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[v1,1/2] x86: Optimize strlen-evex.S

Message ID 20210417025215.874105-1-goldstein.w.n@gmail.com
State Superseded
Delegated to: H.J. Lu
Headers show
Series [v1,1/2] x86: Optimize strlen-evex.S | expand

Commit Message

Noah Goldstein April 17, 2021, 2:52 a.m. UTC
No bug. This commit optimizes strlen-evex.S. The
optimizations are mostly small things but they add up to roughly
10-30% performance improvement for strlen. The results for strnlen are
bit more ambiguous. test-strlen, test-strnlen, test-wcslen, and
test-wcsnlen are all passing.

Signed-off-by: Noah Goldstein <goldstein.w.n@gmail.com>
---
Tests where run on the following CPUs:

Skylake: https://ark.intel.com/content/www/us/en/ark/products/149091/intel-core-i7-8565u-processor-8m-cache-up-to-4-60-ghz.html

Icelake: https://ark.intel.com/content/www/us/en/ark/products/196597/intel-core-i7-1065g7-processor-8m-cache-up-to-3-90-ghz.html

Tigerlake: https://ark.intel.com/content/www/us/en/ark/products/208921/intel-core-i7-1165g7-processor-12m-cache-up-to-4-70-ghz-with-ipu.html

All times are the geometric mean of N=20. The unit of time is
seconds.

"Cur" refers to the current implementation
"New" refers to this patches implementation


The strlen numbers are universal improvements:

Results For Skylake strlen-avx2
size, algn, Cur T , New T , Win , Dif 
1   , 0   , 4.76  , 4.27  , New , 0.49
2   , 0   , 4.77  , 4.165 , New , 0.6 
3   , 0   , 4.617 , 4.095 , New , 0.52
4   , 0   , 4.579 , 4.006 , New , 0.57
5   , 0   , 4.608 , 4.008 , New , 0.6 
6   , 0   , 4.655 , 4.086 , New , 0.57
7   , 0   , 4.661 , 4.071 , New , 0.59
8   , 0   , 4.625 , 4.092 , New , 0.53
16  , 0   , 4.608 , 4.021 , New , 0.59
10  , 0   , 4.645 , 4.111 , New , 0.53
32  , 0   , 5.532 , 4.817 , New , 0.71
21  , 0   , 4.636 , 3.775 , New , 0.86
64  , 0   , 5.991 , 5.352 , New , 0.64
42  , 0   , 5.529 , 4.789 , New , 0.74
128 , 0   , 7.042 , 5.473 , New , 1.57
85  , 0   , 6.118 , 5.466 , New , 0.65
256 , 0   , 10.64 , 7.954 , New , 2.69
170 , 0   , 9.918 , 9.585 , New , 0.33
512 , 0   , 12.916, 10.242, New , 2.67
341 , 0   , 10.764, 10.216, New , 0.55
1024, 0   , 18.163, 14.844, New , 3.32
682 , 0   , 15.292, 13.382, New , 1.91
2048, 0   , 38.732, 24.396, New , 14.34
1365, 0   , 22.299, 20.08 , New , 2.22
4096, 0   , 79.054, 68.682, New , 10.37
2730, 0   , 61.47 , 40.705, New , 20.77

Results For Icelake strlen-avx2
size, algn, Cur T , New T , Win , Dif 
1   , 0   , 2.681 , 1.99  , New , 0.69
2   , 0   , 2.823 , 2.232 , New , 0.59
3   , 0   , 2.57  , 2.077 , New , 0.49
4   , 0   , 2.659 , 2.128 , New , 0.53
5   , 0   , 2.666 , 2.109 , New , 0.56
6   , 0   , 2.596 , 2.053 , New , 0.54
7   , 0   , 2.623 , 2.152 , New , 0.47
8   , 0   , 2.675 , 2.178 , New , 0.5 
16  , 0   , 2.675 , 2.202 , New , 0.47
10  , 0   , 2.672 , 2.2   , New , 0.47
32  , 0   , 3.383 , 2.868 , New , 0.52
21  , 0   , 2.693 , 2.032 , New , 0.66
64  , 0   , 3.404 , 3.056 , New , 0.35
42  , 0   , 3.511 , 2.967 , New , 0.54
128 , 0   , 4.191 , 3.627 , New , 0.56
85  , 0   , 3.559 , 2.922 , New , 0.64
256 , 0   , 6.782 , 5.493 , New , 1.29
170 , 0   , 6.24  , 4.988 , New , 1.25
512 , 0   , 9.305 , 7.308 , New , 2.0 
341 , 0   , 7.626 , 6.272 , New , 1.35
1024, 0   , 14.455, 11.544, New , 2.91
682 , 0   , 10.728, 8.738 , New , 1.99
2048, 0   , 24.171, 24.101, New , 0.07
1365, 0   , 17.474, 14.387, New , 3.09
4096, 0   , 57.659, 51.675, New , 5.98
2730, 0   , 44.702, 28.04 , New , 16.66

Results For Tigerlake strlen-avx2
size, algn, Cur T , New T , Win , Dif 
1   , 0   , 4.369 , 3.008 , New , 1.36
2   , 0   , 4.054 , 3.231 , New , 0.82
3   , 0   , 4.081 , 3.243 , New , 0.84
4   , 0   , 3.904 , 3.17  , New , 0.73
5   , 0   , 3.915 , 3.178 , New , 0.74
6   , 0   , 3.924 , 3.184 , New , 0.74
7   , 0   , 3.917 , 3.177 , New , 0.74
8   , 0   , 3.889 , 3.209 , New , 0.68
16  , 0   , 3.878 , 3.03  , New , 0.85
10  , 0   , 3.892 , 3.004 , New , 0.89
32  , 0   , 4.957 , 4.162 , New , 0.79
21  , 0   , 3.866 , 3.18  , New , 0.69
64  , 0   , 5.035 , 4.521 , New , 0.51
42  , 0   , 5.039 , 4.276 , New , 0.76
128 , 0   , 6.117 , 5.253 , New , 0.86
85  , 0   , 4.932 , 4.421 , New , 0.51
256 , 0   , 10.019, 8.221 , New , 1.8 
170 , 0   , 8.954 , 7.404 , New , 1.55
512 , 0   , 14.071, 10.948, New , 3.12
341 , 0   , 11.177, 9.246 , New , 1.93
1024, 0   , 21.808, 17.034, New , 4.77
682 , 0   , 16.07 , 12.941, New , 3.13
2048, 0   , 37.332, 29.853, New , 7.48
1365, 0   , 26.394, 21.516, New , 4.88
4096, 0   , 87.951, 80.35 , New , 7.6 
2730, 0   , 62.768, 44.247, New , 18.52

Results For Icelake strlen-evex
size, algn, Cur T , New T , Win , Dif 
1   , 0   , 2.681 , 1.99  , New , 0.69
2   , 0   , 2.823 , 2.232 , New , 0.59
3   , 0   , 2.57  , 2.077 , New , 0.49
4   , 0   , 2.659 , 2.128 , New , 0.53
5   , 0   , 2.666 , 2.109 , New , 0.56
6   , 0   , 2.596 , 2.053 , New , 0.54
7   , 0   , 2.623 , 2.152 , New , 0.47
8   , 0   , 2.675 , 2.178 , New , 0.5 
16  , 0   , 2.675 , 2.202 , New , 0.47
10  , 0   , 2.672 , 2.2   , New , 0.47
32  , 0   , 3.383 , 2.868 , New , 0.52
21  , 0   , 2.693 , 2.032 , New , 0.66
64  , 0   , 3.404 , 3.056 , New , 0.35
42  , 0   , 3.511 , 2.967 , New , 0.54
128 , 0   , 4.191 , 3.627 , New , 0.56
85  , 0   , 3.559 , 2.922 , New , 0.64
256 , 0   , 6.782 , 5.493 , New , 1.29
170 , 0   , 6.24  , 4.988 , New , 1.25
512 , 0   , 9.305 , 7.308 , New , 2.0 
341 , 0   , 7.626 , 6.272 , New , 1.35
1024, 0   , 14.455, 11.544, New , 2.91
682 , 0   , 10.728, 8.738 , New , 1.99
2048, 0   , 24.171, 24.101, New , 0.07
1365, 0   , 17.474, 14.387, New , 3.09
4096, 0   , 57.659, 51.675, New , 5.98
2730, 0   , 44.702, 28.04 , New , 16.66

Results For Tigerlake strlen-evex
size, algn, Cur T , New T , Win , Dif 
1   , 0   , 4.369 , 3.008 , New , 1.36
2   , 0   , 4.054 , 3.231 , New , 0.82
3   , 0   , 4.081 , 3.243 , New , 0.84
4   , 0   , 3.904 , 3.17  , New , 0.73
5   , 0   , 3.915 , 3.178 , New , 0.74
6   , 0   , 3.924 , 3.184 , New , 0.74
7   , 0   , 3.917 , 3.177 , New , 0.74
8   , 0   , 3.889 , 3.209 , New , 0.68
16  , 0   , 3.878 , 3.03  , New , 0.85
10  , 0   , 3.892 , 3.004 , New , 0.89
32  , 0   , 4.957 , 4.162 , New , 0.79
21  , 0   , 3.866 , 3.18  , New , 0.69
64  , 0   , 5.035 , 4.521 , New , 0.51
42  , 0   , 5.039 , 4.276 , New , 0.76
128 , 0   , 6.117 , 5.253 , New , 0.86
85  , 0   , 4.932 , 4.421 , New , 0.51
256 , 0   , 10.019, 8.221 , New , 1.8 
170 , 0   , 8.954 , 7.404 , New , 1.55
512 , 0   , 14.071, 10.948, New , 3.12
341 , 0   , 11.177, 9.246 , New , 1.93
1024, 0   , 21.808, 17.034, New , 4.77
682 , 0   , 16.07 , 12.941, New , 3.13
2048, 0   , 37.332, 29.853, New , 7.48
1365, 0   , 26.394, 21.516, New , 4.88
4096, 0   , 87.951, 80.35 , New , 7.6 
2730, 0   , 62.768, 44.247, New , 18.52

The strnlen numbers are a bit more of a mixed bag but I think
generally positive. Its possible that the current version should be
kept. Let me know.

Results For Skylake strnlen-avx2
size, algn, Cur T , Sub T , Win , Dif 
1   , 0   , 4.06  , 4.1   , Cur , 0.04
2   , 0   , 4.15  , 4.08  , New , 0.07
3   , 0   , 4.1   , 4.03  , New , 0.07
4   , 0   , 3.95  , 3.91  , New , 0.04
5   , 0   , 4.07  , 3.9   , New , 0.17
6   , 0   , 4.04  , 3.92  , New , 0.12
7   , 0   , 4.03  , 3.89  , New , 0.14
1   , 1   , 3.75  , 3.79  , Cur , 0.04
2   , 2   , 4.0   , 3.91  , New , 0.09
3   , 3   , 4.04  , 3.92  , New , 0.12
4   , 4   , 3.95  , 3.86  , New , 0.09
5   , 5   , 3.97  , 3.91  , New , 0.06
6   , 6   , 3.96  , 3.92  , New , 0.04
7   , 7   , 3.97  , 3.91  , New , 0.06
4   , 1   , 3.76  , 3.83  , Cur , 0.07
8   , 0   , 3.73  , 4.01  , Cur , 0.28
8   , 1   , 3.73  , 3.88  , Cur , 0.15
16  , 0   , 3.68  , 3.84  , Cur , 0.16
16  , 1   , 3.75  , 3.92  , Cur , 0.17
32  , 0   , 5.93  , 5.95  , Cur , 0.02
32  , 1   , 5.95  , 5.98  , Cur , 0.03
64  , 0   , 6.46  , 5.31  , New , 1.15
64  , 1   , 6.66  , 5.43  , New , 1.23
128 , 0   , 7.42  , 6.02  , New , 1.4 
128 , 1   , 7.57  , 5.81  , New , 1.76
256 , 0   , 12.02 , 9.89  , New , 2.13
256 , 1   , 11.91 , 9.84  , New , 2.07
512 , 0   , 15.06 , 11.77 , New , 3.29
512 , 1   , 14.79 , 11.75 , New , 3.04
1024, 0   , 23.61 , 16.98 , New , 6.63
1024, 1   , 23.63 , 16.91 , New , 6.72

