[llvm-commits] [llvm] r96654 - /llvm/trunk/lib/Target/ARM/ARMInstrInfo.td

[Johnny Chen]

OK.  I've modified ARMInstPrinter.cpp to handle the printing of ARM::MOVs:

void ARMInstPrinter::printInst(const MCInst *MI) {
  // Check for MOVs and print canonical forms, instead.
  if (MI->getOpcode() == ARM::MOVs) {
    const MCOperand &Dst = MI->getOperand(0);
    const MCOperand &MO1 = MI->getOperand(1);
    const MCOperand &MO2 = MI->getOperand(2);
    const MCOperand &MO3 = MI->getOperand(3);

    O << '\t' << ARM_AM::getShiftOpcStr(ARM_AM::getSORegShOp(MO3.getImm()));
    printSBitModifierOperand(MI, 6);
    printPredicateOperand(MI, 4);

    O << '\t' << getRegisterName(Dst.getReg())
      << ", " << getRegisterName(MO1.getReg());

    if (ARM_AM::getSORegShOp(MO3.getImm()) == ARM_AM::rrx)
      return;

    O << ", ";

    if (MO2.getReg()) {
      O << getRegisterName(MO2.getReg());
      assert(ARM_AM::getSORegOffset(MO3.getImm()) == 0);
    } else {
      O << "#" << ARM_AM::getSORegOffset(MO3.getImm());
    }
    return;
  }

  printInstruction(MI);
 }

I will modify ARMInstrInfo.td to remove the entries in a minute.

Thanks.

On Feb 19, 2010, at 2:00 PM, Chris Lattner wrote:

> 
> On Feb 19, 2010, at 11:33 AM, Johnny Chen wrote:
> 
>> Hi Chris,
>> 
>> These added encodings are are more specific than:
>> 
>> def MOVs : AsI1<0b1101, (outs GPR:$dst), (ins so_reg:$src),
>>               DPSoRegFrm, IIC_iMOVsr,
>>               "mov", "\t$dst, $src", [(set GPR:$dst, so_reg:$src)]>, UnaryDP {
>> let Inst{25} = 0;
>> }
>> 
>> Relying on the decoder to decode a MOVs super-instruction would mean that
>> it prints out:
>> 
>> 	mov		r0, r0, asr #1
>> 
>> which, according to A8.6.98, is a pseudo-instruction and is not the canonical form we want
>> for disassembly (A8-199).  And an added bonus is that MOVs cannot handle RRX (A8-282).
> 
> I'm not sure I understand here.  You added a redundant encoding for the same bits, yes?
> 
> If this is the case, it is better to handle this with code like PPCAsmPrinter::EmitInstruction, where the decoder produces the general 'mov' form of the MCInst, but then the MCInst -> text printer handles the special pseudo op.
> 
> -Chris
>