[gentoo-dev] gcc-3.3.3-r6 internal compiler error while compiling media-sound/lame

[Philipp Hasse]

Hi,

I recently compiled lame-3.96 and the compilation aborted with:

gcc -DHAVE_CONFIG_H -I. -I. -I.. -I../include -I. -I../libmp3lame -I.. -Wall
 -pipe -pipe -march=i486 -mc3 -mmmx -m3dnow -malign-double -maccumulate-outg
oing-args -O3 -fomit-frame-pointer -ffast-math -falign-functions=4 -funroll-
loops -fprefetch-loop-arrays -fforce-addr -MT layer2.lo -MD -MP -MF
.deps/layer2.Tpo -c layer2.c  -fPIC -DPIC -o .libs/layer2.o
layer2.c: In function `init_layer2':
layer2.c:70: internal compiler error: Floating point exception
Please submit a full bug report,
with preprocessed source if appropriate.
See <URL:http://bugs.gentoo.org/> for instructions.
Preprocessed source stored into /var/tmp/portage/lame-3.96/temp/ccLmjNol.out
file, please attach this to your bugreport.
make[2]: *** [layer2.lo] Fehler 1
make[2]: Leaving directory
`/var/tmp/portage/lame-3.96/work/lame-3.96/mpglib'
make[1]: *** [all-recursive] Fehler 1
make[1]: Leaving directory `/var/tmp/portage/lame-3.96/work/lame-3.96'
make: *** [all] Fehler 2

I did some tests on it and found out that this abortion is caused by the
following combination of CFLAGS:
- -march=i486 (or -march=c3 as gcc uses i486 for a C3)
- -O2 (or higher)
- -m3dnow
- -fprefetch-loop-arrays
So CFLAGS could look like
this: -march=i486 -m3dnow -O2 -fomit-frame-pointer -fprefetch-loop-arrays

I wrote a little program that shows the behaviour of gcc without having to
recompile lame (see mpglib/layer2.c for original sources that caused the
abortion):

/**
 * Compile with: gcc -march=i486 -m3dnow -fprefetch-loop-arrays -o gcc-bug.o
gcc-bug.c -O2
 */
int
main(int argc, char **argv)
{
  int *table;

  for (;;)
    *table++ = 10;

  return 0;
}

Could this be a gcc bug?

Greetings
Philipp Hasse


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