memset.S (9339B)
1/* SPDX-License-Identifier: GPL-2.0 */ 2/* Optimized version of the standard memset() function. 3 4 Copyright (c) 2002 Hewlett-Packard Co/CERN 5 Sverre Jarp <Sverre.Jarp@cern.ch> 6 7 Return: dest 8 9 Inputs: 10 in0: dest 11 in1: value 12 in2: count 13 14 The algorithm is fairly straightforward: set byte by byte until we 15 we get to a 16B-aligned address, then loop on 128 B chunks using an 16 early store as prefetching, then loop on 32B chucks, then clear remaining 17 words, finally clear remaining bytes. 18 Since a stf.spill f0 can store 16B in one go, we use this instruction 19 to get peak speed when value = 0. */ 20 21#include <asm/asmmacro.h> 22#include <asm/export.h> 23#undef ret 24 25#define dest in0 26#define value in1 27#define cnt in2 28 29#define tmp r31 30#define save_lc r30 31#define ptr0 r29 32#define ptr1 r28 33#define ptr2 r27 34#define ptr3 r26 35#define ptr9 r24 36#define loopcnt r23 37#define linecnt r22 38#define bytecnt r21 39 40#define fvalue f6 41 42// This routine uses only scratch predicate registers (p6 - p15) 43#define p_scr p6 // default register for same-cycle branches 44#define p_nz p7 45#define p_zr p8 46#define p_unalgn p9 47#define p_y p11 48#define p_n p12 49#define p_yy p13 50#define p_nn p14 51 52#define MIN1 15 53#define MIN1P1HALF 8 54#define LINE_SIZE 128 55#define LSIZE_SH 7 // shift amount 56#define PREF_AHEAD 8 57 58GLOBAL_ENTRY(memset) 59{ .mmi 60 .prologue 61 alloc tmp = ar.pfs, 3, 0, 0, 0 62 lfetch.nt1 [dest] // 63 .save ar.lc, save_lc 64 mov.i save_lc = ar.lc 65 .body 66} { .mmi 67 mov ret0 = dest // return value 68 cmp.ne p_nz, p_zr = value, r0 // use stf.spill if value is zero 69 cmp.eq p_scr, p0 = cnt, r0 70;; } 71{ .mmi 72 and ptr2 = -(MIN1+1), dest // aligned address 73 and tmp = MIN1, dest // prepare to check for correct alignment 74 tbit.nz p_y, p_n = dest, 0 // Do we have an odd address? (M_B_U) 75} { .mib 76 mov ptr1 = dest 77 mux1 value = value, @brcst // create 8 identical bytes in word 78(p_scr) br.ret.dpnt.many rp // return immediately if count = 0 79;; } 80{ .mib 81 cmp.ne p_unalgn, p0 = tmp, r0 // 82} { .mib 83 sub bytecnt = (MIN1+1), tmp // NB: # of bytes to move is 1 higher than loopcnt 84 cmp.gt p_scr, p0 = 16, cnt // is it a minimalistic task? 85(p_scr) br.cond.dptk.many .move_bytes_unaligned // go move just a few (M_B_U) 86;; } 87{ .mmi 88(p_unalgn) add ptr1 = (MIN1+1), ptr2 // after alignment 89(p_unalgn) add ptr2 = MIN1P1HALF, ptr2 // after alignment 90(p_unalgn) tbit.nz.unc p_y, p_n = bytecnt, 3 // should we do a st8 ? 91;; } 92{ .mib 93(p_y) add cnt = -8, cnt // 94(p_unalgn) tbit.nz.unc p_yy, p_nn = bytecnt, 2 // should we do a st4 ? 95} { .mib 96(p_y) st8 [ptr2] = value,-4 // 97(p_n) add ptr2 = 4, ptr2 // 98;; } 99{ .mib 100(p_yy) add cnt = -4, cnt // 101(p_unalgn) tbit.nz.unc p_y, p_n = bytecnt, 1 // should we do a st2 ? 102} { .mib 103(p_yy) st4 [ptr2] = value,-2 // 104(p_nn) add ptr2 = 2, ptr2 // 105;; } 106{ .mmi 107 mov tmp = LINE_SIZE+1 // for compare 108(p_y) add cnt = -2, cnt // 109(p_unalgn) tbit.nz.unc p_yy, p_nn = bytecnt, 0 // should we do a st1 ? 