Results For Icelake strnlen-avx2
size, algn, Cur T , Sub T , Win , Dif 
1   , 0   , 2.81  , 2.51  , New , 0.3 
2   , 0   , 2.8   , 2.53  , New , 0.27
3   , 0   , 2.7   , 2.57  , New , 0.13
4   , 0   , 2.68  , 2.55  , New , 0.13
5   , 0   , 2.7   , 2.57  , New , 0.13
6   , 0   , 2.73  , 2.6   , New , 0.13
7   , 0   , 2.69  , 2.61  , New , 0.08
1   , 1   , 2.53  , 2.5   , New , 0.03
2   , 2   , 2.67  , 2.6   , New , 0.07
3   , 3   , 2.67  , 2.59  , New , 0.08
4   , 4   , 2.66  , 2.57  , New , 0.09
5   , 5   , 2.65  , 2.56  , New , 0.09
6   , 6   , 2.67  , 2.59  , New , 0.08
7   , 7   , 2.65  , 2.62  , New , 0.03
4   , 1   , 2.65  , 2.41  , New , 0.24
8   , 0   , 2.68  , 2.56  , New , 0.12
8   , 1   , 2.62  , 2.55  , New , 0.07
16  , 0   , 2.66  , 2.56  , New , 0.1 
16  , 1   , 2.63  , 2.55  , New , 0.08
32  , 0   , 3.62  , 3.19  , New , 0.43
32  , 1   , 3.74  , 3.45  , New , 0.29
64  , 0   , 3.9   , 3.7   , New , 0.2 
64  , 1   , 4.13  , 3.68  , New , 0.45
128 , 0   , 4.34  , 4.17  , New , 0.17
128 , 1   , 4.59  , 4.07  , New , 0.52
256 , 0   , 6.74  , 6.56  , New , 0.18
256 , 1   , 7.34  , 7.13  , New , 0.21
512 , 0   , 9.64  , 8.67  , New , 0.97
512 , 1   , 9.49  , 8.56  , New , 0.93
1024, 0   , 13.57 , 12.35 , New , 1.22
1024, 1   , 13.57 , 12.59 , New , 0.98

Results For Tigerlake strnlen-avx2
size, algn, Cur T , Sub T , Win , Dif 
1   , 0   , 4.21  , 3.91  , New , 0.3 
2   , 0   , 4.1   , 3.79  , New , 0.31
3   , 0   , 4.02  , 3.81  , New , 0.21
4   , 0   , 4.06  , 3.82  , New , 0.24
5   , 0   , 4.1   , 3.81  , New , 0.29
6   , 0   , 4.08  , 3.82  , New , 0.26
7   , 0   , 4.07  , 3.87  , New , 0.2 
1   , 1   , 3.95  , 3.8   , New , 0.15
2   , 2   , 4.11  , 3.88  , New , 0.23
3   , 3   , 4.08  , 3.88  , New , 0.2 
4   , 4   , 4.05  , 3.94  , New , 0.11
5   , 5   , 4.02  , 3.89  , New , 0.13
6   , 6   , 4.02  , 3.89  , New , 0.13
7   , 7   , 4.08  , 3.84  , New , 0.24
4   , 1   , 4.07  , 3.7   , New , 0.37
8   , 0   , 4.08  , 3.95  , New , 0.13
8   , 1   , 4.01  , 4.02  , Cur , 0.01
16  , 0   , 4.03  , 4.03  , Eq  , 0.0
16  , 1   , 4.05  , 4.0   , New , 0.05
32  , 0   , 5.86  , 5.23  , New , 0.63
32  , 1   , 5.88  , 5.36  , New , 0.52
64  , 0   , 6.38  , 5.73  , New , 0.65
64  , 1   , 6.49  , 5.56  , New , 0.93
128 , 0   , 7.17  , 6.39  , New , 0.78
128 , 1   , 7.1   , 6.41  , New , 0.69
256 , 0   , 11.65 , 11.0  , New , 0.65
256 , 1   , 11.37 , 10.97 , New , 0.4 
512 , 0   , 14.86 , 13.43 , New , 1.43
512 , 1   , 14.63 , 13.35 , New , 1.28
1024, 0   , 20.92 , 19.33 , New , 1.59
1024, 1   , 20.85 , 19.38 , New , 1.47

Results For Icelake strnlen-evex
size, algn, Cur T , Sub T , Win , Dif 
1   , 0   , 2.9   , 2.66  , New , 0.24
2   , 0   , 2.99  , 2.72  , New , 0.27
3   , 0   , 2.93  , 2.64  , New , 0.29
4   , 0   , 2.83  , 2.55  , New , 0.28
5   , 0   , 2.92  , 2.64  , New , 0.28
6   , 0   , 2.95  , 2.64  , New , 0.31
7   , 0   , 2.91  , 2.65  , New , 0.26
1   , 1   , 2.63  , 2.49  , New , 0.14
2   , 2   , 2.89  , 2.6   , New , 0.29
3   , 3   , 2.89  , 2.59  , New , 0.3 
4   , 4   , 2.9   , 2.58  , New , 0.32
5   , 5   , 2.87  , 2.57  , New , 0.3 
6   , 6   , 2.9   , 2.57  , New , 0.33
7   , 7   , 2.88  , 2.64  , New , 0.24
4   , 1   , 2.65  , 2.39  , New , 0.26
8   , 0   , 2.85  , 2.57  , New , 0.28
8   , 1   , 2.62  , 2.4   , New , 0.22
16  , 0   , 2.83  , 2.56  , New , 0.27
16  , 1   , 2.63  , 2.39  , New , 0.24
32  , 0   , 3.95  , 3.06  , New , 0.89
32  , 1   , 3.95  , 3.15  , New , 0.8
64  , 0   , 3.98  , 3.6   , New , 0.38
64  , 1   , 3.88  , 3.48  , New , 0.4
128 , 0   , 4.45  , 4.19  , New , 0.26
128 , 1   , 4.57  , 4.21  , New , 0.36
256 , 0   , 6.75  , 6.97  , Cur , 0.22
256 , 1   , 7.55  , 7.76  , Cur , 0.21
512 , 0   , 9.75  , 10.09 , Cur , 0.34
512 , 1   , 9.84  , 10.13 , Cur , 0.29
1024, 0   , 14.45 , 14.4  , New , 0.05
1024, 1   , 14.39 , 14.26 , New , 0.13

Results For Tigerlake strnlen-evex
size, algn, Cur T , Sub T , Win , Dif 
1   , 0   , 3.86  , 3.59  , New , 0.27
2   , 0   , 3.78  , 3.41  , New , 0.37
3   , 0   , 3.69  , 3.4   , New , 0.29
4   , 0   , 3.62  , 3.33  , New , 0.29
5   , 0   , 3.76  , 3.37  , New , 0.39
6   , 0   , 3.73  , 3.39  , New , 0.34
7   , 0   , 3.7   , 3.4   , New , 0.3 
1   , 1   , 3.58  , 3.35  , New , 0.23
2   , 2   , 3.75  , 3.34  , New , 0.41
3   , 3   , 3.72  , 3.39  , New , 0.33
4   , 4   , 3.69  , 3.38  , New , 0.31
5   , 5   , 3.69  , 3.37  , New , 0.32
6   , 6   , 3.68  , 3.37  , New , 0.31
7   , 7   , 3.74  , 3.35  , New , 0.39
4   , 1   , 3.39  , 3.27  , New , 0.12
8   , 0   , 3.4   , 3.29  , New , 0.11
8   , 1   , 3.34  , 3.32  , New , 0.02
16  , 0   , 3.36  , 3.34  , New , 0.02
16  , 1   , 3.39  , 3.3   , New , 0.09
32  , 0   , 5.13  , 5.13  , Eq  , 0.0
32  , 1   , 5.18  , 5.16  , New , 0.02
64  , 0   , 5.87  , 5.44  , New , 0.43
64  , 1   , 5.97  , 5.44  , New , 0.53
128 , 0   , 7.14  , 6.48  , New , 0.66
128 , 1   , 7.08  , 6.63  , New , 0.45
256 , 0   , 11.68 , 12.57 , Cur , 0.89
256 , 1   , 11.67 , 12.23 , Cur , 0.56
512 , 0   , 15.64 , 15.74 , Cur , 0.1 
512 , 1   , 15.52 , 15.69 , Cur , 0.17
1024, 0   , 23.02 , 22.57 , New , 0.45
1024, 1   , 23.0  , 22.8  , New , 0.2
    
 sysdeps/x86_64/multiarch/strlen-evex.S | 569 +++++++++++++------------
 1 file changed, 307 insertions(+), 262 deletions(-)

