lh | 9ed821d | 2023-04-07 01:36:19 -0700 | [diff] [blame^] | 1 | /* Optimized version of the standard memmove() function. |
| 2 | This file is part of the GNU C Library. |
| 3 | Copyright (C) 2000-2015 Free Software Foundation, Inc. |
| 4 | Contributed by Dan Pop <Dan.Pop@cern.ch>. |
| 5 | |
| 6 | The GNU C Library is free software; you can redistribute it and/or |
| 7 | modify it under the terms of the GNU Lesser General Public |
| 8 | License as published by the Free Software Foundation; either |
| 9 | version 2.1 of the License, or (at your option) any later version. |
| 10 | |
| 11 | The GNU C Library is distributed in the hope that it will be useful, |
| 12 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 14 | Lesser General Public License for more details. |
| 15 | |
| 16 | You should have received a copy of the GNU Lesser General Public |
| 17 | License along with the GNU C Library; if not, see |
| 18 | <http://www.gnu.org/licenses/>. */ |
| 19 | |
| 20 | /* Return: dest |
| 21 | |
| 22 | Inputs: |
| 23 | in0: dest |
| 24 | in1: src |
| 25 | in2: byte count |
| 26 | |
| 27 | The core of the function is the memcpy implementation used in memcpy.S. |
| 28 | When bytes have to be copied backwards, only the easy case, when |
| 29 | all arguments are multiples of 8, is optimised. |
| 30 | |
| 31 | In this form, it assumes little endian mode. For big endian mode, |
| 32 | sh1 must be computed using an extra instruction: sub sh1 = 64, sh1 |
| 33 | or the UM.be bit should be cleared at the beginning and set at the end. */ |
| 34 | |
| 35 | #include <sysdep.h> |
| 36 | #undef ret |
| 37 | |
| 38 | #define OP_T_THRES 16 |
| 39 | #define OPSIZ 8 |
| 40 | |
| 41 | #define adest r15 |
| 42 | #define saved_pr r17 |
| 43 | #define saved_lc r18 |
| 44 | #define dest r19 |
| 45 | #define src r20 |
| 46 | #define len r21 |
| 47 | #define asrc r22 |
| 48 | #define tmp2 r23 |
| 49 | #define tmp3 r24 |
| 50 | #define tmp4 r25 |
| 51 | #define ptable r26 |
| 52 | #define ploop56 r27 |
| 53 | #define loopaddr r28 |
| 54 | #define sh1 r29 |
| 55 | #define loopcnt r30 |
| 56 | #define value r31 |
| 57 | |
| 58 | #ifdef GAS_ALIGN_BREAKS_UNWIND_INFO |
| 59 | # define ALIGN(n) { nop 0 } |
| 60 | #else |
| 61 | # define ALIGN(n) .align n |
| 62 | #endif |
| 63 | |
| 64 | #define LOOP(shift) \ |
| 65 | ALIGN(32); \ |
| 66 | .loop##shift##: \ |
| 67 | (p[0]) ld8 r[0] = [asrc], 8 ; /* w1 */ \ |
| 68 | (p[MEMLAT+1]) st8 [dest] = value, 8 ; \ |
| 69 | (p[MEMLAT]) shrp value = r[MEMLAT], r[MEMLAT+1], shift ; \ |
| 70 | nop.b 0 ; \ |
| 71 | nop.b 0 ; \ |
| 72 | br.ctop.sptk .loop##shift ; \ |
| 73 | br.cond.sptk .cpyfew ; /* deal with the remaining bytes */ |
| 74 | |
| 75 | #define MEMLAT 21 |
| 76 | #define Nrot (((2*MEMLAT+3) + 7) & ~7) |
| 77 | |
| 78 | ENTRY(memmove) |
| 79 | .prologue |
| 80 | alloc r2 = ar.pfs, 3, Nrot - 3, 0, Nrot |
| 81 | .rotr r[MEMLAT + 2], q[MEMLAT + 1] |
| 82 | .rotp p[MEMLAT + 2] |
| 83 | mov ret0 = in0 // return value = dest |
| 84 | .save pr, saved_pr |
| 85 | mov saved_pr = pr // save the predicate registers |
| 86 | .save ar.lc, saved_lc |
| 87 | mov saved_lc = ar.lc // save the loop counter |
| 88 | .body |
| 89 | or tmp3 = in0, in1 ;; // tmp3 = dest | src |
| 90 | or tmp3 = tmp3, in2 // tmp3 = dest | src | len |
| 91 | mov dest = in0 // dest |