110} { .mmi 111 setf.sig fvalue=value // transfer value to FLP side 112(p_y) st2 [ptr2] = value,-1 // 113(p_n) add ptr2 = 1, ptr2 // 114;; } 115 116{ .mmi 117(p_yy) st1 [ptr2] = value // 118 cmp.gt p_scr, p0 = tmp, cnt // is it a minimalistic task? 119} { .mbb 120(p_yy) add cnt = -1, cnt // 121(p_scr) br.cond.dpnt.many .fraction_of_line // go move just a few 122;; } 123 124{ .mib 125 nop.m 0 126 shr.u linecnt = cnt, LSIZE_SH 127(p_zr) br.cond.dptk.many .l1b // Jump to use stf.spill 128;; } 129 130 TEXT_ALIGN(32) // --------------------- // L1A: store ahead into cache lines; fill later 131{ .mmi 132 and tmp = -(LINE_SIZE), cnt // compute end of range 133 mov ptr9 = ptr1 // used for prefetching 134 and cnt = (LINE_SIZE-1), cnt // remainder 135} { .mmi 136 mov loopcnt = PREF_AHEAD-1 // default prefetch loop 137 cmp.gt p_scr, p0 = PREF_AHEAD, linecnt // check against actual value 138;; } 139{ .mmi 140(p_scr) add loopcnt = -1, linecnt // 141 add ptr2 = 8, ptr1 // start of stores (beyond prefetch stores) 142 add ptr1 = tmp, ptr1 // first address beyond total range 143;; } 144{ .mmi 145 add tmp = -1, linecnt // next loop count 146 mov.i ar.lc = loopcnt // 147;; } 148.pref_l1a: 149{ .mib 150 stf8 [ptr9] = fvalue, 128 // Do stores one cache line apart 151 nop.i 0 152 br.cloop.dptk.few .pref_l1a 153;; } 154{ .mmi 155 add ptr0 = 16, ptr2 // Two stores in parallel 156 mov.i ar.lc = tmp // 157;; } 158.l1ax: 159 { .mmi 160 stf8 [ptr2] = fvalue, 8 161 stf8 [ptr0] = fvalue, 8 162 ;; } 163 { .mmi 164 stf8 [ptr2] = fvalue, 24 165 stf8 [ptr0] = fvalue, 24 166 ;; } 167 { .mmi 168 stf8 [ptr2] = fvalue, 8 169 stf8 [ptr0] = fvalue, 8 170 ;; } 171 { .mmi 172 stf8 [ptr2] = fvalue, 24 173 stf8 [ptr0] = fvalue, 24 174 ;; } 175 { .mmi 176 stf8 [ptr2] = fvalue, 8 177 stf8 [ptr0] = fvalue, 8 178 ;; } 179 { .mmi 180 stf8 [ptr2] = fvalue, 24 181 stf8 [ptr0] = fvalue, 24 182 ;; } 183 { .mmi 184 stf8 [ptr2] = fvalue, 8 185 stf8 [ptr0] = fvalue, 32 186 cmp.lt p_scr, p0 = ptr9, ptr1 // do we need more prefetching? 187 ;; } 188{ .mmb 189 stf8 [ptr2] = fvalue, 24 190(p_scr) stf8 [ptr9] = fvalue, 128 191 br.cloop.dptk.few .l1ax 192;; } 193{ .mbb 194 cmp.le p_scr, p0 = 8, cnt // just a few bytes left ? 195(p_scr) br.cond.dpnt.many .fraction_of_line // Branch no. 2 196 br.cond.dpnt.many .move_bytes_from_alignment // Branch no. 3 197;; } 198 199 TEXT_ALIGN(32) 200.l1b: // ------------------------------------ // L1B: store ahead into cache lines; fill later 201{ .mmi 202 and tmp = -(LINE_SIZE), cnt // compute end of range 203 mov ptr9 = ptr1 // used for prefetching 204 and cnt = (LINE_SIZE-1), cnt // remainder 205} { .mmi 206 mov loopcnt = PREF_AHEAD-1 // default prefetch loop 207 cmp.gt p_scr, p0 = PREF_AHEAD, linecnt // check against actual value 208;; } 209{ .mmi 210(p_scr) add loopcnt = -1, linecnt 211 add ptr2 = 16, ptr1 // start of stores (beyond prefetch stores) 212 add ptr1 = tmp, ptr1 // first address beyond total range 213;; } 214{ .mmi 215 add tmp = -1, linecnt // next loop count 216 mov.i ar.lc = loopcnt 217;; } 218.pref_l1b: 219{ .mib 220 stf.spill [ptr9] = f0, 128 // Do stores one cache line apart 221 nop.i 0 222 br.cloop.dptk.few .pref_l1b 223;; } 224{ .mmi 225 add ptr0 = 16, ptr2 // Two stores in parallel 226 mov.i ar.lc = tmp 227;; } 228.l1bx: 229 { .mmi 230 stf.spill [ptr2] = f0, 32 231 stf.spill [ptr0] = f0, 32 232 ;; } 233 { .mmi 234 stf.spill [ptr2] = f0, 32 235 stf.spill [ptr0] = f0, 32 236 ;; } 237 { .mmi 238 stf.spill [ptr2] = f0, 32 239 stf.spill [ptr0] = f0, 64 240 cmp.lt p_scr, p0 = ptr9, ptr1 // do we need more prefetching? 