Comments

H.J. Lu April 17, 2021, 6:56 p.m. UTC | #1
On Fri, Apr 16, 2021 at 7:53 PM Noah Goldstein <goldstein.w.n@gmail.com> wrote:
>
> No bug. This commit optimizes strlen-evex.S. The
> optimizations are mostly small things but they add up to roughly
> 10-30% performance improvement for strlen. The results for strnlen are
> bit more ambiguous. test-strlen, test-strnlen, test-wcslen, and
> test-wcsnlen are all passing.
>
> Signed-off-by: Noah Goldstein <goldstein.w.n@gmail.com>
> ---
> Tests where run on the following CPUs:
>
> Skylake: https://ark.intel.com/content/www/us/en/ark/products/149091/intel-core-i7-8565u-processor-8m-cache-up-to-4-60-ghz.html
>
> Icelake: https://ark.intel.com/content/www/us/en/ark/products/196597/intel-core-i7-1065g7-processor-8m-cache-up-to-3-90-ghz.html
>
> Tigerlake: https://ark.intel.com/content/www/us/en/ark/products/208921/intel-core-i7-1165g7-processor-12m-cache-up-to-4-70-ghz-with-ipu.html
>
> All times are the geometric mean of N=20. The unit of time is
> seconds.
>
> "Cur" refers to the current implementation
> "New" refers to this patches implementation
>
>
> The strlen numbers are universal improvements:
>
> Results For Skylake strlen-avx2
> size, algn, Cur T , New T , Win , Dif
> 1   , 0   , 4.76  , 4.27  , New , 0.49
> 2   , 0   , 4.77  , 4.165 , New , 0.6
> 3   , 0   , 4.617 , 4.095 , New , 0.52
> 4   , 0   , 4.579 , 4.006 , New , 0.57
> 5   , 0   , 4.608 , 4.008 , New , 0.6
> 6   , 0   , 4.655 , 4.086 , New , 0.57
> 7   , 0   , 4.661 , 4.071 , New , 0.59
> 8   , 0   , 4.625 , 4.092 , New , 0.53
> 16  , 0   , 4.608 , 4.021 , New , 0.59
> 10  , 0   , 4.645 , 4.111 , New , 0.53
> 32  , 0   , 5.532 , 4.817 , New , 0.71
> 21  , 0   , 4.636 , 3.775 , New , 0.86
> 64  , 0   , 5.991 , 5.352 , New , 0.64
> 42  , 0   , 5.529 , 4.789 , New , 0.74
> 128 , 0   , 7.042 , 5.473 , New , 1.57
> 85  , 0   , 6.118 , 5.466 , New , 0.65
> 256 , 0   , 10.64 , 7.954 , New , 2.69
> 170 , 0   , 9.918 , 9.585 , New , 0.33
> 512 , 0   , 12.916, 10.242, New , 2.67
> 341 , 0   , 10.764, 10.216, New , 0.55
> 1024, 0   , 18.163, 14.844, New , 3.32
> 682 , 0   , 15.292, 13.382, New , 1.91
> 2048, 0   , 38.732, 24.396, New , 14.34
> 1365, 0   , 22.299, 20.08 , New , 2.22
> 4096, 0   , 79.054, 68.682, New , 10.37
> 2730, 0   , 61.47 , 40.705, New , 20.77
>
> Results For Icelake strlen-avx2
> size, algn, Cur T , New T , Win , Dif
> 1   , 0   , 2.681 , 1.99  , New , 0.69
> 2   , 0   , 2.823 , 2.232 , New , 0.59
> 3   , 0   , 2.57  , 2.077 , New , 0.49
> 4   , 0   , 2.659 , 2.128 , New , 0.53
> 5   , 0   , 2.666 , 2.109 , New , 0.56
> 6   , 0   , 2.596 , 2.053 , New , 0.54
> 7   , 0   , 2.623 , 2.152 , New , 0.47
> 8   , 0   , 2.675 , 2.178 , New , 0.5
> 16  , 0   , 2.675 , 2.202 , New , 0.47
> 10  , 0   , 2.672 , 2.2   , New , 0.47
> 32  , 0   , 3.383 , 2.868 , New , 0.52
> 21  , 0   , 2.693 , 2.032 , New , 0.66
> 64  , 0   , 3.404 , 3.056 , New , 0.35
> 42  , 0   , 3.511 , 2.967 , New , 0.54
> 128 , 0   , 4.191 , 3.627 , New , 0.56
> 85  , 0   , 3.559 , 2.922 , New , 0.64
> 256 , 0   , 6.782 , 5.493 , New , 1.29
> 170 , 0   , 6.24  , 4.988 , New , 1.25
> 512 , 0   , 9.305 , 7.308 , New , 2.0
> 341 , 0   , 7.626 , 6.272 , New , 1.35
> 1024, 0   , 14.455, 11.544, New , 2.91
> 682 , 0   , 10.728, 8.738 , New , 1.99
> 2048, 0   , 24.171, 24.101, New , 0.07
> 1365, 0   , 17.474, 14.387, New , 3.09
> 4096, 0   , 57.659, 51.675, New , 5.98
> 2730, 0   , 44.702, 28.04 , New , 16.66
>
> Results For Tigerlake strlen-avx2
> size, algn, Cur T , New T , Win , Dif
> 1   , 0   , 4.369 , 3.008 , New , 1.36
> 2   , 0   , 4.054 , 3.231 , New , 0.82
> 3   , 0   , 4.081 , 3.243 , New , 0.84
> 4   , 0   , 3.904 , 3.17  , New , 0.73
> 5   , 0   , 3.915 , 3.178 , New , 0.74
> 6   , 0   , 3.924 , 3.184 , New , 0.74
> 7   , 0   , 3.917 , 3.177 , New , 0.74
> 8   , 0   , 3.889 , 3.209 , New , 0.68
> 16  , 0   , 3.878 , 3.03  , New , 0.85
> 10  , 0   , 3.892 , 3.004 , New , 0.89
> 32  , 0   , 4.957 , 4.162 , New , 0.79
> 21  , 0   , 3.866 , 3.18  , New , 0.69
> 64  , 0   , 5.035 , 4.521 , New , 0.51
> 42  , 0   , 5.039 , 4.276 , New , 0.76
> 128 , 0   , 6.117 , 5.253 , New , 0.86
> 85  , 0   , 4.932 , 4.421 , New , 0.51
> 256 , 0   , 10.019, 8.221 , New , 1.8
> 170 , 0   , 8.954 , 7.404 , New , 1.55
> 512 , 0   , 14.071, 10.948, New , 3.12
> 341 , 0   , 11.177, 9.246 , New , 1.93
> 1024, 0   , 21.808, 17.034, New , 4.77
> 682 , 0   , 16.07 , 12.941, New , 3.13
> 2048, 0   , 37.332, 29.853, New , 7.48
> 1365, 0   , 26.394, 21.516, New , 4.88
> 4096, 0   , 87.951, 80.35 , New , 7.6
> 2730, 0   , 62.768, 44.247, New , 18.52
>
> Results For Icelake strlen-evex
> size, algn, Cur T , New T , Win , Dif
> 1   , 0   , 2.681 , 1.99  , New , 0.69
> 2   , 0   , 2.823 , 2.232 , New , 0.59
> 3   , 0   , 2.57  , 2.077 , New , 0.49
> 4   , 0   , 2.659 , 2.128 , New , 0.53
> 5   , 0   , 2.666 , 2.109 , New , 0.56
> 6   , 0   , 2.596 , 2.053 , New , 0.54
> 7   , 0   , 2.623 , 2.152 , New , 0.47
> 8   , 0   , 2.675 , 2.178 , New , 0.5
> 16  , 0   , 2.675 , 2.202 , New , 0.47
> 10  , 0   , 2.672 , 2.2   , New , 0.47
> 32  , 0   , 3.383 , 2.868 , New , 0.52
> 21  , 0   , 2.693 , 2.032 , New , 0.66
> 64  , 0   , 3.404 , 3.056 , New , 0.35
> 42  , 0   , 3.511 , 2.967 , New , 0.54
> 128 , 0   , 4.191 , 3.627 , New , 0.56
> 85  , 0   , 3.559 , 2.922 , New , 0.64
> 256 , 0   , 6.782 , 5.493 , New , 1.29
> 170 , 0   , 6.24  , 4.988 , New , 1.25
> 512 , 0   , 9.305 , 7.308 , New , 2.0
> 341 , 0   , 7.626 , 6.272 , New , 1.35
> 1024, 0   , 14.455, 11.544, New , 2.91
> 682 , 0   , 10.728, 8.738 , New , 1.99
> 2048, 0   , 24.171, 24.101, New , 0.07
> 1365, 0   , 17.474, 14.387, New , 3.09
> 4096, 0   , 57.659, 51.675, New , 5.98
> 2730, 0   , 44.702, 28.04 , New , 16.66
>
> Results For Tigerlake strlen-evex
> size, algn, Cur T , New T , Win , Dif
> 1   , 0   , 4.369 , 3.008 , New , 1.36
> 2   , 0   , 4.054 , 3.231 , New , 0.82
> 3   , 0   , 4.081 , 3.243 , New , 0.84
> 4   , 0   , 3.904 , 3.17  , New , 0.73
> 5   , 0   , 3.915 , 3.178 , New , 0.74
> 6   , 0   , 3.924 , 3.184 , New , 0.74
> 7   , 0   , 3.917 , 3.177 , New , 0.74
> 8   , 0   , 3.889 , 3.209 , New , 0.68
> 16  , 0   , 3.878 , 3.03  , New , 0.85
> 10  , 0   , 3.892 , 3.004 , New , 0.89
> 32  , 0   , 4.957 , 4.162 , New , 0.79
> 21  , 0   , 3.866 , 3.18  , New , 0.69
> 64  , 0   , 5.035 , 4.521 , New , 0.51
> 42  , 0   , 5.039 , 4.276 , New , 0.76
> 128 , 0   , 6.117 , 5.253 , New , 0.86
> 85  , 0   , 4.932 , 4.421 , New , 0.51
> 256 , 0   , 10.019, 8.221 , New , 1.8
> 170 , 0   , 8.954 , 7.404 , New , 1.55
> 512 , 0   , 14.071, 10.948, New , 3.12
> 341 , 0   , 11.177, 9.246 , New , 1.93
> 1024, 0   , 21.808, 17.034, New , 4.77
> 682 , 0   , 16.07 , 12.941, New , 3.13
> 2048, 0   , 37.332, 29.853, New , 7.48
> 1365, 0   , 26.394, 21.516, New , 4.88
> 4096, 0   , 87.951, 80.35 , New , 7.6
> 2730, 0   , 62.768, 44.247, New , 18.52
>
> The strnlen numbers are a bit more of a mixed bag but I think
> generally positive. Its possible that the current version should be
> kept. Let me know.
>
> Results For Skylake strnlen-avx2
> size, algn, Cur T , Sub T , Win , Dif
> 1   , 0   , 4.06  , 4.1   , Cur , 0.04
> 2   , 0   , 4.15  , 4.08  , New , 0.07
> 3   , 0   , 4.1   , 4.03  , New , 0.07
> 4   , 0   , 3.95  , 3.91  , New , 0.04
> 5   , 0   , 4.07  , 3.9   , New , 0.17
> 6   , 0   , 4.04  , 3.92  , New , 0.12
> 7   , 0   , 4.03  , 3.89  , New , 0.14
> 1   , 1   , 3.75  , 3.79  , Cur , 0.04
> 2   , 2   , 4.0   , 3.91  , New , 0.09
> 3   , 3   , 4.04  , 3.92  , New , 0.12
> 4   , 4   , 3.95  , 3.86  , New , 0.09
> 5   , 5   , 3.97  , 3.91  , New , 0.06
> 6   , 6   , 3.96  , 3.92  , New , 0.04
> 7   , 7   , 3.97  , 3.91  , New , 0.06
> 4   , 1   , 3.76  , 3.83  , Cur , 0.07
> 8   , 0   , 3.73  , 4.01  , Cur , 0.28
> 8   , 1   , 3.73  , 3.88  , Cur , 0.15
> 16  , 0   , 3.68  , 3.84  , Cur , 0.16
> 16  , 1   , 3.75  , 3.92  , Cur , 0.17
> 32  , 0   , 5.93  , 5.95  , Cur , 0.02
> 32  , 1   , 5.95  , 5.98  , Cur , 0.03
> 64  , 0   , 6.46  , 5.31  , New , 1.15
> 64  , 1   , 6.66  , 5.43  , New , 1.23
> 128 , 0   , 7.42  , 6.02  , New , 1.4
> 128 , 1   , 7.57  , 5.81  , New , 1.76
> 256 , 0   , 12.02 , 9.89  , New , 2.13
> 256 , 1   , 11.91 , 9.84  , New , 2.07
> 512 , 0   , 15.06 , 11.77 , New , 3.29
> 512 , 1   , 14.79 , 11.75 , New , 3.04
> 1024, 0   , 23.61 , 16.98 , New , 6.63
> 1024, 1   , 23.63 , 16.91 , New , 6.72
>
> Results For Icelake strnlen-avx2
> size, algn, Cur T , Sub T , Win , Dif
> 1   , 0   , 2.81  , 2.51  , New , 0.3
> 2   , 0   , 2.8   , 2.53  , New , 0.27
> 3   , 0   , 2.7   , 2.57  , New , 0.13
> 4   , 0   , 2.68  , 2.55  , New , 0.13
> 5   , 0   , 2.7   , 2.57  , New , 0.13
> 6   , 0   , 2.73  , 2.6   , New , 0.13
> 7   , 0   , 2.69  , 2.61  , New , 0.08
> 1   , 1   , 2.53  , 2.5   , New , 0.03
> 2   , 2   , 2.67  , 2.6   , New , 0.07
> 3   , 3   , 2.67  , 2.59  , New , 0.08
> 4   , 4   , 2.66  , 2.57  , New , 0.09
> 5   , 5   , 2.65  , 2.56  , New , 0.09
> 6   , 6   , 2.67  , 2.59  , New , 0.08
> 7   , 7   , 2.65  , 2.62  , New , 0.03
> 4   , 1   , 2.65  , 2.41  , New , 0.24
> 8   , 0   , 2.68  , 2.56  , New , 0.12
> 8   , 1   , 2.62  , 2.55  , New , 0.07
> 16  , 0   , 2.66  , 2.56  , New , 0.1
> 16  , 1   , 2.63  , 2.55  , New , 0.08
> 32  , 0   , 3.62  , 3.19  , New , 0.43
> 32  , 1   , 3.74  , 3.45  , New , 0.29
> 64  , 0   , 3.9   , 3.7   , New , 0.2
> 64  , 1   , 4.13  , 3.68  , New , 0.45
> 128 , 0   , 4.34  , 4.17  , New , 0.17
> 128 , 1   , 4.59  , 4.07  , New , 0.52
> 256 , 0   , 6.74  , 6.56  , New , 0.18
> 256 , 1   , 7.34  , 7.13  , New , 0.21
> 512 , 0   , 9.64  , 8.67  , New , 0.97
> 512 , 1   , 9.49  , 8.56  , New , 0.93
> 1024, 0   , 13.57 , 12.35 , New , 1.22
> 1024, 1   , 13.57 , 12.59 , New , 0.98
>
> Results For Tigerlake strnlen-avx2
> size, algn, Cur T , Sub T , Win , Dif
> 1   , 0   , 4.21  , 3.91  , New , 0.3
> 2   , 0   , 4.1   , 3.79  , New , 0.31
> 3   , 0   , 4.02  , 3.81  , New , 0.21
> 4   , 0   , 4.06  , 3.82  , New , 0.24
> 5   , 0   , 4.1   , 3.81  , New , 0.29
> 6   , 0   , 4.08  , 3.82  , New , 0.26
> 7   , 0   , 4.07  , 3.87  , New , 0.2
> 1   , 1   , 3.95  , 3.8   , New , 0.15
> 2   , 2   , 4.11  , 3.88  , New , 0.23
> 3   , 3   , 4.08  , 3.88  , New , 0.2
> 4   , 4   , 4.05  , 3.94  , New , 0.11
> 5   , 5   , 4.02  , 3.89  , New , 0.13
> 6   , 6   , 4.02  , 3.89  , New , 0.13
> 7   , 7   , 4.08  , 3.84  , New , 0.24
> 4   , 1   , 4.07  , 3.7   , New , 0.37
> 8   , 0   , 4.08  , 3.95  , New , 0.13
> 8   , 1   , 4.01  , 4.02  , Cur , 0.01
> 16  , 0   , 4.03  , 4.03  , Eq  , 0.0
> 16  , 1   , 4.05  , 4.0   , New , 0.05
> 32  , 0   , 5.86  , 5.23  , New , 0.63
> 32  , 1   , 5.88  , 5.36  , New , 0.52
> 64  , 0   , 6.38  , 5.73  , New , 0.65
> 64  , 1   , 6.49  , 5.56  , New , 0.93
> 128 , 0   , 7.17  , 6.39  , New , 0.78
> 128 , 1   , 7.1   , 6.41  , New , 0.69
> 256 , 0   , 11.65 , 11.0  , New , 0.65
> 256 , 1   , 11.37 , 10.97 , New , 0.4
> 512 , 0   , 14.86 , 13.43 , New , 1.43
> 512 , 1   , 14.63 , 13.35 , New , 1.28
> 1024, 0   , 20.92 , 19.33 , New , 1.59
> 1024, 1   , 20.85 , 19.38 , New , 1.47
>
> Results For Icelake strnlen-evex
> size, algn, Cur T , Sub T , Win , Dif
> 1   , 0   , 2.9   , 2.66  , New , 0.24
> 2   , 0   , 2.99  , 2.72  , New , 0.27
> 3   , 0   , 2.93  , 2.64  , New , 0.29
> 4   , 0   , 2.83  , 2.55  , New , 0.28
> 5   , 0   , 2.92  , 2.64  , New , 0.28
> 6   , 0   , 2.95  , 2.64  , New , 0.31
> 7   , 0   , 2.91  , 2.65  , New , 0.26
> 1   , 1   , 2.63  , 2.49  , New , 0.14
> 2   , 2   , 2.89  , 2.6   , New , 0.29
> 3   , 3   , 2.89  , 2.59  , New , 0.3
> 4   , 4   , 2.9   , 2.58  , New , 0.32
> 5   , 5   , 2.87  , 2.57  , New , 0.3
> 6   , 6   , 2.9   , 2.57  , New , 0.33
> 7   , 7   , 2.88  , 2.64  , New , 0.24
> 4   , 1   , 2.65  , 2.39  , New , 0.26
> 8   , 0   , 2.85  , 2.57  , New , 0.28
> 8   , 1   , 2.62  , 2.4   , New , 0.22
> 16  , 0   , 2.83  , 2.56  , New , 0.27
> 16  , 1   , 2.63  , 2.39  , New , 0.24
> 32  , 0   , 3.95  , 3.06  , New , 0.89
> 32  , 1   , 3.95  , 3.15  , New , 0.8
> 64  , 0   , 3.98  , 3.6   , New , 0.38
> 64  , 1   , 3.88  , 3.48  , New , 0.4
> 128 , 0   , 4.45  , 4.19  , New , 0.26
> 128 , 1   , 4.57  , 4.21  , New , 0.36
> 256 , 0   , 6.75  , 6.97  , Cur , 0.22
> 256 , 1   , 7.55  , 7.76  , Cur , 0.21
> 512 , 0   , 9.75  , 10.09 , Cur , 0.34
> 512 , 1   , 9.84  , 10.13 , Cur , 0.29
> 1024, 0   , 14.45 , 14.4  , New , 0.05
> 1024, 1   , 14.39 , 14.26 , New , 0.13
>
> Results For Tigerlake strnlen-evex
> size, algn, Cur T , Sub T , Win , Dif
> 1   , 0   , 3.86  , 3.59  , New , 0.27
> 2   , 0   , 3.78  , 3.41  , New , 0.37
> 3   , 0   , 3.69  , 3.4   , New , 0.29
> 4   , 0   , 3.62  , 3.33  , New , 0.29
> 5   , 0   , 3.76  , 3.37  , New , 0.39
> 6   , 0   , 3.73  , 3.39  , New , 0.34
> 7   , 0   , 3.7   , 3.4   , New , 0.3
> 1   , 1   , 3.58  , 3.35  , New , 0.23
> 2   , 2   , 3.75  , 3.34  , New , 0.41
> 3   , 3   , 3.72  , 3.39  , New , 0.33
> 4   , 4   , 3.69  , 3.38  , New , 0.31
> 5   , 5   , 3.69  , 3.37  , New , 0.32
> 6   , 6   , 3.68  , 3.37  , New , 0.31
> 7   , 7   , 3.74  , 3.35  , New , 0.39
> 4   , 1   , 3.39  , 3.27  , New , 0.12
> 8   , 0   , 3.4   , 3.29  , New , 0.11
> 8   , 1   , 3.34  , 3.32  , New , 0.02
> 16  , 0   , 3.36  , 3.34  , New , 0.02
> 16  , 1   , 3.39  , 3.3   , New , 0.09
> 32  , 0   , 5.13  , 5.13  , Eq  , 0.0
> 32  , 1   , 5.18  , 5.16  , New , 0.02
> 64  , 0   , 5.87  , 5.44  , New , 0.43
> 64  , 1   , 5.97  , 5.44  , New , 0.53
> 128 , 0   , 7.14  , 6.48  , New , 0.66
> 128 , 1   , 7.08  , 6.63  , New , 0.45
> 256 , 0   , 11.68 , 12.57 , Cur , 0.89
> 256 , 1   , 11.67 , 12.23 , Cur , 0.56
> 512 , 0   , 15.64 , 15.74 , Cur , 0.1
> 512 , 1   , 15.52 , 15.69 , Cur , 0.17
> 1024, 0   , 23.02 , 22.57 , New , 0.45
> 1024, 1   , 23.0  , 22.8  , New , 0.2
>
>  sysdeps/x86_64/multiarch/strlen-evex.S | 569 +++++++++++++------------
>  1 file changed, 307 insertions(+), 262 deletions(-)
>
> diff --git a/sysdeps/x86_64/multiarch/strlen-evex.S b/sysdeps/x86_64/multiarch/strlen-evex.S
> index 0583819078..d1aafac76f 100644
> --- a/sysdeps/x86_64/multiarch/strlen-evex.S
> +++ b/sysdeps/x86_64/multiarch/strlen-evex.S
> @@ -29,11 +29,13 @@
>  # ifdef USE_AS_WCSLEN
>  #  define VPCMP                vpcmpd
>  #  define VPMINU       vpminud
> -#  define SHIFT_REG    r9d
> +#  define SHIFT_REG ecx
> +#  define CHAR_SIZE    4
>  # else
>  #  define VPCMP                vpcmpb
>  #  define VPMINU       vpminub
> -#  define SHIFT_REG    ecx
> +#  define SHIFT_REG edx
> +#  define CHAR_SIZE    1
>  # endif
>
>  # define XMMZERO       xmm16
> @@ -46,132 +48,169 @@
>  # define YMM6          ymm22
>
>  # define VEC_SIZE 32
> +# define PAGE_SIZE 4096
> +# define CHAR_PER_VEC (VEC_SIZE / CHAR_SIZE)
>
>         .section .text.evex,"ax",@progbits
>  ENTRY (STRLEN)
>  # ifdef USE_AS_STRNLEN
> -       /* Check for zero length.  */
> +       /* Check zero length.  */
>         test    %RSI_LP, %RSI_LP
>         jz      L(zero)
> -#  ifdef USE_AS_WCSLEN
> -       shl     $2, %RSI_LP
> -#  elif defined __ILP32__
> +#  if !defined USE_AS_WCSLEN && defined __ILP32__
>         /* Clear the upper 32 bits.  */
>         movl    %esi, %esi
>  #  endif
>         mov     %RSI_LP, %R8_LP
>  # endif
> -       movl    %edi, %ecx
> -       movq    %rdi, %rdx
> +       movl    %edi, %eax
> +       sall    $20, %eax
>         vpxorq  %XMMZERO, %XMMZERO, %XMMZERO
> -
>         /* Check if we may cross page boundary with one vector load.  */
> -       andl    $(2 * VEC_SIZE - 1), %ecx
> -       cmpl    $VEC_SIZE, %ecx
> -       ja      L(cros_page_boundary)
> +       cmpl    $((PAGE_SIZE - VEC_SIZE) << 20), %eax
> +       ja      L(cross_page_boundary)
>
> -       /* Check the first VEC_SIZE bytes.  Each bit in K0 represents a
> -          null byte.  */
> +       /* Check the first VEC_SIZE bytes.  */

