1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
|
// This file is part of Eigen, a lightweight C++ template library
// for linear algebra.
//
// Copyright (C) 2014 Pedro Gonnet (pedro.gonnet@gmail.com)
//
// This Source Code Form is subject to the terms of the Mozilla
// Public License v. 2.0. If a copy of the MPL was not distributed
// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
#ifndef EIGEN_MATH_FUNCTIONS_AVX_H
#define EIGEN_MATH_FUNCTIONS_AVX_H
/* The sin and cos functions of this file are loosely derived from
* Julien Pommier's sse math library: http://gruntthepeon.free.fr/ssemath/
*/
namespace Eigen {
namespace internal {
inline Packet8i pshiftleft(Packet8i v, int n)
{
#ifdef EIGEN_VECTORIZE_AVX2
return _mm256_slli_epi32(v, n);
#else
__m128i lo = _mm_slli_epi32(_mm256_extractf128_si256(v, 0), n);
__m128i hi = _mm_slli_epi32(_mm256_extractf128_si256(v, 1), n);
return _mm256_insertf128_si256(_mm256_castsi128_si256(lo), (hi), 1);
#endif
}
// Sine function
// Computes sin(x) by wrapping x to the interval [-Pi/4,3*Pi/4] and
// evaluating interpolants in [-Pi/4,Pi/4] or [Pi/4,3*Pi/4]. The interpolants
// are (anti-)symmetric and thus have only odd/even coefficients
template <>
EIGEN_DEFINE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS EIGEN_UNUSED Packet8f
psin<Packet8f>(const Packet8f& _x) {
Packet8f x = _x;
// Some useful values.
_EIGEN_DECLARE_CONST_Packet8i(one, 1);
_EIGEN_DECLARE_CONST_Packet8f(one, 1.0f);
_EIGEN_DECLARE_CONST_Packet8f(two, 2.0f);
_EIGEN_DECLARE_CONST_Packet8f(one_over_four, 0.25f);
_EIGEN_DECLARE_CONST_Packet8f(one_over_pi, 3.183098861837907e-01f);
_EIGEN_DECLARE_CONST_Packet8f(neg_pi_first, -3.140625000000000e+00f);
_EIGEN_DECLARE_CONST_Packet8f(neg_pi_second, -9.670257568359375e-04f);
_EIGEN_DECLARE_CONST_Packet8f(neg_pi_third, -6.278329571784980e-07f);
_EIGEN_DECLARE_CONST_Packet8f(four_over_pi, 1.273239544735163e+00f);
// Map x from [-Pi/4,3*Pi/4] to z in [-1,3] and subtract the shifted period.
Packet8f z = pmul(x, p8f_one_over_pi);
Packet8f shift = _mm256_floor_ps(padd(z, p8f_one_over_four));
x = pmadd(shift, p8f_neg_pi_first, x);
x = pmadd(shift, p8f_neg_pi_second, x);
x = pmadd(shift, p8f_neg_pi_third, x);
z = pmul(x, p8f_four_over_pi);
// Make a mask for the entries that need flipping, i.e. wherever the shift
// is odd.
Packet8i shift_ints = _mm256_cvtps_epi32(shift);
Packet8i shift_isodd = _mm256_castps_si256(_mm256_and_ps(_mm256_castsi256_ps(shift_ints), _mm256_castsi256_ps(p8i_one)));
Packet8i sign_flip_mask = pshiftleft(shift_isodd, 31);
// Create a mask for which interpolant to use, i.e. if z > 1, then the mask
// is set to ones for that entry.
Packet8f ival_mask = _mm256_cmp_ps(z, p8f_one, _CMP_GT_OQ);
// Evaluate the polynomial for the interval [1,3] in z.
_EIGEN_DECLARE_CONST_Packet8f(coeff_right_0, 9.999999724233232e-01f);
_EIGEN_DECLARE_CONST_Packet8f(coeff_right_2, -3.084242535619928e-01f);
_EIGEN_DECLARE_CONST_Packet8f(coeff_right_4, 1.584991525700324e-02f);
_EIGEN_DECLARE_CONST_Packet8f(coeff_right_6, -3.188805084631342e-04f);
Packet8f z_minus_two = psub(z, p8f_two);
Packet8f z_minus_two2 = pmul(z_minus_two, z_minus_two);
Packet8f right = pmadd(p8f_coeff_right_6, z_minus_two2, p8f_coeff_right_4);
right = pmadd(right, z_minus_two2, p8f_coeff_right_2);
right = pmadd(right, z_minus_two2, p8f_coeff_right_0);
// Evaluate the polynomial for the interval [-1,1] in z.
_EIGEN_DECLARE_CONST_Packet8f(coeff_left_1, 7.853981525427295e-01f);
_EIGEN_DECLARE_CONST_Packet8f(coeff_left_3, -8.074536727092352e-02f);
_EIGEN_DECLARE_CONST_Packet8f(coeff_left_5, 2.489871967827018e-03f);
_EIGEN_DECLARE_CONST_Packet8f(coeff_left_7, -3.587725841214251e-05f);
Packet8f z2 = pmul(z, z);
Packet8f left = pmadd(p8f_coeff_left_7, z2, p8f_coeff_left_5);
left = pmadd(left, z2, p8f_coeff_left_3);
left = pmadd(left, z2, p8f_coeff_left_1);
left = pmul(left, z);
// Assemble the results, i.e. select the left and right polynomials.
left = _mm256_andnot_ps(ival_mask, left);
right = _mm256_and_ps(ival_mask, right);
Packet8f res = _mm256_or_ps(left, right);
// Flip the sign on the odd intervals and return the result.
