tests/test-fenv-env-5.c

   1 /* Test of controlling the floating-point environment.
   2    Copyright (C) 2023-2024 Free Software Foundation, Inc.
   3
   4    This program is free software: you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation, either version 3 of the License, or
   7    (at your option) any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  16
  17 /* Written by Bruno Haible <bruno@clisp.org>, 2023.  */
  18
  19 #include <config.h>
  20
  21 /* Specification.  */
  22 #include <fenv.h>
  23
  24 #include "macros.h"
  25
  26 /* Test the combination of feholdexcept() with feupdateenv().  */
  27
  28 /* On *BSD/powerpc systems, raising FE_INVALID also sets FE_VXSOFT.  */
  29 #ifndef FE_VXSOFT
  30 # define FE_VXSOFT 0
  31 #endif
  32
  33 int
  34 main ()
  35 {
  36 #if defined __GLIBC__ && defined __arm__ && defined __SOFTFP__
  37   fputs ("Skipping test: no floating-point environment exists on this machine\n", stderr);
  38   return 77;
  39 #else
  40   fenv_t env1, env2;
  41
  42   /* Get to a known initial state.  */
  43   ASSERT (feclearexcept (FE_ALL_EXCEPT) == 0);
  44
  45   /* Save the current environment in env1.  */
  46   ASSERT (feholdexcept (&env1) == 0);
  47
  48   /* Modify the current environment.  */
  49   fesetround (FE_UPWARD);
  50   int supports_tracking = (feraiseexcept (FE_INVALID | FE_OVERFLOW | FE_INEXACT) == 0);
  51   int supports_trapping = (feenableexcept (FE_DIVBYZERO) != -1);
  52
  53   /* Save the current environment in env2.  */
  54   ASSERT (feholdexcept (&env2) == 0);
  55
  56   /* Check that the exception flags are cleared.  */
  57   ASSERT (fetestexcept (FE_ALL_EXCEPT) == 0);
  58   /* Check that the exception trap bits are cleared.  */
  59   ASSERT (fegetexcept () == 0);
  60
  61   /* Go back to env1.  */
  62   ASSERT (feupdateenv (&env1) == 0);
  63
  64   /* Check that the rounding direction has been restored.  */
  65   ASSERT (fegetround () == FE_TONEAREST);
  66   /* Check that the exception flags are the union of the saved and of the
  67      current exception flags.  (The saved exception flags and the current
  68      exception flags both happen to be none in this case.)  */
  69   ASSERT (fetestexcept (FE_ALL_EXCEPT) == 0);
  70   /* Check that the exception trap bits have been restored.  */
  71   ASSERT (fegetexcept () == 0);
  72
  73   /* Modify the rounding direction, the exception flags, and the exception
  74      trap bits again.  */
  75   fesetround (FE_DOWNWARD);
  76   ASSERT (fegetround () == FE_DOWNWARD);
  77   feclearexcept (FE_OVERFLOW);
  78   feraiseexcept (FE_UNDERFLOW | FE_INEXACT);
  79   ASSERT (fetestexcept (FE_ALL_EXCEPT) == (supports_tracking ? FE_UNDERFLOW | FE_INEXACT : 0));
  80   feenableexcept (FE_INVALID);
  81   ASSERT (fegetexcept () == (supports_trapping ? FE_INVALID : 0));
  82
  83   /* Go back to env2.  */
  84   ASSERT (feupdateenv (&env2) == 0);
  85
  86   /* Check that the rounding direction has been restored.  */
  87   ASSERT (fegetround () == FE_UPWARD);
  88   /* Check that the exception flags are the union of the saved and of the
  89      current exception flags.  */
  90   if (supports_tracking)
  91     ASSERT ((fetestexcept (FE_ALL_EXCEPT) & ~FE_VXSOFT) == (FE_INVALID | FE_OVERFLOW | FE_UNDERFLOW | FE_INEXACT));
  92   else
  93     ASSERT (fetestexcept (FE_ALL_EXCEPT) == 0);
  94   /* Check that the exception trap bits have been restored.  */
  95   ASSERT (fegetexcept () == (supports_trapping ? FE_DIVBYZERO : 0));
  96
  97   /* ======================================================================== */
  98   /* FE_DFL_ENV */
  99
 100   /* Go back to the default environment.  */
 101   ASSERT (feupdateenv (FE_DFL_ENV) == 0);
 102
 103   /* Check that the rounding direction has been restored,
 104      whereas the exception flags are unmodified.  */
 105   ASSERT (fegetround () == FE_TONEAREST);
 106   if (supports_tracking)
 107     ASSERT ((fetestexcept (FE_ALL_EXCEPT) & ~FE_VXSOFT) == (FE_INVALID | FE_OVERFLOW | FE_UNDERFLOW | FE_INEXACT));
 108   else
 109     ASSERT (fetestexcept (FE_ALL_EXCEPT) == 0);
 110
 111   /* Enable trapping on FE_INVALID.  */
 112   feclearexcept (FE_INVALID);
 113   feenableexcept (FE_INVALID);
 114   ASSERT (fetestexcept (FE_ALL_EXCEPT) == (supports_tracking ? FE_OVERFLOW | FE_UNDERFLOW | FE_INEXACT : 0));
 115
 116   /* Go back to the default environment.  */
 117   ASSERT (feupdateenv (FE_DFL_ENV) == 0);
 118
 119   /* Check that the rounding direction has been restored,
 120      whereas the exception flags are unmodified.  */
 121   ASSERT (fegetround () == FE_TONEAREST);
 122   ASSERT (fetestexcept (FE_ALL_EXCEPT) == (supports_tracking ? FE_OVERFLOW | FE_UNDERFLOW | FE_INEXACT : 0));
 123
 124   /* Check that it has trapping on FE_INVALID disabled.  */
 125   ASSERT (fegetexcept () == 0);
 126   {
 127     double volatile a;
 128     _GL_UNUSED double volatile b;
 129     a = 0; b = a / a;
 130   }
 131
 132   /* ======================================================================== */
 133   /* Check that feholdexcept, unlike fegetenv, disables trapping.  */
 134
 135   /* musl libc does not support floating-point exception trapping, even where
 136      the hardware supports it.  See
 137      <https://wiki.musl-libc.org/functional-differences-from-glibc.html>  */
 138 # if !MUSL_LIBC || GNULIB_FEENABLEEXCEPT
 139   /* Enable trapping on FE_INVALID.  */
 140   feclearexcept (FE_INVALID);
 141   if (feenableexcept (FE_INVALID) != -1)
 142     {
 143       /* Call feholdexcept.  */
 144       ASSERT (feholdexcept (&env1) == 0);
 145
 146       /* Check that it has disabled trapping on FE_INVALID.  */
 147       ASSERT (fegetexcept () == 0);
 148       {
 149         double volatile a;
 150         _GL_UNUSED double volatile b;
 151         a = 0; b = a / a;
 152       }
 153     }
 154 # endif
 155
 156   return test_exit_status;
 157 #endif
 158 }