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
|
/* memcmp - compare memory
*
* Copyright (c) 2013-2022, Arm Limited.
* SPDX-License-Identifier: MIT OR Apache-2.0 WITH LLVM-exception
*/
/* Assumptions:
*
* ARMv8-a, AArch64, Advanced SIMD, unaligned accesses.
*/
#include "asmdefs.h"
#define src1 x0
#define src2 x1
#define limit x2
#define result w0
#define data1 x3
#define data1w w3
#define data2 x4
#define data2w w4
#define data3 x5
#define data3w w5
#define data4 x6
#define data4w w6
#define tmp x6
#define src1end x7
#define src2end x8
ENTRY (__memcmp_aarch64)
PTR_ARG (0)
PTR_ARG (1)
SIZE_ARG (2)
cmp limit, 16
b.lo L(less16)
ldp data1, data3, [src1]
ldp data2, data4, [src2]
ccmp data1, data2, 0, ne
ccmp data3, data4, 0, eq
b.ne L(return2)
add src1end, src1, limit
add src2end, src2, limit
cmp limit, 32
b.ls L(last_bytes)
cmp limit, 160
b.hs L(loop_align)
sub limit, limit, 32
.p2align 4
L(loop32):
ldp data1, data3, [src1, 16]
ldp data2, data4, [src2, 16]
cmp data1, data2
ccmp data3, data4, 0, eq
b.ne L(return2)
cmp limit, 16
b.ls L(last_bytes)
ldp data1, data3, [src1, 32]
ldp data2, data4, [src2, 32]
cmp data1, data2
ccmp data3, data4, 0, eq
b.ne L(return2)
add src1, src1, 32
add src2, src2, 32
L(last64):
subs limit, limit, 32
b.hi L(loop32)
/* Compare last 1-16 bytes using unaligned access. */
L(last_bytes):
ldp data1, data3, [src1end, -16]
ldp data2, data4, [src2end, -16]
L(return2):
cmp data1, data2
csel data1, data1, data3, ne
csel data2, data2, data4, ne
/* Compare data bytes and set return value to 0, -1 or 1. */
L(return):
#ifndef __AARCH64EB__
rev data1, data1
rev data2, data2
#endif
cmp data1, data2
cset result, ne
cneg result, result, lo
ret
.p2align 4
L(less16):
add src1end, src1, limit
add src2end, src2, limit
tbz limit, 3, L(less8)
ldr data1, [src1]
ldr data2, [src2]
ldr data3, [src1end, -8]
ldr data4, [src2end, -8]
b L(return2)
.p2align 4
L(less8):
tbz limit, 2, L(less4)
ldr data1w, [src1]
ldr data2w, [src2]
ldr data3w, [src1end, -4]
ldr data4w, [src2end, -4]
b L(return2)
L(less4):
tbz limit, 1, L(less2)
ldrh data1w, [src1]
ldrh data2w, [src2]
cmp data1w, data2w
b.ne L(return)
L(less2):
mov result, 0
tbz limit, 0, L(return_zero)
ldrb data1w, [src1end, -1]
ldrb data2w, [src2end, -1]
sub result, data1w, data2w
L(return_zero):
ret
L(loop_align):
ldp data1, data3, [src1, 16]
ldp data2, data4, [src2, 16]
cmp data1, data2
ccmp data3, data4, 0, eq
b.ne L(return2)
/* Align src2 and adjust src1, src2 and limit. */
and tmp, src2, 15
sub tmp, tmp, 16
sub src2, src2, tmp
add limit, limit, tmp
sub src1, src1, tmp
sub limit, limit, 64 + 16
.p2align 4
L(loop64):
ldr q0, [src1, 16]
ldr q1, [src2, 16]
subs limit, limit, 64
ldr q2, [src1, 32]
ldr q3, [src2, 32]
eor v0.16b, v0.16b, v1.16b
eor v1.16b, v2.16b, v3.16b
ldr q2, [src1, 48]
ldr q3, [src2, 48]
umaxp v0.16b, v0.16b, v1.16b
ldr q4, [src1, 64]!
ldr q5, [src2, 64]!
eor v1.16b, v2.16b, v3.16b
eor v2.16b, v4.16b, v5.16b
umaxp v1.16b, v1.16b, v2.16b
umaxp v0.16b, v0.16b, v1.16b
umaxp v0.16b, v0.16b, v0.16b
fmov tmp, d0
ccmp tmp, 0, 0, hi
b.eq L(loop64)
/* If equal, process last 1-64 bytes using scalar loop. */
add limit, limit, 64 + 16
cbz tmp, L(last64)
/* Determine the 8-byte aligned offset of the first difference. */
#ifdef __AARCH64EB__
rev16 tmp, tmp
#endif
rev tmp, tmp
clz tmp, tmp
bic tmp, tmp, 7
sub tmp, tmp, 48
ldr data1, [src1, tmp]
ldr data2, [src2, tmp]
#ifndef __AARCH64EB__
rev data1, data1
rev data2, data2
#endif
mov result, 1
cmp data1, data2
cneg result, result, lo
ret
END (__memcmp_aarch64)
|
