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24b6515d87
Some libm functions are unable to use the generic alias macros such as libm_alias_double because they have special symbol versioning requirements for the main float, double or long double public names. To facilitate adding _FloatN / _FloatNx function aliases in future, it's still desirable to have generic macros those functions can use as far as possible. This patch adds macros such as libm_alias_double_other, which only define names for _FloatN / _FloatNx aliases, not for float / double / long double. As present, all these new macros do nothing, but they are called in the appropriate places in macros such as libm_alias_double. This patch also arranges for lgamma implementations, and the recently added optimized float function implementations, to use the new macros to make them ready for addition of _FloatN / _FloatNx aliases. Tested for x86_64, and tested with build-many-glibcs.py that installed stripped shared libraries are unchanged by this patch. * sysdeps/generic/libm-alias-double.h (libm_alias_double_other_r): New macro. (libm_alias_double_other): Likewise. (libm_alias_double_r): Use libm_alias_double_other_r. * sysdeps/generic/libm-alias-float.h (libm_alias_float_other_r): New macro. (libm_alias_float_other): Likewise. (libm_alias_float_r): Use libm_alias_float_other_r. * sysdeps/generic/libm-alias-float128.h (libm_alias_float128_other_r): New macro. (libm_alias_float128_other): Likewise. (libm_alias_float128_r): Use libm_alias_float128_other_r. * sysdeps/generic/libm-alias-ldouble.h (libm_alias_ldouble_other_r): New macro. (libm_alias_ldouble_other): Likewise. (libm_alias_ldouble_r): Use libm_alias_ldouble_other_r. * sysdeps/ieee754/ldbl-opt/libm-alias-double.h (libm_alias_double_other_r): New macro. (libm_alias_double_other): Likewise. (libm_alias_double_r): Use libm_alias_double_other_r. * sysdeps/ieee754/ldbl-opt/libm-alias-ldouble.h (libm_alias_ldouble_other_r): New macro. (libm_alias_ldouble_other): Likewise. (libm_alias_ldouble_r): Use libm_alias_ldouble_other_r. * math/w_lgamma_main.c: Include <libm-alias-double.h>. [!USE_AS_COMPAT]: Use libm_alias_double_other. * math/w_lgammaf_main.c: Include <libm-alias-float.h>. [!USE_AS_COMPAT]: Use libm_alias_float_other. * math/w_lgammal_main.c: Include <libm-alias-ldouble.h>. [!USE_AS_COMPAT]: Use libm_alias_ldouble_other. * math/w_exp2f.c: Use libm_alias_float_other. * math/w_expf.c: Likewise. * math/w_log2f.c: Likewise. * math/w_logf.c: Likewise. * math/w_powf.c: Likewise. * sysdeps/ieee754/flt-32/e_exp2f.c: Include <libm-alias-float.h>. [!__exp2f]: Use libm_alias_float_other. * sysdeps/ieee754/flt-32/e_expf.c: Include <libm-alias-float.h>. [!__expf]: Use libm_alias_float_other. * sysdeps/ieee754/flt-32/e_log2f.c: Include <libm-alias-float.h>. [!__log2f]: Use libm_alias_float_other. * sysdeps/ieee754/flt-32/e_logf.c: Include <libm-alias-float.h>. [!__logf]: Use libm_alias_float_other. * sysdeps/ieee754/flt-32/e_powf.c: Include <libm-alias-float.h>. [!__powf]: Use libm_alias_float_other.
117 lines
3.2 KiB
C
117 lines
3.2 KiB
C
/* Single-precision e^x function.
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Copyright (C) 2017 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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#ifdef __expf
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# undef libm_hidden_proto
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# define libm_hidden_proto(ignored)
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#endif
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#include <math.h>
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#include <stdint.h>
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#include <shlib-compat.h>
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#include <libm-alias-float.h>
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#include "math_config.h"
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/*
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EXP2F_TABLE_BITS = 5
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EXP2F_POLY_ORDER = 3
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ULP error: 0.502 (nearest rounding.)
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Relative error: 1.69 * 2^-34 in [-ln2/64, ln2/64] (before rounding.)
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Wrong count: 170635 (all nearest rounding wrong results with fma.)
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Non-nearest ULP error: 1 (rounded ULP error)
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*/
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#define N (1 << EXP2F_TABLE_BITS)
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#define InvLn2N __exp2f_data.invln2_scaled
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#define T __exp2f_data.tab
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#define C __exp2f_data.poly_scaled
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static inline uint32_t
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top12 (float x)
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{
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return asuint (x) >> 20;
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}
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float
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__expf (float x)
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{
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uint32_t abstop;
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uint64_t ki, t;
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/* double_t for better performance on targets with FLT_EVAL_METHOD==2. */
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double_t kd, xd, z, r, r2, y, s;
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xd = (double_t) x;
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abstop = top12 (x) & 0x7ff;
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if (__glibc_unlikely (abstop >= top12 (88.0f)))
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{
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/* |x| >= 88 or x is nan. */
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if (asuint (x) == asuint (-INFINITY))
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return 0.0f;
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if (abstop >= top12 (INFINITY))
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return x + x;
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if (x > 0x1.62e42ep6f) /* x > log(0x1p128) ~= 88.72 */
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return __math_oflowf (0);
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if (x < -0x1.9fe368p6f) /* x < log(0x1p-150) ~= -103.97 */
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return __math_uflowf (0);
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#if WANT_ERRNO_UFLOW
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if (x < -0x1.9d1d9ep6f) /* x < log(0x1p-149) ~= -103.28 */
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return __math_may_uflowf (0);
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#endif
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}
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/* x*N/Ln2 = k + r with r in [-1/2, 1/2] and int k. */
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z = InvLn2N * xd;
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/* Round and convert z to int, the result is in [-150*N, 128*N] and
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ideally ties-to-even rule is used, otherwise the magnitude of r
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can be bigger which gives larger approximation error. */
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#if TOINT_INTRINSICS
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kd = roundtoint (z);
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ki = converttoint (z);
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#elif TOINT_RINT
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kd = rint (z);
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ki = (long) kd;
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#elif TOINT_SHIFT
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# define SHIFT __exp2f_data.shift
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kd = math_narrow_eval ((double) (z + SHIFT)); /* Needs to be double. */
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ki = asuint64 (kd);
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kd -= SHIFT;
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#endif
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r = z - kd;
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/* exp(x) = 2^(k/N) * 2^(r/N) ~= s * (C0*r^3 + C1*r^2 + C2*r + 1) */
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t = T[ki % N];
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t += ki << (52 - EXP2F_TABLE_BITS);
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s = asdouble (t);
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z = C[0] * r + C[1];
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r2 = r * r;
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y = C[2] * r + 1;
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y = z * r2 + y;
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y = y * s;
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return (float) y;
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}
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#ifndef __expf
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hidden_def (__expf)
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strong_alias (__expf, __ieee754_expf)
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strong_alias (__expf, __expf_finite)
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versioned_symbol (libm, __expf, expf, GLIBC_2_27);
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libm_alias_float_other (__exp, exp)
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#endif
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