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
|
/* Copyright (C) 2000, 2003 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by David Mosberger (davidm@cs.arizona.edu).
EV6 optimized by Rick Gorton <rick.gorton@alpha-processor.com>.
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>
.arch ev6
.set noreorder
.set noat
ENTRY(__memchr)
#ifdef PROF
ldgp gp, 0(pv)
lda AT, _mcount
jsr AT, (AT), _mcount
.prologue 1
#else
.prologue 0
#endif
# Hack -- if someone passes in (size_t)-1, hoping to just
# search til the end of the address space, we will overflow
# below when we find the address of the last byte. Given
# that we will never have a 56-bit address space, cropping
# the length is the easiest way to avoid trouble.
zap $18, 0x80, $5 # U : Bound length
beq $18, $not_found # U :
ldq_u $1, 0($16) # L : load first quadword Latency=3
and $17, 0xff, $17 # E : L L U U : 00000000000000ch
insbl $17, 1, $2 # U : 000000000000ch00
cmpult $18, 9, $4 # E : small (< 1 quad) string?
or $2, $17, $17 # E : 000000000000chch
lda $3, -1($31) # E : U L L U
sll $17, 16, $2 # U : 00000000chch0000
addq $16, $5, $5 # E : Max search address
or $2, $17, $17 # E : 00000000chchchch
sll $17, 32, $2 # U : U L L U : chchchch00000000
or $2, $17, $17 # E : chchchchchchchch
extql $1, $16, $7 # U : $7 is upper bits
beq $4, $first_quad # U :
ldq_u $6, -1($5) # L : L U U L : eight or less bytes to search Latency=3
extqh $6, $16, $6 # U : 2 cycle stall for $6
mov $16, $0 # E :
nop # E :
or $7, $6, $1 # E : L U L U $1 = quadword starting at $16
# Deal with the case where at most 8 bytes remain to be searched
# in $1. E.g.:
# $18 = 6
# $1 = ????c6c5c4c3c2c1
$last_quad:
negq $18, $6 # E :
xor $17, $1, $1 # E :
srl $3, $6, $6 # U : $6 = mask of $18 bits set
cmpbge $31, $1, $2 # E : L U L U
nop
nop
and $2, $6, $2 # E :
beq $2, $not_found # U : U L U L
$found_it:
#if defined(__alpha_fix__) && defined(__alpha_cix__)
/*
* Since we are guaranteed to have set one of the bits, we don't
* have to worry about coming back with a 0x40 out of cttz...
*/
cttz $2, $3 # U0 :
addq $0, $3, $0 # E : All done
nop # E :
ret # L0 : L U L U
#else
/*
* Slow and clunky. It can probably be improved.
* An exercise left for others.
*/
negq $2, $3 # E :
and $2, $3, $2 # E :
and $2, 0x0f, $1 # E :
addq $0, 4, $3 # E :
cmoveq $1, $3, $0 # E : Latency 2, extra map cycle
nop # E : keep with cmov
and $2, 0x33, $1 # E :
addq $0, 2, $3 # E : U L U L : 2 cycle stall on $0
cmoveq $1, $3, $0 # E : Latency 2, extra map cycle
nop # E : keep with cmov
and $2, 0x55, $1 # E :
addq $0, 1, $3 # E : U L U L : 2 cycle stall on $0
cmoveq $1, $3, $0 # E : Latency 2, extra map cycle
nop
nop
ret # L0 : L U L U
#endif
# Deal with the case where $18 > 8 bytes remain to be
# searched. $16 may not be aligned.
.align 4
$first_quad:
andnot $16, 0x7, $0 # E :
insqh $3, $16, $2 # U : $2 = 0000ffffffffffff ($16<0:2> ff)
xor $1, $17, $1 # E :
or $1, $2, $1 # E : U L U L $1 = ====ffffffffffff
cmpbge $31, $1, $2 # E :
bne $2, $found_it # U :
# At least one byte left to process.
ldq $1, 8($0) # L :
subq $5, 1, $18 # E : U L U L
addq $0, 8, $0 # E :
# Make $18 point to last quad to be accessed (the
# last quad may or may not be partial).
andnot $18, 0x7, $18 # E :
cmpult $0, $18, $2 # E :
beq $2, $final # U : U L U L
# At least two quads remain to be accessed.
subq $18, $0, $4 # E : $4 <- nr quads to be processed
and $4, 8, $4 # E : odd number of quads?
bne $4, $odd_quad_count # U :
# At least three quads remain to be accessed
mov $1, $4 # E : L U L U : move prefetched value to correct reg
.align 4
$unrolled_loop:
ldq $1, 8($0) # L : prefetch $1
xor $17, $4, $2 # E :
cmpbge $31, $2, $2 # E :
bne $2, $found_it # U : U L U L
addq $0, 8, $0 # E :
nop # E :
nop # E :
nop # E :
$odd_quad_count:
xor $17, $1, $2 # E :
ldq $4, 8($0) # L : prefetch $4
cmpbge $31, $2, $2 # E :
addq $0, 8, $6 # E :
bne $2, $found_it # U :
cmpult $6, $18, $6 # E :
addq $0, 8, $0 # E :
nop # E :
bne $6, $unrolled_loop # U :
mov $4, $1 # E : move prefetched value into $1
nop # E :
nop # E :
$final: subq $5, $0, $18 # E : $18 <- number of bytes left to do
nop # E :
nop # E :
bne $18, $last_quad # U :
$not_found:
mov $31, $0 # E :
nop # E :
nop # E :
ret # L0 :
END(__memchr)
weak_alias (__memchr, memchr)
#if !__BOUNDED_POINTERS__
weak_alias (__memchr, __ubp_memchr)
#endif
libc_hidden_builtin_def (memchr)
|
