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
|
// Inferno's libkern/memmove-386.s
// https://bitbucket.org/inferno-os/inferno-os/src/master/libkern/memmove-386.s
//
// Copyright © 1994-1999 Lucent Technologies Inc. All rights reserved.
// Revisions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com). All rights reserved.
// Portions Copyright 2009 The Go Authors. All rights reserved.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
//go:build !plan9
#include "go_asm.h"
#include "textflag.h"
// See memmove Go doc for important implementation constraints.
// func memmove(to, from unsafe.Pointer, n uintptr)
TEXT runtime·memmove(SB), NOSPLIT, $0-12
MOVL to+0(FP), DI
MOVL from+4(FP), SI
MOVL n+8(FP), BX
// REP instructions have a high startup cost, so we handle small sizes
// with some straightline code. The REP MOVSL instruction is really fast
// for large sizes. The cutover is approximately 1K. We implement up to
// 128 because that is the maximum SSE register load (loading all data
// into registers lets us ignore copy direction).
tail:
// BSR+branch table make almost all memmove/memclr benchmarks worse. Not worth doing.
TESTL BX, BX
JEQ move_0
CMPL BX, $2
JBE move_1or2
CMPL BX, $4
JB move_3
JE move_4
CMPL BX, $8
JBE move_5through8
CMPL BX, $16
JBE move_9through16
#ifdef GO386_softfloat
JMP nosse2
#endif
CMPL BX, $32
JBE move_17through32
CMPL BX, $64
JBE move_33through64
CMPL BX, $128
JBE move_65through128
nosse2:
/*
* check and set for backwards
*/
CMPL SI, DI
JLS back
/*
* forward copy loop
*/
forward:
// If REP MOVSB isn't fast, don't use it
CMPB internal∕cpu·X86+const_offsetX86HasERMS(SB), $1 // enhanced REP MOVSB/STOSB
JNE fwdBy4
// Check alignment
MOVL SI, AX
ORL DI, AX
TESTL $3, AX
JEQ fwdBy4
// Do 1 byte at a time
MOVL BX, CX
REP; MOVSB
RET
fwdBy4:
// Do 4 bytes at a time
MOVL BX, CX
SHRL $2, CX
ANDL $3, BX
REP; MOVSL
JMP tail
/*
* check overlap
*/
back:
MOVL SI, CX
ADDL BX, CX
CMPL CX, DI
JLS forward
/*
* whole thing backwards has
* adjusted addresses
*/
ADDL BX, DI
ADDL BX, SI
STD
/*
* copy
*/
MOVL BX, CX
SHRL $2, CX
ANDL $3, BX
SUBL $4, DI
SUBL $4, SI
REP; MOVSL
CLD
ADDL $4, DI
ADDL $4, SI
SUBL BX, DI
SUBL BX, SI
JMP tail
move_1or2:
MOVB (SI), AX
MOVB -1(SI)(BX*1), CX
MOVB AX, (DI)
MOVB CX, -1(DI)(BX*1)
RET
move_0:
RET
move_3:
MOVW (SI), AX
MOVB 2(SI), CX
MOVW AX, (DI)
MOVB CX, 2(DI)
RET
move_4:
// We need a separate case for 4 to make sure we write pointers atomically.
MOVL (SI), AX
MOVL AX, (DI)
RET
move_5through8:
MOVL (SI), AX
MOVL -4(SI)(BX*1), CX
MOVL AX, (DI)
MOVL CX, -4(DI)(BX*1)
RET
move_9through16:
MOVL (SI), AX
MOVL 4(SI), CX
MOVL -8(SI)(BX*1), DX
MOVL -4(SI)(BX*1), BP
MOVL AX, (DI)
MOVL CX, 4(DI)
MOVL DX, -8(DI)(BX*1)
MOVL BP, -4(DI)(BX*1)
RET
move_17through32:
MOVOU (SI), X0
MOVOU -16(SI)(BX*1), X1
MOVOU X0, (DI)
MOVOU X1, -16(DI)(BX*1)
RET
move_33through64:
MOVOU (SI), X0
MOVOU 16(SI), X1
MOVOU -32(SI)(BX*1), X2
MOVOU -16(SI)(BX*1), X3
MOVOU X0, (DI)
MOVOU X1, 16(DI)
MOVOU X2, -32(DI)(BX*1)
MOVOU X3, -16(DI)(BX*1)
RET
move_65through128:
MOVOU (SI), X0
MOVOU 16(SI), X1
MOVOU 32(SI), X2
MOVOU 48(SI), X3
MOVOU -64(SI)(BX*1), X4
MOVOU -48(SI)(BX*1), X5
MOVOU -32(SI)(BX*1), X6
MOVOU -16(SI)(BX*1), X7
MOVOU X0, (DI)
MOVOU X1, 16(DI)
MOVOU X2, 32(DI)
MOVOU X3, 48(DI)
MOVOU X4, -64(DI)(BX*1)
MOVOU X5, -48(DI)(BX*1)
MOVOU X6, -32(DI)(BX*1)
MOVOU X7, -16(DI)(BX*1)
RET
|
