LLVM_FALLTHROUGH;
    case ARM::R4:
    case ARM::R5:
    case ARM::R6:
    case ARM::R7:
    case ARM::LR:
      if (Reg == FramePtr)
        FramePtrSpillFI = FI;
      GPRCS1Size += 4;
      break;
    default:
      DPRCSSize += 8;
    }
  }

  if (MBBI != MBB.end() && MBBI->getOpcode() == ARM::tPUSH) {
    ++MBBI;
  }

  // Determine starting offsets of spill areas.
  unsigned DPRCSOffset  = NumBytes - ArgRegsSaveSize - (GPRCS1Size + GPRCS2Size + DPRCSSize);
  unsigned GPRCS2Offset = DPRCSOffset + DPRCSSize;
  unsigned GPRCS1Offset = GPRCS2Offset + GPRCS2Size;
  bool HasFP = hasFP(MF);
  if (HasFP)
    AFI->setFramePtrSpillOffset(MFI.getObjectOffset(FramePtrSpillFI) +
                                NumBytes);
  AFI->setGPRCalleeSavedArea1Offset(GPRCS1Offset);
//.........这里部分代码省略.........

void Thumb1FrameLowering::emitEpilogue(MachineFunction &MF,
                                   MachineBasicBlock &MBB) const {
  MachineBasicBlock::iterator MBBI = MBB.getLastNonDebugInstr();
  assert((MBBI->getOpcode() == ARM::tBX_RET ||
          MBBI->getOpcode() == ARM::tPOP_RET) &&
         "Can only insert epilog into returning blocks");
  DebugLoc dl = MBBI->getDebugLoc();
  MachineFrameInfo *MFI = MF.getFrameInfo();
  ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
  const ThumbRegisterInfo *RegInfo =
      static_cast<const ThumbRegisterInfo *>(STI.getRegisterInfo());
  const Thumb1InstrInfo &TII =
      *static_cast<const Thumb1InstrInfo *>(STI.getInstrInfo());

  unsigned ArgRegsSaveSize = AFI->getArgRegsSaveSize();
  int NumBytes = (int)MFI->getStackSize();
  assert((unsigned)NumBytes >= ArgRegsSaveSize &&
         "ArgRegsSaveSize is included in NumBytes");
  const MCPhysReg *CSRegs = RegInfo->getCalleeSavedRegs(&MF);
  unsigned FramePtr = RegInfo->getFrameRegister(MF);

  if (!AFI->hasStackFrame()) {
    if (NumBytes - ArgRegsSaveSize != 0)
      emitSPUpdate(MBB, MBBI, TII, dl, *RegInfo, NumBytes - ArgRegsSaveSize);
  } else {
    // Unwind MBBI to point to first LDR / VLDRD.
    if (MBBI != MBB.begin()) {
      do
        --MBBI;
      while (MBBI != MBB.begin() && isCSRestore(MBBI, CSRegs));
      if (!isCSRestore(MBBI, CSRegs))
        ++MBBI;
    }

    // Move SP to start of FP callee save spill area.
    NumBytes -= (AFI->getGPRCalleeSavedArea1Size() +
                 AFI->getGPRCalleeSavedArea2Size() +
                 AFI->getDPRCalleeSavedAreaSize() +
                 ArgRegsSaveSize);

