Re: [x32] PATCH: PR middle-end/47725: [x32] error: unable to find a register to spill in class DIREG

["H.J. Lu" <hjl dot tools at gmail dot com>]

On Tue, Mar 22, 2011 at 1:05 PM, Eric Botcazou <ebotcazou@adacore.com> wrote:
>> It leads 2 problems:
>>
>> 1. Redundant zero-extension at function entry.
>> 2. combine doesn't check zero-extension on hard register and leads to
>> internal compiler error.
>>
>> Is there a way to avoid redundant zero-extension at function entry to
>> solve both problems?
>
> Eliminating the redundant extension in the callee seems indeed to be appealing.
> You need to find out who decides that the incoming parameter needs to be zero-
> extended. ?Is that the call to promote_function_mode in assign_parm_setup_reg?
>

It is:

      op0 = parmreg;
      op1 = validated_mem;
      if (icode != CODE_FOR_nothing
          && insn_data[icode].operand[0].predicate (op0, promoted_nominal_mode)
          && insn_data[icode].operand[1].predicate (op1, data->passed_mode))
        {
          enum rtx_code code = unsignedp ? ZERO_EXTEND : SIGN_EXTEND;
          rtx insn, insns;
          HARD_REG_SET hardregs;

          start_sequence ();
          insn = gen_extend_insn (op0, op1, promoted_nominal_mode,
                                  data->passed_mode, unsignedp);
          emit_insn (insn);
          insns = get_insns ();

in assign_parm_setup_reg.

-- 
H.J.