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/*
* Single-precision SVE sin(x) function.
*
* Copyright (c) 2019-2022, Arm Limited.
* SPDX-License-Identifier: MIT OR Apache-2.0 WITH LLVM-exception
*/
#include "sv_math.h"
#if SV_SUPPORTED
#define A3 (sv_f32 (__sv_sinf_data.coeffs[3]))
#define A5 (sv_f32 (__sv_sinf_data.coeffs[2]))
#define A7 (sv_f32 (__sv_sinf_data.coeffs[1]))
#define A9 (sv_f32 (__sv_sinf_data.coeffs[0]))
#define NegPi1 (sv_f32 (-0x1.921fb6p+1f))
#define NegPi2 (sv_f32 (0x1.777a5cp-24f))
#define NegPi3 (sv_f32 (0x1.ee59dap-49f))
#define RangeVal (sv_f32 (0x1p20f))
#define InvPi (sv_f32 (0x1.45f306p-2f))
#define Shift (sv_f32 (0x1.8p+23f))
#define AbsMask (0x7fffffff)
static NOINLINE sv_f32_t
__sv_sinf_specialcase (sv_f32_t x, sv_f32_t y, svbool_t cmp)
{
return sv_call_f32 (sinf, x, y, cmp);
}
/* A fast SVE implementation of sinf.
Maximum error: 1.89 ULPs.
This maximum error is achieved at multiple values in [-2^18, 2^18]
but one example is:
__sv_sinf(0x1.9247a4p+0) got 0x1.fffff6p-1 want 0x1.fffffap-1. */
sv_f32_t
__sv_sinf_x (sv_f32_t x, const svbool_t pg)
{
sv_f32_t n, r, r2, y;
sv_u32_t sign, odd;
svbool_t cmp;
r = sv_as_f32_u32 (svand_n_u32_x (pg, sv_as_u32_f32 (x), AbsMask));
sign = svand_n_u32_x (pg, sv_as_u32_f32 (x), ~AbsMask);
cmp = svcmpge_u32 (pg, sv_as_u32_f32 (r), sv_as_u32_f32 (RangeVal));
/* n = rint(|x|/pi). */
n = sv_fma_f32_x (pg, InvPi, r, Shift);
odd = svlsl_n_u32_x (pg, sv_as_u32_f32 (n), 31);
n = svsub_f32_x (pg, n, Shift);
/* r = |x| - n*pi (range reduction into -pi/2 .. pi/2). */
r = sv_fma_f32_x (pg, NegPi1, n, r);
r = sv_fma_f32_x (pg, NegPi2, n, r);
r = sv_fma_f32_x (pg, NegPi3, n, r);
/* sin(r) approx using a degree 9 polynomial from the Taylor series
expansion. Note that only the odd terms of this are non-zero. */
r2 = svmul_f32_x (pg, r, r);
y = sv_fma_f32_x (pg, A9, r2, A7);
y = sv_fma_f32_x (pg, y, r2, A5);
y = sv_fma_f32_x (pg, y, r2, A3);
y = sv_fma_f32_x (pg, svmul_f32_x (pg, y, r2), r, r);
/* sign = y^sign^odd. */
y = sv_as_f32_u32 (
sveor_u32_x (pg, sv_as_u32_f32 (y), sveor_u32_x (pg, sign, odd)));
/* No need to pass pg to specialcase here since cmp is a strict subset,
guaranteed by the cmpge above. */
if (unlikely (svptest_any (pg, cmp)))
return __sv_sinf_specialcase (x, y, cmp);
return y;
}
strong_alias (__sv_sinf_x, _ZGVsMxv_sinf)
#endif
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