[FFmpeg-devel] [HACK] 50% faster H.264 decoding

Måns Rullgård mans
Mon Aug 23 20:03:26 CEST 2010

Luca Barbato <lu_zero at gentoo.org> writes:

> On 08/22/2010 04:58 AM, Jason Garrett-Glaser wrote:
>>> Keep in mind that some compilers (like open64) might support inline asm
>>> and cannot do link time optimizations on yasm generated binaries...
>> Why would I want the compiler doing link-time "optimization" on my
>> asm?  I would consider that inability a benefit.
> It cannot perform link time optimization at all if you are trying to
> link something foreign apparently, that is an annoying limitation but
> that is. By your reasoning you would consider hand writing everything in
> asm since you would get it right better than a compiler.

Lack of LTO for hand-written asm is a non-issue for a very simple
reason: if the link-time optimiser could outdo a human, so could the
compiler, and there would be no need for hand-written asm in the first
place.  In other words, with external asm, the compiler/linker is
unable to perform an optimisation it is unable to perform at all in
the first place.

M?ns Rullg?rd
mans at mansr.com

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