    if (AFI->shouldRestoreSPFromFP()) {
      NumBytes = AFI->getFramePtrSpillOffset() - NumBytes;
      // Reset SP based on frame pointer only if the stack frame extends beyond
      // frame pointer stack slot, the target is ELF and the function has FP, or
      // the target uses var sized objects.
      if (NumBytes) {
        assert(MF.getRegInfo().isPhysRegUsed(ARM::R4) &&
               "No scratch register to restore SP from FP!");
        emitThumbRegPlusImmediate(MBB, MBBI, dl, ARM::R4, FramePtr, -NumBytes,
                                  TII, *RegInfo);
        AddDefaultPred(BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVr),
                               ARM::SP)
          .addReg(ARM::R4));
      } else
        AddDefaultPred(BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVr),
                               ARM::SP)
          .addReg(FramePtr));
    } else {
      if (MBBI->getOpcode() == ARM::tBX_RET &&
          &MBB.front() != MBBI &&
          std::prev(MBBI)->getOpcode() == ARM::tPOP) {
        MachineBasicBlock::iterator PMBBI = std::prev(MBBI);
        if (!tryFoldSPUpdateIntoPushPop(STI, MF, PMBBI, NumBytes))
          emitSPUpdate(MBB, PMBBI, TII, dl, *RegInfo, NumBytes);
      } else if (!tryFoldSPUpdateIntoPushPop(STI, MF, MBBI, NumBytes))
        emitSPUpdate(MBB, MBBI, TII, dl, *RegInfo, NumBytes);
    }
  }

  bool IsV4PopReturn = false;
  for (const CalleeSavedInfo &CSI : MFI->getCalleeSavedInfo())
    if (CSI.getReg() == ARM::LR)
      IsV4PopReturn = true;
  IsV4PopReturn &= STI.hasV4TOps() && !STI.hasV5TOps();

  // Unlike T2 and ARM mode, the T1 pop instruction cannot restore
  // to LR, and we can't pop the value directly to the PC since
  // we need to update the SP after popping the value. So instead
  // we have to emit:
  //   POP {r3}
  //   ADD sp, #offset
  //   BX r3
  // If this would clobber a return value, then generate this sequence instead:
  //   MOV ip, r3
  //   POP {r3}
  //   ADD sp, #offset
  //   MOV lr, r3
  //   MOV r3, ip
  //   BX lr
  if (ArgRegsSaveSize || IsV4PopReturn) {
    // Get the last instruction, tBX_RET
    MBBI = MBB.getLastNonDebugInstr();
    assert (MBBI->getOpcode() == ARM::tBX_RET);
    DebugLoc dl = MBBI->getDebugLoc();

    if (AFI->getReturnRegsCount() <= 3) {
      // Epilogue: pop saved LR to R3 and branch off it. 
      AddDefaultPred(BuildMI(MBB, MBBI, dl, TII.get(ARM::tPOP)))
        .addReg(ARM::R3, RegState::Define);

//.........这里部分代码省略.........

void Thumb1FrameLowering::emitEpilogue(MachineFunction &MF,
                                   MachineBasicBlock &MBB) const {
  MachineBasicBlock::iterator MBBI = MBB.getLastNonDebugInstr();
  assert((MBBI->getOpcode() == ARM::tBX_RET ||
          MBBI->getOpcode() == ARM::tPOP_RET) &&
         "Can only insert epilog into returning blocks");
  DebugLoc dl = MBBI->getDebugLoc();
  MachineFrameInfo *MFI = MF.getFrameInfo();
  ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
  const Thumb1RegisterInfo *RegInfo =
    static_cast<const Thumb1RegisterInfo*>(MF.getTarget().getRegisterInfo());
  const Thumb1InstrInfo &TII =
    *static_cast<const Thumb1InstrInfo*>(MF.getTarget().getInstrInfo());

  unsigned VARegSaveSize = AFI->getVarArgsRegSaveSize();
  int NumBytes = (int)MFI->getStackSize();
  const unsigned *CSRegs = RegInfo->getCalleeSavedRegs();
  unsigned FramePtr = RegInfo->getFrameRegister(MF);

  if (!AFI->hasStackFrame()) {
    if (NumBytes != 0)
      emitSPUpdate(MBB, MBBI, TII, dl, *RegInfo, NumBytes);
  } else {
    // Unwind MBBI to point to first LDR / VLDRD.
    if (MBBI != MBB.begin()) {
      do
        --MBBI;
      while (MBBI != MBB.begin() && isCSRestore(MBBI, CSRegs));
      if (!isCSRestore(MBBI, CSRegs))
        ++MBBI;
    }

