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183a34dc4a
The operand modifier %s on powerpc is an undocumented internal implementation detail of GCC. Besides that, the GCC community wants to remove it. This patch rewrites the expressions that use this modifier with logically equivalent expressions that don't require it. Explanation for the substitution: The %s modifier takes an immediate operand and prints 32 less such immediate. Thus, in the previous code, the expression resulted in: 32 - __builtin_ffs(e) where e was guaranteed to have exactly a single bit set, by the following expressions: (e & (e-1) == 0) : e has at most one bit set. (e != 0) : e is not zero, thus it has at least one bit set. Since we guarantee that there is exactly only one bit set, the following statement is true: 32 - __builtin_ffs(e) == __builtin_clz(e) Thus, we can replace __builtin_ffs with __builtin_clz and remove the %s operand modifier.
80 lines
2.8 KiB
C
80 lines
2.8 KiB
C
/* Inline floating-point environment handling functions for powerpc.
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Copyright (C) 1995-2016 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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#if defined __GNUC__ && !defined _SOFT_FLOAT && !defined __NO_FPRS__
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/* Inline definition for fegetround. */
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# define __fegetround() \
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(__extension__ ({ int __fegetround_result; \
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__asm__ __volatile__ \
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("mcrfs 7,7 ; mfcr %0" \
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: "=r"(__fegetround_result) : : "cr7"); \
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__fegetround_result & 3; }))
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# define fegetround() __fegetround ()
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# ifndef __NO_MATH_INLINES
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/* The weird 'i#*X' constraints on the following suppress a gcc
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warning when __excepts is not a constant. Otherwise, they mean the
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same as just plain 'i'. */
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# if __GNUC_PREREQ(3, 4)
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/* Inline definition for feraiseexcept. */
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# define feraiseexcept(__excepts) \
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(__extension__ ({ \
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int __e = __excepts; \
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int __ret; \
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if (__builtin_constant_p (__e) \
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&& (__e & (__e - 1)) == 0 \
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&& __e != FE_INVALID) \
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{ \
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if (__e != 0) \
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__asm__ __volatile__ ("mtfsb1 %0" \
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: : "i#*X" (__builtin_clz (__e))); \
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__ret = 0; \
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} \
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else \
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__ret = feraiseexcept (__e); \
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__ret; \
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}))
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/* Inline definition for feclearexcept. */
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# define feclearexcept(__excepts) \
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(__extension__ ({ \
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int __e = __excepts; \
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int __ret; \
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if (__builtin_constant_p (__e) \
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&& (__e & (__e - 1)) == 0 \
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&& __e != FE_INVALID) \
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{ \
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if (__e != 0) \
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__asm__ __volatile__ ("mtfsb0 %0" \
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: : "i#*X" (__builtin_clz (__e))); \
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__ret = 0; \
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} \
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else \
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__ret = feclearexcept (__e); \
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__ret; \
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}))
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# endif /* __GNUC_PREREQ(3, 4). */
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# endif /* !__NO_MATH_INLINES. */
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#endif /* __GNUC__ && !_SOFT_FLOAT && !__NO_FPRS__ */
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