Re: [PATCH 08/28] tcg/ppc: Split out tcg_out_bswap32

[Peter Maydell]

On Mon, 14 Jun 2021 at 09:42, Richard Henderson
<richard.henderson@linaro.org> wrote:
>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>  tcg/ppc/tcg-target.c.inc | 28 ++++++++++++----------------
>  1 file changed, 12 insertions(+), 16 deletions(-)
>
> diff --git a/tcg/ppc/tcg-target.c.inc b/tcg/ppc/tcg-target.c.inc
> index 64c24382a8..f0e42e4b88 100644
> --- a/tcg/ppc/tcg-target.c.inc
> +++ b/tcg/ppc/tcg-target.c.inc
> @@ -798,6 +798,17 @@ static void tcg_out_bswap16(TCGContext *s, TCGReg dst, 
> TCGReg src)
>      tcg_out_mov(s, TCG_TYPE_REG, dst, tmp);
>  }
>
> +static void tcg_out_bswap32(TCGContext *s, TCGReg dst, TCGReg src)
> +{
> +    TCGReg tmp = dst == src ? TCG_REG_R0 : dst;
> +
> +    /* Stolen from gcc's builtin_bswap32.             src = abcd */
> +    tcg_out_rlw(s, RLWINM, tmp, src, 8, 0, 31);    /* tmp = bcda */
> +    tcg_out_rlw(s, RLWIMI, tmp, src, 24, 0, 7);    /* tmp = dcda */
> +    tcg_out_rlw(s, RLWIMI, tmp, src, 24, 16, 23);  /* tmp = dcba */
> +    tcg_out_mov(s, TCG_TYPE_REG, dst, tmp);
> +}
> +
>  /* Emit a move into ret of arg, if it can be done in one insn.  */
>  static bool tcg_out_movi_one(TCGContext *s, TCGReg ret, tcg_target_long arg)
>  {
> @@ -2791,24 +2802,9 @@ static void tcg_out_op(TCGContext *s, TCGOpcode opc,
>      case INDEX_op_bswap16_i64:
>          tcg_out_bswap16(s, args[0], args[1]);
>          break;
> -
>      case INDEX_op_bswap32_i32:
>      case INDEX_op_bswap32_i64:
> -        /* Stolen from gcc's builtin_bswap32 */
> -        a1 = args[1];
> -        a0 = args[0] == a1 ? TCG_REG_R0 : args[0];
> -
> -        /* a1 = args[1] # abcd */
> -        /* a0 = rotate_left (a1, 8) # bcda */
> -        tcg_out_rlw(s, RLWINM, a0, a1, 8, 0, 31);
> -        /* a0 = (a0 & ~0xff000000) | ((a1 r<< 24) & 0xff000000) # dcda */
> -        tcg_out_rlw(s, RLWIMI, a0, a1, 24, 0, 7);
> -        /* a0 = (a0 & ~0x0000ff00) | ((a1 r<< 24) & 0x0000ff00) # dcba */
> -        tcg_out_rlw(s, RLWIMI, a0, a1, 24, 16, 23);
> -
> -        if (a0 == TCG_REG_R0) {
> -            tcg_out_mov(s, TCG_TYPE_REG, args[0], a0);
> -        }
> +        tcg_out_bswap32(s, args[0], args[1]);
>          break;
>

Same remark about keeping the comments; otherwise
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>

thanks
-- PMM