[Bug tree-optimization/59025] [4.9 Regression] Revision 203979 causes failure in CPU2006 benchmark 435.gromacs

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59025

--- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
If I remember well, there was one spot where it could result in swapped order
of commutative operation's operand at the tree level, plus of course if
RA/scheduling is affected by SSA_NAME_VERSION of the temporaries (or, because
the new SSA_NAMEs intentionally are anonymous, while previously they could
still be from some original vars with underlying decls on them, it could result
in slightly different SSA partitioning).  But none of that sounds like a
compiler bug, perhaps just 435.gromacs worked with -ffast-math on ppc
previously just by accident, perhaps the test isn't prepared to handle
reordering of floating point operations allowed by -ffast-math?