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The powerpc implementations of fabsl for ldbl-128ibm (both powerpc32 and powerpc64) wrongly raise the "invalid" exception for sNaN arguments. fabs functions should be quiet for all inputs including signaling NaNs. The problem is the use of a comparison instruction fcmpu to determine if the high part of the argument is negative and so the low part needs to be negated; such instructions raise "invalid" for sNaNs. There is a pure integer implementation of fabsl in sysdeps/ieee754/ldbl-128ibm/s_fabsl.c. However, it's not necessary to use it to avoid such exceptions. The fsel instruction does not raise exceptions for sNaNs, and can be used in place of the original comparison. (Note that if the high part is zero or a NaN, it does not matter whether the low part is negated; the choice of whether the low part of a zero is +0 or -0 does not affect the value, and the low part of a NaN does not affect the value / payload either.) The condition in GCC for fsel to be available is TARGET_PPC_GFXOPT, corresponding to the _ARCH_PPCGR predefined macro. fsel is available on all 64-bit processors supported by GCC. A few 32-bit processors supported by GCC do not have TARGET_PPC_GFXOPT despite having hard float support. To support those processors, integer code (similar to that in copysignl) is included for the !_ARCH_PPCGR case for powerpc32. Tested for powerpc32 (configurations with and without _ARCH_PPCGR) and powerpc64. [BZ #20157] * sysdeps/powerpc/powerpc32/fpu/s_fabsl.S (__fabsl): Use fsel to determine whether to negate low half if [_ARCH_PPCGR], and integer comparison otherwise. * sysdeps/powerpc/powerpc64/fpu/s_fabsl.S (__fabsl): Use fsel to determine whether to negate low half.
35 lines
1.2 KiB
ArmAsm
35 lines
1.2 KiB
ArmAsm
/* Copy a sign bit between floating-point values.
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IBM extended format long double version.
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Copyright (C) 2004-2016 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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#include <sysdep.h>
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#include <math_ldbl_opt.h>
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ENTRY(__fabsl)
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/* long double [f1,f2] fabs (long double [f1,f2] x);
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fabs(x,y) returns a value with the magnitude of x and
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with the sign bit of y. */
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fmr fp0,fp1
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fabs fp1,fp1
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fneg fp3,fp2
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fsel fp2,fp0,fp2,fp3
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blr
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END (__fabsl)
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long_double_symbol (libm, __fabsl, fabsl)
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