    // Move SP to start of FP callee save spill area.
    NumBytes -= (AFI->getGPRCalleeSavedArea1Size() +
                 AFI->getGPRCalleeSavedArea2Size() +
                 AFI->getDPRCalleeSavedAreaSize());

    if (AFI->shouldRestoreSPFromFP()) {
      NumBytes = AFI->getFramePtrSpillOffset() - NumBytes;
      // Reset SP based on frame pointer only if the stack frame extends beyond
      // frame pointer stack slot, the target is ELF and the function has FP, or
      // the target uses var sized objects.
      if (NumBytes) {
        assert(MF.getRegInfo().isPhysRegUsed(ARM::R4) &&
               "No scratch register to restore SP from FP!");
        emitThumbRegPlusImmediate(MBB, MBBI, dl, ARM::R4, FramePtr, -NumBytes,
                                  TII, *RegInfo);
        AddDefaultPred(BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVr),
                               ARM::SP)
          .addReg(ARM::R4));
      } else
        AddDefaultPred(BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVr),
                               ARM::SP)
          .addReg(FramePtr));
    } else {
      if (MBBI->getOpcode() == ARM::tBX_RET &&
          &MBB.front() != MBBI &&
          prior(MBBI)->getOpcode() == ARM::tPOP) {
        MachineBasicBlock::iterator PMBBI = prior(MBBI);
        emitSPUpdate(MBB, PMBBI, TII, dl, *RegInfo, NumBytes);
      } else
        emitSPUpdate(MBB, MBBI, TII, dl, *RegInfo, NumBytes);
    }
  }

  if (VARegSaveSize) {
    // Unlike T2 and ARM mode, the T1 pop instruction cannot restore
    // to LR, and we can't pop the value directly to the PC since
    // we need to update the SP after popping the value. Therefore, we
    // pop the old LR into R3 as a temporary.

    // Move back past the callee-saved register restoration
    while (MBBI != MBB.end() && isCSRestore(MBBI, CSRegs))
      ++MBBI;
    // Epilogue for vararg functions: pop LR to R3 and branch off it.
    AddDefaultPred(BuildMI(MBB, MBBI, dl, TII.get(ARM::tPOP)))
      .addReg(ARM::R3, RegState::Define);

    emitSPUpdate(MBB, MBBI, TII, dl, *RegInfo, VARegSaveSize);

    AddDefaultPred(BuildMI(MBB, MBBI, dl, TII.get(ARM::tBX_RET_vararg))
      .addReg(ARM::R3, RegState::Kill));
    // erase the old tBX_RET instruction
    MBB.erase(MBBI);
  }
}

//.........这里部分代码省略.........
        break;
      }
    }
  }

  bool ForceLRSpill = false;
  if (!LRSpilled && AFI->isThumb1OnlyFunction()) {
    unsigned FnSize = GetFunctionSizeInBytes(MF, TII);
    // Force LR to be spilled if the Thumb function size is > 2048. This enables
    // use of BL to implement far jump. If it turns out that it's not needed
    // then the branch fix up path will undo it.
    if (FnSize >= (1 << 11)) {
      CanEliminateFrame = false;
      ForceLRSpill = true;
    }
  }

