Example #1
0
void ARMBaseRegisterInfo::
eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
                              MachineBasicBlock::iterator I) const {
  const TargetFrameLowering *TFI = MF.getTarget().getFrameLowering();
  if (!TFI->hasReservedCallFrame(MF)) {
    // If we have alloca, convert as follows:
    // ADJCALLSTACKDOWN -> sub, sp, sp, amount
    // ADJCALLSTACKUP   -> add, sp, sp, amount
    MachineInstr *Old = I;
    DebugLoc dl = Old->getDebugLoc();
    unsigned Amount = Old->getOperand(0).getImm();
    if (Amount != 0) {
      // We need to keep the stack aligned properly.  To do this, we round the
      // amount of space needed for the outgoing arguments up to the next
      // alignment boundary.
      unsigned Align = TFI->getStackAlignment();
      Amount = (Amount+Align-1)/Align*Align;

      ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
      assert(!AFI->isThumb1OnlyFunction() &&
             "This eliminateCallFramePseudoInstr does not support Thumb1!");
      bool isARM = !AFI->isThumbFunction();

      // Replace the pseudo instruction with a new instruction...
      unsigned Opc = Old->getOpcode();
      int PIdx = Old->findFirstPredOperandIdx();
      ARMCC::CondCodes Pred = (PIdx == -1)
        ? ARMCC::AL : (ARMCC::CondCodes)Old->getOperand(PIdx).getImm();
      if (Opc == ARM::ADJCALLSTACKDOWN || Opc == ARM::tADJCALLSTACKDOWN) {
        // Note: PredReg is operand 2 for ADJCALLSTACKDOWN.
        unsigned PredReg = Old->getOperand(2).getReg();
        emitSPUpdate(isARM, MBB, I, dl, TII, -Amount, Pred, PredReg);
      } else {
        // Note: PredReg is operand 3 for ADJCALLSTACKUP.
        unsigned PredReg = Old->getOperand(3).getReg();
        assert(Opc == ARM::ADJCALLSTACKUP || Opc == ARM::tADJCALLSTACKUP);
        emitSPUpdate(isARM, MBB, I, dl, TII, Amount, Pred, PredReg);
      }
    }
  }
  MBB.erase(I);
}