gnulib/tests/test-fenv-env-3.c

/* Test of controlling the floating-point environment.
   Copyright (C) 2023-2026 Free Software Foundation, Inc.

   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */

/* Written by Bruno Haible <bruno@clisp.org>, 2023.  */

#include <config.h>

/* Specification.  */
#include <fenv.h>

#include "macros.h"

/* Test the combination of fegetenv() with feupdateenv().  */

/* Some CPUs don't support FE_UPWARD and FE_DOWNWARD in hardware.  */
#if defined __sh__
# ifndef FE_UPWARD
#  define FE_UPWARD   FE_TOWARDZERO
#  define FE_DOWNWARD FE_TONEAREST
# endif
#endif

/* On *BSD/powerpc systems, raising FE_INVALID also sets FE_VXSOFT.  */
#ifndef FE_VXSOFT
# define FE_VXSOFT 0
#endif

int
main ()
{
#if defined __GLIBC__ && defined __arm__ && defined __SOFTFP__
  fputs ("Skipping test: no floating-point environment exists on this machine\n", stderr);
  return 77;
#else
  fenv_t env1, env2;

  /* Get to a known initial state.  */
  ASSERT (feclearexcept (FE_ALL_EXCEPT) == 0);

  /* Save the current environment in env1.  */
  ASSERT (fegetenv (&env1) == 0);

  /* Modify the current environment.  */
  fesetround (FE_UPWARD);
  int supports_tracking = (feraiseexcept (FE_INVALID | FE_OVERFLOW | FE_INEXACT) == 0);
  int supports_trapping = (feenableexcept (FE_DIVBYZERO) != -1);

  /* Save the current environment in env2.  */
  ASSERT (fegetenv (&env2) == 0);

  /* Check that the exception flags are unmodified.  */
  if (supports_tracking)
    ASSERT ((fetestexcept (FE_ALL_EXCEPT) & ~FE_VXSOFT) == (FE_INVALID | FE_OVERFLOW | FE_INEXACT));
  else
    ASSERT (fetestexcept (FE_ALL_EXCEPT) == 0);
  /* Check that the exception trap bits are unmodified.  */
  ASSERT (fegetexcept () == (supports_trapping ? FE_DIVBYZERO : 0));

  /* Go back to env1.  */
  ASSERT (feupdateenv (&env1) == 0);

  /* Check that the rounding direction has been restored.  */
  ASSERT (fegetround () == FE_TONEAREST);
  /* Check that the exception flags are the union of the saved and of the
     current exception flags.  (The saved exception flags happen to be none
     in this case.)  */
  if (supports_tracking)
    ASSERT ((fetestexcept (FE_ALL_EXCEPT) & ~FE_VXSOFT) == (FE_INVALID | FE_OVERFLOW | FE_INEXACT));
  else
    ASSERT (fetestexcept (FE_ALL_EXCEPT) == 0);
  /* Check that the exception trap bits have been restored.  */
  ASSERT (fegetexcept () == 0);

  /* Modify the rounding direction, the exception flags, and the exception
     trap bits again.  */
  fesetround (FE_DOWNWARD);
  ASSERT (fegetround () == FE_DOWNWARD);
  feclearexcept (FE_INVALID | FE_OVERFLOW);
  feraiseexcept (FE_UNDERFLOW | FE_INEXACT);
  ASSERT (fetestexcept (FE_ALL_EXCEPT) == (supports_tracking ? FE_UNDERFLOW | FE_INEXACT : 0));
  feenableexcept (FE_INVALID);
  ASSERT (fegetexcept () == (supports_trapping ? FE_INVALID : 0));

  /* Go back to env2.  */
  ASSERT (feupdateenv (&env2) == 0);

  /* Check that the rounding direction has been restored.  */
  ASSERT (fegetround () == FE_UPWARD);
  /* Check that the exception flags are the union of the saved and of the
     current exception flags.  */
  if (supports_tracking)
    ASSERT ((fetestexcept (FE_ALL_EXCEPT) & ~FE_VXSOFT) == (FE_INVALID | FE_OVERFLOW | FE_UNDERFLOW | FE_INEXACT));
  else
    ASSERT (fetestexcept (FE_ALL_EXCEPT) == 0);
  /* Check that the exception trap bits have been restored.  */
  ASSERT (fegetexcept () == (supports_trapping ? FE_DIVBYZERO : 0));

  /* ======================================================================== */
  /* FE_DFL_ENV */

  /* Go back to the default environment.  */
  ASSERT (feupdateenv (FE_DFL_ENV) == 0);

  /* Check that the rounding direction has been restored,
     whereas the exception flags are unmodified.  */
  ASSERT (fegetround () == FE_TONEAREST);
  if (supports_tracking)
    ASSERT ((fetestexcept (FE_ALL_EXCEPT) & ~FE_VXSOFT) == (FE_INVALID | FE_OVERFLOW | FE_UNDERFLOW | FE_INEXACT));
  else
    ASSERT (fetestexcept (FE_ALL_EXCEPT) == 0);

  /* Enable trapping on FE_INVALID.  */
  feclearexcept (FE_INVALID);
  feenableexcept (FE_INVALID);
  ASSERT (fetestexcept (FE_ALL_EXCEPT) == (supports_tracking ? FE_OVERFLOW | FE_UNDERFLOW | FE_INEXACT : 0));

  /* Go back to the default environment.  */
  ASSERT (feupdateenv (FE_DFL_ENV) == 0);

  /* Check that the rounding direction has been restored,
     whereas the exception flags are unmodified.  */
  ASSERT (fegetround () == FE_TONEAREST);
  ASSERT (fetestexcept (FE_ALL_EXCEPT) == (supports_tracking ? FE_OVERFLOW | FE_UNDERFLOW | FE_INEXACT : 0));

  /* Check that it has trapping on FE_INVALID disabled.  */
  ASSERT (fegetexcept () == 0);
  {
    double volatile a;
    _GL_UNUSED double volatile b;
    a = 0; b = a / a;
  }

  /* ======================================================================== */
  /* Check that feupdateenv restores the trapping behaviour.  */

  /* Enable trapping on FE_INVALID.  */
  feclearexcept (FE_INVALID);
  feenableexcept (FE_INVALID);

  /* Go back to env1.  */
  ASSERT (feupdateenv (&env1) == 0);

  /* Check that it has disabled trapping on FE_INVALID.  */
  ASSERT (fegetexcept () == 0);
  {
    double volatile a;
    _GL_UNUSED double volatile b;
    a = 0; b = a / a;
  }

  return test_exit_status;
#endif
}