tests/test-fenv-env-3.c

   1 /* Test of controlling the floating-point environment.
   2    Copyright (C) 2023-2025 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 fegetenv() 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 (fegetenv (&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 (fegetenv (&env2) == 0);
  55
  56   /* Check that the exception flags are unmodified.  */
  57   if (supports_tracking)
  58     ASSERT ((fetestexcept (FE_ALL_EXCEPT) & ~FE_VXSOFT) == (FE_INVALID | FE_OVERFLOW | FE_INEXACT));
  59   else
  60     ASSERT (fetestexcept (FE_ALL_EXCEPT) == 0);
  61   /* Check that the exception trap bits are unmodified.  */
  62   ASSERT (fegetexcept () == (supports_trapping ? FE_DIVBYZERO : 0));
  63
  64   /* Go back to env1.  */
  65   ASSERT (feupdateenv (&env1) == 0);
  66
  67   /* Check that the rounding direction has been restored.  */
  68   ASSERT (fegetround () == FE_TONEAREST);
  69   /* Check that the exception flags are the union of the saved and of the
  70      current exception flags.  (The saved exception flags happen to be none
  71      in this case.)  */
  72   if (supports_tracking)
  73     ASSERT ((fetestexcept (FE_ALL_EXCEPT) & ~FE_VXSOFT) == (FE_INVALID | FE_OVERFLOW | FE_INEXACT));
  74   else
  75     ASSERT (fetestexcept (FE_ALL_EXCEPT) == 0);
  76   /* Check that the exception trap bits have been restored.  */
  77   ASSERT (fegetexcept () == 0);
  78
  79   /* Modify the rounding direction, the exception flags, and the exception
  80      trap bits again.  */
  81   fesetround (FE_DOWNWARD);
  82   ASSERT (fegetround () == FE_DOWNWARD);
  83   feclearexcept (FE_INVALID | FE_OVERFLOW);
  84   feraiseexcept (FE_UNDERFLOW | FE_INEXACT);
  85   ASSERT (fetestexcept (FE_ALL_EXCEPT) == (supports_tracking ? FE_UNDERFLOW | FE_INEXACT : 0));
  86   feenableexcept (FE_INVALID);
  87   ASSERT (fegetexcept () == (supports_trapping ? FE_INVALID : 0));
  88
  89   /* Go back to env2.  */
  90   ASSERT (feupdateenv (&env2) == 0);
  91
  92   /* Check that the rounding direction has been restored.  */
  93   ASSERT (fegetround () == FE_UPWARD);
  94   /* Check that the exception flags are the union of the saved and of the
  95      current exception flags.  */
  96   if (supports_tracking)
  97     ASSERT ((fetestexcept (FE_ALL_EXCEPT) & ~FE_VXSOFT) == (FE_INVALID | FE_OVERFLOW | FE_UNDERFLOW | FE_INEXACT));
  98   else
  99     ASSERT (fetestexcept (FE_ALL_EXCEPT) == 0);
 100   /* Check that the exception trap bits have been restored.  */
 101   ASSERT (fegetexcept () == (supports_trapping ? FE_DIVBYZERO : 0));
 102
 103   /* ======================================================================== */
 104   /* FE_DFL_ENV */
 105
 106   /* Go back to the default environment.  */
 107   ASSERT (feupdateenv (FE_DFL_ENV) == 0);
 108
 109   /* Check that the rounding direction has been restored,
 110      whereas the exception flags are unmodified.  */
 111   ASSERT (fegetround () == FE_TONEAREST);
 112   if (supports_tracking)
 113     ASSERT ((fetestexcept (FE_ALL_EXCEPT) & ~FE_VXSOFT) == (FE_INVALID | FE_OVERFLOW | FE_UNDERFLOW | FE_INEXACT));
 114   else
 115     ASSERT (fetestexcept (FE_ALL_EXCEPT) == 0);
 116
 117   /* Enable trapping on FE_INVALID.  */
 118   feclearexcept (FE_INVALID);
 119   feenableexcept (FE_INVALID);
 120   ASSERT (fetestexcept (FE_ALL_EXCEPT) == (supports_tracking ? FE_OVERFLOW | FE_UNDERFLOW | FE_INEXACT : 0));
 121
 122   /* Go back to the default environment.  */
 123   ASSERT (feupdateenv (FE_DFL_ENV) == 0);
 124
 125   /* Check that the rounding direction has been restored,
 126      whereas the exception flags are unmodified.  */
 127   ASSERT (fegetround () == FE_TONEAREST);
 128   ASSERT (fetestexcept (FE_ALL_EXCEPT) == (supports_tracking ? FE_OVERFLOW | FE_UNDERFLOW | FE_INEXACT : 0));
 129
 130   /* Check that it has trapping on FE_INVALID disabled.  */
 131   ASSERT (fegetexcept () == 0);
 132   {
 133     double volatile a;
 134     _GL_UNUSED double volatile b;
 135     a = 0; b = a / a;
 136   }
 137
 138   /* ======================================================================== */
 139   /* Check that feupdateenv restores the trapping behaviour.  */
 140
 141   /* Enable trapping on FE_INVALID.  */
 142   feclearexcept (FE_INVALID);
 143   feenableexcept (FE_INVALID);
 144
 145   /* Go back to env1.  */
 146   ASSERT (feupdateenv (&env1) == 0);
 147
 148   /* Check that it has disabled trapping on FE_INVALID.  */
 149   ASSERT (fegetexcept () == 0);
 150   {
 151     double volatile a;
 152     _GL_UNUSED double volatile b;
 153     a = 0; b = a / a;
 154   }
 155
 156   return test_exit_status;
 157 #endif
 158 }