Re: [Qemu-devel] [PATCH 6/7] tcg: Tidy brcond optimization

[Aurelien Jarno <aurelien@aurel32.net>]

On Thu, Sep 27, 2012 at 10:19:56AM -0700, Richard Henderson wrote:
> Do the memset once.  Don't reset_temp before doing so.
> 
> Signed-off-by: Richard Henderson <rth@twiddle.net>
> ---
>  tcg/optimize.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/tcg/optimize.c b/tcg/optimize.c
> index c1881fa..dfac877 100644
> --- a/tcg/optimize.c
> +++ b/tcg/optimize.c
> @@ -771,22 +771,22 @@ static TCGArg *tcg_constant_folding(TCGContext *s, uint16_t *tcg_opc_ptr,
>              tmp = do_constant_folding_cond(op, args[0], args[1], args[2]);
>              if (tmp != 2) {
>                  if (tmp) {
> -                    memset(temps, 0, nb_temps * sizeof(struct tcg_temp_info));
>                      gen_opc_buf[op_index] = INDEX_op_br;
>                      gen_args[0] = args[3];
>                      gen_args += 1;
>                  } else {
>                      gen_opc_buf[op_index] = INDEX_op_nop;
> +                    args += 4;
> +                    break;
>                  }
>              } else {
> -                memset(temps, 0, nb_temps * sizeof(struct tcg_temp_info));
> -                reset_temp(args[0]);
>                  gen_args[0] = args[0];
>                  gen_args[1] = args[1];
>                  gen_args[2] = args[2];
>                  gen_args[3] = args[3];
>                  gen_args += 4;
>              }
> +            memset(temps, 0, nb_temps * sizeof(struct tcg_temp_info));
>              args += 4;
>              break;
>          CASE_OP_32_64(movcond):
> -- 
> 1.7.11.4
> 

Removing the useless reset_temp() is indeed something to do. I am not so
sure that factorizing the memset() and putting a break in the nop case
is easier to read. Nevertheless:

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

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