Re: [Qemu-devel] [PATCH v14 28/33] target-tilegx: Handle v1cmpeq, v1cmpne

[Peter Maydell]

On 24 August 2015 at 17:17, Richard Henderson <address@hidden> wrote:
> Signed-off-by: Richard Henderson <address@hidden>
> ---
>  target-tilegx/translate.c | 51 
> +++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 51 insertions(+)
>
> diff --git a/target-tilegx/translate.c b/target-tilegx/translate.c
> index af4b34a..1224a8e 100644
> --- a/target-tilegx/translate.c
> +++ b/target-tilegx/translate.c
> @@ -93,6 +93,8 @@ typedef struct {
>  #define OE_IM(E,XY)    OE(IMM8_OPCODE_##XY, E##_IMM8_OPCODE_##XY, XY)
>  #define OE_SH(E,XY)    OE(SHIFT_OPCODE_##XY, E##_SHIFT_OPCODE_##XY, XY)
>
> +#define V1_IMM(X)      (((X) & 0xff) * 0x0101010101010101ull)
> +
>
>  static void gen_exception(DisasContext *dc, TileExcp num)
>  {
> @@ -238,6 +240,41 @@ static void gen_mul_half(TCGv tdest, TCGv tsrca, TCGv 
> tsrcb, int ha, int hb)
>      tcg_temp_free(t);
>  }
>
> +/* Equality comparison with zero can be done quickly and efficiently.  */
> +static void gen_v1cmpeq0(TCGv v)
> +{
> +    TCGv m = tcg_const_tl(V1_IMM(0x7f));
> +    TCGv c = tcg_temp_new();
> +
> +    /* ~(((a & m) + m) | m | a).  Sets the msb for each byte == 0.  */
> +    tcg_gen_and_tl(c, v, m);
> +    tcg_gen_add_tl(c, c, m);
> +    tcg_gen_or_tl(c, c, m);
> +    tcg_gen_nor_tl(c, c, v);
> +    tcg_temp_free(m);

It would be nice to be consistent with whether we're using 'v'
or 'a' for the input value in the code and the comment.

otherwise
Reviewed-by: Peter Maydell <address@hidden>

thanks
-- PMM