mirror of git://sourceware.org/git/glibc.git
99 lines
3.1 KiB
C
99 lines
3.1 KiB
C
/* Single-precision AdvSIMD log1p
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Copyright (C) 2023-2024 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 "v_log1pf_inline.h"
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#if WANT_SIMD_EXCEPT
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const static struct data
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{
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uint32x4_t minus_one, thresh;
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struct v_log1pf_data d;
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} data = {
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.d = V_LOG1PF_CONSTANTS_TABLE,
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.thresh = V4 (0x4b800000), /* asuint32(INFINITY) - TinyBound. */
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.minus_one = V4 (0xbf800000),
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};
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/* asuint32(0x1p-23). ulp=0.5 at 0x1p-23. */
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# define TinyBound v_u32 (0x34000000)
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static float32x4_t NOINLINE VPCS_ATTR
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special_case (float32x4_t x, uint32x4_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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float32x4_t x_nospecial = v_zerofy_f32 (x, cmp);
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return v_call_f32 (log1pf, x, log1pf_inline (x_nospecial, &d->d), cmp);
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}
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/* Vector log1pf approximation using polynomial on reduced interval. Worst-case
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error is 1.69 ULP:
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_ZGVnN4v_log1pf(0x1.04418ap-2) got 0x1.cfcbd8p-3
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want 0x1.cfcbdcp-3. */
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VPCS_ATTR float32x4_t V_NAME_F1 (log1p) (float32x4_t x)
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{
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const struct data *d = ptr_barrier (&data);
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uint32x4_t ix = vreinterpretq_u32_f32 (x);
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uint32x4_t ia = vreinterpretq_u32_f32 (vabsq_f32 (x));
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uint32x4_t special_cases
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= vorrq_u32 (vcgeq_u32 (vsubq_u32 (ia, TinyBound), d->thresh),
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vcgeq_u32 (ix, d->minus_one));
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if (__glibc_unlikely (v_any_u32 (special_cases)))
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return special_case (x, special_cases, d);
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return log1pf_inline (x, &d->d);
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}
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#else
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const static struct v_log1pf_data data = V_LOG1PF_CONSTANTS_TABLE;
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static float32x4_t NOINLINE VPCS_ATTR
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special_case (float32x4_t x, uint32x4_t cmp)
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{
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return v_call_f32 (log1pf, x, log1pf_inline (x, ptr_barrier (&data)), cmp);
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}
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/* Vector log1pf approximation using polynomial on reduced interval. Worst-case
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error is 1.63 ULP:
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_ZGVnN4v_log1pf(0x1.216d12p-2) got 0x1.fdcb12p-3
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want 0x1.fdcb16p-3. */
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VPCS_ATTR float32x4_t V_NAME_F1 (log1p) (float32x4_t x)
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{
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uint32x4_t special_cases = vornq_u32 (vcleq_f32 (x, v_f32 (-1)),
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vcaleq_f32 (x, v_f32 (0x1p127f)));
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if (__glibc_unlikely (v_any_u32 (special_cases)))
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return special_case (x, special_cases);
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return log1pf_inline (x, ptr_barrier (&data));
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}
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#endif
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libmvec_hidden_def (V_NAME_F1 (log1p))
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HALF_WIDTH_ALIAS_F1 (log1p)
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strong_alias (V_NAME_F1 (log1p), V_NAME_F1 (logp1))
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libmvec_hidden_def (V_NAME_F1 (logp1))
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HALF_WIDTH_ALIAS_F1 (logp1)
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