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Diffstat (limited to 'include/math-narrow-eval.h')
| -rw-r--r-- | include/math-narrow-eval.h | 47 |
1 files changed, 47 insertions, 0 deletions
diff --git a/include/math-narrow-eval.h b/include/math-narrow-eval.h new file mode 100644 index 0000000000..4361aa06c0 --- /dev/null +++ b/include/math-narrow-eval.h @@ -0,0 +1,47 @@ +/* Narrow floating-point values to their semantic type. + Copyright (C) 2015-2018 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <http://www.gnu.org/licenses/>. */ + +#ifndef _MATH_NARROW_EVAL_H +#define _MATH_NARROW_EVAL_H 1 + +#include <float.h> + +/* math_narrow_eval reduces its floating-point argument to the range + and precision of its semantic type. (The original evaluation may + still occur with excess range and precision, so the result may be + affected by double rounding.) */ +#if FLT_EVAL_METHOD == 0 +# define math_narrow_eval(x) (x) +#else +# if FLT_EVAL_METHOD == 1 +# define excess_precision(type) __builtin_types_compatible_p (type, float) +# else +# define excess_precision(type) (__builtin_types_compatible_p (type, float) \ + || __builtin_types_compatible_p (type, \ + double)) +# endif +# define math_narrow_eval(x) \ + ({ \ + __typeof (x) math_narrow_eval_tmp = (x); \ + if (excess_precision (__typeof (math_narrow_eval_tmp))) \ + __asm__ ("" : "+m" (math_narrow_eval_tmp)); \ + math_narrow_eval_tmp; \ + }) +#endif + +#endif /* math-narrow-eval.h */ |