1/* Copyright (C) 2000-2022 Free Software Foundation, Inc.
2 EV67 optimized by Rick Gorton <rick.gorton@alpha-processor.com>.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library. If not, see
17 <https://www.gnu.org/licenses/>. */
18
19/* Return the address of the last occurrence of a given character
20 within a null-terminated string, or null if it is not found. */
21
22#include <sysdep.h>
23
24 .arch ev6
25 .set noreorder
26 .set noat
27
28ENTRY(strrchr)
29#ifdef PROF
30 ldgp gp, 0(pv)
31 lda AT, _mcount
32 jsr AT, (AT), _mcount
33 .prologue 1
34#else
35 .prologue 0
36#endif
37
38 and a1, 0xff, t2 # E : 00000000000000ch
39 insbl a1, 1, t4 # U : 000000000000ch00
40 insbl a1, 2, t5 # U : 0000000000ch0000
41 ldq_u t0, 0(a0) # L : load first quadword Latency=3
42
43 mov zero, t6 # E : t6 is last match aligned addr
44 or t2, t4, a1 # E : 000000000000chch
45 sll t5, 8, t3 # U : 00000000ch000000
46 mov zero, t8 # E : t8 is last match byte compare mask
47
48 andnot a0, 7, v0 # E : align source addr
49 or t5, t3, t3 # E : 00000000chch0000
50 sll a1, 32, t2 # U : 0000chch00000000
51 sll a1, 48, t4 # U : chch000000000000
52
53 or t4, a1, a1 # E : chch00000000chch
54 or t2, t3, t2 # E : 0000chchchch0000
55 or a1, t2, a1 # E : chchchchchchchch
56 lda t5, -1 # E : build garbage mask
57
58 cmpbge zero, t0, t1 # E : bits set iff byte == zero
59 mskqh t5, a0, t4 # E : Complete garbage mask
60 xor t0, a1, t2 # E : make bytes == c zero
61 cmpbge zero, t4, t4 # E : bits set iff byte is garbage
62
63 cmpbge zero, t2, t3 # E : bits set iff byte == c
64 andnot t1, t4, t1 # E : clear garbage from null test
65 andnot t3, t4, t3 # E : clear garbage from char test
66 bne t1, $eos # U : did we already hit the terminator?
67
68 /* Character search main loop */
69$loop:
70 ldq t0, 8(v0) # L : load next quadword
71 cmovne t3, v0, t6 # E : save previous comparisons match
72 nop # : Latency=2, extra map slot (keep nop with cmov)
73 nop
74
75 cmovne t3, t3, t8 # E : Latency=2, extra map slot
76 nop # : keep with cmovne
77 addq v0, 8, v0 # E :
78 xor t0, a1, t2 # E :
79
80 cmpbge zero, t0, t1 # E : bits set iff byte == zero
81 cmpbge zero, t2, t3 # E : bits set iff byte == c
82 beq t1, $loop # U : if we havnt seen a null, loop
83 nop
84
85 /* Mask out character matches after terminator */
86$eos:
87 negq t1, t4 # E : isolate first null byte match
88 and t1, t4, t4 # E :
89 subq t4, 1, t5 # E : build a mask of the bytes upto...
90 or t4, t5, t4 # E : ... and including the null
91
92 and t3, t4, t3 # E : mask out char matches after null
93 cmovne t3, t3, t8 # E : save it, if match found Latency=2, extra map slot
94 nop # : Keep with cmovne
95 nop
96
97 cmovne t3, v0, t6 # E :
98 nop # : Keep with cmovne
99 /* Locate the address of the last matched character */
100 ctlz t8, t2 # U0 : Latency=3 (0x40 for t8=0)
101 nop
102
103 cmoveq t8, 0x3f, t2 # E : Compensate for case when no match is seen
104 nop # E : hide the cmov latency (2) behind ctlz latency
105 lda t5, 0x3f($31) # E :
106 subq t5, t2, t5 # E : Normalize leading zero count
107
108 addq t6, t5, v0 # E : and add to quadword address
109 ret # L0 : Latency=3
110 nop
111 nop
112
113END(strrchr)
114
115weak_alias (strrchr, rindex)
116libc_hidden_builtin_def (strrchr)
117

source code of glibc/sysdeps/alpha/alphaev67/strrchr.S