Re: [Qemu-devel] [PATCH 10/13] target-arm: A64: add support for bitfield insns

[Richard Henderson]

On 12/06/2013 10:51 AM, Peter Maydell wrote:
> From: Claudio Fontana <address@hidden>
> 
> This patch implements the C3.4.2 Bitfield instructions:
> SBFM, BFM, UBFM.
> 
> Signed-off-by: Claudio Fontana <address@hidden>
> Signed-off-by: Peter Maydell <address@hidden>
> ---
>  target-arm/translate-a64.c |   54 
> ++++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 52 insertions(+), 2 deletions(-)

Reviewed-by: Richard Henderson <address@hidden>

> +    if (opc != 1) { /* SBFM or UBFM */
> +        tcg_gen_movi_i64(tcg_rd, 0);
> +    }
> +
> +    /* do the bit move operation */
> +    if (si >= ri) {
> +        /* Wd<s-r:0> = Wn<s:r> */
> +        tcg_gen_shri_i64(tcg_tmp, tcg_tmp, ri);
> +        pos = 0;
> +        len = (si - ri) + 1;
> +    } else {
> +        /* Wd<32+s-r,32-r> = Wn<s:0> */
> +        pos = bitsize - ri;
> +        len = si + 1;
> +    }
> +
> +    tcg_gen_deposit_i64(tcg_rd, tcg_rd, tcg_tmp, pos, len);
> +
> +    if (opc == 0) { /* SBFM - sign extend the destination field */
> +        tcg_gen_shli_i64(tcg_rd, tcg_rd, 64 - (pos + len));
> +        tcg_gen_sari_i64(tcg_rd, tcg_rd, 64 - (pos + len));
> +    }

OPTME: It's probably worth recognizing the common cases of ext{8,16,32}{u,s}.


r~