mirror of git://sourceware.org/git/glibc.git
98 lines
3.3 KiB
C
98 lines
3.3 KiB
C
/* Double-precision vector (SVE) sin function.
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Copyright (C) 2023 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 "sv_math.h"
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static const struct data
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{
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double inv_pi, half_pi, inv_pi_over_2, pi_over_2_1, pi_over_2_2, pi_over_2_3,
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shift;
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} data = {
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/* Polynomial coefficients are hard-wired in the FTMAD instruction. */
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.inv_pi = 0x1.45f306dc9c883p-2,
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.half_pi = 0x1.921fb54442d18p+0,
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.inv_pi_over_2 = 0x1.45f306dc9c882p-1,
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.pi_over_2_1 = 0x1.921fb50000000p+0,
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.pi_over_2_2 = 0x1.110b460000000p-26,
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.pi_over_2_3 = 0x1.1a62633145c07p-54,
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.shift = 0x1.8p52
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};
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#define RangeVal 0x4160000000000000 /* asuint64 (0x1p23). */
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static svfloat64_t NOINLINE
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special_case (svfloat64_t x, svfloat64_t y, svbool_t cmp)
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{
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return sv_call_f64 (sin, x, y, cmp);
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}
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/* A fast SVE implementation of sin based on trigonometric
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instructions (FTMAD, FTSSEL, FTSMUL).
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Maximum observed error in 2.52 ULP:
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SV_NAME_D1 (sin)(0x1.2d2b00df69661p+19) got 0x1.10ace8f3e786bp-40
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want 0x1.10ace8f3e7868p-40. */
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svfloat64_t SV_NAME_D1 (sin) (svfloat64_t x, const svbool_t pg)
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{
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const struct data *d = ptr_barrier (&data);
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svfloat64_t r = svabs_f64_x (pg, x);
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svuint64_t sign
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= sveor_u64_x (pg, svreinterpret_u64_f64 (x), svreinterpret_u64_f64 (r));
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svbool_t cmp = svcmpge_n_u64 (pg, svreinterpret_u64_f64 (r), RangeVal);
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/* Load first two pio2-related constants to one vector. */
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svfloat64_t invpio2_and_pio2_1
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= svld1rq_f64 (svptrue_b64 (), &d->inv_pi_over_2);
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/* n = rint(|x|/(pi/2)). */
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svfloat64_t q = svmla_lane_f64 (sv_f64 (d->shift), r, invpio2_and_pio2_1, 0);
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svfloat64_t n = svsub_n_f64_x (pg, q, d->shift);
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/* r = |x| - n*(pi/2) (range reduction into -pi/4 .. pi/4). */
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r = svmls_lane_f64 (r, n, invpio2_and_pio2_1, 1);
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r = svmls_n_f64_x (pg, r, n, d->pi_over_2_2);
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r = svmls_n_f64_x (pg, r, n, d->pi_over_2_3);
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/* Final multiplicative factor: 1.0 or x depending on bit #0 of q. */
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svfloat64_t f = svtssel_f64 (r, svreinterpret_u64_f64 (q));
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/* sin(r) poly approx. */
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svfloat64_t r2 = svtsmul_f64 (r, svreinterpret_u64_f64 (q));
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svfloat64_t y = sv_f64 (0.0);
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y = svtmad_f64 (y, r2, 7);
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y = svtmad_f64 (y, r2, 6);
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y = svtmad_f64 (y, r2, 5);
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y = svtmad_f64 (y, r2, 4);
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y = svtmad_f64 (y, r2, 3);
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y = svtmad_f64 (y, r2, 2);
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y = svtmad_f64 (y, r2, 1);
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y = svtmad_f64 (y, r2, 0);
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/* Apply factor. */
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y = svmul_f64_x (pg, f, y);
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/* sign = y^sign. */
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y = svreinterpret_f64_u64 (
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sveor_u64_x (pg, svreinterpret_u64_f64 (y), sign));
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if (__glibc_unlikely (svptest_any (pg, cmp)))
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return special_case (x, y, cmp);
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return y;
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}
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