Vorbis dev - Oct 1999 - EGCS broken; tested 2.95 through CVS current

Just so folks know, all the modern variants of EGCS (now named gcc) out there
appear to be producing occasionally bogus x86 FPU code at -O1 or higher.  Guess
what... Vorbis trips the bug whatever it is.

I just grabbed and built the latest CVS code, and it's also broken.  I'm
constructing a small failure case example for a bug report now.  It looks like
FPU arithmetic into a register isn't being stored back into memory.  I
don't know for sure yet; I don't read Pentium FPU code well :-P

The results have been confirmed on multiple machines running different
distributions.  The bug is entirely deterministic.

GCC 2.7.2.2 tests OK.  I'm looking for a copy of 2.8 to try as well.

So, for the immediate moment (until EGCS is fixed or I find a workaround), do
not use EGCS with optimization to compile Vorbis.   Yes, I know this sucks.

Monty

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ikewillis has egcs-2.91.66, which doesn't appear to have any problems.

Tony Arcieri

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On Thu, Oct 14, 1999 at 05:01:08PM -0700, Monty wrote:
> 
> Just so folks know, all the modern variants of EGCS (now named gcc) out
there
> appear to be producing occasionally bogus x86 FPU code at -O1 or higher. 
Guess
> what... Vorbis trips the bug whatever it is.
> 
> I just grabbed and built the latest CVS code, and it's also broken. 
I'm constructing a small failure case example for a bug report now.  It
looks like FPU arithmetic into a register isn't being stored back into
memory.  I don't know for sure yet; I don't read Pentium FPU code well
:-P
> 
> The results have been confirmed on multiple machines running different
distributions.  The bug is entirely deterministic.
> 
> GCC 2.7.2.2 tests OK.  I'm looking for a copy of 2.8 to try as well.
> 
> So, for the immediate moment (until EGCS is fixed or I find a
> workaround), do not use EGCS with optimization to compile Vorbis.
> Yes, I know this sucks.
dbt@pianosa:~>gcc -v
Reading specs from /usr/lib/gcc-lib/i386-unknown-openbsd2.5/2.8.1/specs
gcc version 2.8.1

Thus far I've just been watching from the sidelines.  I'm interested in 
the project and watching development -- I'm going to try building tonight
on OpenBSD -- stay tuned for some crossplatform patches.  But I can 
try with gcc 2.8.1.


-- 
David Terrell                             | dbt@meat.net
Prime Minister, Nebcorp Inc               | http://wwn.nebcorp.com/

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