[Bug 257124] multimedia/ffmpeg: Fails to link: ld: error: inline assembly requires more registers than available at line [on i386 with LTO option]

From: <bugzilla-noreply_at_freebsd.org>
Date: Mon, 12 Jul 2021 16:21:11 +0000
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=257124

--- Comment #7 from Mikhail Teterin <mi_at_FreeBSD.org> ---
> Yes, it's likely that the low number of registers
I'm confused... Is not the number of registers the same on the same processor
-- whether it is running in 32- or 64-bit mode? Even if they are named/accessed
differently?

> combined with more aggressive whole program optimization (in particular
> inlining) will lead to this type of error.
Frankly, if optimization results in errors, then it is not an optimization... I
don't blame anyone here for the failure, just debating terminology :-)

If the otherwise valid code cannot be compiled (and/or linked), than it is a
compiler (and/or linker) bug, is not it? Would it make sense to bring this up
with LLVM-project directly?

> Yes, the benefit of fixing LTO for i386 is not worth the effort
> it will require.
I would've thought, with multimedia every CPU-instruction counts... Even if the
hardware is fast enough for regular realtime playback, when performing
format-conversions, CPU is almost always the bottleneck even on the fastest
computers.

Perhaps, the option should carry a warning -- and be disabled by default on
i386 -- but disabling it altogether seems too drastic.

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Received on Mon Jul 12 2021 - 16:21:11 UTC

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