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Fortran: simplification of NEAREST for large argument [PR109186]

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gcc/fortran/ChangeLog:

	PR fortran/109186
	* simplify.cc (gfc_simplify_nearest): Fix off-by-one error in setting
	up real kind-specific maximum exponent for mpfr.

gcc/testsuite/ChangeLog:

	PR fortran/109186
	* gfortran.dg/nearest_6.f90: New test.
This commit is contained in:
Harald Anlauf 2023-03-19 21:29:46 +01:00
parent fbd50e867e
commit 4410a08b80
2 changed files with 27 additions and 1 deletions
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2
gcc/fortran/simplify.cc
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@ -6114,7 +6114,7 @@ gfc_simplify_nearest (gfc_expr *x, gfc_expr *s)
kind = gfc_validate_kind (BT_REAL, x->ts.kind, 0);
mpfr_set_emin ((mpfr_exp_t) gfc_real_kinds[kind].min_exponent -
mpfr_get_prec(result->value.real) + 1);
mpfr_set_emax ((mpfr_exp_t) gfc_real_kinds[kind].max_exponent - 1);
mpfr_set_emax ((mpfr_exp_t) gfc_real_kinds[kind].max_exponent);
mpfr_check_range (result->value.real, 0, MPFR_RNDU);
if (mpfr_sgn (s->value.real) > 0)

26
gcc/testsuite/gfortran.dg/nearest_6.f90 Normal file
View file

@ -0,0 +1,26 @@
! { dg-do run }
! PR fortran/109186 - Verify that NEAREST produces same results at
! compile-time and run-time for corner cases
! Reported by John Harper
program p
implicit none
integer, parameter :: sp = selected_real_kind (6)
integer, parameter :: dp = selected_real_kind (13)
real(sp), parameter :: x1 = huge (1._sp), t1 = tiny (1._sp)
real(dp), parameter :: x2 = huge (1._dp), t2 = tiny (1._dp)
real(sp), volatile :: y1, z1
real(dp), volatile :: y2, z2
y1 = x1
z1 = nearest (y1, -1._sp)
if (nearest (x1, -1._sp) /= z1) stop 1
y2 = x2
z2 = nearest (y2, -1._dp)
if (nearest (x2, -1._dp) /= z2) stop 2
y1 = t1
z1 = nearest (y1, 1._sp)
if (nearest (t1, 1._sp) /= z1) stop 3
y2 = t2
z2 = nearest (y2, 1._dp)
if (nearest (t2, 1._dp) /= z2) stop 4
end