[FFmpeg-devel] [PATCH 1/2] lavu/bswap: remove some inline assembler

Rémi Denis-Courmont remi at remlab.net
Tue Jun 11 18:28:30 EEST 2024


Le tiistaina 11. kesäkuuta 2024, 16.15.19 EEST Michael Niedermayer a écrit :
> On Fri, Jun 07, 2024 at 09:19:46PM +0300, Rémi Denis-Courmont wrote:
> > C code or compiler built-ins are preferable over inline assembler for
> > byte-swaps as it allows for better optimisations (e.g. instruction
> > scheduling) which would otherwise be impossible.
> > 
> > As with f64c2e710fa1a7b59753224e717f57c48462076f for x86 and Arm,
> > this removes the inline assembler on GCC (and Clang) since we now
> > require recent enough compiler versions (this indeed seems to work on
> > AArch64).
> > ---
> > 
> >  libavutil/aarch64/bswap.h | 56 ---------------------------------------
> >  libavutil/avr32/bswap.h   | 44 ------------------------------
> >  libavutil/bswap.h         |  8 +-----
> >  libavutil/sh4/bswap.h     | 48 ---------------------------------
> 
> As you are writing that this preferrable for better optimisations
> Please provide benchmarks (for sh4, avr32)

How would someone benchmark an architecture like AVR32 that is not just dead 
but barely even commercially existed at all, and for which there exist no 
known C11 compiler and thus cannot even compile FFmpeg?

That toxic attitude of yours is very demotivating, and not just to me.

-- 
Rémi Denis-Courmont
http://www.remlab.net/





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