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38 lines
1.7 KiB
C
38 lines
1.7 KiB
C
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/* Control when floating-point expressions are evaluated. Generic version.
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Copyright (C) 2007-2018 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#ifndef _MATH_BARRIERS_H
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#define _MATH_BARRIERS_H 1
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/* math_opt_barrier evaluates and returns its floating-point argument
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and ensures that the evaluation of any expression using the result
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of math_opt_barrier is not moved before the call. math_force_eval
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ensures that its floating-point argument is evaluated for its side
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effects even if its value is apparently unused, and that the
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evaluation of its argument is not moved after the call. Both these
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macros are used to ensure the correct ordering of floating-point
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expression evaluations with respect to accesses to the
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floating-point environment. */
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#define math_opt_barrier(x) \
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({ __typeof (x) __x = (x); __asm ("" : "+m" (__x)); __x; })
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#define math_force_eval(x) \
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({ __typeof (x) __x = (x); __asm __volatile__ ("" : : "m" (__x)); })
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#endif /* math-barriers.h */
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