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
|
/* memset/bzero -- set memory area to CH/0
Optimized version for x86-64.
Copyright (C) 2002, 2003 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Andreas Jaeger <aj@suse.de>.
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, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA. */
#include <sysdep.h>
#include "asm-syntax.h"
#include "bp-sym.h"
#include "bp-asm.h"
/* BEWARE: `#ifdef memset' means that memset is redefined as `bzero' */
#define BZERO_P (defined memset)
/* This is somehow experimental and could made dependend on the cache
size. */
#define LARGE $120000
.text
ENTRY (memset)
#if BZERO_P
mov %rsi,%rdx /* Adjust parameter. */
xorq %rsi,%rsi /* Fill with 0s. */
#endif
cmp $0x7,%rdx /* Check for small length. */
mov %rdi,%rcx /* Save ptr as return value. */
jbe 7f
#if BZERO_P
mov %rsi,%r8 /* Just copy 0. */
#else
/* Populate 8 bit data to full 64-bit. */
movabs $0x0101010101010101,%r8
movzbl %sil,%eax
imul %rax,%r8
#endif
test $0x7,%edi /* Check for alignment. */
je 2f
.p2align 4
1: /* Align ptr to 8 byte. */
mov %sil,(%rcx)
dec %rdx
inc %rcx
test $0x7,%ecx
jne 1b
2: /* Check for really large regions. */
mov %rdx,%rax
shr $0x6,%rax
je 4f
cmp LARGE, %rdx
jae 11f
.p2align 4
3: /* Copy 64 bytes. */
mov %r8,(%rcx)
mov %r8,0x8(%rcx)
mov %r8,0x10(%rcx)
mov %r8,0x18(%rcx)
mov %r8,0x20(%rcx)
mov %r8,0x28(%rcx)
mov %r8,0x30(%rcx)
mov %r8,0x38(%rcx)
add $0x40,%rcx
dec %rax
jne 3b
4: /* Copy final bytes. */
and $0x3f,%edx
mov %rdx,%rax
shr $0x3,%rax
je 6f
5: /* First in chunks of 8 bytes. */
mov %r8,(%rcx)
add $0x8,%rcx
dec %rax
jne 5b
6:
and $0x7,%edx
7:
test %rdx,%rdx
je 9f
8: /* And finally as bytes (up to 7). */
mov %sil,(%rcx)
inc %rcx
dec %rdx
jne 8b
9:
#if BZERO_P
nop
#else
/* Load result (only if used as memset). */
mov %rdi,%rax /* start address of destination is result */
#endif
retq
.p2align 4
11: /* Copy 64 bytes without polluting the cache. */
/* We could use movntdq %xmm0,(%rcx) here to further
speed up for large cases but let's not use XMM registers. */
movnti %r8,(%rcx)
movnti %r8,0x8(%rcx)
movnti %r8,0x10(%rcx)
movnti %r8,0x18(%rcx)
movnti %r8,0x20(%rcx)
movnti %r8,0x28(%rcx)
movnti %r8,0x30(%rcx)
movnti %r8,0x38(%rcx)
add $0x40,%rcx
dec %rax
jne 11b
jmp 4b
END (memset)
#if !BZERO_P
libc_hidden_builtin_def (memset)
#endif
|
