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Diffstat (limited to 'pl/math/sv_exp10_1u5.c')
| -rw-r--r-- | pl/math/sv_exp10_1u5.c | 122 |
1 files changed, 0 insertions, 122 deletions
diff --git a/pl/math/sv_exp10_1u5.c b/pl/math/sv_exp10_1u5.c deleted file mode 100644 index 519693afcab0..000000000000 --- a/pl/math/sv_exp10_1u5.c +++ /dev/null @@ -1,122 +0,0 @@ -/* - * Double-precision SVE 10^x function. - * - * Copyright (c) 2023, Arm Limited. - * SPDX-License-Identifier: MIT OR Apache-2.0 WITH LLVM-exception - */ - -#include "sv_math.h" -#include "pl_sig.h" -#include "pl_test.h" -#include "poly_sve_f64.h" - -#define SpecialBound 307.0 /* floor (log10 (2^1023)). */ - -static const struct data -{ - double poly[5]; - double shift, log10_2, log2_10_hi, log2_10_lo, scale_thres, special_bound; -} data = { - /* Coefficients generated using Remez algorithm. - rel error: 0x1.9fcb9b3p-60 - abs error: 0x1.a20d9598p-60 in [ -log10(2)/128, log10(2)/128 ] - max ulp err 0.52 +0.5. */ - .poly = { 0x1.26bb1bbb55516p1, 0x1.53524c73cd32ap1, 0x1.0470591daeafbp1, - 0x1.2bd77b1361ef6p0, 0x1.142b5d54e9621p-1 }, - /* 1.5*2^46+1023. This value is further explained below. */ - .shift = 0x1.800000000ffc0p+46, - .log10_2 = 0x1.a934f0979a371p1, /* 1/log2(10). */ - .log2_10_hi = 0x1.34413509f79ffp-2, /* log2(10). */ - .log2_10_lo = -0x1.9dc1da994fd21p-59, - .scale_thres = 1280.0, - .special_bound = SpecialBound, -}; - -#define SpecialOffset 0x6000000000000000 /* 0x1p513. */ -/* SpecialBias1 + SpecialBias1 = asuint(1.0). */ -#define SpecialBias1 0x7000000000000000 /* 0x1p769. */ -#define SpecialBias2 0x3010000000000000 /* 0x1p-254. */ - -/* Update of both special and non-special cases, if any special case is - detected. */ -static inline svfloat64_t -special_case (svbool_t pg, svfloat64_t s, svfloat64_t y, svfloat64_t n, - const struct data *d) -{ - /* s=2^n may overflow, break it up into s=s1*s2, - such that exp = s + s*y can be computed as s1*(s2+s2*y) - and s1*s1 overflows only if n>0. */ - - /* If n<=0 then set b to 0x6, 0 otherwise. */ - svbool_t p_sign = svcmple (pg, n, 0.0); /* n <= 0. */ - svuint64_t b = svdup_u64_z (p_sign, SpecialOffset); - - /* Set s1 to generate overflow depending on sign of exponent n. */ - svfloat64_t s1 = svreinterpret_f64 (svsubr_x (pg, b, SpecialBias1)); - /* Offset s to avoid overflow in final result if n is below threshold. */ - svfloat64_t s2 = svreinterpret_f64 ( - svadd_x (pg, svsub_x (pg, svreinterpret_u64 (s), SpecialBias2), b)); - - /* |n| > 1280 => 2^(n) overflows. */ - svbool_t p_cmp = svacgt (pg, n, d->scale_thres); - - svfloat64_t r1 = svmul_x (pg, s1, s1); - svfloat64_t r2 = svmla_x (pg, s2, s2, y); - svfloat64_t r0 = svmul_x (pg, r2, s1); - - return svsel (p_cmp, r1, r0); -} - -/* Fast vector implementation of exp10 using FEXPA instruction. - Maximum measured error is 1.02 ulp. - SV_NAME_D1 (exp10)(-0x1.2862fec805e58p+2) got 0x1.885a89551d782p-16 - want 0x1.885a89551d781p-16. */ -svfloat64_t SV_NAME_D1 (exp10) (svfloat64_t x, svbool_t pg) -{ - const struct data *d = ptr_barrier (&data); - svbool_t no_big_scale = svacle (pg, x, d->special_bound); - svbool_t special = svnot_z (pg, no_big_scale); - - /* n = round(x/(log10(2)/N)). */ - svfloat64_t shift = sv_f64 (d->shift); - svfloat64_t z = svmla_x (pg, shift, x, d->log10_2); - svfloat64_t n = svsub_x (pg, z, shift); - - /* r = x - n*log10(2)/N. */ - svfloat64_t log2_10 = svld1rq (svptrue_b64 (), &d->log2_10_hi); - svfloat64_t r = x; - r = svmls_lane (r, n, log2_10, 0); - r = svmls_lane (r, n, log2_10, 1); - - /* scale = 2^(n/N), computed using FEXPA. FEXPA does not propagate NaNs, so - for consistent NaN handling we have to manually propagate them. This - comes at significant performance cost. */ - svuint64_t u = svreinterpret_u64 (z); - svfloat64_t scale = svexpa (u); - - /* Approximate exp10(r) using polynomial. */ - svfloat64_t r2 = svmul_x (pg, r, r); - svfloat64_t y = svmla_x (pg, svmul_x (pg, r, d->poly[0]), r2, - sv_pairwise_poly_3_f64_x (pg, r, r2, d->poly + 1)); - - /* Assemble result as exp10(x) = 2^n * exp10(r). If |x| > SpecialBound - multiplication may overflow, so use special case routine. */ - if (unlikely (svptest_any (pg, special))) - { - /* FEXPA zeroes the sign bit, however the sign is meaningful to the - special case function so needs to be copied. - e = sign bit of u << 46. */ - svuint64_t e = svand_x (pg, svlsl_x (pg, u, 46), 0x8000000000000000); - /* Copy sign to scale. */ - scale = svreinterpret_f64 (svadd_x (pg, e, svreinterpret_u64 (scale))); - return special_case (pg, scale, y, n, d); - } - - /* No special case. */ - return svmla_x (pg, scale, scale, y); -} - -PL_SIG (SV, D, 1, exp10, -9.9, 9.9) -PL_TEST_ULP (SV_NAME_D1 (exp10), 0.52) -PL_TEST_SYM_INTERVAL (SV_NAME_D1 (exp10), 0, 307, 10000) -PL_TEST_SYM_INTERVAL (SV_NAME_D1 (exp10), 307, inf, 1000) |