mirror of git://sourceware.org/git/glibc.git
84 lines
2.7 KiB
C
84 lines
2.7 KiB
C
/* Double-precision vector (Advanced SIMD) sinh function
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Copyright (C) 2024-2025 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 "v_expm1_inline.h"
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static const struct data
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{
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struct v_expm1_data d;
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uint64x2_t halff;
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#if WANT_SIMD_EXCEPT
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uint64x2_t tiny_bound, thresh;
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#else
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float64x2_t large_bound;
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#endif
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} data = {
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.d = V_EXPM1_DATA,
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.halff = V2 (0x3fe0000000000000),
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#if WANT_SIMD_EXCEPT
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/* 2^-26, below which sinh(x) rounds to x. */
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.tiny_bound = V2 (0x3e50000000000000),
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/* asuint(large_bound) - asuint(tiny_bound). */
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.thresh = V2 (0x0230000000000000),
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#else
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/* 2^9. expm1 helper overflows for large input. */
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.large_bound = V2 (0x1p+9),
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#endif
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};
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static float64x2_t NOINLINE VPCS_ATTR
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special_case (float64x2_t x)
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{
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return v_call_f64 (sinh, x, x, v_u64 (-1));
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}
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/* Approximation for vector double-precision sinh(x) using expm1.
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sinh(x) = (exp(x) - exp(-x)) / 2.
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The greatest observed error is 2.52 ULP:
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_ZGVnN2v_sinh(-0x1.a098a2177a2b9p-2) got -0x1.ac2f05bb66fccp-2
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want -0x1.ac2f05bb66fc9p-2. */
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float64x2_t VPCS_ATTR V_NAME_D1 (sinh) (float64x2_t x)
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{
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const struct data *d = ptr_barrier (&data);
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float64x2_t ax = vabsq_f64 (x);
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uint64x2_t ix = vreinterpretq_u64_f64 (x);
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float64x2_t halfsign = vreinterpretq_f64_u64 (
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vbslq_u64 (v_u64 (0x8000000000000000), ix, d->halff));
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#if WANT_SIMD_EXCEPT
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uint64x2_t special = vcgeq_u64 (
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vsubq_u64 (vreinterpretq_u64_f64 (ax), d->tiny_bound), d->thresh);
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#else
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uint64x2_t special = vcageq_f64 (x, d->large_bound);
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#endif
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/* Fall back to scalar variant for all lanes if any of them are special. */
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if (__glibc_unlikely (v_any_u64 (special)))
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return special_case (x);
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/* Up to the point that expm1 overflows, we can use it to calculate sinh
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using a slight rearrangement of the definition of sinh. This allows us to
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retain acceptable accuracy for very small inputs. */
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float64x2_t t = expm1_inline (ax, &d->d);
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t = vaddq_f64 (t, vdivq_f64 (t, vaddq_f64 (t, v_f64 (1.0))));
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return vmulq_f64 (t, halfsign);
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}
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