tests/test-fenv-env-4.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 fesetenv().  */
  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 (fesetenv (&env1) == 0);
  63
  64   /* Check that the rounding direction has been restored.  */
  65   ASSERT (fegetround () == FE_TONEAREST);
  66   /* Check that the exception flags have been restored.  */
  67   ASSERT (fetestexcept (FE_ALL_EXCEPT) == 0);
  68   /* Check that the exception trap bits have been restored.  */
  69   ASSERT (fegetexcept () == 0);
  70
  71   /* Modify the rounding direction, the exception flags, and the exception
  72      trap bits again.  */
  73   fesetround (FE_DOWNWARD);
  74   ASSERT (fegetround () == FE_DOWNWARD);
  75   feclearexcept (FE_OVERFLOW);
  76   feraiseexcept (FE_UNDERFLOW | FE_INEXACT);
  77   ASSERT (fetestexcept (FE_ALL_EXCEPT) == (supports_tracking ? FE_UNDERFLOW | FE_INEXACT : 0));
  78   feenableexcept (FE_INVALID);
  79   ASSERT (fegetexcept () == (supports_trapping ? FE_INVALID : 0));
  80
  81   /* Go back to env2.  */
  82   ASSERT (fesetenv (&env2) == 0);
  83
  84   /* Check that the rounding direction has been restored.  */
  85   ASSERT (fegetround () == FE_UPWARD);
  86   /* Check that the exception flags have been restored.  */
  87   if (supports_tracking)
  88     ASSERT ((fetestexcept (FE_ALL_EXCEPT) & ~FE_VXSOFT) == (FE_INVALID | FE_OVERFLOW | FE_INEXACT));
  89   else
  90     ASSERT (fetestexcept (FE_ALL_EXCEPT) == 0);
  91   /* Check that the exception trap bits have been restored.  */
  92   ASSERT (fegetexcept () == (supports_trapping ? FE_DIVBYZERO : 0));
  93
  94   /* ======================================================================== */
  95   /* FE_DFL_ENV */
  96
  97   /* Enable trapping on FE_INVALID.  */
  98   feclearexcept (FE_INVALID);
  99   feenableexcept (FE_INVALID);
 100   ASSERT (fetestexcept (FE_ALL_EXCEPT) == (supports_tracking ? FE_OVERFLOW | FE_INEXACT : 0));
 101
 102   /* Go back to the default environment.  */
 103   ASSERT (fesetenv (FE_DFL_ENV) == 0);
 104
 105   /* Check its contents.  */
 106   ASSERT (fegetround () == FE_TONEAREST);
 107   ASSERT (fetestexcept (FE_ALL_EXCEPT) == 0);
 108
 109   /* Check that it has trapping on FE_INVALID disabled.  */
 110   ASSERT (fegetexcept () == 0);
 111   {
 112     double volatile a;
 113     _GL_UNUSED double volatile b;
 114     a = 0; b = a / a;
 115   }
 116
 117   /* ======================================================================== */
 118   /* Check that feholdexcept, unlike fegetenv, disables trapping.  */
 119
 120   /* musl libc does not support floating-point exception trapping, even where
 121      the hardware supports it.  See
 122      <https://wiki.musl-libc.org/functional-differences-from-glibc.html>  */
 123 # if !MUSL_LIBC || GNULIB_FEENABLEEXCEPT
 124   /* Enable trapping on FE_INVALID.  */
 125   feclearexcept (FE_INVALID);
 126   if (feenableexcept (FE_INVALID) != -1)
 127     {
 128       /* Call feholdexcept.  */
 129       ASSERT (feholdexcept (&env1) == 0);
 130
 131       /* Check that it has disabled trapping on FE_INVALID.  */
 132       ASSERT (fegetexcept () == 0);
 133       {
 134         double volatile a;
 135         _GL_UNUSED double volatile b;
 136         a = 0; b = a / a;
 137       }
 138     }
 139 # endif
 140
 141   return test_exit_status;
 142 #endif
 143 }