res = _mm256_xor_ps(res, _mm256_castsi256_ps(sign_flip_mask));
return res;
}
template <>
EIGEN_DEFINE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS EIGEN_UNUSED Packet8f
plog<Packet8f>(const Packet8f& _x) {
return plog_float(_x);
}
// Exponential function. Works by writing "x = m*log(2) + r" where
// "m = floor(x/log(2)+1/2)" and "r" is the remainder. The result is then
// "exp(x) = 2^m*exp(r)" where exp(r) is in the range [-1,1).
template <>
EIGEN_DEFINE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS EIGEN_UNUSED Packet8f
pexp<Packet8f>(const Packet8f& _x) {
return pexp_float(_x);
}
// Hyperbolic Tangent function.
template <>
EIGEN_DEFINE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS EIGEN_UNUSED Packet8f
ptanh<Packet8f>(const Packet8f& x) {
return internal::generic_fast_tanh_float(x);
}
template <>
EIGEN_DEFINE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS EIGEN_UNUSED Packet4d
pexp<Packet4d>(const Packet4d& x) {
return pexp_double(x);
}
// Functions for sqrt.
// The EIGEN_FAST_MATH version uses the _mm_rsqrt_ps approximation and one step
// of Newton's method, at a cost of 1-2 bits of precision as opposed to the
// exact solution. It does not handle +inf, or denormalized numbers correctly.
// The main advantage of this approach is not just speed, but also the fact that
// it can be inlined and pipelined with other computations, further reducing its
// effective latency. This is similar to Quake3's fast inverse square root.
// For detail see here: http://www.beyond3d.com/content/articles/8/
#if EIGEN_FAST_MATH
template <>
EIGEN_DEFINE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS EIGEN_UNUSED Packet8f
psqrt<Packet8f>(const Packet8f& _x) {
Packet8f half = pmul(_x, pset1<Packet8f>(.5f));
Packet8f denormal_mask = _mm256_and_ps(
_mm256_cmp_ps(_x, pset1<Packet8f>((std::numeric_limits<float>::min)()),
_CMP_LT_OQ),
_mm256_cmp_ps(_x, _mm256_setzero_ps(), _CMP_GE_OQ));
// Compute approximate reciprocal sqrt.
Packet8f x = _mm256_rsqrt_ps(_x);
// Do a single step of Newton's iteration.
x = pmul(x, psub(pset1<Packet8f>(1.5f), pmul(half, pmul(x,x))));
// Flush results for denormals to zero.
return _mm256_andnot_ps(denormal_mask, pmul(_x,x));
}
#else
template <> EIGEN_DEFINE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS EIGEN_UNUSED
Packet8f psqrt<Packet8f>(const Packet8f& x) {
return _mm256_sqrt_ps(x);
}
#endif
template <> EIGEN_DEFINE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS EIGEN_UNUSED
Packet4d psqrt<Packet4d>(const Packet4d& x) {
return _mm256_sqrt_pd(x);
}
#if EIGEN_FAST_MATH
template<> EIGEN_DEFINE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS EIGEN_UNUSED
Packet8f prsqrt<Packet8f>(const Packet8f& _x) {
_EIGEN_DECLARE_CONST_Packet8f_FROM_INT(inf, 0x7f800000);
_EIGEN_DECLARE_CONST_Packet8f_FROM_INT(nan, 0x7fc00000);
_EIGEN_DECLARE_CONST_Packet8f(one_point_five, 1.5f);
_EIGEN_DECLARE_CONST_Packet8f(minus_half, -0.5f);
_EIGEN_DECLARE_CONST_Packet8f_FROM_INT(flt_min, 0x00800000);
Packet8f neg_half = pmul(_x, p8f_minus_half);
// select only the inverse sqrt of positive normal inputs (denormals are
// flushed to zero and cause infs as well).
Packet8f le_zero_mask = _mm256_cmp_ps(_x, p8f_flt_min, _CMP_LT_OQ);
Packet8f x = _mm256_andnot_ps(le_zero_mask, _mm256_rsqrt_ps(_x));
// Fill in NaNs and Infs for the negative/zero entries.
Packet8f neg_mask = _mm256_cmp_ps(_x, _mm256_setzero_ps(), _CMP_LT_OQ);
Packet8f zero_mask = _mm256_andnot_ps(neg_mask, le_zero_mask);
Packet8f infs_and_nans = _mm256_or_ps(_mm256_and_ps(neg_mask, p8f_nan),
_mm256_and_ps(zero_mask, p8f_inf));
// Do a single step of Newton's iteration.
x = pmul(x, pmadd(neg_half, pmul(x, x), p8f_one_point_five));
// Insert NaNs and Infs in all the right places.
return _mm256_or_ps(x, infs_and_nans);
}
#else
template <> EIGEN_DEFINE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS EIGEN_UNUSED
Packet8f prsqrt<Packet8f>(const Packet8f& x) {
_EIGEN_DECLARE_CONST_Packet8f(one, 1.0f);
return _mm256_div_ps(p8f_one, _mm256_sqrt_ps(x));
}
#endif
template <> EIGEN_DEFINE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS EIGEN_UNUSED
Packet4d prsqrt<Packet4d>(const Packet4d& x) {
_EIGEN_DECLARE_CONST_Packet4d(one, 1.0);
return _mm256_div_pd(p4d_one, _mm256_sqrt_pd(x));
}
} // end namespace internal
} // end namespace Eigen
#endif // EIGEN_MATH_FUNCTIONS_AVX_H
|
