[Mesa-dev] [PATCH] radeonsi: use shifts for sign extension

[Marek Olšák]

Reviewed-by: Marek Olšák <marek.olsak at amd.com>

Marek

On Wed, Jun 20, 2018 at 3:25 PM, Grazvydas Ignotas <notasas at gmail.com> wrote:
> Avoids a branch and reduces code size a tiny bit:
>     text   data     bss      dec    hex filename
> 10804563 398653 2070368 13273584 ca89f0 /tmp/radeonsi_dri.so.old
> 10804499 398653 2070368 13273520 ca89b0 /tmp/radeonsi_dri.so
> ---
>  src/gallium/drivers/radeonsi/si_descriptors.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/src/gallium/drivers/radeonsi/si_descriptors.c b/src/gallium/drivers/radeonsi/si_descriptors.c
> index 57a3124..f368ea6 100644
> --- a/src/gallium/drivers/radeonsi/si_descriptors.c
> +++ b/src/gallium/drivers/radeonsi/si_descriptors.c
> @@ -98,12 +98,12 @@ static uint64_t si_desc_extract_buffer_address(const uint32_t *desc)
>  {
>         uint64_t va = desc[0] |
>                       ((uint64_t)G_008F04_BASE_ADDRESS_HI(desc[1]) << 32);
>
>         /* Sign-extend the 48-bit address. */
> -       if (va & (1ull << 47))
> -               va |= 0xffffull << 48;
> +       va <<= 16;
> +       va = (int64_t)va >> 16;
>         return va;
>  }
>
>  static void si_init_descriptor_list(uint32_t *desc_list,
>                                     unsigned element_dw_size,
> --
> 2.7.4
>
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