  // If any of the stack slot references may be out of range of an immediate
  // offset, make sure a register (or a spill slot) is available for the
  // register scavenger. Note that if we're indexing off the frame pointer, the
  // effective stack size is 4 bytes larger since the FP points to the stack
  // slot of the previous FP. Also, if we have variable sized objects in the
  // function, stack slot references will often be negative, and some of
  // our instructions are positive-offset only, so conservatively consider
  // that case to want a spill slot (or register) as well. Similarly, if
  // the function adjusts the stack pointer during execution and the
  // adjustments aren't already part of our stack size estimate, our offset
  // calculations may be off, so be conservative.
  // FIXME: We could add logic to be more precise about negative offsets
  //        and which instructions will need a scratch register for them. Is it
  //        worth the effort and added fragility?
  bool BigStack =
    (RS &&
     (estimateStackSize(MF) + ((hasFP(MF) && AFI->hasStackFrame()) ? 4:0) >=
      estimateRSStackSizeLimit(MF, this)))
    || MFI->hasVarSizedObjects()
    || (MFI->adjustsStack() && !canSimplifyCallFramePseudos(MF));

  bool ExtraCSSpill = false;
  if (BigStack || !CanEliminateFrame || RegInfo->cannotEliminateFrame(MF)) {
    AFI->setHasStackFrame(true);

    // If LR is not spilled, but at least one of R4, R5, R6, and R7 is spilled.
    // Spill LR as well so we can fold BX_RET to the registers restore (LDM).
    if (!LRSpilled && CS1Spilled) {
      MF.getRegInfo().setPhysRegUsed(ARM::LR);
      NumGPRSpills++;
      UnspilledCS1GPRs.erase(std::find(UnspilledCS1GPRs.begin(),
                                    UnspilledCS1GPRs.end(), (unsigned)ARM::LR));
      ForceLRSpill = false;
      ExtraCSSpill = true;
    }

    if (hasFP(MF)) {
      MF.getRegInfo().setPhysRegUsed(FramePtr);
      NumGPRSpills++;
    }

    // If stack and double are 8-byte aligned and we are spilling an odd number
    // of GPRs, spill one extra callee save GPR so we won't have to pad between
    // the integer and double callee save areas.
    unsigned TargetAlign = getStackAlignment();
    if (TargetAlign == 8 && (NumGPRSpills & 1)) {
      if (CS1Spilled && !UnspilledCS1GPRs.empty()) {
        for (unsigned i = 0, e = UnspilledCS1GPRs.size(); i != e; ++i) {
          unsigned Reg = UnspilledCS1GPRs[i];

void ARMFrameLowering::emitEpilogue(MachineFunction &MF,
                                    MachineBasicBlock &MBB) const {
  MachineBasicBlock::iterator MBBI = MBB.getLastNonDebugInstr();
  assert(MBBI->getDesc().isReturn() &&
         "Can only insert epilog into returning blocks");
  unsigned RetOpcode = MBBI->getOpcode();
  DebugLoc dl = MBBI->getDebugLoc();
  MachineFrameInfo *MFI = MF.getFrameInfo();
  ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
  const TargetRegisterInfo *RegInfo = MF.getTarget().getRegisterInfo();
  const ARMBaseInstrInfo &TII =
    *static_cast<const ARMBaseInstrInfo*>(MF.getTarget().getInstrInfo());
  assert(!AFI->isThumb1OnlyFunction() &&
         "This emitEpilogue does not support Thumb1!");
  bool isARM = !AFI->isThumbFunction();

  unsigned VARegSaveSize = AFI->getVarArgsRegSaveSize();
  int NumBytes = (int)MFI->getStackSize();
  unsigned FramePtr = RegInfo->getFrameRegister(MF);

  if (!AFI->hasStackFrame()) {
    if (NumBytes != 0)
      emitSPUpdate(isARM, MBB, MBBI, dl, TII, NumBytes);
  } else {
    // Unwind MBBI to point to first LDR / VLDRD.
    const unsigned *CSRegs = RegInfo->getCalleeSavedRegs();
    if (MBBI != MBB.begin()) {
      do
        --MBBI;
      while (MBBI != MBB.begin() && isCSRestore(MBBI, TII, CSRegs));
      if (!isCSRestore(MBBI, TII, CSRegs))
        ++MBBI;
    }

