mirror of git://sourceware.org/git/glibc.git
88 lines
3.0 KiB
C
88 lines
3.0 KiB
C
/* Double-precision (Advanced SIMD) sinpi function
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Copyright (C) 2024 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 "v_math.h"
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#include "poly_advsimd_f64.h"
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static const struct data
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{
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float64x2_t poly[10];
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} data = {
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/* Polynomial coefficients generated using Remez algorithm,
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see sinpi.sollya for details. */
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.poly = { V2 (0x1.921fb54442d184p1), V2 (-0x1.4abbce625be53p2),
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V2 (0x1.466bc6775ab16p1), V2 (-0x1.32d2cce62dc33p-1),
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V2 (0x1.507834891188ep-4), V2 (-0x1.e30750a28c88ep-8),
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V2 (0x1.e8f48308acda4p-12), V2 (-0x1.6fc0032b3c29fp-16),
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V2 (0x1.af86ae521260bp-21), V2 (-0x1.012a9870eeb7dp-25) },
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};
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#if WANT_SIMD_EXCEPT
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# define TinyBound v_u64 (0x3bf0000000000000) /* asuint64(0x1p-64). */
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/* asuint64(0x1p64) - TinyBound. */
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# define Thresh v_u64 (0x07f0000000000000)
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static float64x2_t VPCS_ATTR NOINLINE
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special_case (float64x2_t x, float64x2_t y, uint64x2_t odd, uint64x2_t cmp)
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{
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/* Fall back to scalar code. */
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y = vreinterpretq_f64_u64 (veorq_u64 (vreinterpretq_u64_f64 (y), odd));
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return v_call_f64 (sinpi, x, y, cmp);
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}
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#endif
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/* Approximation for vector double-precision sinpi(x).
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Maximum Error 3.05 ULP:
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_ZGVnN2v_sinpi(0x1.d32750db30b4ap-2) got 0x1.fb295878301c7p-1
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want 0x1.fb295878301cap-1. */
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float64x2_t VPCS_ATTR V_NAME_D1 (sinpi) (float64x2_t x)
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{
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const struct data *d = ptr_barrier (&data);
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#if WANT_SIMD_EXCEPT
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uint64x2_t ir = vreinterpretq_u64_f64 (vabsq_f64 (x));
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uint64x2_t cmp = vcgeq_u64 (vsubq_u64 (ir, TinyBound), Thresh);
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/* When WANT_SIMD_EXCEPT = 1, special lanes should be set to 0
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to avoid them under/overflowing and throwing exceptions. */
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float64x2_t r = v_zerofy_f64 (x, cmp);
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#else
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float64x2_t r = x;
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#endif
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/* If r is odd, the sign of the result should be inverted. */
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uint64x2_t odd
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= vshlq_n_u64 (vreinterpretq_u64_s64 (vcvtaq_s64_f64 (r)), 63);
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/* r = x - rint(x). Range reduction to -1/2 .. 1/2. */
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r = vsubq_f64 (r, vrndaq_f64 (r));
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/* y = sin(r). */
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float64x2_t r2 = vmulq_f64 (r, r);
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float64x2_t r4 = vmulq_f64 (r2, r2);
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float64x2_t y = vmulq_f64 (v_pw_horner_9_f64 (r2, r4, d->poly), r);
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#if WANT_SIMD_EXCEPT
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if (__glibc_unlikely (v_any_u64 (cmp)))
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return special_case (x, y, odd, cmp);
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#endif
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return vreinterpretq_f64_u64 (veorq_u64 (vreinterpretq_u64_f64 (y), odd));
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}
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