1 /* 2 * Single-precision vector tanh(x) function. 3 * 4 * Copyright (c) 2022-2023, Arm Limited. 5 * SPDX-License-Identifier: MIT OR Apache-2.0 WITH LLVM-exception 6 */ 7 8 #include "v_math.h" 9 #include "pl_sig.h" 10 #include "pl_test.h" 11 12 #if V_SUPPORTED 13 14 #include "v_expm1f_inline.h" 15 16 #define BoringBound \ 17 0x41102cb3 /* 0x1.205966p+3, above which tanhf rounds to 1 (or -1 for \ 18 negative). */ 19 #define AbsMask 0x7fffffff 20 21 static NOINLINE v_f32_t 22 special_case (v_f32_t x, v_f32_t y, v_u32_t special) 23 { 24 return v_call_f32 (tanhf, x, y, special); 25 } 26 27 /* Approximation for single-precision vector tanh(x), using a simplified version 28 of expm1f. The maximum error is 2.58 ULP: 29 __v_tanhf(0x1.fa5eep-5) got 0x1.f9ba02p-5 30 want 0x1.f9ba08p-5. */ 31 VPCS_ATTR v_f32_t V_NAME (tanhf) (v_f32_t x) 32 { 33 v_u32_t ix = v_as_u32_f32 (x); 34 v_u32_t iax = ix & AbsMask; 35 v_u32_t sign = ix & ~AbsMask; 36 v_u32_t is_boring = v_cond_u32 (iax > BoringBound); 37 v_f32_t boring = v_as_f32_u32 (sign | One); 38 39 #if WANT_SIMD_EXCEPT 40 /* If fp exceptions are to be triggered properly, set all special and boring 41 lanes to 1, which will trigger no exceptions, and fix them up later. */ 42 v_u32_t special = v_cond_u32 ((iax > 0x7f800000) | (iax < 0x34000000)); 43 ix = v_sel_u32 (is_boring, v_u32 (One), ix); 44 if (unlikely (v_any_u32 (special))) 45 ix = v_sel_u32 (special, v_u32 (One), ix); 46 #else 47 v_u32_t special = v_cond_u32 ((iax > 0x7f800000) | (iax == 0)); 48 #endif 49 50 /* tanh(x) = (e^2x - 1) / (e^2x + 1). */ 51 v_f32_t q = expm1f_inline (2 * v_as_f32_u32 (ix)); 52 v_f32_t y = q / (q + 2); 53 y = v_sel_f32 (is_boring, boring, y); 54 if (unlikely (v_any_u32 (special))) 55 return special_case (x, y, special); 56 return y; 57 } 58 VPCS_ALIAS 59 60 PL_SIG (V, F, 1, tanh, -10.0, 10.0) 61 PL_TEST_ULP (V_NAME (tanhf), 2.09) 62 PL_TEST_EXPECT_FENV (V_NAME (tanhf), WANT_SIMD_EXCEPT) 63 PL_TEST_INTERVAL (V_NAME (tanhf), 0, 0x1p-23, 1000) 64 PL_TEST_INTERVAL (V_NAME (tanhf), -0, -0x1p-23, 1000) 65 PL_TEST_INTERVAL (V_NAME (tanhf), 0x1p-23, 0x1.205966p+3, 100000) 66 PL_TEST_INTERVAL (V_NAME (tanhf), -0x1p-23, -0x1.205966p+3, 100000) 67 PL_TEST_INTERVAL (V_NAME (tanhf), 0x1.205966p+3, inf, 100) 68 PL_TEST_INTERVAL (V_NAME (tanhf), -0x1.205966p+3, -inf, 100) 69 #endif 70