[Webkit-unassigned] [Bug 73789] Need SSE optimization for SincResampler::Process()

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=73789


Benjamin Poulain <benjamin at webkit.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
 Attachment #117871|review?                     |review-
               Flag|                            |




--- Comment #14 from Benjamin Poulain <benjamin at webkit.org>  2011-12-05 10:16:33 PST ---
(From update of attachment 117871)
View in context: https://bugs.webkit.org/attachment.cgi?id=117871&action=review

> Source/WebCore/ChangeLog:7
> +        Implement the SSE optimization in SincResampler::process()
> +        https://bugs.webkit.org/show_bug.cgi?id=73789
> +
> +        Reviewed by NOBODY (OOPS!).
> +

You should add a little description, mentioning the performance gain of the change.

> Source/WebCore/ChangeLog:10
> +        * platform/audio/SincResampler.cpp:
> +        (WebCore::SincResampler::process):
>  2011-12-05  Roland Steiner  <rolandsteiner at chromium.org>

Missing space at the end of the ChangeLog.

> Source/WebCore/platform/audio/SincResampler.cpp:264
> +            while ((reinterpret_cast<size_t>(inputP) & 0x0F) && n) {

This should be uintptr_t instead of size_t.

> Source/WebCore/platform/audio/SincResampler.cpp:270
> +            int group = n / 4;

Instead of tracking this, you could find the end, and then loop until the end: 
while (mInput < end) {
   ...
}
The advantage is you remove the computation of group-- from a tight loop.

> Source/WebCore/platform/audio/SincResampler.cpp:282
> +            sums1 = _mm_setzero_ps();
> +            sums2 = _mm_setzero_ps();

You can move those to the lines where you declare sums1 and sums2.

> Source/WebCore/platform/audio/SincResampler.cpp:284
> +            k1Aligned = !(reinterpret_cast<size_t>(k1) & 0x0F);
> +            k2Aligned = !(reinterpret_cast<size_t>(k2) & 0x0F);

This should be uintptr_t instead of size_t.

> Source/WebCore/platform/audio/SincResampler.cpp:298
> +                    mul1 = _mm_mul_ps(mInput, mK1);
> +                    mul2 = _mm_mul_ps(mInput, mK2);
> +                    sums1 = _mm_add_ps(sums1, mul1);
> +                    sums2 = _mm_add_ps(sums2, mul2);
> +
> +                    inputP += 4;
> +                    k1 += 4;
> +                    k2 += 4;

This code is copied three time. It could be moved to a macro CONVOLVE_4_SAMPLE_SSE.
You can try an inline function but I think that will fail with MSVC compiler due to a bug when passing vectors as arguments.

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