1  /* Narrow floating-point values to their semantic type.
       2     Copyright (C) 2015-2023 Free Software Foundation, Inc.
       3     This file is part of the GNU C Library.
       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  #ifndef _MATH_NARROW_EVAL_H
      20  #define _MATH_NARROW_EVAL_H	1
      21  
      22  #include <float.h>
      23  
      24  /* math_narrow_eval reduces its floating-point argument to the range
      25     and precision of its semantic type.  (The original evaluation may
      26     still occur with excess range and precision, so the result may be
      27     affected by double rounding.)  */
      28  #if FLT_EVAL_METHOD == 0
      29  # define math_narrow_eval(x) (x)
      30  #else
      31  # if FLT_EVAL_METHOD == 1
      32  #  define excess_precision(type) __builtin_types_compatible_p (type, float)
      33  # else
      34  #  define excess_precision(type) (__builtin_types_compatible_p (type, float) \
      35  				  || __builtin_types_compatible_p (type, \
      36  								   double))
      37  # endif
      38  # define math_narrow_eval(x)					\
      39    ({								\
      40      __typeof (x) math_narrow_eval_tmp = (x);			\
      41      if (excess_precision (__typeof (math_narrow_eval_tmp)))	\
      42        __asm__ ("" : "+m" (math_narrow_eval_tmp));		\
      43      math_narrow_eval_tmp;					\
      44     })
      45  #endif
      46  
      47  #endif /* math-narrow-eval.h */