mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-25 22:40:05 +00:00
86 lines
3.0 KiB
C
86 lines
3.0 KiB
C
/* Single-precision vector (SVE) cos function.
|
|
|
|
Copyright (C) 2023-2024 Free Software Foundation, Inc.
|
|
This file is part of the GNU C Library.
|
|
|
|
The GNU C Library is free software; you can redistribute it and/or
|
|
modify it under the terms of the GNU Lesser General Public
|
|
License as published by the Free Software Foundation; either
|
|
version 2.1 of the License, or (at your option) any later version.
|
|
|
|
The GNU C Library is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
Lesser General Public License for more details.
|
|
|
|
You should have received a copy of the GNU Lesser General Public
|
|
License along with the GNU C Library; if not, see
|
|
<https://www.gnu.org/licenses/>. */
|
|
|
|
#include "sv_math.h"
|
|
|
|
static const struct data
|
|
{
|
|
float neg_pio2_1, neg_pio2_2, neg_pio2_3, inv_pio2, shift;
|
|
} data = {
|
|
/* Polynomial coefficients are hard-wired in FTMAD instructions. */
|
|
.neg_pio2_1 = -0x1.921fb6p+0f,
|
|
.neg_pio2_2 = 0x1.777a5cp-25f,
|
|
.neg_pio2_3 = 0x1.ee59dap-50f,
|
|
.inv_pio2 = 0x1.45f306p-1f,
|
|
/* Original shift used in AdvSIMD cosf,
|
|
plus a contribution to set the bit #0 of q
|
|
as expected by trigonometric instructions. */
|
|
.shift = 0x1.800002p+23f
|
|
};
|
|
|
|
#define RangeVal 0x49800000 /* asuint32(0x1p20f). */
|
|
|
|
static svfloat32_t NOINLINE
|
|
special_case (svfloat32_t x, svfloat32_t y, svbool_t oob)
|
|
{
|
|
return sv_call_f32 (cosf, x, y, oob);
|
|
}
|
|
|
|
/* A fast SVE implementation of cosf based on trigonometric
|
|
instructions (FTMAD, FTSSEL, FTSMUL).
|
|
Maximum measured error: 2.06 ULPs.
|
|
SV_NAME_F1 (cos)(0x1.dea2f2p+19) got 0x1.fffe7ap-6
|
|
want 0x1.fffe76p-6. */
|
|
svfloat32_t SV_NAME_F1 (cos) (svfloat32_t x, const svbool_t pg)
|
|
{
|
|
const struct data *d = ptr_barrier (&data);
|
|
|
|
svfloat32_t r = svabs_x (pg, x);
|
|
svbool_t oob = svcmpge (pg, svreinterpret_u32 (r), RangeVal);
|
|
|
|
/* Load some constants in quad-word chunks to minimise memory access. */
|
|
svfloat32_t negpio2_and_invpio2 = svld1rq (svptrue_b32 (), &d->neg_pio2_1);
|
|
|
|
/* n = rint(|x|/(pi/2)). */
|
|
svfloat32_t q = svmla_lane (sv_f32 (d->shift), r, negpio2_and_invpio2, 3);
|
|
svfloat32_t n = svsub_x (pg, q, d->shift);
|
|
|
|
/* r = |x| - n*(pi/2) (range reduction into -pi/4 .. pi/4). */
|
|
r = svmla_lane (r, n, negpio2_and_invpio2, 0);
|
|
r = svmla_lane (r, n, negpio2_and_invpio2, 1);
|
|
r = svmla_lane (r, n, negpio2_and_invpio2, 2);
|
|
|
|
/* Final multiplicative factor: 1.0 or x depending on bit #0 of q. */
|
|
svfloat32_t f = svtssel (r, svreinterpret_u32 (q));
|
|
|
|
/* cos(r) poly approx. */
|
|
svfloat32_t r2 = svtsmul (r, svreinterpret_u32 (q));
|
|
svfloat32_t y = sv_f32 (0.0f);
|
|
y = svtmad (y, r2, 4);
|
|
y = svtmad (y, r2, 3);
|
|
y = svtmad (y, r2, 2);
|
|
y = svtmad (y, r2, 1);
|
|
y = svtmad (y, r2, 0);
|
|
|
|
if (__glibc_unlikely (svptest_any (pg, oob)))
|
|
return special_case (x, svmul_x (svnot_z (pg, oob), f, y), oob);
|
|
/* Apply factor. */
|
|
return svmul_x (pg, f, y);
|
|
}
|