1 /* 2 * Single-precision SVE tanh(x) function. 3 * 4 * Copyright (c) 2023-2024, Arm Limited. 5 * SPDX-License-Identifier: MIT OR Apache-2.0 WITH LLVM-exception 6 */ 7 8 #include "sv_math.h" 9 #include "test_sig.h" 10 #include "test_defs.h" 11 #include "sv_expm1f_inline.h" 12 13 /* Largest value of x for which tanhf(x) rounds to 1 (or -1 for negative). */ 14 #define BoringBound 0x1.205966p+3f 15 16 static const struct data 17 { 18 struct sv_expm1f_data expm1f_consts; 19 uint32_t onef, special_bound; 20 float boring_bound; 21 } data = { 22 .expm1f_consts = SV_EXPM1F_DATA, 23 .onef = 0x3f800000, 24 .special_bound = 0x7f800000, 25 .boring_bound = BoringBound, 26 }; 27 28 static svfloat32_t NOINLINE 29 special_case (svfloat32_t x, svbool_t pg, svbool_t is_boring, 30 svfloat32_t boring, svfloat32_t q, svbool_t special) 31 { 32 svfloat32_t y 33 = svsel_f32 (is_boring, boring, svdiv_x (pg, q, svadd_x (pg, q, 2.0))); 34 return sv_call_f32 (tanhf, x, y, special); 35 } 36 37 /* Approximation for single-precision SVE tanh(x), using a simplified 38 version of expm1f. The maximum error is 2.57 ULP: 39 _ZGVsMxv_tanhf (0x1.fc1832p-5) got 0x1.fb71a4p-5 40 want 0x1.fb71aap-5. */ 41 svfloat32_t SV_NAME_F1 (tanh) (svfloat32_t x, const svbool_t pg) 42 { 43 const struct data *d = ptr_barrier (&data); 44 45 svfloat32_t ax = svabs_x (pg, x); 46 svuint32_t iax = svreinterpret_u32 (ax); 47 svuint32_t sign = sveor_x (pg, svreinterpret_u32 (x), iax); 48 svfloat32_t boring = svreinterpret_f32 (svorr_x (pg, sign, d->onef)); 49 svbool_t special = svcmpgt (pg, iax, d->special_bound); 50 svbool_t is_boring = svacgt (pg, x, d->boring_bound); 51 52 /* tanh(x) = (e^2x - 1) / (e^2x + 1). */ 53 svfloat32_t q = expm1f_inline (svmul_x (svptrue_b32 (), x, 2.0), pg, 54 &d->expm1f_consts); 55 56 if (unlikely (svptest_any (pg, special))) 57 return special_case (x, pg, is_boring, boring, q, special); 58 svfloat32_t y = svdiv_x (pg, q, svadd_x (pg, q, 2.0)); 59 return svsel_f32 (is_boring, boring, y); 60 } 61 62 TEST_SIG (SV, F, 1, tanh, -10.0, 10.0) 63 TEST_ULP (SV_NAME_F1 (tanh), 2.07) 64 TEST_DISABLE_FENV (SV_NAME_F1 (tanh)) 65 TEST_SYM_INTERVAL (SV_NAME_F1 (tanh), 0, 0x1p-23, 1000) 66 TEST_SYM_INTERVAL (SV_NAME_F1 (tanh), 0x1p-23, BoringBound, 100000) 67 TEST_SYM_INTERVAL (SV_NAME_F1 (tanh), BoringBound, inf, 100) 68 CLOSE_SVE_ATTR 69