1b3a04ed5SBabu Moger/* 2b3a04ed5SBabu Moger * M7memset.S: SPARC M7 optimized memset. 3b3a04ed5SBabu Moger * 4b3a04ed5SBabu Moger * Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved. 5b3a04ed5SBabu Moger */ 6b3a04ed5SBabu Moger 7b3a04ed5SBabu Moger/* 8b3a04ed5SBabu Moger * M7memset.S: M7 optimized memset. 9b3a04ed5SBabu Moger * 10b3a04ed5SBabu Moger * char *memset(sp, c, n) 11b3a04ed5SBabu Moger * 12b3a04ed5SBabu Moger * Set an array of n chars starting at sp to the character c. 13b3a04ed5SBabu Moger * Return sp. 14b3a04ed5SBabu Moger * 15b3a04ed5SBabu Moger * Fast assembler language version of the following C-program for memset 16b3a04ed5SBabu Moger * which represents the `standard' for the C-library. 17b3a04ed5SBabu Moger * 18b3a04ed5SBabu Moger * void * 19b3a04ed5SBabu Moger * memset(void *sp1, int c, size_t n) 20b3a04ed5SBabu Moger * { 21b3a04ed5SBabu Moger * if (n != 0) { 22b3a04ed5SBabu Moger * char *sp = sp1; 23b3a04ed5SBabu Moger * do { 24b3a04ed5SBabu Moger * *sp++ = (char)c; 25b3a04ed5SBabu Moger * } while (--n != 0); 26b3a04ed5SBabu Moger * } 27b3a04ed5SBabu Moger * return (sp1); 28b3a04ed5SBabu Moger * } 29b3a04ed5SBabu Moger * 30b3a04ed5SBabu Moger * The algorithm is as follows : 31b3a04ed5SBabu Moger * 32b3a04ed5SBabu Moger * For small 6 or fewer bytes stores, bytes will be stored. 33b3a04ed5SBabu Moger * 34b3a04ed5SBabu Moger * For less than 32 bytes stores, align the address on 4 byte boundary. 35b3a04ed5SBabu Moger * Then store as many 4-byte chunks, followed by trailing bytes. 36b3a04ed5SBabu Moger * 37b3a04ed5SBabu Moger * For sizes greater than 32 bytes, align the address on 8 byte boundary. 38b3a04ed5SBabu Moger * if (count >= 64) { 39b3a04ed5SBabu Moger * store 8-bytes chunks to align the address on 64 byte boundary 40b3a04ed5SBabu Moger * if (value to be set is zero && count >= MIN_ZERO) { 41b3a04ed5SBabu Moger * Using BIS stores, set the first long word of each 42b3a04ed5SBabu Moger * 64-byte cache line to zero which will also clear the 43b3a04ed5SBabu Moger * other seven long words of the cache line. 44b3a04ed5SBabu Moger * } 45b3a04ed5SBabu Moger * else if (count >= MIN_LOOP) { 46b3a04ed5SBabu Moger * Using BIS stores, set the first long word of each of 47b3a04ed5SBabu Moger * ST_CHUNK cache lines (64 bytes each) before the main 48b3a04ed5SBabu Moger * loop is entered. 49b3a04ed5SBabu Moger * In the main loop, continue pre-setting the first long 50b3a04ed5SBabu Moger * word of each cache line ST_CHUNK lines in advance while 51b3a04ed5SBabu Moger * setting the other seven long words (56 bytes) of each 52b3a04ed5SBabu Moger * cache line until fewer than ST_CHUNK*64 bytes remain. 