[FFmpeg-devel] Amazing intrinsics improvments in gcc 4
Wed Mar 19 19:21:14 CET 2008
Michael Niedermayer wrote:
> I thought some people here would be interrested as there were various claims
> on gccs abilities and improvments posted here lately ...
------- Comment #23 From Uros Bizjak 2008-03-19 10:45 -------
As said in PR 19161:
The LCM infrastructure doesn't support mode switching in the way that
usable for emms. Additionally, there are MANY problems expected when sharing
x87 and MMX registers (i.e. handling of uninitialized x87 registers at the
beginning of the function - this is the reason we don't implement x87
Automatic MMX vectorization is not exactly a much usable feature
have SSE that works quite well here). Due to recent changes in MMX register
allocation area, excellent code is produced using MMX intrinsics, I'm
this bug as WONTFIX.
Also, auto-vectorization would produce either MMX or SSE code, but not
#define UNITS_PER_SIMD_WORD (TARGET_SSE ? 16 : UNITS_PER_WORD)
Seems Uros is fighting your battle and providing some interesting code.
Still, the root of the problem is that x86 sucks.
Gentoo Council Member
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