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aaee3cd88e
This patch continues cleaning up the math_private.h header, which contains lots of different definitions many of which are only needed by a limited subset of files using that header (and some of which are overridden by architectures that only want to override selected parts of the header), by moving the math_narrow_eval macro out to a separate math-narrow-eval.h header, only included by those files that need it. That header is placed in include/ (since it's used in stdlib/, not just files built in math/, but no sysdeps variants are needed at present). Tested for x86_64, and with build-many-glibcs.py. (Installed stripped shared libraries change because of line numbers in assertions in strtod_l.c.) * include/math-narrow-eval.h: New file. Contents moved from .... * sysdeps/generic/math_private.h: ... here. (math_narrow_eval): Remove macro. Moved to math-narrow-eval.h. [FLT_EVAL_METHOD != 0] (excess_precision): Likewise. * math/s_fdim_template.c: Include <math-narrow-eval.h>. * stdlib/strtod_l.c: Likewise. * sysdeps/i386/fpu/s_f32xaddf64.c: Likewise. * sysdeps/i386/fpu/s_f32xsubf64.c: Likewise. * sysdeps/i386/fpu/s_fdim.c: Likewise. * sysdeps/ieee754/dbl-64/e_cosh.c: Likewise. * sysdeps/ieee754/dbl-64/e_gamma_r.c: Likewise. * sysdeps/ieee754/dbl-64/e_j1.c: Likewise. * sysdeps/ieee754/dbl-64/e_jn.c: Likewise. * sysdeps/ieee754/dbl-64/e_lgamma_r.c: Likewise. * sysdeps/ieee754/dbl-64/e_sinh.c: Likewise. * sysdeps/ieee754/dbl-64/gamma_productf.c: Likewise. * sysdeps/ieee754/dbl-64/k_rem_pio2.c: Likewise. * sysdeps/ieee754/dbl-64/lgamma_neg.c: Likewise. * sysdeps/ieee754/dbl-64/s_erf.c: Likewise. * sysdeps/ieee754/dbl-64/s_llrint.c: Likewise. * sysdeps/ieee754/dbl-64/s_lrint.c: Likewise. * sysdeps/ieee754/flt-32/e_coshf.c: Likewise. * sysdeps/ieee754/flt-32/e_exp2f.c: Likewise. * sysdeps/ieee754/flt-32/e_expf.c: Likewise. * sysdeps/ieee754/flt-32/e_gammaf_r.c: Likewise. * sysdeps/ieee754/flt-32/e_j1f.c: Likewise. * sysdeps/ieee754/flt-32/e_jnf.c: Likewise. * sysdeps/ieee754/flt-32/e_lgammaf_r.c: Likewise. * sysdeps/ieee754/flt-32/e_sinhf.c: Likewise. * sysdeps/ieee754/flt-32/k_rem_pio2f.c: Likewise. * sysdeps/ieee754/flt-32/lgamma_negf.c: Likewise. * sysdeps/ieee754/flt-32/s_erff.c: Likewise. * sysdeps/ieee754/flt-32/s_llrintf.c: Likewise. * sysdeps/ieee754/flt-32/s_lrintf.c: Likewise. * sysdeps/ieee754/ldbl-96/gamma_product.c: Likewise.
97 lines
2.7 KiB
C
97 lines
2.7 KiB
C
/* Single-precision 2^x function.
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Copyright (C) 2017-2018 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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#include <math.h>
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#include <math-narrow-eval.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 [-1/64, 1/64] (before rounding.)
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Wrong count: 168353 (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 T __exp2f_data.tab
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#define C __exp2f_data.poly
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#define SHIFT __exp2f_data.shift_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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__exp2f (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 (128.0f)))
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{
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/* |x| >= 128 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 > 0.0f)
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return __math_oflowf (0);
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if (x <= -150.0f)
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return __math_uflowf (0);
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#if WANT_ERRNO_UFLOW
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if (x < -149.0f)
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return __math_may_uflowf (0);
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#endif
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}
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/* x = k/N + r with r in [-1/(2N), 1/(2N)] and int k. */
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kd = math_narrow_eval ((double) (xd + SHIFT)); /* Needs to be double. */
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ki = asuint64 (kd);
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kd -= SHIFT; /* k/N for int k. */
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r = xd - kd;
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/* exp2(x) = 2^(k/N) * 2^r ~= 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 __exp2f
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strong_alias (__exp2f, __ieee754_exp2f)
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strong_alias (__exp2f, __exp2f_finite)
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versioned_symbol (libm, __exp2f, exp2f, GLIBC_2_27);
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libm_alias_float_other (__exp2, exp2)
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#endif
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