| 92 | mov src = in1 // src |
| 93 | mov len = in2 // len |
| 94 | sub tmp2 = r0, in0 // tmp2 = -dest |
| 95 | cmp.eq p6, p0 = in2, r0 // if (len == 0) |
| 96 | (p6) br.cond.spnt .restore_and_exit;;// return dest; |
| 97 | and tmp4 = 7, tmp3 // tmp4 = (dest | src | len) & 7 |
| 98 | cmp.le p6, p0 = dest, src // if dest <= src it's always safe |
| 99 | (p6) br.cond.spnt .forward // to copy forward |
| 100 | add tmp3 = src, len;; |
| 101 | cmp.lt p6, p0 = dest, tmp3 // if dest > src && dest < src + len |
| 102 | (p6) br.cond.spnt .backward // we have to copy backward |
| 103 | |
| 104 | .forward: |
| 105 | shr.u loopcnt = len, 4 ;; // loopcnt = len / 16 |
| 106 | cmp.ne p6, p0 = tmp4, r0 // if ((dest | src | len) & 7 != 0) |
| 107 | (p6) br.cond.sptk .next // goto next; |
| 108 | |
| 109 | // The optimal case, when dest, src and len are all multiples of 8 |
| 110 | |
| 111 | and tmp3 = 0xf, len |
| 112 | mov pr.rot = 1 << 16 // set rotating predicates |
| 113 | mov ar.ec = MEMLAT + 1 ;; // set the epilog counter |
| 114 | cmp.ne p6, p0 = tmp3, r0 // do we have to copy an extra word? |
| 115 | adds loopcnt = -1, loopcnt;; // --loopcnt |
| 116 | (p6) ld8 value = [src], 8;; |
| 117 | (p6) st8 [dest] = value, 8 // copy the "odd" word |
| 118 | mov ar.lc = loopcnt // set the loop counter |
| 119 | cmp.eq p6, p0 = 8, len |
| 120 | (p6) br.cond.spnt .restore_and_exit;;// the one-word special case |
| 121 | adds adest = 8, dest // set adest one word ahead of dest |
| 122 | adds asrc = 8, src ;; // set asrc one word ahead of src |
| 123 | nop.b 0 // get the "golden" alignment for |
| 124 | nop.b 0 // the next loop |
| 125 | .l0: |
| 126 | (p[0]) ld8 r[0] = [src], 16 |
| 127 | (p[0]) ld8 q[0] = [asrc], 16 |
| 128 | (p[MEMLAT]) st8 [dest] = r[MEMLAT], 16 |
| 129 | (p[MEMLAT]) st8 [adest] = q[MEMLAT], 16 |
| 130 | br.ctop.dptk .l0 ;; |
| 131 | |
| 132 | mov pr = saved_pr, -1 // restore the predicate registers |
| 133 | mov ar.lc = saved_lc // restore the loop counter |
| 134 | br.ret.sptk.many b0 |
| 135 | .next: |
| 136 | cmp.ge p6, p0 = OP_T_THRES, len // is len <= OP_T_THRES |
| 137 | and loopcnt = 7, tmp2 // loopcnt = -dest % 8 |
| 138 | (p6) br.cond.spnt .cpyfew // copy byte by byte |
| 139 | ;; |
| 140 | cmp.eq p6, p0 = loopcnt, r0 |
| 141 | (p6) br.cond.sptk .dest_aligned |
| 142 | sub len = len, loopcnt // len -= -dest % 8 |
| 143 | adds loopcnt = -1, loopcnt // --loopcnt |
| 144 | ;; |
| 145 | mov ar.lc = loopcnt |
| 146 | .l1: // copy -dest % 8 bytes |
| 147 | ld1 value = [src], 1 // value = *src++ |
| 148 | ;; |
| 149 | st1 [dest] = value, 1 // *dest++ = value |
| 150 | br.cloop.dptk .l1 |
| 151 | .dest_aligned: |
| 152 | and sh1 = 7, src // sh1 = src % 8 |
| 153 | and tmp2 = -8, len // tmp2 = len & -OPSIZ |
| 154 | and asrc = -8, src // asrc = src & -OPSIZ -- align src |
| 155 | shr.u loopcnt = len, 3 // loopcnt = len / 8 |
| 156 | and len = 7, len;; // len = len % 8 |
| 157 | adds loopcnt = -1, loopcnt // --loopcnt |
| 158 | addl tmp4 = @ltoff(.table), gp |
| 159 | addl tmp3 = @ltoff(.loop56), gp |
| 160 | mov ar.ec = MEMLAT + 1 // set EC |
| 161 | mov pr.rot = 1 << 16;; // set rotating predicates |
| 162 | mov ar.lc = loopcnt // set LC |
| 163 | cmp.eq p6, p0 = sh1, r0 // is the src aligned? |
| 164 | (p6) br.cond.sptk .src_aligned |
