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Diffstat (limited to 'math/aarch64/sve/atan2f.c')
| -rw-r--r-- | math/aarch64/sve/atan2f.c | 113 |
1 files changed, 113 insertions, 0 deletions
diff --git a/math/aarch64/sve/atan2f.c b/math/aarch64/sve/atan2f.c new file mode 100644 index 000000000000..563b708cfcbb --- /dev/null +++ b/math/aarch64/sve/atan2f.c @@ -0,0 +1,113 @@ +/* + * Single-precision vector atan2f(x) function. + * + * Copyright (c) 2021-2024, Arm Limited. + * SPDX-License-Identifier: MIT OR Apache-2.0 WITH LLVM-exception + */ + +#include "sv_math.h" +#include "test_sig.h" +#include "test_defs.h" +#include "sv_poly_f32.h" + +static const struct data +{ + float32_t poly[8]; + float32_t pi_over_2; +} data = { + /* Coefficients of polynomial P such that atan(x)~x+x*P(x^2) on + [2**-128, 1.0]. */ + .poly = { -0x1.55555p-2f, 0x1.99935ep-3f, -0x1.24051ep-3f, 0x1.bd7368p-4f, + -0x1.491f0ep-4f, 0x1.93a2c0p-5f, -0x1.4c3c60p-6f, 0x1.01fd88p-8f }, + .pi_over_2 = 0x1.921fb6p+0f, +}; + +/* Special cases i.e. 0, infinity, nan (fall back to scalar calls). */ +static svfloat32_t NOINLINE +special_case (svfloat32_t y, svfloat32_t x, svfloat32_t ret, + const svbool_t cmp) +{ + return sv_call2_f32 (atan2f, y, x, ret, cmp); +} + +/* Returns a predicate indicating true if the input is the bit representation + of 0, infinity or nan. */ +static inline svbool_t +zeroinfnan (svuint32_t i, const svbool_t pg) +{ + return svcmpge (pg, svsub_x (pg, svlsl_x (pg, i, 1), 1), + sv_u32 (2 * 0x7f800000lu - 1)); +} + +/* Fast implementation of SVE atan2f based on atan(x) ~ shift + z + z^3 * + P(z^2) with reduction to [0,1] using z=1/x and shift = pi/2. Maximum + observed error is 2.95 ULP: + _ZGVsMxvv_atan2f (0x1.93836cp+6, 0x1.8cae1p+6) got 0x1.967f06p-1 + want 0x1.967f00p-1. */ +svfloat32_t SV_NAME_F2 (atan2) (svfloat32_t y, svfloat32_t x, + const svbool_t pg) +{ + const struct data *data_ptr = ptr_barrier (&data); + + svuint32_t ix = svreinterpret_u32 (x); + svuint32_t iy = svreinterpret_u32 (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); + + svfloat32_t ax = svabs_x (pg, x); + svfloat32_t ay = svabs_x (pg, y); + svuint32_t iax = svreinterpret_u32 (ax); + svuint32_t iay = svreinterpret_u32 (ay); + + svuint32_t sign_x = sveor_x (pg, ix, iax); + svuint32_t sign_y = sveor_x (pg, iy, iay); + svuint32_t sign_xy = sveor_x (pg, sign_x, sign_y); + + svbool_t pred_aygtax = svcmpgt (pg, ay, ax); + + /* Set up z for call to atan. */ + svfloat32_t n = svsel (pred_aygtax, svneg_x (pg, ax), ay); + svfloat32_t d = svsel (pred_aygtax, ay, ax); + svfloat32_t z = svdiv_x (pg, n, d); + + /* Work out the correct shift. */ + svfloat32_t shift = svreinterpret_f32 (svlsr_x (pg, sign_x, 1)); + shift = svsel (pred_aygtax, sv_f32 (1.0), shift); + shift = svreinterpret_f32 (svorr_x (pg, sign_x, svreinterpret_u32 (shift))); + shift = svmul_x (pg, shift, sv_f32 (data_ptr->pi_over_2)); + + /* Use pure Estrin scheme for P(z^2) with deg(P)=7. */ + svfloat32_t z2 = svmul_x (pg, z, z); + svfloat32_t z4 = svmul_x (pg, z2, z2); + svfloat32_t z8 = svmul_x (pg, z4, z4); + + svfloat32_t ret = sv_estrin_7_f32_x (pg, z2, z4, z8, data_ptr->poly); + + /* ret = shift + z + z^3 * P(z^2). */ + svfloat32_t z3 = svmul_x (pg, z2, z); + ret = svmla_x (pg, z, z3, ret); + + ret = svadd_m (pg, ret, shift); + + /* Account for the sign of x and y. */ + + if (unlikely (svptest_any (pg, cmp_xy))) + return special_case ( + y, x, + svreinterpret_f32 (sveor_x (pg, svreinterpret_u32 (ret), sign_xy)), + cmp_xy); + + return svreinterpret_f32 (sveor_x (pg, svreinterpret_u32 (ret), sign_xy)); +} + +/* Arity of 2 means no mathbench entry emitted. See test/mathbench_funcs.h. */ +TEST_SIG (SV, F, 2, atan2) +TEST_ULP (SV_NAME_F2 (atan2), 2.45) +TEST_DISABLE_FENV (SV_NAME_F2 (atan2)) +TEST_INTERVAL (SV_NAME_F2 (atan2), 0.0, 1.0, 40000) +TEST_INTERVAL (SV_NAME_F2 (atan2), 1.0, 100.0, 40000) +TEST_INTERVAL (SV_NAME_F2 (atan2), 100, inf, 40000) +TEST_INTERVAL (SV_NAME_F2 (atan2), -0, -inf, 40000) +CLOSE_SVE_ATTR |