[Bug fortran/48977] New: -fpe-trap=denormal on x86 GLIBC systems

[burnus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48977

           Summary: -fpe-trap=denormal  on x86 GLIBC systems
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
        AssignedTo: unassig...@gcc.gnu.org
        ReportedBy: bur...@gcc.gnu.org


Kind of follow up to PR 38810 - and motivated by
http://groups.google.com/group/comp.lang.fortran/browse_thread/thread/894fb77cabc6e8c7

GLIBC (and POSIX) do not support FE_DENORMAL and thus -fpe-trap=denormal does
not work. However, gfortran has a target version for denormal trapping:

fpu-387.h has:
  if (options.fpe & GFC_FPE_DENORMAL) cw &= ~_FPU_MASK_DM;
[...]
  if (has_sse())
[...]
      if (options.fpe & GFC_FPE_DENORMAL) cw_sse &= ~(_FPU_MASK_DM << 7);

Expected: If FE_DENORMAL is not supported and target == fpu-387.h, the latter
is used.

(It could also be of interest for the IEEE modules.)