[Ffmpeg-devel] PATCH Blackfin UNALIGNED_STORES_ARE_BAD in bitstream.h
Wed Apr 18 11:23:34 CEST 2007
> > > IMO we should turn this the other way around:
> > >
> > > #if !defined(ARCH_X86) && !defined(...)
> > >
> > > Then the code will ALWAYS work, and just be suboptimal on archs
> > > we
> > > haven't identified yet, rather than crashing on unknown archs.
> > i strongly object to this, noone would ever add any architecture
> > besides x86
> > to it, how should anyone even know of this line?
> It can be documented in a porting file or something. But I strongly
> object to having blatently nonportable code in the default build. If
> were trying to compile ffmpeg on a strange system and not a competent
> coder/debugger, I would have no idea why it crashed and probably just
> assume it was nonportable crapware rather than learning how to
> investigate and "fix" the problem.
Indeed, but ppl on BeOS will currently assume nonportable crapware
because it will fail to build on PRI* macros... just because someone
assumes "portable" to mean porting the OS to ffmpeg instead of the
other way around. but that's another story.
> 1. Enable the nonportable code by default but have a
> --disable-nonportable-assumptions option to configure, or an
> ARCH_GENERIC define included in the above list that configure would
> define when the arch is unknown to inhibit all such optimizations.
Why an option a newbie wouldn't know about ?
You're just shuffling the problem around.
> 2. Just have configure print a message directing users to a porting
> document with references to this line and other similar lines when an
> unknown arch is detected.
#warning "FIXME: Unknown arch, assuming strict alignment. This could be
> > if it crashes and the person sends a bugrport its trivial to add
> > the arch
> > if its just slower than what it could be nothing will happen it
> > will always
> > stay slow
> This assumes the code is maintained and the user is using the latest
> version. The problem is what happens 10 years from now if ffmpeg is
That's assuming gcc will be around in 10 years ;)
> > if configure would print a big warning like
> > WARINING: configure doesnt know your architecture and so has
> > disabled all
> > optimizations, please try the following switches: ... and report
> > bechmarks
> > to ffmpeg-dev so we can automate the optimization selection
> Yes, this would be great.
Either this or the warning, yes.
Or both so ppl who didn't write it would find where to update stuff :)
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