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c7debbdf | 1 | /* Optimized strrchr implementation for PowerPC64/POWER7 using cmpb insn. |
688903eb | 2 | Copyright (C) 2014-2018 Free Software Foundation, Inc. |
c7debbdf RS |
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 | <http://www.gnu.org/licenses/>. */ | |
18 | ||
19 | #include <sysdep.h> | |
20 | ||
21 | /* int [r3] strrchr (char *s [r3], int c [r4]) */ | |
6d15a5c2 WSM |
22 | |
23 | #ifndef STRRCHR | |
24 | # define STRRCHR strrchr | |
25 | #endif | |
26 | ||
c7debbdf | 27 | .machine power7 |
d5b41185 | 28 | ENTRY_TOCLESS (STRRCHR) |
c7debbdf RS |
29 | CALL_MCOUNT 2 |
30 | dcbt 0,r3 | |
31 | clrrdi r8,r3,3 /* Align the address to doubleword boundary. */ | |
32 | cmpdi cr7,r4,0 | |
33 | ld r12,0(r8) /* Load doubleword from memory. */ | |
34 | li r9,0 /* used to store last occurence */ | |
35 | li r0,0 /* Doubleword with null chars to use | |
36 | with cmpb. */ | |
37 | ||
38 | rlwinm r6,r3,3,26,28 /* Calculate padding. */ | |
39 | ||
40 | beq cr7,L(null_match) | |
41 | ||
42 | /* Replicate byte to doubleword. */ | |
43 | insrdi r4,r4,8,48 | |
44 | insrdi r4,r4,16,32 | |
45 | insrdi r4,r4,32,0 | |
46 | ||
47 | /* r4 is changed now ,if its passed as more chars | |
48 | check for null again */ | |
49 | cmpdi cr7,r4,0 | |
50 | beq cr7,L(null_match) | |
51 | /* Now r4 has a doubleword of c bytes and r0 has | |
52 | a doubleword of null bytes. */ | |
53 | ||
54 | cmpb r10,r12,r4 /* Compare each byte against c byte. */ | |
55 | cmpb r11,r12,r0 /* Compare each byte against null byte. */ | |
56 | ||
57 | /* Move the doublewords left and right to discard the bits that are | |
58 | not part of the string and bring them back as zeros. */ | |
59 | #ifdef __LITTLE_ENDIAN__ | |
60 | srd r10,r10,r6 | |
61 | srd r11,r11,r6 | |
62 | sld r10,r10,r6 | |
63 | sld r11,r11,r6 | |
64 | #else | |
65 | sld r10,r10,r6 | |
66 | sld r11,r11,r6 | |
67 | srd r10,r10,r6 | |
68 | srd r11,r11,r6 | |
69 | #endif | |
70 | or r5,r10,r11 /* OR the results to speed things up. */ | |
71 | cmpdi cr7,r5,0 /* If r5 == 0, no c or null bytes | |
72 | have been found. */ | |
73 | bne cr7,L(done) | |
74 | ||
75 | L(align): | |
76 | mtcrf 0x01,r8 | |
77 | ||
78 | /* Are we now aligned to a doubleword boundary? If so, skip to | |
79 | the main loop. Otherwise, go through the alignment code. */ | |
80 | ||
81 | bt 28,L(loop) | |
82 | ||
83 | /* Handle WORD2 of pair. */ | |
84 | ldu r12,8(r8) | |
85 | cmpb r10,r12,r4 | |
86 | cmpb r11,r12,r0 | |
87 | or r5,r10,r11 | |
88 | cmpdi cr7,r5,0 | |
89 | bne cr7,L(done) | |
90 | b L(loop) /* We branch here (rather than falling through) | |
91 | to skip the nops due to heavy alignment | |
92 | of the loop below. */ | |
93 | .p2align 5 | |
94 | L(loop): | |
95 | /* Load two doublewords, compare and merge in a | |
96 | single register for speed. This is an attempt | |
97 | to speed up the null-checking process for bigger strings. */ | |
98 | ld r12,8(r8) | |
99 | ldu r7,16(r8) | |
100 | cmpb r10,r12,r4 | |
101 | cmpb r11,r12,r0 | |
102 | cmpb r6,r7,r4 | |
103 | cmpb r7,r7,r0 | |
104 | or r12,r10,r11 | |
105 | or r5,r6,r7 | |
106 | or r5,r12,r5 | |
107 | cmpdi cr7,r5,0 | |
108 | beq cr7,L(loop) | |
109 | ||
110 | /* OK, one (or both) of the doublewords contains a c/null byte. Check | |
111 | the first doubleword and decrement the address in case the first | |
112 | doubleword really contains a c/null byte. */ | |
113 | cmpdi cr6,r12,0 | |
114 | addi r8,r8,-8 | |
115 | bne cr6,L(done) | |
116 | ||
117 | /* The c/null byte must be in the second doubleword. Adjust the | |
118 | address again and move the result of cmpb to r10 so we can calculate | |
119 | the pointer. */ | |
120 | ||
121 | mr r10,r6 | |
122 | mr r11,r7 | |
123 | addi r8,r8,8 | |
124 | ||
125 | /* r10/r11 have the output of the cmpb instructions, that is, | |
126 | 0xff in the same position as the c/null byte in the original | |
127 | doubleword from the string. Use that to calculate the pointer. */ | |
128 | ||
129 | L(done): | |
130 | /* if there are more than one 0xff in r11, find the first pos of ff | |
131 | in r11 and fill r10 with 0 from that position */ | |
132 | cmpdi cr7,r11,0 | |
133 | beq cr7,L(no_null) | |
134 | #ifdef __LITTLE_ENDIAN__ | |
