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
|
/* Optimized strlen implementation for PowerPC64/POWER9.
Copyright (C) 2020-2022 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <sysdep.h>
#ifndef STRLEN
# define STRLEN __strlen
# define DEFINE_STRLEN_HIDDEN_DEF 1
#endif
/* Implements the function
int [r3] strlen (const void *s [r3])
The implementation can load bytes past a matching byte, but only
up to the next 64B boundary, so it never crosses a page. */
.machine power9
ENTRY_TOCLESS (STRLEN, 4)
CALL_MCOUNT 2
vspltisb v18,0
vspltisb v19,-1
neg r5,r3
rldicl r9,r5,0,60 /* How many bytes to get source 16B aligned? */
/* Align data and fill bytes not loaded with non matching char. */
lvx v0,0,r3
lvsr v1,0,r3
vperm v0,v19,v0,v1
vcmpequb. v6,v0,v18
beq cr6,L(aligned)
vctzlsbb r3,v6
blr
/* Test 64B 16B at a time. The 64B vector loop is optimized for
longer strings. Likewise, we check a multiple of 64B to avoid
breaking the alignment calculation below. */
L(aligned):
add r4,r3,r9
rldicl. r5,r4,60,62 /* Determine the number of 48B loops needed for
alignment to 64B. And test for zero. */
lxv v0+32,0(r4)
vcmpequb. v6,v0,v18
bne cr6,L(tail1)
lxv v0+32,16(r4)
vcmpequb. v6,v0,v18
bne cr6,L(tail2)
lxv v0+32,32(r4)
vcmpequb. v6,v0,v18
bne cr6,L(tail3)
lxv v0+32,48(r4)
vcmpequb. v6,v0,v18
bne cr6,L(tail4)
addi r4,r4,64
/* Speculatively generate a fake 16B aligned address to generate the
vector byte constant 0,1,..,15 using lvsl during reduction. */
li r0,0
/* Skip the alignment if already 64B aligned. */
beq L(loop_64b)
mtctr r5
/* Test 48B per iteration until 64B aligned. */
.p2align 5
L(loop):
lxv v0+32,0(r4)
vcmpequb. v6,v0,v18
bne cr6,L(tail1)
lxv v0+32,16(r4)
vcmpequb. v6,v0,v18
bne cr6,L(tail2)
lxv v0+32,32(r4)
vcmpequb. v6,v0,v18
bne cr6,L(tail3)
addi r4,r4,48
bdnz L(loop)
.p2align 5
L(loop_64b):
lxv v1+32,0(r4) /* Load 4 quadwords. */
lxv v2+32,16(r4)
lxv v3+32,32(r4)
lxv v4+32,48(r4)
vminub v5,v1,v2 /* Compare and merge into one VR for speed. */
vminub v6,v3,v4
vminub v7,v5,v6
vcmpequb. v7,v7,v18 /* Check for NULLs. */
addi r4,r4,64 /* Adjust address for the next iteration. */
bne cr6,L(vmx_zero)
lxv v1+32,0(r4) /* Load 4 quadwords. */
lxv v2+32,16(r4)
lxv v3+32,32(r4)
lxv v4+32,48(r4)
vminub v5,v1,v2 /* Compare and merge into one VR for speed. */
vminub v6,v3,v4
vminub v7,v5,v6
vcmpequb. v7,v7,v18 /* Check for NULLs. */
addi r4,r4,64 /* Adjust address for the next iteration. */
bne cr6,L(vmx_zero)
lxv v1+32,0(r4) /* Load 4 quadwords. */
lxv v2+32,16(r4)
lxv v3+32,32(r4)
lxv v4+32,48(r4)
vminub v5,v1,v2 /* Compare and merge into one VR for speed. */
vminub v6,v3,v4
vminub v7,v5,v6
vcmpequb. v7,v7,v18 /* Check for NULLs. */
addi r4,r4,64 /* Adjust address for the next iteration. */
beq cr6,L(loop_64b)
L(vmx_zero):
/* OK, we found a null byte. Let's look for it in the current 64-byte
block and mark it in its corresponding VR. */
vcmpequb v1,v1,v18
vcmpequb v2,v2,v18
vcmpequb v3,v3,v18
vcmpequb v4,v4,v18
/* We will now 'compress' the result into a single doubleword, so it
can be moved to a GPR for the final calculation. First, we
generate an appropriate mask for vbpermq, so we can permute bits into
the first halfword. */
vspltisb v10,3
lvsl v11,0,r0
vslb v10,v11,v10
/* Permute the first bit of each byte into bits 48-63. */
vbpermq v1,v1,v10
vbpermq v2,v2,v10
vbpermq v3,v3,v10
vbpermq v4,v4,v10
/* Shift each component into its correct position for merging. */
vsldoi v2,v2,v2,2
vsldoi v3,v3,v3,4
vsldoi v4,v4,v4,6
/* Merge the results and move to a GPR. */
vor v1,v2,v1
vor v2,v3,v4
vor v4,v1,v2
mfvrd r10,v4
/* Adjust address to the begninning of the current 64-byte block. */
addi r4,r4,-64
cnttzd r0,r10 /* Count trailing zeros before the match. */
subf r5,r3,r4
add r3,r5,r0 /* Compute final length. */
blr
L(tail1):
vctzlsbb r0,v6
add r4,r4,r0
subf r3,r3,r4
blr
L(tail2):
vctzlsbb r0,v6
add r4,r4,r0
addi r4,r4,16
subf r3,r3,r4
blr
L(tail3):
vctzlsbb r0,v6
add r4,r4,r0
addi r4,r4,32
subf r3,r3,r4
blr
L(tail4):
vctzlsbb r0,v6
add r4,r4,r0
addi r4,r4,48
subf r3,r3,r4
blr
END (STRLEN)
#ifdef DEFINE_STRLEN_HIDDEN_DEF
weak_alias (__strlen, strlen)
libc_hidden_builtin_def (strlen)
#endif
|