241 ;; } 242{ .mmb 243 stf.spill [ptr2] = f0, 32 244(p_scr) stf.spill [ptr9] = f0, 128 245 br.cloop.dptk.few .l1bx 246;; } 247{ .mib 248 cmp.gt p_scr, p0 = 8, cnt // just a few bytes left ? 249(p_scr) br.cond.dpnt.many .move_bytes_from_alignment // 250;; } 251 252.fraction_of_line: 253{ .mib 254 add ptr2 = 16, ptr1 255 shr.u loopcnt = cnt, 5 // loopcnt = cnt / 32 256;; } 257{ .mib 258 cmp.eq p_scr, p0 = loopcnt, r0 259 add loopcnt = -1, loopcnt 260(p_scr) br.cond.dpnt.many .store_words 261;; } 262{ .mib 263 and cnt = 0x1f, cnt // compute the remaining cnt 264 mov.i ar.lc = loopcnt 265;; } 266 TEXT_ALIGN(32) 267.l2: // ------------------------------------ // L2A: store 32B in 2 cycles 268{ .mmb 269 stf8 [ptr1] = fvalue, 8 270 stf8 [ptr2] = fvalue, 8 271;; } { .mmb 272 stf8 [ptr1] = fvalue, 24 273 stf8 [ptr2] = fvalue, 24 274 br.cloop.dptk.many .l2 275;; } 276.store_words: 277{ .mib 278 cmp.gt p_scr, p0 = 8, cnt // just a few bytes left ? 279(p_scr) br.cond.dpnt.many .move_bytes_from_alignment // Branch 280;; } 281 282{ .mmi 283 stf8 [ptr1] = fvalue, 8 // store 284 cmp.le p_y, p_n = 16, cnt 285 add cnt = -8, cnt // subtract 286;; } 287{ .mmi 288(p_y) stf8 [ptr1] = fvalue, 8 // store 289(p_y) cmp.le.unc p_yy, p_nn = 16, cnt 290(p_y) add cnt = -8, cnt // subtract 291;; } 292{ .mmi // store 293(p_yy) stf8 [ptr1] = fvalue, 8 294(p_yy) add cnt = -8, cnt // subtract 295;; } 296 297.move_bytes_from_alignment: 298{ .mib 299 cmp.eq p_scr, p0 = cnt, r0 300 tbit.nz.unc p_y, p0 = cnt, 2 // should we terminate with a st4 ? 301(p_scr) br.cond.dpnt.few .restore_and_exit 302;; } 303{ .mib 304(p_y) st4 [ptr1] = value,4 305 tbit.nz.unc p_yy, p0 = cnt, 1 // should we terminate with a st2 ? 306;; } 307{ .mib 308(p_yy) st2 [ptr1] = value,2 309 tbit.nz.unc p_y, p0 = cnt, 0 // should we terminate with a st1 ? 310;; } 311 312{ .mib 313(p_y) st1 [ptr1] = value 314;; } 315.restore_and_exit: 316{ .mib 317 nop.m 0 318 mov.i ar.lc = save_lc 319 br.ret.sptk.many rp 320;; } 321 322.move_bytes_unaligned: 323{ .mmi 324 .pred.rel "mutex",p_y, p_n 325 .pred.rel "mutex",p_yy, p_nn 326(p_n) cmp.le p_yy, p_nn = 4, cnt 327(p_y) cmp.le p_yy, p_nn = 5, cnt 328(p_n) add ptr2 = 2, ptr1 329} { .mmi 330(p_y) add ptr2 = 3, ptr1 331(p_y) st1 [ptr1] = value, 1 // fill 1 (odd-aligned) byte [15, 14 (or less) left] 332(p_y) add cnt = -1, cnt 333;; } 334{ .mmi 335(p_yy) cmp.le.unc p_y, p0 = 8, cnt 336 add ptr3 = ptr1, cnt // prepare last store 337 mov.i ar.lc = save_lc 338} { .mmi 339(p_yy) st2 [ptr1] = value, 4 // fill 2 (aligned) bytes 340(p_yy) st2 [ptr2] = value, 4 // fill 2 (aligned) bytes [11, 10 (o less) left] 341(p_yy) add cnt = -4, cnt 342;; } 343{ .mmi 344(p_y) cmp.le.unc p_yy, p0 = 8, cnt 345 add ptr3 = -1, ptr3 // last store 346 tbit.nz p_scr, p0 = cnt, 1 // will there be a st2 at the end ? 347} { .mmi 348(p_y) st2 [ptr1] = value, 4 // fill 2 (aligned) bytes 349(p_y) st2 [ptr2] = value, 4 // fill 2 (aligned) bytes [7, 6 (or less) left] 350(p_y) add cnt = -4, cnt 351;; } 352{ .mmi 353(p_yy) st2 [ptr1] = value, 4 // fill 2 (aligned) bytes 354(p_yy) st2 [ptr2] = value, 4 // fill 2 (aligned) bytes [3, 2 (or less) left] 355 tbit.nz p_y, p0 = cnt, 0 // will there be a st1 at the end ? 356} { .mmi 357(p_yy) add cnt = -4, cnt 358;; } 359{ .mmb 360(p_scr) st2 [ptr1] = value // fill 2 (aligned) bytes 361(p_y) st1 [ptr3] = value // fill last byte (using ptr3) 362 br.ret.sptk.many rp 363} 364END(memset) 365EXPORT_SYMBOL(memset)