diff options
Diffstat (limited to 'sysdeps/aarch64/fpu/exp2f_sve.c')
-rw-r--r-- | sysdeps/aarch64/fpu/exp2f_sve.c | 70 |
1 files changed, 40 insertions, 30 deletions
diff --git a/sysdeps/aarch64/fpu/exp2f_sve.c b/sysdeps/aarch64/fpu/exp2f_sve.c index 8a686e3e05..c6216bed9e 100644 --- a/sysdeps/aarch64/fpu/exp2f_sve.c +++ b/sysdeps/aarch64/fpu/exp2f_sve.c @@ -24,54 +24,64 @@ static const struct data { - float poly[5]; + float c0, c2, c4, c1, c3; float shift, thres; } data = { - /* Coefficients copied from the polynomial in AdvSIMD variant, reversed for - compatibility with polynomial helpers. */ - .poly = { 0x1.62e422p-1f, 0x1.ebf9bcp-3f, 0x1.c6bd32p-5f, 0x1.3ce9e4p-7f, - 0x1.59977ap-10f }, + /* Coefficients copied from the polynomial in AdvSIMD variant. */ + .c0 = 0x1.62e422p-1f, + .c1 = 0x1.ebf9bcp-3f, + .c2 = 0x1.c6bd32p-5f, + .c3 = 0x1.3ce9e4p-7f, + .c4 = 0x1.59977ap-10f, /* 1.5*2^17 + 127. */ - .shift = 0x1.903f8p17f, + .shift = 0x1.803f8p17f, /* Roughly 87.3. For x < -Thres, the result is subnormal and not handled correctly by FEXPA. */ .thres = Thres, }; -static svfloat32_t NOINLINE -special_case (svfloat32_t x, svfloat32_t y, svbool_t special) -{ - return sv_call_f32 (exp2f, x, y, special); -} - -/* Single-precision SVE exp2f routine. Implements the same algorithm - as AdvSIMD exp2f. - Worst case error is 1.04 ULPs. - SV_NAME_F1 (exp2)(0x1.943b9p-1) got 0x1.ba7eb2p+0 - want 0x1.ba7ebp+0. */ -svfloat32_t SV_NAME_F1 (exp2) (svfloat32_t x, const svbool_t pg) +static inline svfloat32_t +sv_exp2f_inline (svfloat32_t x, const svbool_t pg, const struct data *d) { - const struct data *d = ptr_barrier (&data); /* exp2(x) = 2^n (1 + poly(r)), with 1 + poly(r) in [1/sqrt(2),sqrt(2)] x = n + r, with r in [-1/2, 1/2]. */ - svfloat32_t shift = sv_f32 (d->shift); - svfloat32_t z = svadd_x (pg, x, shift); - svfloat32_t n = svsub_x (pg, z, shift); - svfloat32_t r = svsub_x (pg, x, n); + svfloat32_t z = svadd_x (svptrue_b32 (), x, d->shift); + svfloat32_t n = svsub_x (svptrue_b32 (), z, d->shift); + svfloat32_t r = svsub_x (svptrue_b32 (), x, n); - svbool_t special = svacgt (pg, x, d->thres); svfloat32_t scale = svexpa (svreinterpret_u32 (z)); /* Polynomial evaluation: poly(r) ~ exp2(r)-1. Evaluate polynomial use hybrid scheme - offset ESTRIN by 1 for coefficients 1 to 4, and apply most significant coefficient directly. */ - svfloat32_t r2 = svmul_x (pg, r, r); - svfloat32_t p14 = sv_pairwise_poly_3_f32_x (pg, r, r2, d->poly + 1); - svfloat32_t p0 = svmul_x (pg, r, d->poly[0]); + svfloat32_t even_coeffs = svld1rq (svptrue_b32 (), &d->c0); + svfloat32_t r2 = svmul_x (svptrue_b32 (), r, r); + svfloat32_t p12 = svmla_lane (sv_f32 (d->c1), r, even_coeffs, 1); + svfloat32_t p34 = svmla_lane (sv_f32 (d->c3), r, even_coeffs, 2); + svfloat32_t p14 = svmla_x (pg, p12, r2, p34); + svfloat32_t p0 = svmul_lane (r, even_coeffs, 0); svfloat32_t poly = svmla_x (pg, p0, r2, p14); - if (__glibc_unlikely (svptest_any (pg, special))) - return special_case (x, svmla_x (pg, scale, scale, poly), special); - return svmla_x (pg, scale, scale, poly); } + +static svfloat32_t NOINLINE +special_case (svfloat32_t x, svbool_t special, const struct data *d) +{ + return sv_call_f32 (exp2f, x, sv_exp2f_inline (x, svptrue_b32 (), d), + special); +} + +/* Single-precision SVE exp2f routine. Implements the same algorithm + as AdvSIMD exp2f. + Worst case error is 1.04 ULPs. + _ZGVsMxv_exp2f(-0x1.af994ap-3) got 0x1.ba6a66p-1 + want 0x1.ba6a64p-1. */ +svfloat32_t SV_NAME_F1 (exp2) (svfloat32_t x, const svbool_t pg) +{ + const struct data *d = ptr_barrier (&data); + svbool_t special = svacgt (pg, x, d->thres); + if (__glibc_unlikely (svptest_any (special, special))) + return special_case (x, special, d); + return sv_exp2f_inline (x, pg, d); +} |