Fortran: add IEEE_MODES_TYPE, IEEE_GET_MODES and IEEE_SET_MODES

The IEEE_MODES_TYPE type and the two functions that get and set it
were added in Fortran 2018.  They can be implemented using the already
existing target-specific functions.  A future optimization could, on
some targets, set/get all modes through one or two instructions only,
but that would need a new set of functions in all config/fpu-* files.

2022-09-04  Francois-Xavier Coudert  <fxcoudert@gcc.gnu.org>

libgfortran/

	* ieee/ieee_exceptions.F90: Add IEEE_MODES_TYPE, IEEE_GET_MODES
	and IEEE_SET_MODES.
	* ieee/ieee_arithmetic.F90: Make them public in IEEE_ARITHMETIC
	as well.

gcc/testsuite/

	* gfortran.dg/ieee/modes_1.f90: New test.

1 files changed, 95 insertions, 0 deletions

diff --git a/gcc/testsuite/gfortran.dg/ieee/modes_1.f90 b/gcc/testsuite/gfortran.dg/ieee/modes_1.f90
new file mode 100644
index 0000000..b6ab288
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/ieee/modes_1.f90
@@ -0,0 +1,95 @@
+! { dg-do run }
+!
+! Test IEEE_MODES_TYPE, IEEE_GET_MODES and IEEE_SET_MODES
+
+
+! The symbols should be accessible from both IEEE_EXCEPTIONS
+! and IEEE_ARITHMETIC.
+
+subroutine test_1
+  use ieee_exceptions, only : IEEE_GET_MODES, IEEE_SET_MODES
+end subroutine
+
+subroutine test_2
+  use ieee_arithmetic, only : IEEE_GET_MODES, IEEE_SET_MODES
+end subroutine
+
+subroutine test_3
+  use ieee_exceptions, only : IEEE_MODES_TYPE
+end subroutine
+
+subroutine test_4
+  use ieee_arithmetic, only : IEEE_MODES_TYPE
+end subroutine
+
+
+! Check that the functions actually do the job
+
+program foo
+  use ieee_arithmetic
+  implicit none
+
+  type(ieee_modes_type) :: modes1, modes2
+  type(ieee_round_type) :: rmode
+  logical :: f
+
+  ! Set some modes
+  if (ieee_support_underflow_control()) then
+    call ieee_set_underflow_mode(gradual=.false.)
+  endif
+  if (ieee_support_rounding(ieee_up)) then
+    call ieee_set_rounding_mode(ieee_up)
+  endif
+  if (ieee_support_halting(ieee_overflow)) then
+    call ieee_set_halting_mode(ieee_overflow, .true.)
+  endif
+
+  call ieee_get_modes(modes1)
+
+  ! Change modes
+  if (ieee_support_underflow_control()) then
+    call ieee_set_underflow_mode(gradual=.true.)
+  endif
+  if (ieee_support_rounding(ieee_down)) then
+    call ieee_set_rounding_mode(ieee_down)
+  endif
+  if (ieee_support_halting(ieee_overflow)) then
+    call ieee_set_halting_mode(ieee_overflow, .false.)
+  endif
+
+  ! Save and restore the previous modes
+  call ieee_get_modes(modes2)
+  call ieee_set_modes(modes1)
+
+  ! Check them
+  if (ieee_support_underflow_control()) then
+    call ieee_get_underflow_mode(f)
+    if (f) stop 1
+  endif
+  if (ieee_support_rounding(ieee_down)) then
+    call ieee_get_rounding_mode(rmode)
+    if (rmode /= ieee_up) stop 2
+  endif
+  if (ieee_support_halting(ieee_overflow)) then
+    call ieee_get_halting_mode(ieee_overflow, f)
+    if (.not. f) stop 3
+  endif
+
+  ! Restore the second set of modes
+  call ieee_set_modes(modes2)
+
+  ! Check again
+  if (ieee_support_underflow_control()) then
+    call ieee_get_underflow_mode(f)
+    if (.not. f) stop 3
+  endif
+  if (ieee_support_rounding(ieee_down)) then
+    call ieee_get_rounding_mode(rmode)
+    if (rmode /= ieee_down) stop 4
+  endif
+  if (ieee_support_halting(ieee_overflow)) then
+    call ieee_get_halting_mode(ieee_overflow, f)
+    if (f) stop 5
+  endif
+
+end program foo