53b3a04ed5SBabu Moger * Then set the remaining seven long words of each cache 54b3a04ed5SBabu Moger * line that has already had its first long word set. 55b3a04ed5SBabu Moger * } 56b3a04ed5SBabu Moger * store remaining data in 64-byte chunks until less than 57b3a04ed5SBabu Moger * 64 bytes remain. 58b3a04ed5SBabu Moger * } 59b3a04ed5SBabu Moger * Store as many 8-byte chunks, followed by trailing bytes. 60b3a04ed5SBabu Moger * 61b3a04ed5SBabu Moger * BIS = Block Init Store 62b3a04ed5SBabu Moger * Doing the advance store of the first element of the cache line 63b3a04ed5SBabu Moger * initiates the displacement of a cache line while only using a single 64b3a04ed5SBabu Moger * instruction in the pipeline. That avoids various pipeline delays, 65b3a04ed5SBabu Moger * such as filling the miss buffer. The performance effect is 66b3a04ed5SBabu Moger * similar to prefetching for normal stores. 67b3a04ed5SBabu Moger * The special case for zero fills runs faster and uses fewer instruction 68b3a04ed5SBabu Moger * cycles than the normal memset loop. 69b3a04ed5SBabu Moger * 70b3a04ed5SBabu Moger * We only use BIS for memset of greater than MIN_LOOP bytes because a sequence 71b3a04ed5SBabu Moger * BIS stores must be followed by a membar #StoreStore. The benefit of 72b3a04ed5SBabu Moger * the BIS store must be balanced against the cost of the membar operation. 73b3a04ed5SBabu Moger */ 74b3a04ed5SBabu Moger 75b3a04ed5SBabu Moger/* 76b3a04ed5SBabu Moger * ASI_STBI_P marks the cache line as "least recently used" 77b3a04ed5SBabu Moger * which means if many threads are active, it has a high chance 78b3a04ed5SBabu Moger * of being pushed out of the cache between the first initializing 79b3a04ed5SBabu Moger * store and the final stores. 80b3a04ed5SBabu Moger * Thus, we use ASI_STBIMRU_P which marks the cache line as 81b3a04ed5SBabu Moger * "most recently used" for all but the last store to the cache line. 82b3a04ed5SBabu Moger */ 83b3a04ed5SBabu Moger 84b3a04ed5SBabu Moger#include <asm/asi.h> 85b3a04ed5SBabu Moger#include <asm/page.h> 86b3a04ed5SBabu Moger 87b3a04ed5SBabu Moger#define ASI_STBI_P ASI_BLK_INIT_QUAD_LDD_P 88b3a04ed5SBabu Moger#define ASI_STBIMRU_P ASI_ST_BLKINIT_MRU_P 89b3a04ed5SBabu Moger 90b3a04ed5SBabu Moger 91b3a04ed5SBabu Moger#define ST_CHUNK 24 /* multiple of 4 due to loop unrolling */ 92b3a04ed5SBabu Moger#define MIN_LOOP 16320 93b3a04ed5SBabu Moger#define MIN_ZERO 512 94b3a04ed5SBabu Moger 95b3a04ed5SBabu Moger .section ".text" 96b3a04ed5SBabu Moger .align 32 97b3a04ed5SBabu Moger 98b3a04ed5SBabu Moger/* 99b3a04ed5SBabu Moger * Define clear_page(dest) as memset(dest, 0, PAGE_SIZE) 100b3a04ed5SBabu Moger * (can create a more optimized version later.) 