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8014d1e832
* Update ULP comment reflecting a new observed max in [-pi/2, pi/2] * Use the same polynomial in AdvSIMD and SVE, rather than FTRIG instructions * Improve register use near special-case branch Also use overloaded intrinsics for SVE.
102 lines
3.4 KiB
C
102 lines
3.4 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, pi_1, pi_2, pi_3, shift, range_val;
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double poly[7];
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} data = {
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.poly = { -0x1.555555555547bp-3, 0x1.1111111108a4dp-7, -0x1.a01a019936f27p-13,
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0x1.71de37a97d93ep-19, -0x1.ae633919987c6p-26,
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0x1.60e277ae07cecp-33, -0x1.9e9540300a1p-41, },
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.inv_pi = 0x1.45f306dc9c883p-2,
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.pi_1 = 0x1.921fb54442d18p+1,
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.pi_2 = 0x1.1a62633145c06p-53,
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.pi_3 = 0x1.c1cd129024e09p-106,
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.shift = 0x1.8p52,
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.range_val = 0x1p23,
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};
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#define C(i) sv_f64 (d->poly[i])
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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.
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Maximum observed error in [-pi/2, pi/2], where argument is not reduced,
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is 2.87 ULP:
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_ZGVsMxv_sin (0x1.921d5c6a07142p+0) got 0x1.fffffffa7dc02p-1
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want 0x1.fffffffa7dc05p-1
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Maximum observed error in the entire non-special domain ([-2^23, 2^23])
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is 3.22 ULP:
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_ZGVsMxv_sin (0x1.5702447b6f17bp+22) got 0x1.ffdcd125c84fbp-3
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want 0x1.ffdcd125c84f8p-3. */
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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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/* Load some values in quad-word chunks to minimise memory access. */
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const svbool_t ptrue = svptrue_b64 ();
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svfloat64_t shift = sv_f64 (d->shift);
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svfloat64_t inv_pi_and_pi1 = svld1rq (ptrue, &d->inv_pi);
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svfloat64_t pi2_and_pi3 = svld1rq (ptrue, &d->pi_2);
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/* n = rint(|x|/pi). */
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svfloat64_t n = svmla_lane (shift, x, inv_pi_and_pi1, 0);
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svuint64_t odd = svlsl_x (pg, svreinterpret_u64 (n), 63);
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n = svsub_x (pg, n, shift);
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/* r = |x| - n*(pi/2) (range reduction into -pi/2 .. pi/2). */
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svfloat64_t r = x;
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r = svmls_lane (r, n, inv_pi_and_pi1, 1);
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r = svmls_lane (r, n, pi2_and_pi3, 0);
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r = svmls_lane (r, n, pi2_and_pi3, 1);
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/* sin(r) poly approx. */
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svfloat64_t r2 = svmul_x (pg, r, r);
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svfloat64_t r3 = svmul_x (pg, r2, r);
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svfloat64_t r4 = svmul_x (pg, r2, r2);
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svfloat64_t t1 = svmla_x (pg, C (4), C (5), r2);
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svfloat64_t t2 = svmla_x (pg, C (2), C (3), r2);
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svfloat64_t t3 = svmla_x (pg, C (0), C (1), r2);
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svfloat64_t y = svmla_x (pg, t1, C (6), r4);
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y = svmla_x (pg, t2, y, r4);
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y = svmla_x (pg, t3, y, r4);
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y = svmla_x (pg, r, y, r3);
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svbool_t cmp = svacle (pg, x, d->range_val);
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cmp = svnot_z (pg, cmp);
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if (__glibc_unlikely (svptest_any (pg, cmp)))
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return special_case (x,
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svreinterpret_f64 (sveor_z (
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svnot_z (pg, cmp), svreinterpret_u64 (y), odd)),
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cmp);
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/* Copy sign. */
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return svreinterpret_f64 (sveor_z (pg, svreinterpret_u64 (y), odd));
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}
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