    // Move SP to start of FP callee save spill area.
    NumBytes -= (AFI->getGPRCalleeSavedArea1Size() +
                 AFI->getGPRCalleeSavedArea2Size() +
                 AFI->getDPRCalleeSavedAreaSize());

    // Reset SP based on frame pointer only if the stack frame extends beyond
    // frame pointer stack slot or target is ELF and the function has FP.
    if (AFI->shouldRestoreSPFromFP()) {
      NumBytes = AFI->getFramePtrSpillOffset() - NumBytes;
      if (NumBytes) {
        if (isARM)
          emitARMRegPlusImmediate(MBB, MBBI, dl, ARM::SP, FramePtr, -NumBytes,
                                  ARMCC::AL, 0, TII);
        else {
          // It's not possible to restore SP from FP in a single instruction.
          // For Darwin, this looks like:
          // mov sp, r7
          // sub sp, #24
          // This is bad, if an interrupt is taken after the mov, sp is in an
          // inconsistent state.
          // Use the first callee-saved register as a scratch register.
          assert(MF.getRegInfo().isPhysRegUsed(ARM::R4) &&
                 "No scratch register to restore SP from FP!");
          emitT2RegPlusImmediate(MBB, MBBI, dl, ARM::R4, FramePtr, -NumBytes,
                                 ARMCC::AL, 0, TII);
          AddDefaultPred(BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVr),
                                 ARM::SP)
            .addReg(ARM::R4));
        }
      } else {
        // Thumb2 or ARM.
        if (isARM)
          BuildMI(MBB, MBBI, dl, TII.get(ARM::MOVr), ARM::SP)
            .addReg(FramePtr).addImm((unsigned)ARMCC::AL).addReg(0).addReg(0);
        else
          AddDefaultPred(BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVr),
                                 ARM::SP)
            .addReg(FramePtr));
      }
    } else if (NumBytes)
      emitSPUpdate(isARM, MBB, MBBI, dl, TII, NumBytes);

    // Increment past our save areas.
    if (AFI->getDPRCalleeSavedAreaSize()) {
      MBBI++;
      // Since vpop register list cannot have gaps, there may be multiple vpop
      // instructions in the epilogue.
      while (MBBI->getOpcode() == ARM::VLDMDIA_UPD)
        MBBI++;
    }
    if (AFI->getGPRCalleeSavedArea2Size()) MBBI++;
    if (AFI->getGPRCalleeSavedArea1Size()) MBBI++;
  }

  if (RetOpcode == ARM::TCRETURNdi || RetOpcode == ARM::TCRETURNdiND ||
      RetOpcode == ARM::TCRETURNri || RetOpcode == ARM::TCRETURNriND) {
    // Tail call return: adjust the stack pointer and jump to callee.
    MBBI = MBB.getLastNonDebugInstr();
    MachineOperand &JumpTarget = MBBI->getOperand(0);

    // Jump to label or value in register.
    if (RetOpcode == ARM::TCRETURNdi || RetOpcode == ARM::TCRETURNdiND) {
      unsigned TCOpcode = (RetOpcode == ARM::TCRETURNdi)
        ? (STI.isThumb() ? ARM::tTAILJMPd : ARM::TAILJMPd)
        : (STI.isThumb() ? ARM::tTAILJMPdND : ARM::TAILJMPdND);
      MachineInstrBuilder MIB = BuildMI(MBB, MBBI, dl, TII.get(TCOpcode));
//.........这里部分代码省略.........