Here are some quick comments:

1.  The change is incorrect for x32:

FAIL: wcsmbs/tst-size_t-wcsnlen
$ cat wcsmbs/tst-size_t-wcsnlen.out
Didn't expect signal from child: got `Segmentation fault'

Your patch removed/changed special handling for x32.

2.  Some of comment changes removed some detailed information, like

-  /* Check the first VEC_SIZE bytes.  Each bit in K0 represents a
-     null byte.  */
+  /* Check the first VEC_SIZE bytes.  */

You should put them back.

3. You need to add more comments for changes which aren't 100%
obvious.

>         VPCMP   $0, (%rdi), %YMMZERO, %k0
>         kmovd   %k0, %eax
> -       testl   %eax, %eax
> -
>  # ifdef USE_AS_STRNLEN
> -       jnz     L(first_vec_x0_check)
> -       /* Adjust length and check the end of data.  */
> -       subq    $VEC_SIZE, %rsi
> -       jbe     L(max)
> -# else
> -       jnz     L(first_vec_x0)
> +       /* If length < VEC_SIZE handle special.  */
> +       cmpq    $CHAR_PER_VEC, %rsi
> +       jbe     L(first_vec_x0)
>  # endif
> -
> -       /* Align data for aligned loads in the loop.  */
> -       addq    $VEC_SIZE, %rdi
> -       andl    $(VEC_SIZE - 1), %ecx
> -       andq    $-VEC_SIZE, %rdi
> -
> +       testl   %eax, %eax
> +       jz      L(aligned_more)
> +       tzcntl  %eax, %eax
> +       ret
>  # ifdef USE_AS_STRNLEN
> -       /* Adjust length.  */
> -       addq    %rcx, %rsi
> +L(zero):
> +       xorl    %eax, %eax
> +       ret
>
> -       subq    $(VEC_SIZE * 4), %rsi
> -       jbe     L(last_4x_vec_or_less)
> +       .p2align 4
> +L(first_vec_x0):
> +       /* Select min of length and position of first null.  */
> +       btsq    %rsi, %rax
> +       tzcntl  %eax, %eax
> +       ret
>  # endif
> -       jmp     L(more_4x_vec)
>
>         .p2align 4
> -L(cros_page_boundary):
> -       andl    $(VEC_SIZE - 1), %ecx
> -       andq    $-VEC_SIZE, %rdi
> -
> -# ifdef USE_AS_WCSLEN
> -       /* NB: Divide shift count by 4 since each bit in K0 represent 4
> -          bytes.  */
> -       movl    %ecx, %SHIFT_REG
> -       sarl    $2, %SHIFT_REG
> +L(first_vec_x1):
> +       tzcntl  %eax, %eax
> +       /* Safe to use 32 bit instructions as these are only called for
> +          size = [1, 159].  */
> +# ifdef USE_AS_STRNLEN
> +       /* Use ecx which was computed earlier to compute correct value.
> +       */
> +#  ifdef USE_AS_WCSLEN
> +       sarl    $2, %ecx
> +#  endif
> +       leal    -(CHAR_PER_VEC * 4 + 1)(%rcx, %rax), %eax
> +# else
> +       subl    %edx, %edi
> +#  ifdef USE_AS_WCSLEN
> +       sarl    $2, %edi
> +#  endif
> +       leal    CHAR_PER_VEC(%rdi, %rax), %eax
>  # endif
> -       VPCMP   $0, (%rdi), %YMMZERO, %k0
> -       kmovd   %k0, %eax
> +       ret
>
> -       /* Remove the leading bytes.  */
> -       sarxl   %SHIFT_REG, %eax, %eax
> -       testl   %eax, %eax
> -       jz      L(aligned_more)
> +       .p2align 4
> +L(first_vec_x2):
>         tzcntl  %eax, %eax
> -# ifdef USE_AS_WCSLEN
> -       /* NB: Multiply wchar_t count by 4 to get the number of bytes.  */
> -       sall    $2, %eax
> -# endif
> +       /* Safe to use 32 bit instructions as these are only called for
> +          size = [1, 159].  */
>  # ifdef USE_AS_STRNLEN
> -       /* Check the end of data.  */
> -       cmpq    %rax, %rsi
> -       jbe     L(max)
> -# endif
> -       addq    %rdi, %rax
> -       addq    %rcx, %rax
> -       subq    %rdx, %rax
> -# ifdef USE_AS_WCSLEN
> -       shrq    $2, %rax
> +       /* Use ecx which was computed earlier to compute correct value.
> +       */
> +#  ifdef USE_AS_WCSLEN
> +       sarl    $2, %ecx
> +#  endif
> +       leal    -(CHAR_PER_VEC * 3 + 1)(%rcx, %rax), %eax
> +# else
> +       subl    %edx, %edi
> +#  ifdef USE_AS_WCSLEN
> +       sarl    $2, %edi
> +#  endif
> +       leal    (CHAR_PER_VEC * 2)(%rdi, %rax), %eax
>  # endif
>         ret
>
>         .p2align 4
> -L(aligned_more):
> +L(first_vec_x3):
> +       tzcntl  %eax, %eax
> +       /* Safe to use 32 bit instructions as these are only called for
> +          size = [1, 159].  */
>  # ifdef USE_AS_STRNLEN
> -        /* "rcx" is less than VEC_SIZE.  Calculate "rdx + rcx - VEC_SIZE"
> -           with "rdx - (VEC_SIZE - rcx)" instead of "(rdx + rcx) - VEC_SIZE"
> -           to void possible addition overflow.  */
> -       negq    %rcx
> -       addq    $VEC_SIZE, %rcx
> -
> -       /* Check the end of data.  */
> -       subq    %rcx, %rsi
> -       jbe     L(max)
> +       /* Use ecx which was computed earlier to compute correct value.
> +       */
> +#  ifdef USE_AS_WCSLEN
> +       sarl    $2, %ecx
> +#  endif
> +       leal    -(CHAR_PER_VEC * 2 + 1)(%rcx, %rax), %eax
> +# else
> +       subl    %edx, %edi
> +#  ifdef USE_AS_WCSLEN
> +       sarl    $2, %edi
> +#  endif
> +       leal    (CHAR_PER_VEC * 3)(%rdi, %rax), %eax
>  # endif
> +       ret
>
> -       addq    $VEC_SIZE, %rdi
> -
> +       .p2align 4
> +L(first_vec_x4):
> +       tzcntl  %eax, %eax
> +       /* Safe to use 32 bit instructions as these are only called for
> +          size = [1, 159].  */
>  # ifdef USE_AS_STRNLEN
> -       subq    $(VEC_SIZE * 4), %rsi
> -       jbe     L(last_4x_vec_or_less)
> +       /* Use ecx which was computed earlier to compute correct value.
> +       */
> +#  ifdef USE_AS_WCSLEN
> +       sarl    $2, %ecx
> +#  endif
> +       leal    -(CHAR_PER_VEC + 1)(%rcx, %rax), %eax
> +# else
> +       subl    %edx, %edi
> +#  ifdef USE_AS_WCSLEN
> +       sarl    $2, %edi
> +#  endif
> +       leal    (CHAR_PER_VEC * 4)(%rdi, %rax), %eax
>  # endif
> +       ret
>
> -L(more_4x_vec):
> +       /* strnlen jumps here. strlen falls through.  */
> +       .p2align 5
> +L(aligned_more):
> +       movq    %rdi, %rdx
> +       /* Align data to VEC_SIZE.  */
> +       andq    $-(VEC_SIZE), %rdi
> +L(cross_page_continue):
>         /* Check the first 4 * VEC_SIZE.  Only one VEC_SIZE at a time
>            since data is only aligned to VEC_SIZE.  */
> -       VPCMP   $0, (%rdi), %YMMZERO, %k0
> -       kmovd   %k0, %eax
> -       testl   %eax, %eax
> -       jnz     L(first_vec_x0)
> -
> +# ifdef USE_AS_STRNLEN
> +#  ifdef USE_AS_WCSLEN
> +       salq    $2, %rsi
> +#  endif
> +       /* + CHAR_SIZE because it simplies the logic in
> +          last_4x_vec_or_less.  */
> +       leaq    (VEC_SIZE * 5 + CHAR_SIZE)(%rdi), %rcx
> +       subq    %rdx, %rcx
> +# endif
> +       /* Load first VEC regardless.  */
>         VPCMP   $0, VEC_SIZE(%rdi), %YMMZERO, %k0
> +# ifdef USE_AS_STRNLEN
> +       /* Adjust length. If near end handle specially.  */
> +       subq    %rcx, %rsi
> +       jb      L(last_4x_vec_or_less)
> +# endif
>         kmovd   %k0, %eax
>         testl   %eax, %eax
>         jnz     L(first_vec_x1)
>
>         VPCMP   $0, (VEC_SIZE * 2)(%rdi), %YMMZERO, %k0
>         kmovd   %k0, %eax
> -       testl   %eax, %eax
> +       test    %eax, %eax
>         jnz     L(first_vec_x2)
>
>         VPCMP   $0, (VEC_SIZE * 3)(%rdi), %YMMZERO, %k0
> @@ -179,258 +218,264 @@ L(more_4x_vec):
>         testl   %eax, %eax
>         jnz     L(first_vec_x3)
>
> -       addq    $(VEC_SIZE * 4), %rdi
> -
> -# ifdef USE_AS_STRNLEN
> -       subq    $(VEC_SIZE * 4), %rsi
> -       jbe     L(last_4x_vec_or_less)
> -# endif
> -
> -       /* Align data to 4 * VEC_SIZE.  */
> -       movq    %rdi, %rcx
> -       andl    $(4 * VEC_SIZE - 1), %ecx
> -       andq    $-(4 * VEC_SIZE), %rdi
> +       VPCMP   $0, (VEC_SIZE * 4)(%rdi), %YMMZERO, %k0
> +       kmovd   %k0, %eax
> +       testl   %eax, %eax
> +       jnz     L(first_vec_x4)
>
> +       addq    $VEC_SIZE, %rdi
>  # ifdef USE_AS_STRNLEN
> -       /* Adjust length.  */
> +       /* Check if at last VEC_SIZE * 4 length.  */
> +       cmpq    $(VEC_SIZE * 4 - 1), %rsi
> +       jbe     L(last_4x_vec_or_less_load)
> +       movl    %edi, %ecx
> +       andl    $(VEC_SIZE * 4 - 1), %ecx
> +       /* Readjust length.  */
>         addq    %rcx, %rsi
>  # endif
> +       /* Align data to VEC_SIZE * 4.  */
> +       andq    $-(VEC_SIZE * 4), %rdi
>
> +       /* Compare 4 * VEC at a time forward.  */
>         .p2align 4
>  L(loop_4x_vec):
> -       /* Compare 4 * VEC at a time forward.  */
> -       VMOVA   (%rdi), %YMM1
> -       VMOVA   VEC_SIZE(%rdi), %YMM2
> -       VMOVA   (VEC_SIZE * 2)(%rdi), %YMM3
> -       VMOVA   (VEC_SIZE * 3)(%rdi), %YMM4
> -
> -       VPMINU  %YMM1, %YMM2, %YMM5
> -       VPMINU  %YMM3, %YMM4, %YMM6
> +       /* Load first VEC regardless.  */
> +       VMOVA   (VEC_SIZE * 4)(%rdi), %YMM1
> +# ifdef USE_AS_STRNLEN
> +       /* Break if at end of length.  */
> +       subq    $(VEC_SIZE * 4), %rsi
> +       jb      L(last_4x_vec_or_less_cmpeq)
> +# endif
> +       VPMINU  (VEC_SIZE * 5)(%rdi), %YMM1, %YMM2
> +       VMOVA   (VEC_SIZE * 6)(%rdi), %YMM3
> +       VPMINU  (VEC_SIZE * 7)(%rdi), %YMM3, %YMM4
> +       VPCMP   $0, %YMM2, %YMMZERO, %k0
> +       VPCMP   $0, %YMM4, %YMMZERO, %k1
> +       subq    $-(VEC_SIZE * 4), %rdi
> +       kortestd        %k0, %k1
> +       jz      L(loop_4x_vec)
> +
> +       /* Check if end was in first half.  */
> +       kmovd   %k0, %eax
> +       subq    %rdx, %rdi
> +# ifdef USE_AS_WCSLEN
> +       shrq    $2, %rdi
> +# endif
> +       testl   %eax, %eax
> +       jz      L(second_vec_return)
>
> -       VPMINU  %YMM5, %YMM6, %YMM5
> -       VPCMP   $0, %YMM5, %YMMZERO, %k0
> -       ktestd  %k0, %k0
> -       jnz     L(4x_vec_end)
> +       VPCMP   $0, %YMM1, %YMMZERO, %k2
> +       kmovd   %k2, %edx
> +       /* Combine YMM1 matches (k2) with YMM2 matches (k0).  */
> +# ifdef USE_AS_WCSLEN
> +       sall    $CHAR_PER_VEC, %eax
> +       orl     %edx, %eax
> +       tzcntl  %eax, %eax
> +# else
> +       salq    $CHAR_PER_VEC, %rax
> +       orq     %rdx, %rax
> +       tzcntq  %rax, %rax
> +# endif
> +       addq    %rdi, %rax
> +       ret
>
> -       addq    $(VEC_SIZE * 4), %rdi
>
> -# ifndef USE_AS_STRNLEN
> -       jmp     L(loop_4x_vec)
> -# else
> -       subq    $(VEC_SIZE * 4), %rsi
> -       ja      L(loop_4x_vec)
