[Bug testsuite/51057] FAIL: gfortran.dg/quad_2.f90 -O0 execution test on powerpc*-*-*

["sgk at troutmask dot apl.washington.edu" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51057

--- Comment #7 from Steve Kargl <sgk at troutmask dot apl.washington.edu> 2011-12-03 22:24:30 UTC ---
On Sat, Dec 03, 2011 at 10:01:22PM +0000, dominiq at lps dot ens.fr wrote:
> 
> --- Comment #6 from Dominique d'Humieres <dominiq at lps dot ens.fr> 2011-12-03 22:01:22 UTC ---
> The main problem with this test is not ppc platform implementing real(16) as
> two real(8), but rather platforms that don't have sqrtl (see
> http://gcc.gnu.org/ml/fortran/2011-11/msg00079.html ).

Did you read the thread?  I specifically recommended that
the testcase should be XFAILed for the missing sqrtl, too;
because no one is going to implement a suitable sqrtl in
c99_functions.c.

> Now this test has been motivated by the libquadmath, but is not specific and I
> don't see why it should be xfailed if real(16) is available on a platform as
> long as it gives a sensible answer as it is the case for ppc.

The test is designed to test float128 (aka IEEE 754 binary 128 format).
Double-double math gives you 106 bits of precision, which means it is
impossible to meet the requirements of a 113 bit precision type.
Lowering the accuracy of the test to allow ppc to pass opens up the
possibility of missing a bug in libquadmath when someone makes a
change to the library.