math/w_pow_compat.c

   1 /* Copyright (C) 2011-2021 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Ulrich Drepper <drepper@gmail.com>, 2011.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <math.h>
  20 #include <math_private.h>
  21 #include <math-svid-compat.h>
  22 #include <libm-alias-double.h>
  23
  24
  25 #if LIBM_SVID_COMPAT && (SHLIB_COMPAT (libm, GLIBC_2_0, GLIBC_2_29) \
  26                          || defined NO_LONG_DOUBLE \
  27                          || defined LONG_DOUBLE_COMPAT)
  28 /* wrapper pow */
  29 double
  30 __pow_compat (double x, double y)
  31 {
  32   double z = __ieee754_pow (x, y);
  33   if (__glibc_unlikely (!isfinite (z)))
  34     {
  35       if (_LIB_VERSION != _IEEE_)
  36         {
  37           if (isfinite (x) && isfinite (y))
  38             {
  39               if (isnan (z))
  40                 /* pow neg**non-int */
  41                 return __kernel_standard (x, y, 24);
  42               else if (x == 0.0 && y < 0.0)
  43                 {
  44                   if (signbit (x) && signbit (z))
  45                     /* pow(-0.0,negative) */
  46                     return __kernel_standard (x, y, 23);
  47                   else
  48                     /* pow(+0.0,negative) */
  49                     return __kernel_standard (x, y, 43);
  50                 }
  51               else
  52                 /* pow overflow */
  53                 return __kernel_standard (x, y, 21);
  54             }
  55         }
  56     }
  57   else if (__builtin_expect (z == 0.0, 0)
  58            && isfinite (x) && x != 0 && isfinite (y)
  59            && _LIB_VERSION != _IEEE_)
  60     /* pow underflow */
  61     return __kernel_standard (x, y, 22);
  62
  63   return z;
  64 }
  65 # if SHLIB_COMPAT (libm, GLIBC_2_0, GLIBC_2_29)
  66 compat_symbol (libm, __pow_compat, pow, GLIBC_2_0);
  67 # endif
  68 # ifdef NO_LONG_DOUBLE
  69 weak_alias (__pow_compat, powl)
  70 # endif
  71 # ifdef LONG_DOUBLE_COMPAT
  72 /* Work around gas bug "multiple versions for symbol".  */
  73 weak_alias (__pow_compat, __pow_compat_alias)
  74
  75 LONG_DOUBLE_COMPAT_CHOOSE_libm_powl (
  76   compat_symbol (libm, __pow_compat_alias, powl, FIRST_VERSION_libm_powl), );
  77 # endif
  78 #endif