[Webkit-unassigned] [Bug 54456] Optimizing lightning filter to ARM-neon SIMD instruction set

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=54456





--- Comment #32 from Gabor Loki <loki at webkit.org>  2011-03-07 04:49:05 PST ---
> Other issues:
> - Make the code easier to understand. Naturally, it is still required to know the SVG standard to understand it.
>   - I have added several comments.

Although the asm code itself and the neonized algorithm were also readable before, but the comments are really needed for non-ARM observers.

> - Using intrinsics: unfortunately intrinsics offers to access only a small subset of Advanced SIMD features, and nothing more. This is a whole function, including a mixture of ARM, VFP and Advanced SIMD instructions. According to an ARM expert, the normal assembly code is the best soultion for this at the moment.
>   - Moreover, at the moment the GCC support for intrinsics is poor. Maybe it will change in the future, but it is not recommended to use at the moment.

I totally agree with you. The GCC's intrinsics does not offer accurate controlling of the NEON infrastructure. The most painful parts are the inaccessible register mapping and the instruction mixing.

> I soon upload the hopefully final patch.

I still think this patch is fine for landing.
Gavin, what do you think about it?

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