[Webkit-unassigned] [Bug 77950] SSE optimization for vsvesq and vmaxmgv

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=77950





--- Comment #10 from xingnan.wang at intel.com  2012-02-23 22:17:15 PST ---
(From update of attachment 128369)
View in context: https://bugs.webkit.org/attachment.cgi?id=128369&action=review

>> Source/WebCore/platform/audio/VectorMath.cpp:500
>> +            source = _mm_and_ps(source, mMask);
> 
> You mentioned that the performance with and_ps is less than the previous version with min_ps.  Is this because and_ps is slower or maybe because of some pipelining isues?  I'm just curious as to why this is slower.

It`s not slower with and_ps, my expression may not be clear so sorry for misleading you. I mean the performance between using and_ps and min_ps is not too much different, so I think the performance data is no needed to be updated.

>> Source/WebCore/platform/audio/VectorMath.cpp:508
>> +        max = std::max(groupMaxP[2], groupMaxP[3]);
> 
> The assignment to max here at line 508 overwrites the max computed in line 485 when the source is not aligned.  This needs to be rearranged a little so as not to destroy that.

I`ll fix it.

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