diff options
Diffstat (limited to 'sysdeps/aarch64/fpu/atan2pi_sve.c')
| -rw-r--r-- | sysdeps/aarch64/fpu/atan2pi_sve.c | 159 |
1 files changed, 159 insertions, 0 deletions
diff --git a/sysdeps/aarch64/fpu/atan2pi_sve.c b/sysdeps/aarch64/fpu/atan2pi_sve.c new file mode 100644 index 0000000..f1d1f1c --- /dev/null +++ b/sysdeps/aarch64/fpu/atan2pi_sve.c @@ -0,0 +1,159 @@ +/* Double-Precision vector (SVE) inverse tan2pi function + + Copyright (C) 2025 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 "math_config.h" +#include "sv_math.h" + +static const struct data +{ + float64_t c2, c4, c6, c8, c10, c12, c14, c16, c18, c20; + float64_t c0, c1, c3, c5, c7, c9, c11, c13, c15, c17, c19; + float64_t shift_val; +} data = { + /* Coefficients of polnomial P such that atan(x)~x+x*P(x^2) on + [2^-1022, 1.0]. */ + .c0 = 0x1.45f306dc9c883p-2, .c1 = -0x1.b2995e7b7ba4ap-4, + .c2 = 0x1.04c26be3d2c1p-4, .c3 = -0x1.7483759c17ea1p-5, + .c4 = 0x1.21bb95c315d57p-5, .c5 = -0x1.da1bdc3d453f3p-6, + .c6 = 0x1.912d20459b4bfp-6, .c7 = -0x1.5bbd4545cad1fp-6, + .c8 = 0x1.331b83bec30a1p-6, .c9 = -0x1.13d6457f44de3p-6, + .c10 = 0x1.f8e802974db94p-7, .c11 = -0x1.d7e173ab04a1ap-7, + .c12 = 0x1.bdfa47d6a4f28p-7, .c13 = -0x1.9ba78f3232ceep-7, + .c14 = 0x1.5e6044590ab4fp-7, .c15 = -0x1.01ccfdeb9f77fp-7, + .c16 = 0x1.345cf0d4eb1c1p-8, .c17 = -0x1.19e5f00f67e3ap-9, + .c18 = 0x1.6d3035ac7625bp-11, .c19 = -0x1.286bb9ae4ed79p-13, + .c20 = 0x1.c37ec36da0e1ap-17, .shift_val = 0.5, +}; + +#define OneOverPi sv_f64 (0x1.45f306dc9c883p-2) + +/* Special cases i.e. 0, infinity, nan (fall back to scalar calls). */ +static svfloat64_t NOINLINE +special_case (svfloat64_t y, svfloat64_t x, svfloat64_t ret, + const svbool_t cmp) +{ + ret = sv_call2_f64 (atan2, y, x, ret, cmp); + return svmul_f64_m (cmp, ret, OneOverPi); +} + +/* Returns a predicate indicating true if the input is the bit representation + of 0, infinity or nan. */ +static inline svbool_t +zeroinfnan (svuint64_t i, const svbool_t pg) +{ + return svcmpge (pg, svsub_x (pg, svlsl_x (pg, i, 1), 1), + sv_u64 (2 * asuint64 (INFINITY) - 1)); +} + +/* Fast implementation of SVE atan2pi. + Maximum observed error is 3.11 ulps: + _ZGVsMxvv_atan2pi (0x1.ef284a877f6b5p+6, 0x1.03fdde8242b17p+7) + got 0x1.f00f800163079p-3 want 0x1.f00f800163076p-3. */ +svfloat64_t SV_NAME_D2 (atan2pi) (svfloat64_t y, svfloat64_t x, + const svbool_t pg) +{ + const struct data *d = ptr_barrier (&data); + svbool_t ptrue = svptrue_b64 (); + + svuint64_t ix = svreinterpret_u64 (x); + svuint64_t iy = svreinterpret_u64 (y); + + svbool_t cmp_x = zeroinfnan (ix, pg); + svbool_t cmp_y = zeroinfnan (iy, pg); + svbool_t cmp_xy = svorr_z (pg, cmp_x, cmp_y); + + svfloat64_t ax = svabs_x (pg, x); + svfloat64_t ay = svabs_x (pg, y); + svuint64_t iax = svreinterpret_u64 (ax); + svuint64_t iay = svreinterpret_u64 (ay); + + svuint64_t sign_x = sveor_x (pg, ix, iax); + svuint64_t sign_y = sveor_x (pg, iy, iay); + svuint64_t sign_xy = sveor_x (pg, sign_x, sign_y); + + svbool_t pred_aygtax = svcmpgt (pg, ay, ax); + + /* Set up z for evaluation of atanpi. */ + svfloat64_t num = svsel (pred_aygtax, svneg_x (pg, ax), ay); + svfloat64_t den = svsel (pred_aygtax, ay, ax); + svfloat64_t z = svdiv_x (pg, num, den); + + /* Work out the correct shift for atan2pi: + -1.0 when x < 0 and ax < ay + -0.5 when x < 0 and ax > ay + 0 when x >= 0 and ax < ay + 0.5 when x >= 0 and ax > ay. */ + svfloat64_t shift = svreinterpret_f64 (svlsr_x (pg, sign_x, 1)); + shift = svmul_x (ptrue, shift, sv_f64 (d->shift_val)); + shift = svsel (pred_aygtax, sv_f64 (d->shift_val), shift); + shift = svreinterpret_f64 (svorr_x (pg, sign_x, svreinterpret_u64 (shift))); + + /* Use split Estrin scheme for P(z^2) with deg(P)=19. */ + svfloat64_t z2 = svmul_x (pg, z, z); + svfloat64_t z3 = svmul_x (pg, z2, z); + svfloat64_t z4 = svmul_x (pg, z2, z2); + svfloat64_t z8 = svmul_x (pg, z4, z4); + svfloat64_t z16 = svmul_x (pg, z8, z8); + + /* Order-7 Estrin. */ + svfloat64_t c24 = svld1rq (ptrue, &d->c2); + svfloat64_t c68 = svld1rq (ptrue, &d->c6); + + svfloat64_t p12 = svmla_lane (sv_f64 (d->c1), z2, c24, 0); + svfloat64_t p34 = svmla_lane (sv_f64 (d->c3), z2, c24, 1); + svfloat64_t p56 = svmla_lane (sv_f64 (d->c5), z2, c68, 0); + svfloat64_t p78 = svmla_lane (sv_f64 (d->c7), z2, c68, 1); + + svfloat64_t p14 = svmla_x (pg, p12, z4, p34); + svfloat64_t p58 = svmla_x (pg, p56, z4, p78); + svfloat64_t p18 = svmla_x (pg, p14, z8, p58); + + /* Order-11 Estrin. */ + svfloat64_t c1012 = svld1rq (ptrue, &d->c10); + svfloat64_t c1416 = svld1rq (ptrue, &d->c14); + svfloat64_t c1820 = svld1rq (ptrue, &d->c18); + + svfloat64_t p910 = svmla_lane (sv_f64 (d->c9), z2, c1012, 0); + svfloat64_t p1112 = svmla_lane (sv_f64 (d->c11), z2, c1012, 1); + svfloat64_t p912 = svmla_x (pg, p910, z4, p1112); + + svfloat64_t p1314 = svmla_lane (sv_f64 (d->c13), z2, c1416, 0); + svfloat64_t p1516 = svmla_lane (sv_f64 (d->c15), z2, c1416, 1); + svfloat64_t p1316 = svmla_x (pg, p1314, z4, p1516); + + svfloat64_t p1718 = svmla_lane (sv_f64 (d->c17), z2, c1820, 0); + svfloat64_t p1920 = svmla_lane (sv_f64 (d->c19), z2, c1820, 1); + svfloat64_t p1720 = svmla_x (pg, p1718, z4, p1920); + + svfloat64_t p916 = svmla_x (pg, p912, z8, p1316); + svfloat64_t p920 = svmla_x (pg, p916, z16, p1720); + + svfloat64_t poly = svmla_x (pg, p18, z16, p920); + + svfloat64_t ret = svmla_x (pg, shift, z, sv_f64 (d->c0)); + ret = svmla_x (pg, ret, z3, poly); + + /* Account for the sign of x and y. */ + if (__glibc_unlikely (svptest_any (pg, cmp_xy))) + return special_case ( + y, x, + svreinterpret_f64 (sveor_x (pg, svreinterpret_u64 (ret), sign_xy)), + cmp_xy); + return svreinterpret_f64 (sveor_x (pg, svreinterpret_u64 (ret), sign_xy)); +} |