1 /* Control when floating-point expressions are evaluated. Generic version. 2 Copyright (C) 2007-2025 Free Software Foundation, Inc. 3 4 The GNU C Library is free software; you can redistribute it and/or 5 modify it under the terms of the GNU Lesser General Public 6 License as published by the Free Software Foundation; either 7 version 2.1 of the License, or (at your option) any later version. 8 9 The GNU C Library 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 GNU 12 Lesser General Public License for more details. 13 14 You should have received a copy of the GNU Lesser General Public 15 License along with the GNU C Library; if not, see 16 <https://www.gnu.org/licenses/>. */ 17 18 #ifndef _MATH_BARRIERS_H 19 #define _MATH_BARRIERS_H 1 20 21 /* math_opt_barrier evaluates and returns its floating-point argument 22 and ensures that the evaluation of any expression using the result 23 of math_opt_barrier is not moved before the call. math_force_eval 24 ensures that its floating-point argument is evaluated for its side 25 effects even if its value is apparently unused, and that the 26 evaluation of its argument is not moved after the call. Both these 27 macros are used to ensure the correct ordering of floating-point 28 expression evaluations with respect to accesses to the 29 floating-point environment. */ 30 31 #define math_opt_barrier(x) \ 32 ({ __typeof (x) __x = (x); __asm ("" : "+m" (__x)); __x; }) 33 #define math_force_eval(x) \ 34 ({ __typeof (x) __x = (x); __asm __volatile__ ("" : : "m" (__x)); }) 35 36 #endif /* math-barriers.h */ 37