Re: [Qemu-devel] [PATCH 08/20] tcg-ia64: Use SUB_A3 and ADDS_A4 for subtraction

[Aurelien Jarno <aurelien@aurel32.net>]

On Thu, Oct 31, 2013 at 01:21:57PM -0700, Richard Henderson wrote:
> We can subtract from more small constants that just 0 with one insn,
> and we can add the negative for most small constants.
> 
> Signed-off-by: Richard Henderson <rth@twiddle.net>
> ---
>  tcg/ia64/tcg-target.c | 25 +++++++++++++++++++++++--
>  1 file changed, 23 insertions(+), 2 deletions(-)
> 
> diff --git a/tcg/ia64/tcg-target.c b/tcg/ia64/tcg-target.c
> index be74606..d7bccd2 100644
> --- a/tcg/ia64/tcg-target.c
> +++ b/tcg/ia64/tcg-target.c
> @@ -1080,6 +1080,28 @@ static inline void tcg_out_add(TCGContext *s, TCGReg ret, TCGReg arg1,
>      }
>  }
>  
> +static inline void tcg_out_sub(TCGContext *s, TCGReg ret, TCGArg arg1,
> +                               int const_arg1, TCGArg arg2, int const_arg2)
> +{
> +    if (const_arg1 && arg1 == (int8_t)arg1) {
> +        if (const_arg2) {
> +            tcg_out_movi(s, TCG_TYPE_I64, ret, arg1 - arg2);
> +            return;
> +        }
> +        tcg_out_bundle(s, mmI,
> +                       INSN_NOP_M,
> +                       INSN_NOP_M,
> +                       tcg_opc_a3(TCG_REG_P0, OPC_SUB_A3, ret, arg1, arg2));
> +    } else if (const_arg2 && -arg2 == sextract64(-arg2, 0, 14)) {
> +        tcg_out_bundle(s, mmI,
> +                       INSN_NOP_M,
> +                       INSN_NOP_M,
> +                       tcg_opc_a4(TCG_REG_P0, OPC_ADDS_A4, ret, -arg2, arg1));
> +    } else {
> +        tcg_out_alu(s, OPC_SUB_A1, ret, arg1, const_arg1, arg2, const_arg2);
> +    }
> +}
> +
>  static inline void tcg_out_eqv(TCGContext *s, TCGArg ret,
>                                 TCGArg arg1, int const_arg1,
>                                 TCGArg arg2, int const_arg2)
> @@ -2085,8 +2107,7 @@ static inline void tcg_out_op(TCGContext *s, TCGOpcode opc,
>          break;
>      case INDEX_op_sub_i32:
>      case INDEX_op_sub_i64:
> -        tcg_out_alu(s, OPC_SUB_A1, args[0], args[1], const_args[1],
> -                    args[2], const_args[2]);
> +        tcg_out_sub(s, args[0], args[1], const_args[1], args[2], const_args[2]);
>          break;
>  
>      case INDEX_op_and_i32:

Acked-by: Aurelien Jarno <aurelien@aurel32.net>

-- 
Aurelien Jarno                          GPG: 1024D/F1BCDB73
aurelien@aurel32.net                 http://www.aurel32.net