mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-25 14:30:06 +00:00
92 lines
3.1 KiB
C
92 lines
3.1 KiB
C
/* Double-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
|
|
{
|
|
double inv_pio2, pio2_1, pio2_2, pio2_3, shift;
|
|
} data = {
|
|
/* Polynomial coefficients are hardwired in FTMAD instructions. */
|
|
.inv_pio2 = 0x1.45f306dc9c882p-1,
|
|
.pio2_1 = 0x1.921fb50000000p+0,
|
|
.pio2_2 = 0x1.110b460000000p-26,
|
|
.pio2_3 = 0x1.1a62633145c07p-54,
|
|
/* Original shift used in AdvSIMD cos,
|
|
plus a contribution to set the bit #0 of q
|
|
as expected by trigonometric instructions. */
|
|
.shift = 0x1.8000000000001p52
|
|
};
|
|
|
|
#define RangeVal 0x4160000000000000 /* asuint64 (0x1p23). */
|
|
|
|
static svfloat64_t NOINLINE
|
|
special_case (svfloat64_t x, svfloat64_t y, svbool_t oob)
|
|
{
|
|
return sv_call_f64 (cos, x, y, oob);
|
|
}
|
|
|
|
/* A fast SVE implementation of cos based on trigonometric
|
|
instructions (FTMAD, FTSSEL, FTSMUL).
|
|
Maximum measured error: 2.108 ULPs.
|
|
SV_NAME_D1 (cos)(0x1.9b0ba158c98f3p+7) got -0x1.fddd4c65c7f07p-3
|
|
want -0x1.fddd4c65c7f05p-3. */
|
|
svfloat64_t SV_NAME_D1 (cos) (svfloat64_t x, const svbool_t pg)
|
|
{
|
|
const struct data *d = ptr_barrier (&data);
|
|
|
|
svfloat64_t r = svabs_x (pg, x);
|
|
svbool_t oob = svcmpge (pg, svreinterpret_u64 (r), RangeVal);
|
|
|
|
/* Load some constants in quad-word chunks to minimise memory access. */
|
|
svbool_t ptrue = svptrue_b64 ();
|
|
svfloat64_t invpio2_and_pio2_1 = svld1rq (ptrue, &d->inv_pio2);
|
|
svfloat64_t pio2_23 = svld1rq (ptrue, &d->pio2_2);
|
|
|
|
/* n = rint(|x|/(pi/2)). */
|
|
svfloat64_t q = svmla_lane (sv_f64 (d->shift), r, invpio2_and_pio2_1, 0);
|
|
svfloat64_t n = svsub_x (pg, q, d->shift);
|
|
|
|
/* r = |x| - n*(pi/2) (range reduction into -pi/4 .. pi/4). */
|
|
r = svmls_lane (r, n, invpio2_and_pio2_1, 1);
|
|
r = svmls_lane (r, n, pio2_23, 0);
|
|
r = svmls_lane (r, n, pio2_23, 1);
|
|
|
|
/* cos(r) poly approx. */
|
|
svfloat64_t r2 = svtsmul (r, svreinterpret_u64 (q));
|
|
svfloat64_t y = sv_f64 (0.0);
|
|
y = svtmad (y, r2, 7);
|
|
y = svtmad (y, r2, 6);
|
|
y = svtmad (y, r2, 5);
|
|
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);
|
|
|
|
/* Final multiplicative factor: 1.0 or x depending on bit #0 of q. */
|
|
svfloat64_t f = svtssel (r, svreinterpret_u64 (q));
|
|
|
|
if (__glibc_unlikely (svptest_any (pg, oob)))
|
|
return special_case (x, svmul_x (svnot_z (pg, oob), y, f), oob);
|
|
|
|
/* Apply factor. */
|
|
return svmul_x (pg, f, y);
|
|
}
|