mirror of git://sourceware.org/git/glibc.git
63 lines
2.2 KiB
C
63 lines
2.2 KiB
C
/* Double-precision AdvSIMD log1p
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Copyright (C) 2023-2025 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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#define WANT_V_LOG1P_K0_SHORTCUT 0
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#include "v_log1p_inline.h"
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const static struct data
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{
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struct v_log1p_data d;
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uint64x2_t inf, minus_one;
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} data = { .d = V_LOG1P_CONSTANTS_TABLE,
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.inf = V2 (0x7ff0000000000000),
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.minus_one = V2 (0xbff0000000000000) };
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#define BottomMask v_u64 (0xffffffff)
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static float64x2_t NOINLINE VPCS_ATTR
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special_case (float64x2_t x, uint64x2_t cmp, const struct data *d)
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{
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/* Side-step special lanes so fenv exceptions are not triggered
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inadvertently. */
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float64x2_t x_nospecial = v_zerofy_f64 (x, cmp);
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return v_call_f64 (log1p, x, log1p_inline (x_nospecial, &d->d), cmp);
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}
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/* Vector log1p approximation using polynomial on reduced interval. Routine is
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a modification of the algorithm used in scalar log1p, with no shortcut for
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k=0 and no narrowing for f and k. Maximum observed error is 2.45 ULP:
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_ZGVnN2v_log1p(0x1.658f7035c4014p+11) got 0x1.fd61d0727429dp+2
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want 0x1.fd61d0727429fp+2 . */
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VPCS_ATTR float64x2_t V_NAME_D1 (log1p) (float64x2_t x)
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{
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const struct data *d = ptr_barrier (&data);
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uint64x2_t ix = vreinterpretq_u64_f64 (x);
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uint64x2_t ia = vreinterpretq_u64_f64 (vabsq_f64 (x));
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uint64x2_t special_cases
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= vorrq_u64 (vcgeq_u64 (ia, d->inf), vcgeq_u64 (ix, d->minus_one));
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if (__glibc_unlikely (v_any_u64 (special_cases)))
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return special_case (x, special_cases, d);
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return log1p_inline (x, &d->d);
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}
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strong_alias (V_NAME_D1 (log1p), V_NAME_D1 (logp1))
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