> +# ifdef USE_AS_STRNLEN
>
> +L(last_4x_vec_or_less_load):
> +       /* Depending on entry adjust rdi / prepare first VEC in YMM1.  */
> +       VMOVA   (VEC_SIZE * 4)(%rdi), %YMM1
> +L(last_4x_vec_or_less_cmpeq):
> +       VPCMP   $0, %YMM1, %YMMZERO, %k0
> +       addq    $(VEC_SIZE * 3), %rdi
>  L(last_4x_vec_or_less):
> -       /* Less than 4 * VEC and aligned to VEC_SIZE.  */
> -       addl    $(VEC_SIZE * 2), %esi
> -       jle     L(last_2x_vec)
> -
> -       VPCMP   $0, (%rdi), %YMMZERO, %k0
>         kmovd   %k0, %eax
> -       testl   %eax, %eax
> -       jnz     L(first_vec_x0)
> +       /* If remaining length > VEC_SIZE * 2.  */
> +       testl   $(VEC_SIZE * 2), %esi
> +       jnz     L(last_4x_vec)
>
> -       VPCMP   $0, VEC_SIZE(%rdi), %YMMZERO, %k0
> -       kmovd   %k0, %eax
> +       /* length may have been negative or positive depending on where
> +          this was called from. This fixes that.  */
> +       andl    $(VEC_SIZE * 4 - 1), %esi
>         testl   %eax, %eax
> -       jnz     L(first_vec_x1)
> +       jnz     L(last_vec_x1_check)
>
> -       VPCMP   $0, (VEC_SIZE * 2)(%rdi), %YMMZERO, %k0
> -       kmovd   %k0, %eax
> -       testl   %eax, %eax
> -       jnz     L(first_vec_x2_check)
>         subl    $VEC_SIZE, %esi
> -       jle     L(max)
> +       jb      L(max)
>
> -       VPCMP   $0, (VEC_SIZE * 3)(%rdi), %YMMZERO, %k0
> +       VPCMP   $0, (VEC_SIZE * 2)(%rdi), %YMMZERO, %k0
>         kmovd   %k0, %eax
> -       testl   %eax, %eax
> -       jnz     L(first_vec_x3_check)
> -       movq    %r8, %rax
> +       tzcntl  %eax, %eax
>  #  ifdef USE_AS_WCSLEN
> -       shrq    $2, %rax
> +       sarl    $2, %esi
>  #  endif
> -       ret
> -
> -       .p2align 4
> -L(last_2x_vec):
> -       addl    $(VEC_SIZE * 2), %esi
> -
> -       VPCMP   $0, (%rdi), %YMMZERO, %k0
> -       kmovd   %k0, %eax
> -       testl   %eax, %eax
> -       jnz     L(first_vec_x0_check)
> -       subl    $VEC_SIZE, %esi
> -       jle     L(max)
> +       /* Check the end of data.  */
> +       cmpl    %eax, %esi
> +       jb      L(max)
>
> -       VPCMP   $0, VEC_SIZE(%rdi), %YMMZERO, %k0
> -       kmovd   %k0, %eax
> -       testl   %eax, %eax
> -       jnz     L(first_vec_x1_check)
> -       movq    %r8, %rax
> +       subq    %rdx, %rdi
>  #  ifdef USE_AS_WCSLEN
> -       shrq    $2, %rax
> +       sarq    $2, %rdi
>  #  endif
> +       leaq    (CHAR_PER_VEC * 2)(%rdi, %rax), %rax
> +       ret
> +L(max):
> +       movq    %r8, %rax
>         ret
> +# endif
>
>         .p2align 4
> -L(first_vec_x0_check):
> +L(second_vec_return):
> +       VPCMP   $0, %YMM3, %YMMZERO, %k0
> +       /* Combine YMM3 matches (k0) with YMM4 matches (k1).  */
> +# ifdef USE_AS_WCSLEN
> +       kunpckbw        %k0, %k1, %k0
> +       kmovd   %k0, %eax
> +       tzcntl  %eax, %eax
> +# else
> +       kunpckdq        %k0, %k1, %k0
> +       kmovq   %k0, %rax
> +       tzcntq  %rax, %rax
> +# endif
> +       leaq    (CHAR_PER_VEC * 2)(%rdi, %rax), %rax
> +       ret
> +
> +
> +# ifdef USE_AS_STRNLEN
> +L(last_vec_x1_check):
>         tzcntl  %eax, %eax
>  #  ifdef USE_AS_WCSLEN
> -       /* NB: Multiply wchar_t count by 4 to get the number of bytes.  */
> -       sall    $2, %eax
> +       sarl    $2, %esi
>  #  endif
>         /* Check the end of data.  */
> -       cmpq    %rax, %rsi
> -       jbe     L(max)
> -       addq    %rdi, %rax
> -       subq    %rdx, %rax
> +       cmpl    %eax, %esi
> +       jb      L(max)
> +       subq    %rdx, %rdi
>  #  ifdef USE_AS_WCSLEN
> -       shrq    $2, %rax
> +       sarq    $2, %rdi
>  #  endif
> +       leaq    (CHAR_PER_VEC)(%rdi, %rax), %rax
>         ret
>
>         .p2align 4
> -L(first_vec_x1_check):
> +L(last_4x_vec):
> +       /* Test first 2x VEC normally.  */
> +       testl   %eax, %eax
> +       jnz     L(last_vec_x1)
> +
> +       VPCMP   $0, (VEC_SIZE * 2)(%rdi), %YMMZERO, %k0
> +       kmovd   %k0, %eax
> +       testl   %eax, %eax
> +       jnz     L(last_vec_x2)
> +
> +       /* Normalize length.  */
> +       andl    $(VEC_SIZE * 4 - 1), %esi
> +       VPCMP   $0, (VEC_SIZE * 3)(%rdi), %YMMZERO, %k0
> +       kmovd   %k0, %eax
> +       testl   %eax, %eax
> +       jnz     L(last_vec_x3)
> +
> +       subl    $(VEC_SIZE * 3), %esi
> +       jb      L(max)
> +
> +       VPCMP   $0, (VEC_SIZE * 4)(%rdi), %YMMZERO, %k0
> +       kmovd   %k0, %eax
>         tzcntl  %eax, %eax
>  #  ifdef USE_AS_WCSLEN
> -       /* NB: Multiply wchar_t count by 4 to get the number of bytes.  */
> -       sall    $2, %eax
> +       sarl    $2, %esi
>  #  endif
>         /* Check the end of data.  */
> -       cmpq    %rax, %rsi
> -       jbe     L(max)
> -       addq    $VEC_SIZE, %rax
> -       addq    %rdi, %rax
> -       subq    %rdx, %rax
> +       cmpl    %eax, %esi
> +       jb      L(max_end)
> +
> +       subq    %rdx, %rdi
>  #  ifdef USE_AS_WCSLEN
> -       shrq    $2, %rax
> +       sarq    $2, %rdi
>  #  endif
> +       leaq    (CHAR_PER_VEC * 4)(%rdi, %rax), %rax
>         ret
>
>         .p2align 4
> -L(first_vec_x2_check):
> +L(last_vec_x1):
>         tzcntl  %eax, %eax
> +       subq    %rdx, %rdi
>  #  ifdef USE_AS_WCSLEN
> -       /* NB: Multiply wchar_t count by 4 to get the number of bytes.  */
> -       sall    $2, %eax
> +       sarq    $2, %rdi
>  #  endif
> -       /* Check the end of data.  */
> -       cmpq    %rax, %rsi
> -       jbe     L(max)
> -       addq    $(VEC_SIZE * 2), %rax
> -       addq    %rdi, %rax
> -       subq    %rdx, %rax
> +       leaq    (CHAR_PER_VEC)(%rdi, %rax), %rax
> +       ret
> +
> +       .p2align 4
> +L(last_vec_x2):
> +       tzcntl  %eax, %eax
> +       subq    %rdx, %rdi
>  #  ifdef USE_AS_WCSLEN
> -       shrq    $2, %rax
> +       sarq    $2, %rdi
>  #  endif
> +       leaq    (CHAR_PER_VEC * 2)(%rdi, %rax), %rax
>         ret
>
>         .p2align 4
> -L(first_vec_x3_check):
> +L(last_vec_x3):
>         tzcntl  %eax, %eax
>  #  ifdef USE_AS_WCSLEN
> -       /* NB: Multiply wchar_t count by 4 to get the number of bytes.  */
> -       sall    $2, %eax
> +       sarl    $2, %esi
>  #  endif
> +       subl    $(CHAR_PER_VEC * 2), %esi
>         /* Check the end of data.  */
> -       cmpq    %rax, %rsi
> -       jbe     L(max)
> -       addq    $(VEC_SIZE * 3), %rax
> -       addq    %rdi, %rax
> -       subq    %rdx, %rax
> +       cmpl    %eax, %esi
> +       jb      L(max_end)
> +       subq    %rdx, %rdi
>  #  ifdef USE_AS_WCSLEN
> -       shrq    $2, %rax
> +       sarq    $2, %rdi
>  #  endif
> +       leaq    (CHAR_PER_VEC * 3)(%rdi, %rax), %rax
>         ret
> -
> -       .p2align 4
> -L(max):
> +L(max_end):
>         movq    %r8, %rax
> -#  ifdef USE_AS_WCSLEN
> -       shrq    $2, %rax
> -#  endif
> -       ret
> -
> -       .p2align 4
> -L(zero):
> -       xorl    %eax, %eax
>         ret
>  # endif
>
> +       /* Cold case for crossing page with first load.  */
>         .p2align 4
> -L(first_vec_x0):
> -       tzcntl  %eax, %eax
> -# ifdef USE_AS_WCSLEN
> -       /* NB: Multiply wchar_t count by 4 to get the number of bytes.  */
> -       sall    $2, %eax
> -# endif
> -       addq    %rdi, %rax
> -       subq    %rdx, %rax
> +L(cross_page_boundary):
> +       movq    %rdi, %rdx
> +       /* Align data to VEC_SIZE.  */
> +       andq    $-VEC_SIZE, %rdi
> +       VPCMP   $0, (%rdi), %YMMZERO, %k0
> +       kmovd   %k0, %eax
> +       /* Remove the leading bytes.  */
>  # ifdef USE_AS_WCSLEN
> -       shrq    $2, %rax
> +       movl    %edx, %ecx
> +       shrl    $2, %ecx
> +       andl    $(CHAR_PER_VEC - 1), %ecx
>  # endif
> -       ret
> -
> -       .p2align 4
> -L(first_vec_x1):
> +       /* SHIFT_REG is ecx for USE_AS_WCSLEN and edx otherwise.  */
> +       sarxl   %SHIFT_REG, %eax, %eax
> +       testl   %eax, %eax
> +# ifndef USE_AS_STRNLEN
> +       jz      L(cross_page_continue)
>         tzcntl  %eax, %eax
> -# ifdef USE_AS_WCSLEN
> -       /* NB: Multiply wchar_t count by 4 to get the number of bytes.  */
> -       sall    $2, %eax
> -# endif
> -       addq    $VEC_SIZE, %rax
> -       addq    %rdi, %rax
> -       subq    %rdx, %rax
> -# ifdef USE_AS_WCSLEN
> -       shrq    $2, %rax
> -# endif
>         ret
> -
> -       .p2align 4
> -L(first_vec_x2):
> -       tzcntl  %eax, %eax
> -# ifdef USE_AS_WCSLEN
> -       /* NB: Multiply wchar_t count by 4 to get the number of bytes.  */
> -       sall    $2, %eax
> -# endif
> -       addq    $(VEC_SIZE * 2), %rax
> -       addq    %rdi, %rax
> -       subq    %rdx, %rax
> -# ifdef USE_AS_WCSLEN
> -       shrq    $2, %rax
> -# endif
> +# else
> +       jnz     L(cross_page_less_vec)
> +#  ifndef USE_AS_WCSLEN
> +       movl    %edx, %ecx
> +       andl    $(CHAR_PER_VEC - 1), %ecx
> +#  endif
> +       movl    $CHAR_PER_VEC, %eax
> +       subl    %ecx, %eax
> +       cmpq    %rax, %rsi
> +       ja      L(cross_page_continue)
> +       movl    %esi, %eax
>         ret
> -
> -       .p2align 4
> -L(4x_vec_end):
> -       VPCMP   $0, %YMM1, %YMMZERO, %k0
> -       kmovd   %k0, %eax
> -       testl   %eax, %eax
> -       jnz     L(first_vec_x0)
> -       VPCMP   $0, %YMM2, %YMMZERO, %k1
> -       kmovd   %k1, %eax
> -       testl   %eax, %eax
> -       jnz     L(first_vec_x1)
> -       VPCMP   $0, %YMM3, %YMMZERO, %k2
> -       kmovd   %k2, %eax
> -       testl   %eax, %eax
> -       jnz     L(first_vec_x2)
> -       VPCMP   $0, %YMM4, %YMMZERO, %k3
> -       kmovd   %k3, %eax
> -L(first_vec_x3):
> +L(cross_page_less_vec):
>         tzcntl  %eax, %eax
> -# ifdef USE_AS_WCSLEN
> -       /* NB: Multiply wchar_t count by 4 to get the number of bytes.  */
> -       sall    $2, %eax
> -# endif
> -       addq    $(VEC_SIZE * 3), %rax
> -       addq    %rdi, %rax
> -       subq    %rdx, %rax
> -# ifdef USE_AS_WCSLEN
> -       shrq    $2, %rax
> -# endif
> +       /* Select min of length and position of first null.  */
> +       cmpq    %rax, %rsi
> +       cmovb   %esi, %eax
>         ret
> +# endif
>
>  END (STRLEN)
>  #endif
> --
> 2.29.2
>
diff mbox series

