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
|
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/*
* This file is part of the LibreOffice project.
*
* 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/.
*
*/
#include <arraysumfunctor.hxx>
#include <tools/simdsupport.hxx>
namespace sc
{
double ArraySumFunctor::executeSSE2(size_t& i, const double* pCurrent) const
{
#if defined(LO_SSE2_AVAILABLE)
double fSum = 0.0;
size_t nRealSize = mnSize - i;
size_t nUnrolledSize = nRealSize - (nRealSize % 8);
if (nUnrolledSize > 0)
{
__m128d sum1 = _mm_setzero_pd();
__m128d sum2 = _mm_setzero_pd();
__m128d sum3 = _mm_setzero_pd();
__m128d sum4 = _mm_setzero_pd();
__m128d err1 = _mm_setzero_pd();
__m128d err2 = _mm_setzero_pd();
__m128d err3 = _mm_setzero_pd();
__m128d err4 = _mm_setzero_pd();
__m128d y, t;
for (; i < nUnrolledSize; i += 8)
{
// Kahan sum 1
__m128d load1 = _mm_load_pd(pCurrent);
y = _mm_sub_pd(load1, err1);
t = _mm_add_pd(sum1, y);
err1 = _mm_sub_pd(_mm_sub_pd(t, sum1), y);
sum1 = t;
pCurrent += 2;
// Kahan sum 2
__m128d load2 = _mm_load_pd(pCurrent);
y = _mm_sub_pd(load2, err2);
t = _mm_add_pd(sum2, y);
err2 = _mm_sub_pd(_mm_sub_pd(t, sum2), y);
sum2 = t;
pCurrent += 2;
// Kahan sum 3
__m128d load3 = _mm_load_pd(pCurrent);
y = _mm_sub_pd(load3, err3);
t = _mm_add_pd(sum3, y);
err3 = _mm_sub_pd(_mm_sub_pd(t, sum3), y);
sum3 = t;
pCurrent += 2;
// Kahan sum 4
__m128d load4 = _mm_load_pd(pCurrent);
y = _mm_sub_pd(load4, err4);
t = _mm_add_pd(sum4, y);
err4 = _mm_sub_pd(_mm_sub_pd(t, sum4), y);
sum4 = t;
pCurrent += 2;
}
// Now we combine pairwise summation with Kahan summation
// sum 1 + sum 2
y = _mm_sub_pd(sum2, err1);
t = _mm_add_pd(sum1, y);
err1 = _mm_sub_pd(_mm_sub_pd(t, sum1), y);
sum1 = t;
// sum 3 + sum 4
y = _mm_sub_pd(sum4, err3);
t = _mm_add_pd(sum3, y);
sum3 = t;
// sum 1 + sum 3
y = _mm_sub_pd(sum3, err1);
t = _mm_add_pd(sum1, y);
sum1 = t;
double temp;
_mm_storel_pd(&temp, sum1);
fSum += temp;
_mm_storeh_pd(&temp, sum1);
fSum += temp;
}
return fSum;
#else
(void)i;
(void)pCurrent;
return 0.0;
#endif
}
}
|