135 | addi r3,r11,-1 | |
136 | andc r3,r3,r11 | |
137 | popcntd r0,r3 | |
138 | #else | |
139 | cntlzd r0,r11 | |
140 | #endif | |
141 | subfic r0,r0,63 | |
142 | li r6,-1 | |
143 | #ifdef __LITTLE_ENDIAN__ | |
144 | srd r0,r6,r0 | |
145 | #else | |
146 | sld r0,r6,r0 | |
147 | #endif | |
148 | and r10,r0,r10 | |
149 | L(no_null): | |
150 | #ifdef __LITTLE_ENDIAN__ | |
151 | cntlzd r0,r10 /* Count leading zeros before c matches. */ | |
152 | addi r3,r10,-1 | |
153 | andc r3,r3,r10 | |
154 | addi r10,r11,-1 | |
155 | andc r10,r10,r11 | |
156 | cmpld cr7,r3,r10 | |
157 | bgt cr7,L(no_match) | |
158 | #else | |
159 | addi r3,r10,-1 /* Count trailing zeros before c matches. */ | |
160 | andc r3,r3,r10 | |
161 | popcntd r0,r3 | |
162 | cmpld cr7,r11,r10 | |
163 | bgt cr7,L(no_match) | |
164 | #endif | |
165 | srdi r0,r0,3 /* Convert trailing zeros to bytes. */ | |
166 | subfic r0,r0,7 | |
167 | add r9,r8,r0 /* Return address of the matching c byte | |
168 | or null in case c was not found. */ | |
169 | li r0,0 | |
170 | cmpdi cr7,r11,0 /* If r11 == 0, no null's have been found. */ | |
171 | beq cr7,L(align) | |
172 | ||
173 | .align 4 | |
174 | L(no_match): | |
175 | mr r3,r9 | |
176 | blr | |
177 | ||
178 | /* We are here because strrchr was called with a null byte. */ | |
179 | .align 4 | |
180 | L(null_match): | |
181 | /* r0 has a doubleword of null bytes. */ | |
182 | ||
183 | cmpb r5,r12,r0 /* Compare each byte against null bytes. */ | |
184 | ||
185 | /* Move the doublewords left and right to discard the bits that are | |
186 | not part of the string and bring them back as zeros. */ | |
187 | #ifdef __LITTLE_ENDIAN__ | |
188 | srd r5,r5,r6 | |
189 | sld r5,r5,r6 | |
190 | #else | |
191 | sld r5,r5,r6 | |
192 | srd r5,r5,r6 | |
193 | #endif | |
194 | cmpdi cr7,r5,0 /* If r10 == 0, no c or null bytes | |
195 | have been found. */ | |
196 | bne cr7,L(done_null) | |
197 | ||
198 | mtcrf 0x01,r8 | |
199 | ||
200 | /* Are we now aligned to a quadword boundary? If so, skip to | |
201 | the main loop. Otherwise, go through the alignment code. */ | |
202 | ||
203 | bt 28,L(loop_null) | |
204 | ||
205 | /* Handle WORD2 of pair. */ | |
206 | ldu r12,8(r8) | |
207 | cmpb r5,r12,r0 | |
208 | cmpdi cr7,r5,0 | |
209 | bne cr7,L(done_null) | |
210 | b L(loop_null) /* We branch here (rather than falling through) | |
211 | to skip the nops due to heavy alignment | |
212 | of the loop below. */ | |
213 | ||
214 | /* Main loop to look for the end of the string. Since it's a | |
215 | small loop (< 8 instructions), align it to 32-bytes. */ | |
216 | .p2align 5 | |
217 | L(loop_null): | |
218 | /* Load two doublewords, compare and merge in a | |
219 | single register for speed. This is an attempt | |
220 | to speed up the null-checking process for bigger strings. */ | |
221 | ld r12,8(r8) | |
222 | ldu r11,16(r8) | |
223 | cmpb r5,r12,r0 | |
224 | cmpb r10,r11,r0 | |
225 | or r6,r5,r10 | |
226 | cmpdi cr7,r6,0 | |
227 | beq cr7,L(loop_null) | |
228 | ||
229 | /* OK, one (or both) of the doublewords contains a null byte. Check | |
230 | the first doubleword and decrement the address in case the first | |
231 | doubleword really contains a null byte. */ | |
232 | ||
233 | cmpdi cr6,r5,0 | |
234 | addi r8,r8,-8 | |
235 | bne cr6,L(done_null) | |
236 | ||
237 | /* The null byte must be in the second doubleword. Adjust the address | |
238 | again and move the result of cmpb to r10 so we can calculate the | |
239 | pointer. */ | |
240 | ||
241 | mr r5,r10 | |
242 | addi r8,r8,8 | |
243 | ||
244 | /* r5 has the output of the cmpb instruction, that is, it contains | |
245 | 0xff in the same position as the null byte in the original | |
246 | doubleword from the string. Use that to calculate the pointer. */ | |
247 | L(done_null): | |
248 | #ifdef __LITTLE_ENDIAN__ | |
249 | addi r0,r5,-1 | |
250 | andc r0,r0,r5 | |
251 | popcntd r0,r0 | |
252 | #else | |
253 | cntlzd r0,r5 /* Count leading zeros before the match. */ | |
254 | #endif | |
255 | srdi r0,r0,3 /* Convert trailing zeros to bytes. */ | |
256 | add r3,r8,r0 /* Return address of the matching null byte. */ | |
257 | blr | |
6d15a5c2 | 258 | END (STRRCHR) |
c7debbdf RS |
259 | weak_alias (strrchr, rindex) |
260 | libc_hidden_builtin_def (strrchr) |