Patch

diff --git a/sysdeps/x86_64/multiarch/strlen-evex.S b/sysdeps/x86_64/multiarch/strlen-evex.S
index 0583819078..d1aafac76f 100644
--- a/sysdeps/x86_64/multiarch/strlen-evex.S
+++ b/sysdeps/x86_64/multiarch/strlen-evex.S
@@ -29,11 +29,13 @@ 
 # ifdef USE_AS_WCSLEN
 #  define VPCMP		vpcmpd
 #  define VPMINU	vpminud
-#  define SHIFT_REG	r9d
+#  define SHIFT_REG ecx
+#  define CHAR_SIZE	4
 # else
 #  define VPCMP		vpcmpb
 #  define VPMINU	vpminub
-#  define SHIFT_REG	ecx
+#  define SHIFT_REG edx
+#  define CHAR_SIZE	1
 # endif
 
 # define XMMZERO	xmm16
@@ -46,132 +48,169 @@ 
 # define YMM6		ymm22
 
 # define VEC_SIZE 32
+# define PAGE_SIZE 4096
+# define CHAR_PER_VEC (VEC_SIZE / CHAR_SIZE)
 
 	.section .text.evex,"ax",@progbits
 ENTRY (STRLEN)
 # ifdef USE_AS_STRNLEN
-	/* Check for zero length.  */
+	/* Check zero length.  */
 	test	%RSI_LP, %RSI_LP
 	jz	L(zero)
-#  ifdef USE_AS_WCSLEN
-	shl	$2, %RSI_LP
-#  elif defined __ILP32__
+#  if !defined USE_AS_WCSLEN && defined __ILP32__
 	/* Clear the upper 32 bits.  */
 	movl	%esi, %esi
 #  endif
 	mov	%RSI_LP, %R8_LP
 # endif
-	movl	%edi, %ecx
-	movq	%rdi, %rdx
+	movl	%edi, %eax
+	sall	$20, %eax
 	vpxorq	%XMMZERO, %XMMZERO, %XMMZERO
-
 	/* Check if we may cross page boundary with one vector load.  */
-	andl	$(2 * VEC_SIZE - 1), %ecx
-	cmpl	$VEC_SIZE, %ecx
-	ja	L(cros_page_boundary)
+	cmpl	$((PAGE_SIZE - VEC_SIZE) << 20), %eax
+	ja	L(cross_page_boundary)
 