void ARMFrameLowering::emitPrologue(MachineFunction &MF) const {
  MachineBasicBlock &MBB = MF.front();
  MachineBasicBlock::iterator MBBI = MBB.begin();
  MachineFrameInfo  *MFI = MF.getFrameInfo();
  ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
  const ARMBaseRegisterInfo *RegInfo =
    static_cast<const ARMBaseRegisterInfo*>(MF.getTarget().getRegisterInfo());
  const ARMBaseInstrInfo &TII =
    *static_cast<const ARMBaseInstrInfo*>(MF.getTarget().getInstrInfo());
  assert(!AFI->isThumb1OnlyFunction() &&
         "This emitPrologue does not support Thumb1!");
  bool isARM = !AFI->isThumbFunction();
  unsigned VARegSaveSize = AFI->getVarArgsRegSaveSize();
  unsigned NumBytes = MFI->getStackSize();
  const std::vector<CalleeSavedInfo> &CSI = MFI->getCalleeSavedInfo();
  DebugLoc dl = MBBI != MBB.end() ? MBBI->getDebugLoc() : DebugLoc();
  unsigned FramePtr = RegInfo->getFrameRegister(MF);

  // Determine the sizes of each callee-save spill areas and record which frame
  // belongs to which callee-save spill areas.
  unsigned GPRCS1Size = 0, GPRCS2Size = 0, DPRCSSize = 0;
  int FramePtrSpillFI = 0;

  // Allocate the vararg register save area. This is not counted in NumBytes.
  if (VARegSaveSize)
    emitSPUpdate(isARM, MBB, MBBI, dl, TII, -VARegSaveSize,
                 MachineInstr::FrameSetup);

  if (!AFI->hasStackFrame()) {
    if (NumBytes != 0)
      emitSPUpdate(isARM, MBB, MBBI, dl, TII, -NumBytes,
                   MachineInstr::FrameSetup);
    return;
  }

  for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
    unsigned Reg = CSI[i].getReg();
    int FI = CSI[i].getFrameIdx();
    switch (Reg) {
    case ARM::R4:
    case ARM::R5:
    case ARM::R6:
    case ARM::R7:
    case ARM::LR:
      if (Reg == FramePtr)
        FramePtrSpillFI = FI;
      AFI->addGPRCalleeSavedArea1Frame(FI);
      GPRCS1Size += 4;
      break;
    case ARM::R8:
    case ARM::R9:
    case ARM::R10:
    case ARM::R11:
      if (Reg == FramePtr)
        FramePtrSpillFI = FI;
      if (STI.isTargetDarwin()) {
        AFI->addGPRCalleeSavedArea2Frame(FI);
        GPRCS2Size += 4;
      } else {
        AFI->addGPRCalleeSavedArea1Frame(FI);
        GPRCS1Size += 4;
      }
      break;
    default:
      AFI->addDPRCalleeSavedAreaFrame(FI);
      DPRCSSize += 8;
    }
  }

  // Move past area 1.
  if (GPRCS1Size > 0) MBBI++;

  // Set FP to point to the stack slot that contains the previous FP.
  // For Darwin, FP is R7, which has now been stored in spill area 1.
  // Otherwise, if this is not Darwin, all the callee-saved registers go
  // into spill area 1, including the FP in R11.  In either case, it is
  // now safe to emit this assignment.
  bool HasFP = hasFP(MF);
  if (HasFP) {
    unsigned ADDriOpc = !AFI->isThumbFunction() ? ARM::ADDri : ARM::t2ADDri;
    MachineInstrBuilder MIB =
      BuildMI(MBB, MBBI, dl, TII.get(ADDriOpc), FramePtr)
      .addFrameIndex(FramePtrSpillFI).addImm(0)
      .setMIFlag(MachineInstr::FrameSetup);
    AddDefaultCC(AddDefaultPred(MIB));
  }

  // Move past area 2.
  if (GPRCS2Size > 0) MBBI++;

  // Determine starting offsets of spill areas.
  unsigned DPRCSOffset  = NumBytes - (GPRCS1Size + GPRCS2Size + DPRCSSize);
  unsigned GPRCS2Offset = DPRCSOffset + DPRCSSize;
  unsigned GPRCS1Offset = GPRCS2Offset + GPRCS2Size;
  if (HasFP)
    AFI->setFramePtrSpillOffset(MFI->getObjectOffset(FramePtrSpillFI) +
                                NumBytes);
  AFI->setGPRCalleeSavedArea1Offset(GPRCS1Offset);
  AFI->setGPRCalleeSavedArea2Offset(GPRCS2Offset);
  AFI->setDPRCalleeSavedAreaOffset(DPRCSOffset);
//.........这里部分代码省略.........

