Possible bug with -O2 -march=athlon[-tbird]

[Lawrence Gold <gold at shell dot aros dot net>]

Since I've already lost face by making a false bug report on GNATS, I 
might as well risk doing it on the mailing list this time...

When I try to compile one of the files from xmess-0.561.1 using

	gcc -c -O2 -march=athlon[-tbird]

I get this error:

	/tmp/ccRddfe9.s: Assembler messages:
	/tmp/ccRddfe9.s:5300: Error: bad register name `%sil'

The file in question is available from 

	http://www.aros.net/~gold/z80gb_flattened.c.bz2

I don't see any inline assembly in the file, so it doesn't appear that 
incorrect register constraints are to blame.  If I reduce the optimization 
to -O1 or use -march=i686, the error does not occur.

I'm running on Linux 2.4.18, glibc-2.2.5, binutils 2.12 on an Athlon
Thunderbird 1.2GHz.  The output of gcc -v is

Reading specs from 
/usr/local/gcc-3.1/lib/gcc-lib/i686-pc-linux-gnu/3.1/specs
Configured with: ../configure --prefix=/usr/local/gcc-3.1
Thread model: single
gcc version 3.1

gcc-3.1 was built with "make bootstrap" using gcc-2.95.3; CFLAGS and 
CXXFLAGS were unset.  The result is the same if I build with gcc-3.0.4.

Thanks in advance for your help.  If this appears to be a genuine bug, 
I'll file a report in GNATS.