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authorAndrew Turner <andrew@FreeBSD.org>2025-01-10 10:34:52 +0000
committerAndrew Turner <andrew@FreeBSD.org>2025-01-10 10:39:34 +0000
commit9d1de25930735261c16ed874a933b4c1f1d9041e (patch)
treeb0cac1c933cc1ecb885c7e757b89ffbf13f1f012 /pl/math/sv_log1pf_1u3.c
parentedc5c0de794f521eb620d2b6cbaee2434442a8f3 (diff)
Diffstat (limited to 'pl/math/sv_log1pf_1u3.c')
-rw-r--r--pl/math/sv_log1pf_1u3.c97
1 files changed, 0 insertions, 97 deletions
diff --git a/pl/math/sv_log1pf_1u3.c b/pl/math/sv_log1pf_1u3.c
deleted file mode 100644
index ea1a3dbf723a..000000000000
--- a/pl/math/sv_log1pf_1u3.c
+++ /dev/null
@@ -1,97 +0,0 @@
-/*
- * Single-precision vector log(x + 1) 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_f32.h"
-
-static const struct data
-{
- float poly[8];
- float ln2, exp_bias;
- uint32_t four, three_quarters;
-} data = {.poly = {/* Do not store first term of polynomial, which is -0.5, as
- this can be fmov-ed directly instead of including it in
- the main load-and-mla polynomial schedule. */
- 0x1.5555aap-2f, -0x1.000038p-2f, 0x1.99675cp-3f,
- -0x1.54ef78p-3f, 0x1.28a1f4p-3f, -0x1.0da91p-3f,
- 0x1.abcb6p-4f, -0x1.6f0d5ep-5f},
- .ln2 = 0x1.62e43p-1f,
- .exp_bias = 0x1p-23f,
- .four = 0x40800000,
- .three_quarters = 0x3f400000};
-
-#define SignExponentMask 0xff800000
-
-static svfloat32_t NOINLINE
-special_case (svfloat32_t x, svfloat32_t y, svbool_t special)
-{
- return sv_call_f32 (log1pf, x, y, special);
-}
-
-/* Vector log1pf approximation using polynomial on reduced interval. Worst-case
- error is 1.27 ULP very close to 0.5.
- _ZGVsMxv_log1pf(0x1.fffffep-2) got 0x1.9f324p-2
- want 0x1.9f323ep-2. */
-svfloat32_t SV_NAME_F1 (log1p) (svfloat32_t x, svbool_t pg)
-{
- const struct data *d = ptr_barrier (&data);
- /* x < -1, Inf/Nan. */
- svbool_t special = svcmpeq (pg, svreinterpret_u32 (x), 0x7f800000);
- special = svorn_z (pg, special, svcmpge (pg, x, -1));
-
- /* With x + 1 = t * 2^k (where t = m + 1 and k is chosen such that m
- is in [-0.25, 0.5]):
- log1p(x) = log(t) + log(2^k) = log1p(m) + k*log(2).
-
- We approximate log1p(m) with a polynomial, then scale by
- k*log(2). Instead of doing this directly, we use an intermediate
- scale factor s = 4*k*log(2) to ensure the scale is representable
- as a normalised fp32 number. */
- svfloat32_t m = svadd_x (pg, x, 1);
-
- /* Choose k to scale x to the range [-1/4, 1/2]. */
- svint32_t k
- = svand_x (pg, svsub_x (pg, svreinterpret_s32 (m), d->three_quarters),
- sv_s32 (SignExponentMask));
-
- /* Scale x by exponent manipulation. */
- svfloat32_t m_scale = svreinterpret_f32 (
- svsub_x (pg, svreinterpret_u32 (x), svreinterpret_u32 (k)));
-
- /* Scale up to ensure that the scale factor is representable as normalised
- fp32 number, and scale m down accordingly. */
- svfloat32_t s = svreinterpret_f32 (svsubr_x (pg, k, d->four));
- m_scale = svadd_x (pg, m_scale, svmla_x (pg, sv_f32 (-1), s, 0.25));
-
- /* Evaluate polynomial on reduced interval. */
- svfloat32_t ms2 = svmul_x (pg, m_scale, m_scale),
- ms4 = svmul_x (pg, ms2, ms2);
- svfloat32_t p = sv_estrin_7_f32_x (pg, m_scale, ms2, ms4, d->poly);
- p = svmad_x (pg, m_scale, p, -0.5);
- p = svmla_x (pg, m_scale, m_scale, svmul_x (pg, m_scale, p));
-
- /* The scale factor to be applied back at the end - by multiplying float(k)
- by 2^-23 we get the unbiased exponent of k. */
- svfloat32_t scale_back = svmul_x (pg, svcvt_f32_x (pg, k), d->exp_bias);
-
- /* Apply the scaling back. */
- svfloat32_t y = svmla_x (pg, p, scale_back, d->ln2);
-
- if (unlikely (svptest_any (pg, special)))
- return special_case (x, y, special);
-
- return y;
-}
-
-PL_SIG (SV, F, 1, log1p, -0.9, 10.0)
-PL_TEST_ULP (SV_NAME_F1 (log1p), 0.77)
-PL_TEST_SYM_INTERVAL (SV_NAME_F1 (log1p), 0, 0x1p-23, 5000)
-PL_TEST_SYM_INTERVAL (SV_NAME_F1 (log1p), 0x1p-23, 1, 5000)
-PL_TEST_INTERVAL (SV_NAME_F1 (log1p), 1, inf, 10000)
-PL_TEST_INTERVAL (SV_NAME_F1 (log1p), -1, -inf, 10)