void Thumb1RegisterInfo::emitEpilogue(MachineFunction &MF,
                                      MachineBasicBlock &MBB) const {
  MachineBasicBlock::iterator MBBI = prior(MBB.end());
  assert((MBBI->getOpcode() == ARM::tBX_RET ||
          MBBI->getOpcode() == ARM::tPOP_RET) &&
         "Can only insert epilog into returning blocks");
  DebugLoc dl = MBBI->getDebugLoc();
  MachineFrameInfo *MFI = MF.getFrameInfo();
  ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
  unsigned VARegSaveSize = AFI->getVarArgsRegSaveSize();
  int NumBytes = (int)MFI->getStackSize();

  if (!AFI->hasStackFrame()) {
    if (NumBytes != 0)
      emitSPUpdate(MBB, MBBI, TII, dl, *this, NumBytes);
  } else {
    // Unwind MBBI to point to first LDR / VLDRD.
    const unsigned *CSRegs = getCalleeSavedRegs();
    if (MBBI != MBB.begin()) {
      do
        --MBBI;
      while (MBBI != MBB.begin() && isCSRestore(MBBI, CSRegs));
      if (!isCSRestore(MBBI, CSRegs))
        ++MBBI;
    }

    // Move SP to start of FP callee save spill area.
    NumBytes -= (AFI->getGPRCalleeSavedArea1Size() +
                 AFI->getGPRCalleeSavedArea2Size() +
                 AFI->getDPRCalleeSavedAreaSize());

    if (hasFP(MF)) {
      NumBytes = AFI->getFramePtrSpillOffset() - NumBytes;
      // Reset SP based on frame pointer only if the stack frame extends beyond
      // frame pointer stack slot or target is ELF and the function has FP.
      if (NumBytes)
        emitThumbRegPlusImmediate(MBB, MBBI, ARM::SP, FramePtr, -NumBytes,
                                  TII, *this, dl);
      else
        BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVtgpr2gpr), ARM::SP)
          .addReg(FramePtr);
    } else {
      if (MBBI->getOpcode() == ARM::tBX_RET &&
          &MBB.front() != MBBI &&
          prior(MBBI)->getOpcode() == ARM::tPOP) {
        MachineBasicBlock::iterator PMBBI = prior(MBBI);
        emitSPUpdate(MBB, PMBBI, TII, dl, *this, NumBytes);
      } else
        emitSPUpdate(MBB, MBBI, TII, dl, *this, NumBytes);
    }
  }

  if (VARegSaveSize) {
    // Epilogue for vararg functions: pop LR to R3 and branch off it.
    AddDefaultPred(BuildMI(MBB, MBBI, dl, TII.get(ARM::tPOP)))
      .addReg(0) // No write back.
      .addReg(ARM::R3, RegState::Define);

    emitSPUpdate(MBB, MBBI, TII, dl, *this, VARegSaveSize);

    BuildMI(MBB, MBBI, dl, TII.get(ARM::tBX_RET_vararg))
      .addReg(ARM::R3, RegState::Kill);
    MBB.erase(MBBI);
  }
}

void Thumb1RegisterInfo::emitPrologue(MachineFunction &MF) const {
  MachineBasicBlock &MBB = MF.front();
  MachineBasicBlock::iterator MBBI = MBB.begin();
  MachineFrameInfo  *MFI = MF.getFrameInfo();
  ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
  unsigned VARegSaveSize = AFI->getVarArgsRegSaveSize();
  unsigned NumBytes = MFI->getStackSize();
  const std::vector<CalleeSavedInfo> &CSI = MFI->getCalleeSavedInfo();
  DebugLoc dl = (MBBI != MBB.end() ?
                 MBBI->getDebugLoc() : DebugLoc::getUnknownLoc());