-	/* Check the first VEC_SIZE bytes.  Each bit in K0 represents a
-	   null byte.  */
+	/* Check the first VEC_SIZE bytes.  */
 	VPCMP	$0, (%rdi), %YMMZERO, %k0
 	kmovd	%k0, %eax
-	testl	%eax, %eax
-
 # ifdef USE_AS_STRNLEN
-	jnz	L(first_vec_x0_check)
-	/* Adjust length and check the end of data.  */
-	subq	$VEC_SIZE, %rsi
-	jbe	L(max)
-# else
-	jnz	L(first_vec_x0)
+	/* If length < VEC_SIZE handle special.  */
+	cmpq	$CHAR_PER_VEC, %rsi
+	jbe	L(first_vec_x0)
 # endif
-
-	/* Align data for aligned loads in the loop.  */
-	addq	$VEC_SIZE, %rdi
-	andl	$(VEC_SIZE - 1), %ecx
-	andq	$-VEC_SIZE, %rdi
-
+	testl	%eax, %eax
+	jz	L(aligned_more)
+	tzcntl	%eax, %eax
+	ret
 # ifdef USE_AS_STRNLEN
-	/* Adjust length.  */
-	addq	%rcx, %rsi
+L(zero):
+	xorl	%eax, %eax
+	ret
 
-	subq	$(VEC_SIZE * 4), %rsi
-	jbe	L(last_4x_vec_or_less)
+	.p2align 4
+L(first_vec_x0):
+	/* Select min of length and position of first null.  */
+	btsq	%rsi, %rax
+	tzcntl	%eax, %eax
+	ret
 # endif
-	jmp	L(more_4x_vec)
 
 	.p2align 4
-L(cros_page_boundary):
-	andl	$(VEC_SIZE - 1), %ecx
-	andq	$-VEC_SIZE, %rdi
-
-# ifdef USE_AS_WCSLEN
-	/* NB: Divide shift count by 4 since each bit in K0 represent 4
-	   bytes.  */
-	movl	%ecx, %SHIFT_REG
-	sarl	$2, %SHIFT_REG
+L(first_vec_x1):
+	tzcntl	%eax, %eax
+	/* Safe to use 32 bit instructions as these are only called for
+	   size = [1, 159].  */
+# ifdef USE_AS_STRNLEN
+	/* Use ecx which was computed earlier to compute correct value.
+	*/
+#  ifdef USE_AS_WCSLEN
+	sarl	$2, %ecx
+#  endif
+	leal	-(CHAR_PER_VEC * 4 + 1)(%rcx, %rax), %eax
+# else
+	subl	%edx, %edi
+#  ifdef USE_AS_WCSLEN
+	sarl	$2, %edi
+#  endif
+	leal	CHAR_PER_VEC(%rdi, %rax), %eax
 # endif
-	VPCMP	$0, (%rdi), %YMMZERO, %k0
-	kmovd	%k0, %eax
+	ret
 
-	/* Remove the leading bytes.  */
-	sarxl	%SHIFT_REG, %eax, %eax
-	testl	%eax, %eax
-	jz	L(aligned_more)
+	.p2align 4
+L(first_vec_x2):
 	tzcntl	%eax, %eax
-# ifdef USE_AS_WCSLEN
-	/* NB: Multiply wchar_t count by 4 to get the number of bytes.  */
-	sall	$2, %eax
-# endif
+	/* Safe to use 32 bit instructions as these are only called for
+	   size = [1, 159].  */
 # ifdef USE_AS_STRNLEN
-	/* Check the end of data.  */
-	cmpq	%rax, %rsi
-	jbe	L(max)
-# endif
-	addq	%rdi, %rax
-	addq	%rcx, %rax
-	subq	%rdx, %rax
-# ifdef USE_AS_WCSLEN
-	shrq	$2, %rax
+	/* Use ecx which was computed earlier to compute correct value.
+	*/
+#  ifdef USE_AS_WCSLEN
+	sarl	$2, %ecx
+#  endif
+	leal	-(CHAR_PER_VEC * 3 + 1)(%rcx, %rax), %eax
+# else
+	subl	%edx, %edi
+#  ifdef USE_AS_WCSLEN
+	sarl	$2, %edi
+#  endif
+	leal	(CHAR_PER_VEC * 2)(%rdi, %rax), %eax
 # endif
 	ret
 
 	.p2align 4
-L(aligned_more):
+L(first_vec_x3):
+	tzcntl	%eax, %eax
+	/* Safe to use 32 bit instructions as these are only called for
+	   size = [1, 159].  */
 # ifdef USE_AS_STRNLEN
-        /* "rcx" is less than VEC_SIZE.  Calculate "rdx + rcx - VEC_SIZE"
-	    with "rdx - (VEC_SIZE - rcx)" instead of "(rdx + rcx) - VEC_SIZE"
-	    to void possible addition overflow.  */
-	negq	%rcx
-	addq	$VEC_SIZE, %rcx
-
-	/* Check the end of data.  */
-	subq	%rcx, %rsi
-	jbe	L(max)
+	/* Use ecx which was computed earlier to compute correct value.
+	*/
+#  ifdef USE_AS_WCSLEN
+	sarl	$2, %ecx
+#  endif
+	leal	-(CHAR_PER_VEC * 2 + 1)(%rcx, %rax), %eax
+# else
+	subl	%edx, %edi
+#  ifdef USE_AS_WCSLEN
+	sarl	$2, %edi
+#  endif
+	leal	(CHAR_PER_VEC * 3)(%rdi, %rax), %eax
 # endif
+	ret
 
-	addq	$VEC_SIZE, %rdi
-
+	.p2align 4
+L(first_vec_x4):
+	tzcntl	%eax, %eax
+	/* Safe to use 32 bit instructions as these are only called for
+	   size = [1, 159].  */
 # ifdef USE_AS_STRNLEN
-	subq	$(VEC_SIZE * 4), %rsi
-	jbe	L(last_4x_vec_or_less)
+	/* Use ecx which was computed earlier to compute correct value.
+	*/
+#  ifdef USE_AS_WCSLEN
+	sarl	$2, %ecx
+#  endif
+	leal	-(CHAR_PER_VEC + 1)(%rcx, %rax), %eax
+# else
+	subl	%edx, %edi
+#  ifdef USE_AS_WCSLEN
+	sarl	$2, %edi
+#  endif
+	leal	(CHAR_PER_VEC * 4)(%rdi, %rax), %eax
 # endif
+	ret
 
-L(more_4x_vec):
+	/* strnlen jumps here. strlen falls through.  */
+	.p2align 5
+L(aligned_more):
+	movq	%rdi, %rdx
+	/* Align data to VEC_SIZE.  */
+	andq	$-(VEC_SIZE), %rdi
+L(cross_page_continue):
 	/* Check the first 4 * VEC_SIZE.  Only one VEC_SIZE at a time
 	   since data is only aligned to VEC_SIZE.  */
-	VPCMP	$0, (%rdi), %YMMZERO, %k0
-	kmovd	%k0, %eax
-	testl	%eax, %eax
-	jnz	L(first_vec_x0)
-
+# ifdef USE_AS_STRNLEN
+#  ifdef USE_AS_WCSLEN
+	salq	$2, %rsi
+#  endif
+	/* + CHAR_SIZE because it simplies the logic in
+	   last_4x_vec_or_less.  */
+	leaq	(VEC_SIZE * 5 + CHAR_SIZE)(%rdi), %rcx
+	subq	%rdx, %rcx
+# endif
+	/* Load first VEC regardless.  */
 	VPCMP	$0, VEC_SIZE(%rdi), %YMMZERO, %k0
+# ifdef USE_AS_STRNLEN
+	/* Adjust length. If near end handle specially.  */
+	subq	%rcx, %rsi
+	jb	L(last_4x_vec_or_less)
+# endif
 	kmovd	%k0, %eax
 	testl	%eax, %eax
 	jnz	L(first_vec_x1)
 
 	VPCMP	$0, (VEC_SIZE * 2)(%rdi), %YMMZERO, %k0
 	kmovd	%k0, %eax
-	testl	%eax, %eax
+	test	%eax, %eax
 	jnz	L(first_vec_x2)
 
 	VPCMP	$0, (VEC_SIZE * 3)(%rdi), %YMMZERO, %k0
@@ -179,258 +218,264 @@  L(more_4x_vec):
 	testl	%eax, %eax
 	jnz	L(first_vec_x3)
 
-	addq	$(VEC_SIZE * 4), %rdi
-
-# ifdef USE_AS_STRNLEN
-	subq	$(VEC_SIZE * 4), %rsi
-	jbe	L(last_4x_vec_or_less)
-# endif
-
-	/* Align data to 4 * VEC_SIZE.  */
-	movq	%rdi, %rcx
-	andl	$(4 * VEC_SIZE - 1), %ecx
-	andq	$-(4 * VEC_SIZE), %rdi
+	VPCMP	$0, (VEC_SIZE * 4)(%rdi), %YMMZERO, %k0
+	kmovd	%k0, %eax
+	testl	%eax, %eax
+	jnz	L(first_vec_x4)
 
+	addq	$VEC_SIZE, %rdi
 # ifdef USE_AS_STRNLEN
-	/* Adjust length.  */
+	/* Check if at last VEC_SIZE * 4 length.  */
+	cmpq	$(VEC_SIZE * 4 - 1), %rsi
+	jbe	L(last_4x_vec_or_less_load)
+	movl	%edi, %ecx
+	andl	$(VEC_SIZE * 4 - 1), %ecx
+	/* Readjust length.  */
 	addq	%rcx, %rsi
 # endif
+	/* Align data to VEC_SIZE * 4.  */
+	andq	$-(VEC_SIZE * 4), %rdi
 
+	/* Compare 4 * VEC at a time forward.  */
 	.p2align 4
 L(loop_4x_vec):
-	/* Compare 4 * VEC at a time forward.  */
-	VMOVA	(%rdi), %YMM1
-	VMOVA	VEC_SIZE(%rdi), %YMM2
-	VMOVA	(VEC_SIZE * 2)(%rdi), %YMM3
-	VMOVA	(VEC_SIZE * 3)(%rdi), %YMM4
-
-	VPMINU	%YMM1, %YMM2, %YMM5
-	VPMINU	%YMM3, %YMM4, %YMM6
+	/* Load first VEC regardless.  */
+	VMOVA	(VEC_SIZE * 4)(%rdi), %YMM1
+# ifdef USE_AS_STRNLEN
+	/* Break if at end of length.  */
+	subq	$(VEC_SIZE * 4), %rsi
+	jb	L(last_4x_vec_or_less_cmpeq)
+# endif
+	VPMINU	(VEC_SIZE * 5)(%rdi), %YMM1, %YMM2
+	VMOVA	(VEC_SIZE * 6)(%rdi), %YMM3
+	VPMINU	(VEC_SIZE * 7)(%rdi), %YMM3, %YMM4
+	VPCMP	$0, %YMM2, %YMMZERO, %k0
+	VPCMP	$0, %YMM4, %YMMZERO, %k1
+	subq	$-(VEC_SIZE * 4), %rdi
+	kortestd	%k0, %k1
+	jz	L(loop_4x_vec)
+
+	/* Check if end was in first half.  */
+	kmovd	%k0, %eax
+	subq	%rdx, %rdi
+# ifdef USE_AS_WCSLEN
+	shrq	$2, %rdi
+# endif
+	testl	%eax, %eax
+	jz	L(second_vec_return)
 
-	VPMINU	%YMM5, %YMM6, %YMM5
-	VPCMP	$0, %YMM5, %YMMZERO, %k0
-	ktestd	%k0, %k0
-	jnz	L(4x_vec_end)
+	VPCMP	$0, %YMM1, %YMMZERO, %k2
+	kmovd	%k2, %edx
+	/* Combine YMM1 matches (k2) with YMM2 matches (k0).  */
+# ifdef USE_AS_WCSLEN
+	sall	$CHAR_PER_VEC, %eax
+	orl	%edx, %eax
+	tzcntl	%eax, %eax
+# else
+	salq	$CHAR_PER_VEC, %rax
+	orq	%rdx, %rax
+	tzcntq	%rax, %rax
+# endif
+	addq	%rdi, %rax
+	ret
 
-	addq	$(VEC_SIZE * 4), %rdi
 
-# ifndef USE_AS_STRNLEN
-	jmp	L(loop_4x_vec)
-# else
-	subq	$(VEC_SIZE * 4), %rsi
-	ja	L(loop_4x_vec)
+# ifdef USE_AS_STRNLEN
 
