From 4410a08b80cc40342eeaa5b6af824cd4352b218c Mon Sep 17 00:00:00 2001
From: Harald Anlauf <anlauf@gmx.de>
Date: Sun, 19 Mar 2023 21:29:46 +0100
Subject: [PATCH] Fortran: simplification of NEAREST for large argument
[PR109186]
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.
---
gcc/fortran/simplify.cc | 2 +-
gcc/testsuite/gfortran.dg/nearest_6.f90 | 26 +++++++++++++++++++++++++
2 files changed, 27 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/gfortran.dg/nearest_6.f90
diff --git a/gcc/fortran/simplify.cc b/gcc/fortran/simplify.cc
index 20ea38e0007a..ecf0e3558dfe 100644
--- a/gcc/fortran/simplify.cc
+++ b/gcc/fortran/simplify.cc
@@ -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)
diff --git a/gcc/testsuite/gfortran.dg/nearest_6.f90 b/gcc/testsuite/gfortran.dg/nearest_6.f90
new file mode 100644
index 000000000000..00d1ebe618ca
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/nearest_6.f90
@@ -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
--
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