1*f3087befSAndrew Turner /* 2*f3087befSAndrew Turner * Single-precision vector tanh(x) function. 3*f3087befSAndrew Turner * 4*f3087befSAndrew Turner * Copyright (c) 2022-2024, Arm Limited. 5*f3087befSAndrew Turner * SPDX-License-Identifier: MIT OR Apache-2.0 WITH LLVM-exception 6*f3087befSAndrew Turner */ 7*f3087befSAndrew Turner 8*f3087befSAndrew Turner #include "v_math.h" 9*f3087befSAndrew Turner #include "test_sig.h" 10*f3087befSAndrew Turner #include "test_defs.h" 11*f3087befSAndrew Turner #include "v_expm1f_inline.h" 12*f3087befSAndrew Turner 13*f3087befSAndrew Turner static const struct data 14*f3087befSAndrew Turner { 15*f3087befSAndrew Turner struct v_expm1f_data expm1f_consts; 16*f3087befSAndrew Turner uint32x4_t boring_bound, large_bound, onef; 17*f3087befSAndrew Turner } data = { 18*f3087befSAndrew Turner .expm1f_consts = V_EXPM1F_DATA, 19*f3087befSAndrew Turner /* 0x1.205966p+3, above which tanhf rounds to 1 (or -1 for negative). */ 20*f3087befSAndrew Turner .boring_bound = V4 (0x41102cb3), 21*f3087befSAndrew Turner .large_bound = V4 (0x7f800000), 22*f3087befSAndrew Turner }; 23*f3087befSAndrew Turner 24*f3087befSAndrew Turner static float32x4_t NOINLINE VPCS_ATTR 25*f3087befSAndrew Turner special_case (float32x4_t x, uint32x4_t is_boring, float32x4_t boring, 26*f3087befSAndrew Turner float32x4_t q, uint32x4_t special) 27*f3087befSAndrew Turner { 28*f3087befSAndrew Turner return v_call_f32 ( 29*f3087befSAndrew Turner tanhf, x, 30*f3087befSAndrew Turner vbslq_f32 (is_boring, boring, vdivq_f32 (q, vaddq_f32 (q, v_f32 (2.0)))), 31*f3087befSAndrew Turner special); 32*f3087befSAndrew Turner } 33*f3087befSAndrew Turner 34*f3087befSAndrew Turner /* Approximation for single-precision vector tanh(x), using a simplified 35*f3087befSAndrew Turner version of expm1f. The maximum error is 2.58 ULP: 36*f3087befSAndrew Turner _ZGVnN4v_tanhf (0x1.fa5eep-5) got 0x1.f9ba02p-5 37*f3087befSAndrew Turner want 0x1.f9ba08p-5. */ 38*f3087befSAndrew Turner float32x4_t VPCS_ATTR NOINLINE V_NAME_F1 (tanh) (float32x4_t x) 39*f3087befSAndrew Turner { 40*f3087befSAndrew Turner const struct data *d = ptr_barrier (&data); 41*f3087befSAndrew Turner 42*f3087befSAndrew Turner uint32x4_t ix = vreinterpretq_u32_f32 (x); 43*f3087befSAndrew Turner float32x4_t ax = vabsq_f32 (x); 44*f3087befSAndrew Turner uint32x4_t iax = vreinterpretq_u32_f32 (ax); 45*f3087befSAndrew Turner uint32x4_t sign = veorq_u32 (ix, iax); 46*f3087befSAndrew Turner uint32x4_t is_boring = vcgtq_u32 (iax, d->boring_bound); 47*f3087befSAndrew Turner /* expm1 exponent bias is 1.0f reinterpreted to int. */ 48*f3087befSAndrew Turner float32x4_t boring = vreinterpretq_f32_u32 (vorrq_u32 ( 49*f3087befSAndrew Turner sign, vreinterpretq_u32_s32 (d->expm1f_consts.exponent_bias))); 50*f3087befSAndrew Turner 51*f3087befSAndrew Turner #if WANT_SIMD_EXCEPT 52*f3087befSAndrew Turner /* If fp exceptions are to be triggered properly, set all special and boring 53*f3087befSAndrew Turner lanes to 0, which will trigger no exceptions, and fix them up later. */ 54*f3087befSAndrew Turner uint32x4_t special = vorrq_u32 (vcgtq_u32 (iax, d->large_bound), 55*f3087befSAndrew Turner vcltq_u32 (iax, v_u32 (0x34000000))); 56*f3087befSAndrew Turner x = v_zerofy_f32 (x, is_boring); 57*f3087befSAndrew Turner if (unlikely (v_any_u32 (special))) 58*f3087befSAndrew Turner x = v_zerofy_f32 (x, special); 59*f3087befSAndrew Turner #else 60*f3087befSAndrew Turner uint32x4_t special = vcgtq_u32 (iax, d->large_bound); 61*f3087befSAndrew Turner #endif 62*f3087befSAndrew Turner 63*f3087befSAndrew Turner /* tanh(x) = (e^2x - 1) / (e^2x + 1). */ 64*f3087befSAndrew Turner float32x4_t q = expm1f_inline (vmulq_n_f32 (x, 2), &d->expm1f_consts); 65*f3087befSAndrew Turner 66*f3087befSAndrew Turner if (unlikely (v_any_u32 (special))) 67*f3087befSAndrew Turner return special_case (vreinterpretq_f32_u32 (ix), is_boring, boring, q, 68*f3087befSAndrew Turner special); 69*f3087befSAndrew Turner 70*f3087befSAndrew Turner float32x4_t y = vdivq_f32 (q, vaddq_f32 (q, v_f32 (2.0))); 71*f3087befSAndrew Turner return vbslq_f32 (is_boring, boring, y); 72*f3087befSAndrew Turner } 73*f3087befSAndrew Turner 74*f3087befSAndrew Turner HALF_WIDTH_ALIAS_F1 (tanh) 75*f3087befSAndrew Turner 76*f3087befSAndrew Turner TEST_SIG (V, F, 1, tanh, -10.0, 10.0) 77*f3087befSAndrew Turner TEST_ULP (V_NAME_F1 (tanh), 2.09) 78*f3087befSAndrew Turner TEST_DISABLE_FENV_IF_NOT (V_NAME_F1 (tanh), WANT_SIMD_EXCEPT) 79*f3087befSAndrew Turner TEST_SYM_INTERVAL (V_NAME_F1 (tanh), 0, 0x1p-23, 1000) 80*f3087befSAndrew Turner TEST_SYM_INTERVAL (V_NAME_F1 (tanh), 0x1p-23, 0x1.205966p+3, 100000) 81*f3087befSAndrew Turner TEST_SYM_INTERVAL (V_NAME_F1 (tanh), 0x1.205966p+3, inf, 100) 82