https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91690
Wilco <wilco at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |wilco at gcc dot gnu.org
--- Comment #4 from Wilco <wilco at gcc dot gnu.org> ---
(In reply to Steve Kargl from comment #3)
> On Mon, Sep 09, 2019 at 08:05:33AM +0000, rguenth at gcc dot gnu.org wrote:
> > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91690
> >
> > --- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
> > __builtin_isnan is required to preserve FPU state, not sure why the Fortran
> > FE
> > thinks it needs some extra magic around it?
> >
>
> The magic seems to come from trans-decl.c
>
> /* Generate code for a function. */
>
> void
> gfc_generate_function_code (gfc_namespace * ns)
> {
>
> ...
>
> /* Check if an IEEE module is used in the procedure. If so, save
> the floating point state. */
> ieee = is_ieee_module_used (ns);
> if (ieee)
> fpstate = gfc_save_fp_state (&init);
>
> ...
>
> /* If IEEE modules are loaded, restore the floating-point state. */
> if (ieee)
> gfc_restore_fp_state (&cleanup, fpstate);
>
> }
>
> The Fortran standard may require this behavior. 18-007r1 page 435
But none of that is needed since a correct implementation of isnan etc does not
affect the floating point state at all (see PR66462).
