reassign 324455 libc6.1 2.3.5-3 retitle 324455 regression from 2.3.2 in __divqu on alpha thanks
On Mon, Aug 22, 2005 at 07:05:46PM -0700, Steve Langasek wrote:
> On Mon, Aug 22, 2005 at 06:11:05PM +0200, Laurent Fousse wrote:
> > * Laurent Fousse [Mon, Aug 22, 2005 at 05:42:32PM +0200]:
> > > > Could you do me a favour? Try building with -O2.
> > > The same test failed with -O2, gcc 4.0.1-5. Trying with gcc-3.4 now.
> > Failed with 3.4 and 3.3, both using -O2. Something is wrong in the
> > toolchain, only somewhere else.
> Ok, having looked at the test in greater detail, it seems to have just been
> the luck of the draw that the test never failed before on alpha.
> [EMAIL PROTECTED]:/home/devel/release/gmp-4.1.4/tests/mpz$ ./dive_ui 500
> [EMAIL PROTECTED]:/home/devel/release/gmp-4.1.4/tests/mpz$ ./dive_ui 1000
> mpz_divexact_ui wrong
> a=15555198415671637283
> d=15555198415671637283
> q=1
> got=0
> Aborted
> $
> Amusing that it's only dividing a number by itself that seems to give gmp
> fits here. :-) If I special-case q=1 out, I get a full sequence of 5000
> tests without errors. Other values that don't fail the test include
> d=0x0056e18e03a9de91 and d=0x459f9e46f19b39d8; others that do include
> d=0xa679fe5e2536755c and d=0xd2e85bb7873d8a7e. Looks suspiciously like
> signed/unsigned breakage, as only values with the high bit set appear to be
> affected.
> Will continue investigating.
Buggy division function in glibc 2.3.5.
$ .libs/dive_ui
mpz_divexact_ui wrong
a=15555198415671637283
d=15555198415671637283
q=1
got=0
Aborted
$ LD_LIBRARY_PATH=./libc6/lib/ ./libc6/lib/ld-linux.so.2 .libs/dive_ui && echo
success
success
$
Simple test case:
int main() {
unsigned long a= 1UL << 63;
unsigned long b= 1UL << 63;
exit (a/b != 1);
}
Appears to be a bug in the implementation of __divqu. Upgrading to 2.3.5-4,
to confirm whether the bug still exists.
--
Steve Langasek Give me a lever long enough and a Free OS
Debian Developer to set it on, and I can move the world.
[EMAIL PROTECTED] http://www.debian.org/
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