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347a5b592c
Converting double precision constants to float is now affected by the runtime dynamic rounding mode instead of being evaluated at compile time with default rounding mode (except static object initializers). This can change the computed result and cause performance regression. The known correctness issues (increased ulp errors) are already fixed, this patch fixes remaining cases of unnecessary runtime conversions. Add float M_* macros to math.h as new GNU extension API. To avoid conversions the new M_* macros are used and instead of casting double literals to float, use float literals (only required if the conversion is inexact). The patch was tested on aarch64 where the following symbols had new spurious conversion instructions that got fixed: __clog10f __gammaf_r_finite@GLIBC_2.17 __j0f_finite@GLIBC_2.17 __j1f_finite@GLIBC_2.17 __jnf_finite@GLIBC_2.17 __kernel_casinhf __lgamma_negf __log1pf __y0f_finite@GLIBC_2.17 __y1f_finite@GLIBC_2.17 cacosf cacoshf casinhf catanf catanhf clogf gammaf_positive Fixes bug 28713. Reviewed-by: Paul Zimmermann <Paul.Zimmermann@inria.fr>
123 lines
3.5 KiB
C
123 lines
3.5 KiB
C
/* Compute complex base 10 logarithm.
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Copyright (C) 1997-2022 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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<https://www.gnu.org/licenses/>. */
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#include <complex.h>
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#include <math.h>
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#include <math_private.h>
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#include <math-underflow.h>
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#include <float.h>
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/* log_10 (2). */
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#define LOG10_2 M_LIT (0.3010299956639811952137388947244930267682)
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/* pi * log10 (e). */
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#define PI_LOG10E M_LIT (1.364376353841841347485783625431355770210)
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CFLOAT
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M_DECL_FUNC (__clog10) (CFLOAT x)
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{
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CFLOAT result;
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int rcls = fpclassify (__real__ x);
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int icls = fpclassify (__imag__ x);
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if (__glibc_unlikely (rcls == FP_ZERO && icls == FP_ZERO))
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{
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/* Real and imaginary part are 0.0. */
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__imag__ result = signbit (__real__ x) ? PI_LOG10E : 0;
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__imag__ result = M_COPYSIGN (__imag__ result, __imag__ x);
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/* Yes, the following line raises an exception. */
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__real__ result = -1 / M_FABS (__real__ x);
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}
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else if (__glibc_likely (rcls != FP_NAN && icls != FP_NAN))
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{
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/* Neither real nor imaginary part is NaN. */
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FLOAT absx = M_FABS (__real__ x), absy = M_FABS (__imag__ x);
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int scale = 0;
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if (absx < absy)
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{
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FLOAT t = absx;
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absx = absy;
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absy = t;
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}
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if (absx > M_MAX / 2)
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{
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scale = -1;
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absx = M_SCALBN (absx, scale);
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absy = (absy >= M_MIN * 2 ? M_SCALBN (absy, scale) : 0);
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}
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else if (absx < M_MIN && absy < M_MIN)
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{
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scale = M_MANT_DIG;
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absx = M_SCALBN (absx, scale);
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absy = M_SCALBN (absy, scale);
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}
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if (absx == 1 && scale == 0)
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{
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__real__ result = (M_LOG1P (absy * absy)
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* (M_MLIT (M_LOG10E) / 2));
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math_check_force_underflow_nonneg (__real__ result);
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}
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else if (absx > 1 && absx < 2 && absy < 1 && scale == 0)
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{
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FLOAT d2m1 = (absx - 1) * (absx + 1);
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if (absy >= M_EPSILON)
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d2m1 += absy * absy;
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__real__ result = M_LOG1P (d2m1) * (M_MLIT (M_LOG10E) / 2);
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}
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else if (absx < 1
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&& absx >= M_LIT (0.5)
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&& absy < M_EPSILON / 2
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&& scale == 0)
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{
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FLOAT d2m1 = (absx - 1) * (absx + 1);
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__real__ result = M_LOG1P (d2m1) * (M_MLIT (M_LOG10E) / 2);
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}
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else if (absx < 1
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&& absx >= M_LIT (0.5)
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&& scale == 0
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&& absx * absx + absy * absy >= M_LIT (0.5))
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{
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FLOAT d2m1 = M_SUF (__x2y2m1) (absx, absy);
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__real__ result = M_LOG1P (d2m1) * (M_MLIT (M_LOG10E) / 2);
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}
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else
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{
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FLOAT d = M_HYPOT (absx, absy);
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__real__ result = M_SUF (__ieee754_log10) (d) - scale * LOG10_2;
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}
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__imag__ result = M_MLIT (M_LOG10E) * M_ATAN2 (__imag__ x, __real__ x);
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}
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else
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{
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__imag__ result = M_NAN;
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if (rcls == FP_INFINITE || icls == FP_INFINITE)
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/* Real or imaginary part is infinite. */
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__real__ result = M_HUGE_VAL;
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else
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__real__ result = M_NAN;
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}
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return result;
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}
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declare_mgen_alias (__clog10, clog10)
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