Re: [Qemu-devel] [PATCH v2 7/7] tcg-i386: Make use of zero-extended memory helper routines

[Aurelien Jarno <aurelien@aurel32.net>]

On Thu, Aug 29, 2013 at 03:06:01PM -0700, Richard Henderson wrote:
> For 8 and 16-bit unsigned loads, rely on the zero-extension
> from the helper and use a smaller 32-bit move insn.
> 
> Signed-off-by: Richard Henderson <rth@twiddle.net>
> ---
>  tcg/i386/tcg-target.c | 15 ++++++---------
>  1 file changed, 6 insertions(+), 9 deletions(-)
> 
> diff --git a/tcg/i386/tcg-target.c b/tcg/i386/tcg-target.c
> index 5aee0fa..e9d6c49 100644
> --- a/tcg/i386/tcg-target.c
> +++ b/tcg/i386/tcg-target.c
> @@ -1520,20 +1520,17 @@ static void tcg_out_qemu_ld_slow_path(TCGContext *s, TCGLabelQemuLdst *l)
>      case 1 | 4:
>          tcg_out_ext16s(s, data_reg, TCG_REG_EAX, P_REXW);
>          break;
> -    case 0:
> -        tcg_out_ext8u(s, data_reg, TCG_REG_EAX);
> -        break;
> -    case 1:
> -        tcg_out_ext16u(s, data_reg, TCG_REG_EAX);
> -        break;
> -    case 2:
> -        tcg_out_mov(s, TCG_TYPE_I32, data_reg, TCG_REG_EAX);
> -        break;
>  #if TCG_TARGET_REG_BITS == 64
>      case 2 | 4:
>          tcg_out_ext32s(s, data_reg, TCG_REG_EAX);
>          break;
>  #endif
> +    case 0:
> +    case 1:
> +        /* Note that the helpers have zero-extended to tcg_target_long.  */
> +    case 2:
> +        tcg_out_mov(s, TCG_TYPE_I32, data_reg, TCG_REG_EAX);
> +        break;
>      case 3:
>          if (TCG_TARGET_REG_BITS == 64) {
>              tcg_out_mov(s, TCG_TYPE_I64, data_reg, TCG_REG_RAX);

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

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