  // Thumb add/sub sp, imm8 instructions implicitly multiply the offset by 4.
  NumBytes = (NumBytes + 3) & ~3;
  MFI->setStackSize(NumBytes);

  // Determine the sizes of each callee-save spill areas and record which frame
  // belongs to which callee-save spill areas.
  unsigned GPRCS1Size = 0, GPRCS2Size = 0, DPRCSSize = 0;
  int FramePtrSpillFI = 0;

  if (VARegSaveSize)
    emitSPUpdate(MBB, MBBI, TII, dl, *this, -VARegSaveSize);

  if (!AFI->hasStackFrame()) {
    if (NumBytes != 0)
      emitSPUpdate(MBB, MBBI, TII, dl, *this, -NumBytes);
    return;
  }

  for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
    unsigned Reg = CSI[i].getReg();
    int FI = CSI[i].getFrameIdx();
    switch (Reg) {
    case ARM::R4:
    case ARM::R5:
    case ARM::R6:
    case ARM::R7:
    case ARM::LR:
      if (Reg == FramePtr)
        FramePtrSpillFI = FI;
      AFI->addGPRCalleeSavedArea1Frame(FI);
      GPRCS1Size += 4;
      break;
    case ARM::R8:
    case ARM::R9:
    case ARM::R10:
    case ARM::R11:
      if (Reg == FramePtr)
        FramePtrSpillFI = FI;
      if (STI.isTargetDarwin()) {
        AFI->addGPRCalleeSavedArea2Frame(FI);
        GPRCS2Size += 4;
      } else {
        AFI->addGPRCalleeSavedArea1Frame(FI);
        GPRCS1Size += 4;
      }
      break;
    default:
      AFI->addDPRCalleeSavedAreaFrame(FI);
      DPRCSSize += 8;
    }
  }

  if (MBBI != MBB.end() && MBBI->getOpcode() == ARM::tPUSH) {
    ++MBBI;
    if (MBBI != MBB.end())
      dl = MBBI->getDebugLoc();
  }

  // Darwin ABI requires FP to point to the stack slot that contains the
  // previous FP.
  if (STI.isTargetDarwin() || hasFP(MF)) {
    BuildMI(MBB, MBBI, dl, TII.get(ARM::tADDrSPi), FramePtr)
      .addFrameIndex(FramePtrSpillFI).addImm(0);
  }

  // Determine starting offsets of spill areas.
  unsigned DPRCSOffset  = NumBytes - (GPRCS1Size + GPRCS2Size + DPRCSSize);
  unsigned GPRCS2Offset = DPRCSOffset + DPRCSSize;
  unsigned GPRCS1Offset = GPRCS2Offset + GPRCS2Size;
  AFI->setFramePtrSpillOffset(MFI->getObjectOffset(FramePtrSpillFI) + NumBytes);
  AFI->setGPRCalleeSavedArea1Offset(GPRCS1Offset);
  AFI->setGPRCalleeSavedArea2Offset(GPRCS2Offset);
  AFI->setDPRCalleeSavedAreaOffset(DPRCSOffset);

  NumBytes = DPRCSOffset;
  if (NumBytes) {
    // Insert it after all the callee-save spills.
    emitSPUpdate(MBB, MBBI, TII, dl, *this, -NumBytes);
  }

  if (STI.isTargetELF() && hasFP(MF)) {
    MFI->setOffsetAdjustment(MFI->getOffsetAdjustment() -
                             AFI->getFramePtrSpillOffset());
  }

  AFI->setGPRCalleeSavedArea1Size(GPRCS1Size);
  AFI->setGPRCalleeSavedArea2Size(GPRCS2Size);
  AFI->setDPRCalleeSavedAreaSize(DPRCSSize);
}