[Bug fortran/46842] [4.6 Regression] 465.tonto test run miscompares (even with -O0)

["burnus at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46842

--- Comment #11 from Tobias Burnus <burnus at gcc dot gnu.org> 2010-12-09 11:22:14 UTC ---
I fear that debugging this will be not easy - especially as to my knowledge
none of the gfortran developers has access to SPEC CPU 2006.

 * * *

I tried
http://sourceforge.net/projects/tonto-chem/files/tonto/2.3/tonto-2.3.1.tar.bz2/download

If I compile it with a version before the regression, namely
  4.6.0 20100909 (experimental) [trunk revision 164046]
I get only failures with "make tests" - I have to recompile with
"-fno-sign-zero" to reduce the failures. However, I still get failures (=
differences) to the result of the Intel compiler.

I think one could still try to find differences between such a version and a
version after the TRANSPOSE committal.

Compiling notice: You need to remove the "-std=f95" and - to speed up the very
slow compile a tiny bit - remove also "-Wall -O". Additionally, as mentioned
above, consider using "-fno-sign-zero". (In my case, the configuration is in
platforms/GNU-gfortran-on-LINUX.) Unfortunately, almost all changes trigger a
complete recompilation - and "make -j5" does not work.

 * * *

I could find TRANSPOSEs in the files mo_localiser.F90, molecule.F90,
vec{atom}.F90, marchingcube.F90, isosurface.F90, mat{cpx}.F90, mat3{real}.F90,
spacegroup.F90, periodic_fmm_level.F90, cluster.F90, mat{real}.F90,
run_mat{real}.F90, molecule.main.F90, unit_cell.F90 and crystal.F90. I tried to
create some failing test myself, but they were handled properly.