diff options
Diffstat (limited to 'sysdeps/aarch64/fpu/log10_sve.c')
| -rw-r--r-- | sysdeps/aarch64/fpu/log10_sve.c | 47 |
1 files changed, 36 insertions, 11 deletions
diff --git a/sysdeps/aarch64/fpu/log10_sve.c b/sysdeps/aarch64/fpu/log10_sve.c index ab7362128d..f1cad2759a 100644 --- a/sysdeps/aarch64/fpu/log10_sve.c +++ b/sysdeps/aarch64/fpu/log10_sve.c @@ -23,28 +23,49 @@ #define Min 0x0010000000000000 #define Max 0x7ff0000000000000 #define Thres 0x7fe0000000000000 /* Max - Min. */ -#define Off 0x3fe6900900000000 #define N (1 << V_LOG10_TABLE_BITS) +static const struct data +{ + double c0, c2; + double c1, c3; + double invln10, log10_2; + double c4; + uint64_t off; +} data = { + .c0 = -0x1.bcb7b1526e506p-3, + .c1 = 0x1.287a7636be1d1p-3, + .c2 = -0x1.bcb7b158af938p-4, + .c3 = 0x1.63c78734e6d07p-4, + .c4 = -0x1.287461742fee4p-4, + .invln10 = 0x1.bcb7b1526e50ep-2, + .log10_2 = 0x1.34413509f79ffp-2, + .off = 0x3fe6900900000000, +}; + static svfloat64_t NOINLINE -special_case (svfloat64_t x, svfloat64_t y, svbool_t special) +special_case (svfloat64_t hi, svuint64_t tmp, svfloat64_t y, svfloat64_t r2, + svbool_t special, const struct data *d) { - return sv_call_f64 (log10, x, y, special); + svfloat64_t x = svreinterpret_f64 (svadd_x (svptrue_b64 (), tmp, d->off)); + return sv_call_f64 (log10, x, svmla_x (svptrue_b64 (), hi, r2, y), special); } -/* SVE log10 algorithm. +/* Double-precision SVE log10 routine. Maximum measured error is 2.46 ulps. SV_NAME_D1 (log10)(0x1.131956cd4b627p+0) got 0x1.fffbdf6eaa669p-6 want 0x1.fffbdf6eaa667p-6. */ svfloat64_t SV_NAME_D1 (log10) (svfloat64_t x, const svbool_t pg) { + const struct data *d = ptr_barrier (&data); + svuint64_t ix = svreinterpret_u64 (x); svbool_t special = svcmpge (pg, svsub_x (pg, ix, Min), Thres); /* x = 2^k z; where z is in range [Off,2*Off) and exact. The range is split into N subintervals. The ith subinterval contains z and c is near its center. */ - svuint64_t tmp = svsub_x (pg, ix, Off); + svuint64_t tmp = svsub_x (pg, ix, d->off); svuint64_t i = svlsr_x (pg, tmp, 51 - V_LOG10_TABLE_BITS); i = svand_x (pg, i, (N - 1) << 1); svfloat64_t k = svcvt_f64_x (pg, svasr_x (pg, svreinterpret_s64 (tmp), 52)); @@ -62,15 +83,19 @@ svfloat64_t SV_NAME_D1 (log10) (svfloat64_t x, const svbool_t pg) svfloat64_t r = svmad_x (pg, invc, z, -1.0); /* hi = log(c) + k*log(2). */ - svfloat64_t w = svmla_x (pg, logc, r, __v_log10_data.invln10); - svfloat64_t hi = svmla_x (pg, w, k, __v_log10_data.log10_2); + svfloat64_t invln10_log10_2 = svld1rq_f64 (svptrue_b64 (), &d->invln10); + svfloat64_t w = svmla_lane_f64 (logc, r, invln10_log10_2, 0); + svfloat64_t hi = svmla_lane_f64 (w, k, invln10_log10_2, 1); /* y = r2*(A0 + r*A1 + r2*(A2 + r*A3 + r2*A4)) + hi. */ - svfloat64_t r2 = svmul_x (pg, r, r); - svfloat64_t y = sv_pw_horner_4_f64_x (pg, r, r2, __v_log10_data.poly); + svfloat64_t odd_coeffs = svld1rq_f64 (svptrue_b64 (), &d->c1); + svfloat64_t r2 = svmul_x (svptrue_b64 (), r, r); + svfloat64_t y = svmla_lane_f64 (sv_f64 (d->c2), r, odd_coeffs, 1); + svfloat64_t p = svmla_lane_f64 (sv_f64 (d->c0), r, odd_coeffs, 0); + y = svmla_x (pg, y, r2, d->c4); + y = svmla_x (pg, p, r2, y); if (__glibc_unlikely (svptest_any (pg, special))) - return special_case (x, svmla_x (svnot_z (pg, special), hi, r2, y), - special); + return special_case (hi, tmp, y, r2, special, d); return svmla_x (pg, hi, r2, y); } |