[Pixman] [PATCH] sse2: Skip src pixels that are zero in sse2_composite_over_8888_n_8888()

[Rodrigo Kumpera]

This patch doesn't handle cases where alpha is zero but components are not.
Not sure
if this is either possible or frequent.



On Mon, Dec 20, 2010 at 8:50 PM, Søren Sandmann <sandmann at daimi.au.dk>wrote:

> From: Søren Sandmann Pedersen <ssp at redhat.com>
>
> This is a big speed-up in the SVG helicopter game:
>
>   http://ie.microsoft.com/testdrive/Performance/Helicopter/Default.xhtml
>
> when rendered by Firefox 4 since it is compositing big images
> consisting almost entirely of zeros.
> ---
>  pixman/pixman-sse2.c |   75
> +++++++++++++++++++++++++++++--------------------
>  1 files changed, 44 insertions(+), 31 deletions(-)
>
> diff --git a/pixman/pixman-sse2.c b/pixman/pixman-sse2.c
> index 5907de0..032f13b 100644
> --- a/pixman/pixman-sse2.c
> +++ b/pixman/pixman-sse2.c
> @@ -3051,37 +3051,45 @@ sse2_composite_over_8888_n_8888
> (pixman_implementation_t *imp,
>        while (w && (unsigned long)dst & 15)
>        {
>            uint32_t s = *src++;
> -           uint32_t d = *dst;
> -
> -           __m64 ms = unpack_32_1x64 (s);
> -           __m64 alpha    = expand_alpha_1x64 (ms);
> -           __m64 dest     = _mm_movepi64_pi64 (xmm_mask);
> -           __m64 alpha_dst = unpack_32_1x64 (d);
> -
> -           *dst++ = pack_1x64_32 (
> -               in_over_1x64 (&ms, &alpha, &dest, &alpha_dst));
>
> +           if (s)
> +           {
> +               uint32_t d = *dst;
> +
> +               __m64 ms = unpack_32_1x64 (s);
> +               __m64 alpha    = expand_alpha_1x64 (ms);
> +               __m64 dest     = _mm_movepi64_pi64 (xmm_mask);
> +               __m64 alpha_dst = unpack_32_1x64 (d);
> +
> +               *dst = pack_1x64_32 (
> +                   in_over_1x64 (&ms, &alpha, &dest, &alpha_dst));
> +           }
> +           dst++;
>            w--;
>        }
>
>        while (w >= 4)
>        {
>            xmm_src = load_128_unaligned ((__m128i*)src);
> -           xmm_dst = load_128_aligned ((__m128i*)dst);
> -
> -           unpack_128_2x128 (xmm_src, &xmm_src_lo, &xmm_src_hi);
> -           unpack_128_2x128 (xmm_dst, &xmm_dst_lo, &xmm_dst_hi);
> -           expand_alpha_2x128 (xmm_src_lo, xmm_src_hi,
> -                               &xmm_alpha_lo, &xmm_alpha_hi);
> -
> -           in_over_2x128 (&xmm_src_lo, &xmm_src_hi,
> -                          &xmm_alpha_lo, &xmm_alpha_hi,
> -                          &xmm_mask, &xmm_mask,
> -                          &xmm_dst_lo, &xmm_dst_hi);
> -
> -           save_128_aligned (
> -               (__m128i*)dst, pack_2x128_128 (xmm_dst_lo, xmm_dst_hi));
>
> +           if (!is_zero (xmm_src))
> +           {
> +               xmm_dst = load_128_aligned ((__m128i*)dst);
> +
> +               unpack_128_2x128 (xmm_src, &xmm_src_lo, &xmm_src_hi);
> +               unpack_128_2x128 (xmm_dst, &xmm_dst_lo, &xmm_dst_hi);
> +               expand_alpha_2x128 (xmm_src_lo, xmm_src_hi,
> +                                   &xmm_alpha_lo, &xmm_alpha_hi);
> +
> +               in_over_2x128 (&xmm_src_lo, &xmm_src_hi,
> +                              &xmm_alpha_lo, &xmm_alpha_hi,
> +                              &xmm_mask, &xmm_mask,
> +                              &xmm_dst_lo, &xmm_dst_hi);
> +
> +               save_128_aligned (
> +                   (__m128i*)dst, pack_2x128_128 (xmm_dst_lo,
> xmm_dst_hi));
> +           }
> +
>            dst += 4;
>            src += 4;
>            w -= 4;
> @@ -3090,16 +3098,21 @@ sse2_composite_over_8888_n_8888
> (pixman_implementation_t *imp,
>        while (w)
>        {
>            uint32_t s = *src++;
> -           uint32_t d = *dst;
>
> -           __m64 ms = unpack_32_1x64 (s);
> -           __m64 alpha = expand_alpha_1x64 (ms);
> -           __m64 mask  = _mm_movepi64_pi64 (xmm_mask);
> -           __m64 dest  = unpack_32_1x64 (d);
> -
> -           *dst++ = pack_1x64_32 (
> -               in_over_1x64 (&ms, &alpha, &mask, &dest));
> +           if (s)
> +           {
> +               uint32_t d = *dst;
> +
> +               __m64 ms = unpack_32_1x64 (s);
> +               __m64 alpha = expand_alpha_1x64 (ms);
> +               __m64 mask  = _mm_movepi64_pi64 (xmm_mask);
> +               __m64 dest  = unpack_32_1x64 (d);
> +
> +               *dst = pack_1x64_32 (
> +                   in_over_1x64 (&ms, &alpha, &mask, &dest));
> +           }
>
> +           dst++;
>            w--;
>        }
>     }
> --
> 1.7.3.1
>
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