+L(last_4x_vec_or_less_load):
+	/* Depending on entry adjust rdi / prepare first VEC in YMM1.  */
+	VMOVA	(VEC_SIZE * 4)(%rdi), %YMM1
+L(last_4x_vec_or_less_cmpeq):
+	VPCMP	$0, %YMM1, %YMMZERO, %k0
+	addq	$(VEC_SIZE * 3), %rdi
 L(last_4x_vec_or_less):
-	/* Less than 4 * VEC and aligned to VEC_SIZE.  */
-	addl	$(VEC_SIZE * 2), %esi
-	jle	L(last_2x_vec)
-
-	VPCMP	$0, (%rdi), %YMMZERO, %k0
 	kmovd	%k0, %eax
-	testl	%eax, %eax
-	jnz	L(first_vec_x0)
+	/* If remaining length > VEC_SIZE * 2.  */
+	testl	$(VEC_SIZE * 2), %esi
+	jnz	L(last_4x_vec)
 
-	VPCMP	$0, VEC_SIZE(%rdi), %YMMZERO, %k0
-	kmovd	%k0, %eax
+	/* length may have been negative or positive depending on where
+	   this was called from. This fixes that.  */
+	andl	$(VEC_SIZE * 4 - 1), %esi
 	testl	%eax, %eax
-	jnz	L(first_vec_x1)
+	jnz	L(last_vec_x1_check)
 
-	VPCMP	$0, (VEC_SIZE * 2)(%rdi), %YMMZERO, %k0
-	kmovd	%k0, %eax
-	testl	%eax, %eax
-	jnz	L(first_vec_x2_check)
 	subl	$VEC_SIZE, %esi
-	jle	L(max)
+	jb	L(max)
 
-	VPCMP	$0, (VEC_SIZE * 3)(%rdi), %YMMZERO, %k0
+	VPCMP	$0, (VEC_SIZE * 2)(%rdi), %YMMZERO, %k0
 	kmovd	%k0, %eax
-	testl	%eax, %eax
-	jnz	L(first_vec_x3_check)
-	movq	%r8, %rax
+	tzcntl	%eax, %eax
 #  ifdef USE_AS_WCSLEN
-	shrq	$2, %rax
+	sarl	$2, %esi
 #  endif
-	ret
-
-	.p2align 4
-L(last_2x_vec):
-	addl	$(VEC_SIZE * 2), %esi
-
-	VPCMP	$0, (%rdi), %YMMZERO, %k0
-	kmovd	%k0, %eax
-	testl	%eax, %eax
-	jnz	L(first_vec_x0_check)
-	subl	$VEC_SIZE, %esi
-	jle	L(max)
+	/* Check the end of data.  */
+	cmpl	%eax, %esi
+	jb	L(max)
 
-	VPCMP	$0, VEC_SIZE(%rdi), %YMMZERO, %k0
-	kmovd	%k0, %eax
-	testl	%eax, %eax
-	jnz	L(first_vec_x1_check)
-	movq	%r8, %rax
+	subq	%rdx, %rdi
 #  ifdef USE_AS_WCSLEN
-	shrq	$2, %rax
+	sarq	$2, %rdi
 #  endif
+	leaq	(CHAR_PER_VEC * 2)(%rdi, %rax), %rax
+	ret
+L(max):
+	movq	%r8, %rax
 	ret
+# endif
 
 	.p2align 4
-L(first_vec_x0_check):
+L(second_vec_return):
+	VPCMP	$0, %YMM3, %YMMZERO, %k0
+	/* Combine YMM3 matches (k0) with YMM4 matches (k1).  */
+# ifdef USE_AS_WCSLEN
+	kunpckbw	%k0, %k1, %k0
+	kmovd	%k0, %eax
+	tzcntl	%eax, %eax
+# else
+	kunpckdq	%k0, %k1, %k0
+	kmovq	%k0, %rax
+	tzcntq	%rax, %rax
+# endif
+	leaq	(CHAR_PER_VEC * 2)(%rdi, %rax), %rax
+	ret
+
+
+# ifdef USE_AS_STRNLEN
+L(last_vec_x1_check):
 	tzcntl	%eax, %eax
 #  ifdef USE_AS_WCSLEN
-	/* NB: Multiply wchar_t count by 4 to get the number of bytes.  */
-	sall	$2, %eax
+	sarl	$2, %esi
 #  endif
 	/* Check the end of data.  */
-	cmpq	%rax, %rsi
-	jbe	L(max)
-	addq	%rdi, %rax
-	subq	%rdx, %rax
+	cmpl	%eax, %esi
+	jb	L(max)
+	subq	%rdx, %rdi
 #  ifdef USE_AS_WCSLEN
-	shrq	$2, %rax
+	sarq	$2, %rdi
 #  endif
+	leaq	(CHAR_PER_VEC)(%rdi, %rax), %rax
 	ret
 
 	.p2align 4
-L(first_vec_x1_check):
+L(last_4x_vec):
+	/* Test first 2x VEC normally.  */
+	testl	%eax, %eax
+	jnz	L(last_vec_x1)
+
+	VPCMP	$0, (VEC_SIZE * 2)(%rdi), %YMMZERO, %k0
+	kmovd	%k0, %eax
+	testl	%eax, %eax
+	jnz	L(last_vec_x2)
+
+	/* Normalize length.  */
+	andl	$(VEC_SIZE * 4 - 1), %esi
+	VPCMP	$0, (VEC_SIZE * 3)(%rdi), %YMMZERO, %k0
+	kmovd	%k0, %eax
+	testl	%eax, %eax
+	jnz	L(last_vec_x3)
+
+	subl	$(VEC_SIZE * 3), %esi
+	jb	L(max)
+
+	VPCMP	$0, (VEC_SIZE * 4)(%rdi), %YMMZERO, %k0
+	kmovd	%k0, %eax
 	tzcntl	%eax, %eax
 #  ifdef USE_AS_WCSLEN
-	/* NB: Multiply wchar_t count by 4 to get the number of bytes.  */
-	sall	$2, %eax
+	sarl	$2, %esi
 #  endif
 	/* Check the end of data.  */
-	cmpq	%rax, %rsi
-	jbe	L(max)
-	addq	$VEC_SIZE, %rax
-	addq	%rdi, %rax
-	subq	%rdx, %rax
+	cmpl	%eax, %esi
+	jb	L(max_end)
+
+	subq	%rdx, %rdi
 #  ifdef USE_AS_WCSLEN
-	shrq	$2, %rax
+	sarq	$2, %rdi
 #  endif
+	leaq	(CHAR_PER_VEC * 4)(%rdi, %rax), %rax
 	ret
 
 	.p2align 4
-L(first_vec_x2_check):
+L(last_vec_x1):
 	tzcntl	%eax, %eax
+	subq	%rdx, %rdi
 #  ifdef USE_AS_WCSLEN
-	/* NB: Multiply wchar_t count by 4 to get the number of bytes.  */
-	sall	$2, %eax
+	sarq	$2, %rdi
 #  endif
-	/* Check the end of data.  */
-	cmpq	%rax, %rsi
-	jbe	L(max)
-	addq	$(VEC_SIZE * 2), %rax
-	addq	%rdi, %rax
-	subq	%rdx, %rax
+	leaq	(CHAR_PER_VEC)(%rdi, %rax), %rax
+	ret
+
+	.p2align 4
+L(last_vec_x2):
+	tzcntl	%eax, %eax
+	subq	%rdx, %rdi
 #  ifdef USE_AS_WCSLEN
-	shrq	$2, %rax
+	sarq	$2, %rdi
 #  endif
+	leaq	(CHAR_PER_VEC * 2)(%rdi, %rax), %rax
 	ret
 
 	.p2align 4
-L(first_vec_x3_check):
+L(last_vec_x3):
 	tzcntl	%eax, %eax
 #  ifdef USE_AS_WCSLEN
-	/* NB: Multiply wchar_t count by 4 to get the number of bytes.  */
-	sall	$2, %eax
+	sarl	$2, %esi
 #  endif
+	subl	$(CHAR_PER_VEC * 2), %esi
 	/* Check the end of data.  */
-	cmpq	%rax, %rsi
-	jbe	L(max)
-	addq	$(VEC_SIZE * 3), %rax
-	addq	%rdi, %rax
-	subq	%rdx, %rax
+	cmpl	%eax, %esi
+	jb	L(max_end)
+	subq	%rdx, %rdi
 #  ifdef USE_AS_WCSLEN
-	shrq	$2, %rax
+	sarq	$2, %rdi
 #  endif
+	leaq	(CHAR_PER_VEC * 3)(%rdi, %rax), %rax
 	ret
-
-	.p2align 4
-L(max):
+L(max_end):
 	movq	%r8, %rax
-#  ifdef USE_AS_WCSLEN
-	shrq	$2, %rax
-#  endif
-	ret
-
-	.p2align 4
-L(zero):
-	xorl	%eax, %eax
 	ret
 # endif
 
+	/* Cold case for crossing page with first load.	 */
 	.p2align 4
-L(first_vec_x0):
-	tzcntl	%eax, %eax
-# ifdef USE_AS_WCSLEN
-	/* NB: Multiply wchar_t count by 4 to get the number of bytes.  */
-	sall	$2, %eax
-# endif
-	addq	%rdi, %rax
-	subq	%rdx, %rax
+L(cross_page_boundary):
+	movq	%rdi, %rdx
+	/* Align data to VEC_SIZE.  */
+	andq	$-VEC_SIZE, %rdi
+	VPCMP	$0, (%rdi), %YMMZERO, %k0
+	kmovd	%k0, %eax
+	/* Remove the leading bytes.  */
 # ifdef USE_AS_WCSLEN
-	shrq	$2, %rax
+	movl	%edx, %ecx
+	shrl	$2, %ecx
+	andl	$(CHAR_PER_VEC - 1), %ecx
 # endif
-	ret
-
-	.p2align 4
-L(first_vec_x1):
+	/* SHIFT_REG is ecx for USE_AS_WCSLEN and edx otherwise.  */
+	sarxl	%SHIFT_REG, %eax, %eax
+	testl	%eax, %eax
+# ifndef USE_AS_STRNLEN
+	jz	L(cross_page_continue)
 	tzcntl	%eax, %eax
-# ifdef USE_AS_WCSLEN
-	/* NB: Multiply wchar_t count by 4 to get the number of bytes.  */
-	sall	$2, %eax
-# endif
-	addq	$VEC_SIZE, %rax
-	addq	%rdi, %rax
-	subq	%rdx, %rax
-# ifdef USE_AS_WCSLEN
-	shrq	$2, %rax
-# endif
 	ret
-
-	.p2align 4
-L(first_vec_x2):
-	tzcntl	%eax, %eax
-# ifdef USE_AS_WCSLEN
-	/* NB: Multiply wchar_t count by 4 to get the number of bytes.  */
-	sall	$2, %eax
-# endif
-	addq	$(VEC_SIZE * 2), %rax
-	addq	%rdi, %rax
-	subq	%rdx, %rax
-# ifdef USE_AS_WCSLEN
-	shrq	$2, %rax
-# endif
+# else
+	jnz	L(cross_page_less_vec)
+#  ifndef USE_AS_WCSLEN
+	movl	%edx, %ecx
+	andl	$(CHAR_PER_VEC - 1), %ecx
+#  endif
+	movl	$CHAR_PER_VEC, %eax
+	subl	%ecx, %eax
+	cmpq	%rax, %rsi
+	ja	L(cross_page_continue)
+	movl	%esi, %eax
 	ret
-
-	.p2align 4
-L(4x_vec_end):
-	VPCMP	$0, %YMM1, %YMMZERO, %k0
-	kmovd	%k0, %eax
-	testl	%eax, %eax
-	jnz	L(first_vec_x0)
-	VPCMP	$0, %YMM2, %YMMZERO, %k1
-	kmovd	%k1, %eax
-	testl	%eax, %eax
-	jnz	L(first_vec_x1)
-	VPCMP	$0, %YMM3, %YMMZERO, %k2
-	kmovd	%k2, %eax
-	testl	%eax, %eax
-	jnz	L(first_vec_x2)
-	VPCMP	$0, %YMM4, %YMMZERO, %k3
-	kmovd	%k3, %eax
-L(first_vec_x3):
+L(cross_page_less_vec):
 	tzcntl	%eax, %eax
-# ifdef USE_AS_WCSLEN
-	/* NB: Multiply wchar_t count by 4 to get the number of bytes.  */
-	sall	$2, %eax
-# endif
-	addq	$(VEC_SIZE * 3), %rax
-	addq	%rdi, %rax
-	subq	%rdx, %rax
-# ifdef USE_AS_WCSLEN
-	shrq	$2, %rax
-# endif
+	/* Select min of length and position of first null.  */
+	cmpq	%rax, %rsi
+	cmovb	%esi, %eax
 	ret
+# endif
 
 END (STRLEN)
 #endif