All,
The IEEE modules and -ffpe-trap are to some extent orthogonal
features of gfortran. Unfortunately, some users have the
expectation of using -ffpe-trap for debugging while also using only
some of the mechanisms provided by the IEEE modules. For example,
% t.f90
program test
use, intrinsic :: ieee_arithmetic
real :: inf
inf = ieee_value(inf, ieee_positive_inf)
end program test
% gfc8 -o z -ffpe-trap=overflow t.f90 && ./z
Floating exception (core dumped)
The correct use of the module would be along the lines of
program test
use, intrinsic :: ieee_arithmetic
real :: inf
logical h
call ieee_get_halting_mode(ieee_overflow, h) ! store halting mode
call ieee_set_halting_mode(ieee_overflow, .false.) ! no halting
inf = ieee_value(inf, ieee_positive_inf)
call ieee_set_halting_mode(ieee_overflow, h) ! restore halting mode
end program test
Technically (as I have done in the patch), the user should also
use 'ieee_support_halting(ieee_overflow)', but that's just a detail.
Now, IEEE_VALUE() is specifically included in the Fortran standard
to allow it to provide qNaN, sNaN, +inf, and -inf (among a few other
questionable constants). The attached patch allows gfortran to
generate an executable that does not abort with SIGFPE.
2018-12-24 Steven G. Kargl <kargl@gcc.gnu.org>
PR fortran/88342
* ieee/ieee_arithmetic.F90: Prevent exceptions in IEEE_VALUE if
-ffpe-trap=invalid or -ffpe-trap=overflow is used.
2018-12-24 Steven G. Kargl <kargl@gcc.gnu.org>
PR fortran/88342
* gfortran.dg/ieee/ieee_10.f90: New test.
Regression tested on i586-*-freebsd and x86_64-*-freebsd. OK to commit?