101b3a04ed5SBabu Moger */ 102b3a04ed5SBabu Moger .globl M7clear_page 103b3a04ed5SBabu Moger .globl M7clear_user_page 104b3a04ed5SBabu MogerM7clear_page: /* clear_page(dest) */ 105b3a04ed5SBabu MogerM7clear_user_page: 106b3a04ed5SBabu Moger set PAGE_SIZE, %o1 107b3a04ed5SBabu Moger /* fall through into bzero code */ 108b3a04ed5SBabu Moger 109b3a04ed5SBabu Moger .size M7clear_page,.-M7clear_page 110b3a04ed5SBabu Moger .size M7clear_user_page,.-M7clear_user_page 111b3a04ed5SBabu Moger 112b3a04ed5SBabu Moger/* 113b3a04ed5SBabu Moger * Define bzero(dest, n) as memset(dest, 0, n) 114b3a04ed5SBabu Moger * (can create a more optimized version later.) 115b3a04ed5SBabu Moger */ 116b3a04ed5SBabu Moger .globl M7bzero 117b3a04ed5SBabu MogerM7bzero: /* bzero(dest, size) */ 118b3a04ed5SBabu Moger mov %o1, %o2 119b3a04ed5SBabu Moger mov 0, %o1 120b3a04ed5SBabu Moger /* fall through into memset code */ 121b3a04ed5SBabu Moger 122b3a04ed5SBabu Moger .size M7bzero,.-M7bzero 123b3a04ed5SBabu Moger 124b3a04ed5SBabu Moger .global M7memset 125b3a04ed5SBabu Moger .type M7memset, #function 126b3a04ed5SBabu Moger .register %g3, #scratch 127b3a04ed5SBabu MogerM7memset: 128b3a04ed5SBabu Moger mov %o0, %o5 ! copy sp1 before using it 129b3a04ed5SBabu Moger cmp %o2, 7 ! if small counts, just write bytes 130b3a04ed5SBabu Moger bleu,pn %xcc, .wrchar 131b3a04ed5SBabu Moger and %o1, 0xff, %o1 ! o1 is (char)c 132b3a04ed5SBabu Moger 133b3a04ed5SBabu Moger sll %o1, 8, %o3 134b3a04ed5SBabu Moger or %o1, %o3, %o1 ! now o1 has 2 bytes of c 135b3a04ed5SBabu Moger sll %o1, 16, %o3 136b3a04ed5SBabu Moger cmp %o2, 32 137b3a04ed5SBabu Moger blu,pn %xcc, .wdalign 138b3a04ed5SBabu Moger or %o1, %o3, %o1 ! now o1 has 4 bytes of c 139b3a04ed5SBabu Moger 140b3a04ed5SBabu Moger sllx %o1, 32, %o3 141b3a04ed5SBabu Moger or %o1, %o3, %o1 ! now o1 has 8 bytes of c 142b3a04ed5SBabu Moger 143b3a04ed5SBabu Moger.dbalign: 144b3a04ed5SBabu Moger andcc %o5, 7, %o3 ! is sp1 aligned on a 8 byte bound? 145b3a04ed5SBabu Moger bz,pt %xcc, .blkalign ! already long word aligned 146b3a04ed5SBabu Moger sub %o3, 8, %o3 ! -(bytes till long word aligned) 147b3a04ed5SBabu Moger 148b3a04ed5SBabu Moger add %o2, %o3, %o2 ! update o2 with new count 149b3a04ed5SBabu Moger ! Set -(%o3) bytes till sp1 long word aligned 150b3a04ed5SBabu Moger1: stb %o1, [%o5] ! there is at least 1 byte to set 151b3a04ed5SBabu Moger inccc %o3 ! byte clearing loop 152b3a04ed5SBabu Moger bl,pt %xcc, 1b 153b3a04ed5SBabu Moger inc %o5 154b3a04ed5SBabu Moger 155b3a04ed5SBabu Moger ! Now sp1 is long word aligned (sp1 is found in %o5) 156b3a04ed5SBabu Moger.blkalign: 157b3a04ed5SBabu Moger cmp %o2, 64 ! check if there are 64 bytes to set 158b3a04ed5SBabu Moger blu,pn %xcc, .wrshort 159b3a04ed5SBabu Moger mov %o2, %o3 160b3a04ed5SBabu Moger 161b3a04ed5SBabu Moger andcc %o5, 63, %o3 ! is sp1 block aligned? 