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
|
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
#include "go_asm.h"
#include "textflag.h"
TEXT ·Compare<ABIInternal>(SB),NOSPLIT|NOFRAME,$0-56
#ifdef GOEXPERIMENT_regabiargs
// R0 = a_base (want in R0)
// R1 = a_len (want in R1)
// R2 = a_cap (unused)
// R3 = b_base (want in R2)
// R4 = b_len (want in R3)
// R5 = b_cap (unused)
MOVD R3, R2
MOVD R4, R3
#else
MOVD a_base+0(FP), R0
MOVD a_len+8(FP), R1
MOVD b_base+24(FP), R2
MOVD b_len+32(FP), R3
MOVD $ret+48(FP), R7
#endif
B cmpbody<>(SB)
TEXT runtime·cmpstring<ABIInternal>(SB),NOSPLIT|NOFRAME,$0-40
#ifdef GOEXPERIMENT_regabiargs
// R0 = a_base
// R1 = a_len
// R2 = b_base
// R3 = b_len
#else
MOVD a_base+0(FP), R0
MOVD a_len+8(FP), R1
MOVD b_base+16(FP), R2
MOVD b_len+24(FP), R3
MOVD $ret+32(FP), R7
#endif
B cmpbody<>(SB)
// On entry:
// R0 points to the start of a
// R1 is the length of a
// R2 points to the start of b
// R3 is the length of b
#ifndef GOEXPERIMENT_regabiargs
// R7 points to return value (-1/0/1 will be written here)
#endif
//
// On exit:
#ifdef GOEXPERIMENT_regabiargs
// R0 is the result
#endif
// R4, R5, R6, R8, R9 and R10 are clobbered
TEXT cmpbody<>(SB),NOSPLIT|NOFRAME,$0-0
CMP R0, R2
BEQ samebytes // same starting pointers; compare lengths
CMP R1, R3
CSEL LT, R3, R1, R6 // R6 is min(R1, R3)
CBZ R6, samebytes
BIC $0xf, R6, R10
CBZ R10, small // length < 16
ADD R0, R10 // end of chunk16
// length >= 16
chunk16_loop:
LDP.P 16(R0), (R4, R8)
LDP.P 16(R2), (R5, R9)
CMP R4, R5
BNE cmp
CMP R8, R9
BNE cmpnext
CMP R10, R0
BNE chunk16_loop
AND $0xf, R6, R6
CBZ R6, samebytes
SUBS $8, R6
BLT tail
// the length of tail > 8 bytes
MOVD.P 8(R0), R4
MOVD.P 8(R2), R5
CMP R4, R5
BNE cmp
SUB $8, R6
// compare last 8 bytes
tail:
MOVD (R0)(R6), R4
MOVD (R2)(R6), R5
CMP R4, R5
BEQ samebytes
cmp:
REV R4, R4
REV R5, R5
CMP R4, R5
ret:
MOVD $1, R0
CNEG HI, R0, R0
#ifndef GOEXPERIMENT_regabiargs
MOVD R0, (R7)
#endif
RET
small:
TBZ $3, R6, lt_8
MOVD (R0), R4
MOVD (R2), R5
CMP R4, R5
BNE cmp
SUBS $8, R6
BEQ samebytes
ADD $8, R0
ADD $8, R2
SUB $8, R6
B tail
lt_8:
TBZ $2, R6, lt_4
MOVWU (R0), R4
MOVWU (R2), R5
CMPW R4, R5
BNE cmp
SUBS $4, R6
BEQ samebytes
ADD $4, R0
ADD $4, R2
lt_4:
TBZ $1, R6, lt_2
MOVHU (R0), R4
MOVHU (R2), R5
CMPW R4, R5
BNE cmp
ADD $2, R0
ADD $2, R2
lt_2:
TBZ $0, R6, samebytes
one:
MOVBU (R0), R4
MOVBU (R2), R5
CMPW R4, R5
BNE ret
samebytes:
CMP R3, R1
CSET NE, R0
CNEG LO, R0, R0
#ifndef GOEXPERIMENT_regabiargs
MOVD R0, (R7)
#endif
RET
cmpnext:
REV R8, R4
REV R9, R5
CMP R4, R5
B ret
|