| 165 | add src = src, tmp2 // src += len & -OPSIZ |
| 166 | shl sh1 = sh1, 3 // sh1 = 8 * (src % 8) |
| 167 | ld8 ploop56 = [tmp3] // ploop56 = &loop56 |
| 168 | ld8 ptable = [tmp4];; // ptable = &table |
| 169 | add tmp3 = ptable, sh1;; // tmp3 = &table + sh1 |
| 170 | mov ar.ec = MEMLAT + 1 + 1 // one more pass needed |
| 171 | ld8 tmp4 = [tmp3];; // tmp4 = loop offset |
| 172 | sub loopaddr = ploop56,tmp4 // loopadd = &loop56 - loop offset |
| 173 | ld8 r[1] = [asrc], 8;; // w0 |
| 174 | mov b6 = loopaddr;; |
| 175 | br b6 // jump to the appropriate loop |
| 176 | |
| 177 | LOOP(8) |
| 178 | LOOP(16) |
| 179 | LOOP(24) |
| 180 | LOOP(32) |
| 181 | LOOP(40) |
| 182 | LOOP(48) |
| 183 | LOOP(56) |
| 184 | |
| 185 | .src_aligned: |
| 186 | .l3: |
| 187 | (p[0]) ld8 r[0] = [src], 8 |
| 188 | (p[MEMLAT]) st8 [dest] = r[MEMLAT], 8 |
| 189 | br.ctop.dptk .l3 |
| 190 | .cpyfew: |
| 191 | cmp.eq p6, p0 = len, r0 // is len == 0 ? |
| 192 | adds len = -1, len // --len; |
| 193 | (p6) br.cond.spnt .restore_and_exit ;; |
| 194 | mov ar.lc = len |
| 195 | .l4: |
| 196 | ld1 value = [src], 1 |
| 197 | ;; |
| 198 | st1 [dest] = value, 1 |
| 199 | br.cloop.dptk .l4 ;; |
| 200 | .restore_and_exit: |
| 201 | mov pr = saved_pr, -1 // restore the predicate registers |
| 202 | mov ar.lc = saved_lc // restore the loop counter |
| 203 | br.ret.sptk.many b0 |
| 204 | |
| 205 | // In the case of a backward copy, optimise only the case when everything |
| 206 | // is a multiple of 8, otherwise copy byte by byte. The backward copy is |
| 207 | // used only when the blocks are overlapping and dest > src. |
| 208 | |
| 209 | .backward: |
| 210 | shr.u loopcnt = len, 3 // loopcnt = len / 8 |
| 211 | add src = src, len // src points one byte past the end |
| 212 | add dest = dest, len ;; // dest points one byte past the end |
| 213 | mov ar.ec = MEMLAT + 1 // set the epilog counter |
| 214 | mov pr.rot = 1 << 16 // set rotating predicates |
| 215 | adds loopcnt = -1, loopcnt // --loopcnt |
| 216 | cmp.ne p6, p0 = tmp4, r0 // if ((dest | src | len) & 7 != 0) |
| 217 | (p6) br.cond.sptk .bytecopy ;; // copy byte by byte backward |
| 218 | adds src = -8, src // src points to the last word |
| 219 | adds dest = -8, dest // dest points to the last word |
| 220 | mov ar.lc = loopcnt;; // set the loop counter |
| 221 | .l5: |
| 222 | (p[0]) ld8 r[0] = [src], -8 |
| 223 | (p[MEMLAT]) st8 [dest] = r[MEMLAT], -8 |
| 224 | br.ctop.dptk .l5 |
| 225 | br.cond.sptk .restore_and_exit |
| 226 | .bytecopy: |
| 227 | adds src = -1, src // src points to the last byte |
| 228 | adds dest = -1, dest // dest points to the last byte |
| 229 | adds loopcnt = -1, len;; // loopcnt = len - 1 |
| 230 | mov ar.lc = loopcnt;; // set the loop counter |
| 231 | .l6: |
| 232 | (p[0]) ld1 r[0] = [src], -1 |
| 233 | (p[MEMLAT]) st1 [dest] = r[MEMLAT], -1 |
| 234 | br.ctop.dptk .l6 |
| 235 | br.cond.sptk .restore_and_exit |
| 236 | END(memmove) |
| 237 | |
| 238 | .rodata |
| 239 | .align 8 |
| 240 | .table: |
| 241 | data8 0 // dummy entry |
| 242 | data8 .loop56 - .loop8 |
| 243 | data8 .loop56 - .loop16 |
| 244 | data8 .loop56 - .loop24 |
| 245 | data8 .loop56 - .loop32 |
| 246 | data8 .loop56 - .loop40 |
| 247 | data8 .loop56 - .loop48 |
| 248 | data8 .loop56 - .loop56 |
| 249 | |
| 250 | libc_hidden_builtin_def (memmove) |