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

[Paul B Mahol]

On Tue, Jun 11, 2024 at 5:57 PM Michael Niedermayer <michael at niedermayer.cc>
wrote:

> On Tue, Jun 11, 2024 at 12:38:37PM -0300, James Almer wrote:
> > On 6/11/2024 10:15 AM, Michael Niedermayer wrote:
> > > 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)
> >
> > This is a ridiculous request, considering nobody has such hardware at
> all.
>
> Then I think its a ridiculous claim that this optimizes the code
>
> I mean, at some point there was hardware and these optimisations did
> improve
> speed.
>
> This patch is not removing the code because its a rare (or dead) platform,
> it removes
> it with the claim that this would "allows for better optimisations"
> Iam sorry but i do not see why asking for the claim in the commit message
> to be backed up with facts being ridiculous
> The claim in the commit message may be ridiculous
>

But at same time keeping sonic State of Art of audio codec compression and
maintaining it and responding to high user demand for its new features is
virtue of this project.


>
> thx
>
> [...]
> --
> Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
>
> No great genius has ever existed without some touch of madness. --
> Aristotle
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