1/* Optimized strrchr implementation for PowerPC64/POWER7 using cmpb insn. 2 Copyright (C) 2014-2022 Free Software Foundation, Inc. 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#include <sysdep.h> 20 21/* int [r3] strrchr (char *s [r3], int c [r4]) */ 22 23#ifndef STRRCHR 24# define STRRCHR strrchr 25#endif 26 27 .machine power7 28ENTRY_TOCLESS (STRRCHR) 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 75L(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 94L(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 129L(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 149L(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 174L(no_match): 175 mr r3,r9 176 blr 177 178/* We are here because strrchr was called with a null byte. */ 179 .align 4 180L(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 217L(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. */ 247L(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 258END (STRRCHR) 259weak_alias (strrchr, rindex) 260libc_hidden_builtin_def (strrchr) 261