[Bug target/55939] [4.6/4.7/4.8 regression] gcc miscompiles gmp-5.0.5 on m68k-linux
aldyh at redhat dot com
gcc-bugzilla@gcc.gnu.org
Tue Jan 29 19:47:00 GMT 2013
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55939
--- Comment #16 from Aldy Hernandez <aldyh at redhat dot com> 2013-01-29 19:47:24 UTC ---
>> double d, d2;
>> ...
>> if (d != d2) {
>> dumpd(d,d2);
>> return -1;
>> }
>>
>> By this point, "d" and "d2" are in fp2/fp3, and we compare them in
>> extended-precision real mode (fcmp.x) below:
> At this point alarm bells are already ringing... When I see EQ/NE
> comparisons of floating points, there's a good bet something is wrong.
For the record, only the EQ/NE above comes from GMP. The other one (in
dumpd()) I added myself in testing. But yes, that one "d != d2" is in
the original testcase.
I will try the various suggestions and report back.
Thanks everyone.
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