162b3a04ed5SBabu Moger bz,pt %xcc, .blkwr ! now block aligned 163b3a04ed5SBabu Moger sub %o3, 64, %o3 ! o3 is -(bytes till block aligned) 164b3a04ed5SBabu Moger add %o2, %o3, %o2 ! o2 is the remainder 165b3a04ed5SBabu Moger 166b3a04ed5SBabu Moger ! Store -(%o3) bytes till dst is block (64 byte) aligned. 167b3a04ed5SBabu Moger ! Use long word stores. 168b3a04ed5SBabu Moger ! Recall that dst is already long word aligned 169b3a04ed5SBabu Moger1: 170b3a04ed5SBabu Moger addcc %o3, 8, %o3 171b3a04ed5SBabu Moger stx %o1, [%o5] 172b3a04ed5SBabu Moger bl,pt %xcc, 1b 173b3a04ed5SBabu Moger add %o5, 8, %o5 174b3a04ed5SBabu Moger 175b3a04ed5SBabu Moger ! Now sp1 is block aligned 176b3a04ed5SBabu Moger.blkwr: 177b3a04ed5SBabu Moger andn %o2, 63, %o4 ! calculate size of blocks in bytes 178b3a04ed5SBabu Moger brz,pn %o1, .wrzero ! special case if c == 0 179b3a04ed5SBabu Moger and %o2, 63, %o3 ! %o3 = bytes left after blk stores. 180b3a04ed5SBabu Moger 181b3a04ed5SBabu Moger set MIN_LOOP, %g1 182b3a04ed5SBabu Moger cmp %o4, %g1 ! check there are enough bytes to set 183b3a04ed5SBabu Moger blu,pn %xcc, .short_set ! to justify cost of membar 184b3a04ed5SBabu Moger ! must be > pre-cleared lines 185b3a04ed5SBabu Moger nop 186b3a04ed5SBabu Moger 187b3a04ed5SBabu Moger ! initial cache-clearing stores 188b3a04ed5SBabu Moger ! get store pipeline moving 189b3a04ed5SBabu Moger rd %asi, %g3 ! save %asi to be restored later 190b3a04ed5SBabu Moger wr %g0, ASI_STBIMRU_P, %asi 191b3a04ed5SBabu Moger 192b3a04ed5SBabu Moger ! Primary memset loop for large memsets 193b3a04ed5SBabu Moger.wr_loop: 194b3a04ed5SBabu Moger sub %o5, 8, %o5 ! adjust %o5 for ASI store alignment 195b3a04ed5SBabu Moger mov ST_CHUNK, %g1 196b3a04ed5SBabu Moger.wr_loop_start: 197b3a04ed5SBabu Moger stxa %o1, [%o5+8]%asi 198b3a04ed5SBabu Moger subcc %g1, 4, %g1 199b3a04ed5SBabu Moger stxa %o1, [%o5+8+64]%asi 200b3a04ed5SBabu Moger add %o5, 256, %o5 201b3a04ed5SBabu Moger stxa %o1, [%o5+8-128]%asi 202b3a04ed5SBabu Moger bgu %xcc, .wr_loop_start 203b3a04ed5SBabu Moger stxa %o1, [%o5+8-64]%asi 204b3a04ed5SBabu Moger 205b3a04ed5SBabu Moger sub %o5, ST_CHUNK*64, %o5 ! reset %o5 206b3a04ed5SBabu Moger mov ST_CHUNK, %g1 207b3a04ed5SBabu Moger 208b3a04ed5SBabu Moger.wr_loop_rest: 209b3a04ed5SBabu Moger stxa %o1, [%o5+8+8]%asi 210b3a04ed5SBabu Moger sub %o4, 64, %o4 211b3a04ed5SBabu Moger stxa %o1, [%o5+16+8]%asi 212b3a04ed5SBabu Moger subcc %g1, 1, %g1 213b3a04ed5SBabu Moger stxa %o1, [%o5+24+8]%asi 214b3a04ed5SBabu Moger stxa %o1, [%o5+32+8]%asi 215b3a04ed5SBabu Moger stxa %o1, [%o5+40+8]%asi 216b3a04ed5SBabu Moger add %o5, 64, %o5 217b3a04ed5SBabu Moger stxa %o1, [%o5-8]%asi 218b3a04ed5SBabu Moger bgu %xcc, .wr_loop_rest 219b3a04ed5SBabu Moger stxa %o1, [%o5]ASI_STBI_P 220b3a04ed5SBabu Moger 221b3a04ed5SBabu Moger ! If more than ST_CHUNK*64 bytes remain to set, continue 222b3a04ed5SBabu Moger ! setting the first long word of each cache line in advance 223b3a04ed5SBabu Moger ! to keep the store pipeline moving. 224b3a04ed5SBabu Moger 225b3a04ed5SBabu Moger cmp %o4, ST_CHUNK*64 226b3a04ed5SBabu Moger bge,pt %xcc, .wr_loop_start 227b3a04ed5SBabu Moger mov ST_CHUNK, %g1 228b3a04ed5SBabu Moger 229b3a04ed5SBabu Moger brz,a,pn %o4, .asi_done 230b3a04ed5SBabu Moger add %o5, 8, %o5 ! restore %o5 offset 231b3a04ed5SBabu Moger 232b3a04ed5SBabu Moger.wr_loop_small: 233b3a04ed5SBabu Moger stxa %o1, [%o5+8]%asi 234b3a04ed5SBabu Moger stxa %o1, [%o5+8+8]%asi 235b3a04ed5SBabu Moger stxa %o1, [%o5+16+8]%asi 236b3a04ed5SBabu Moger stxa %o1, [%o5+24+8]%asi 237b3a04ed5SBabu Moger stxa %o1, [%o5+32+8]%asi 238b3a04ed5SBabu Moger subcc %o4, 64, %o4 239b3a04ed5SBabu Moger stxa %o1, [%o5+40+8]%asi 240b3a04ed5SBabu Moger add %o5, 64, %o5 241b3a04ed5SBabu Moger stxa %o1, [%o5-8]%asi 242b3a04ed5SBabu Moger bgu,pt %xcc, .wr_loop_small 243b3a04ed5SBabu Moger stxa %o1, [%o5]ASI_STBI_P 244b3a04ed5SBabu Moger 245b3a04ed5SBabu Moger ba .asi_done 246b3a04ed5SBabu Moger add %o5, 8, %o5 ! restore %o5 offset 247b3a04ed5SBabu Moger 248b3a04ed5SBabu Moger ! Special case loop for zero fill memsets 249b3a04ed5SBabu Moger ! For each 64 byte cache line, single STBI to first element 250b3a04ed5SBabu Moger ! clears line 251b3a04ed5SBabu Moger.wrzero: 252b3a04ed5SBabu Moger cmp %o4, MIN_ZERO ! check if enough bytes to set 253b3a04ed5SBabu Moger ! to pay %asi + membar cost 254b3a04ed5SBabu Moger blu %xcc, .short_set 255b3a04ed5SBabu Moger nop 256b3a04ed5SBabu Moger sub %o4, 256, %o4 257b3a04ed5SBabu Moger 258b3a04ed5SBabu Moger.wrzero_loop: 259b3a04ed5SBabu Moger mov 64, %g3 260b3a04ed5SBabu Moger stxa %o1, [%o5]ASI_STBI_P 261b3a04ed5SBabu Moger subcc %o4, 256, %o4 262b3a04ed5SBabu Moger stxa %o1, [%o5+%g3]ASI_STBI_P 263b3a04ed5SBabu Moger add %o5, 256, %o5 264b3a04ed5SBabu Moger sub %g3, 192, %g3 265b3a04ed5SBabu Moger stxa %o1, [%o5+%g3]ASI_STBI_P 266b3a04ed5SBabu Moger add %g3, 64, %g3 267b3a04ed5SBabu Moger bge,pt %xcc, .wrzero_loop 268b3a04ed5SBabu Moger stxa %o1, [%o5+%g3]ASI_STBI_P 269b3a04ed5SBabu Moger add %o4, 256, %o4 270b3a04ed5SBabu Moger 271b3a04ed5SBabu Moger brz,pn %o4, .bsi_done 272b3a04ed5SBabu Moger nop 273b3a04ed5SBabu Moger 274b3a04ed5SBabu Moger.wrzero_small: 275b3a04ed5SBabu Moger stxa %o1, [%o5]ASI_STBI_P 276b3a04ed5SBabu Moger subcc %o4, 64, %o4 277b3a04ed5SBabu Moger bgu,pt %xcc, .wrzero_small 278b3a04ed5SBabu Moger add %o5, 64, %o5 279b3a04ed5SBabu Moger ba,a .bsi_done 280b3a04ed5SBabu Moger 281b3a04ed5SBabu Moger.asi_done: 282b3a04ed5SBabu Moger wr %g3, 0x0, %asi ! restored saved %asi 283b3a04ed5SBabu Moger.bsi_done: 284b3a04ed5SBabu Moger membar #StoreStore ! required by use of Block Store Init 285b3a04ed5SBabu Moger 286b3a04ed5SBabu Moger.short_set: 287b3a04ed5SBabu Moger cmp %o4, 64 ! check if 64 bytes to set 288b3a04ed5SBabu Moger blu %xcc, 5f 289b3a04ed5SBabu Moger nop 290b3a04ed5SBabu Moger4: ! set final blocks of 64 bytes 291b3a04ed5SBabu Moger stx %o1, [%o5] 292b3a04ed5SBabu Moger stx %o1, [%o5+8] 293b3a04ed5SBabu Moger stx %o1, [%o5+16] 294b3a04ed5SBabu Moger stx %o1, [%o5+24] 295b3a04ed5SBabu Moger subcc %o4, 64, %o4 296b3a04ed5SBabu Moger stx %o1, [%o5+32] 297b3a04ed5SBabu Moger stx %o1, [%o5+40] 298b3a04ed5SBabu Moger add %o5, 64, %o5 299b3a04ed5SBabu Moger stx %o1, [%o5-16] 300b3a04ed5SBabu Moger bgu,pt %xcc, 4b 301b3a04ed5SBabu Moger stx %o1, [%o5-8] 302b3a04ed5SBabu Moger 303b3a04ed5SBabu Moger5: 304b3a04ed5SBabu Moger ! Set the remaining long words 305b3a04ed5SBabu Moger.wrshort: 306b3a04ed5SBabu Moger subcc %o3, 8, %o3 ! Can we store any long words? 307b3a04ed5SBabu Moger blu,pn %xcc, .wrchars 308b3a04ed5SBabu Moger and %o2, 7, %o2 ! calc bytes left after long words 309b3a04ed5SBabu Moger6: 310b3a04ed5SBabu Moger subcc %o3, 8, %o3 311b3a04ed5SBabu Moger stx %o1, [%o5] ! store the long words 312b3a04ed5SBabu Moger bgeu,pt %xcc, 6b 313b3a04ed5SBabu Moger add %o5, 8, %o5 314b3a04ed5SBabu Moger 315b3a04ed5SBabu Moger.wrchars: ! check for extra chars 316b3a04ed5SBabu Moger brnz %o2, .wrfin 317b3a04ed5SBabu Moger nop 318b3a04ed5SBabu Moger retl 319b3a04ed5SBabu Moger nop 320b3a04ed5SBabu Moger 321b3a04ed5SBabu Moger.wdalign: 322b3a04ed5SBabu Moger andcc %o5, 3, %o3 ! is sp1 aligned on a word boundary 323b3a04ed5SBabu Moger bz,pn %xcc, .wrword 324b3a04ed5SBabu Moger andn %o2, 3, %o3 ! create word sized count in %o3 325b3a04ed5SBabu Moger 326b3a04ed5SBabu Moger dec %o2 ! decrement count 327b3a04ed5SBabu Moger stb %o1, [%o5] ! clear a byte 328b3a04ed5SBabu Moger b .wdalign 329b3a04ed5SBabu Moger inc %o5 ! next byte 330b3a04ed5SBabu Moger 331b3a04ed5SBabu Moger.wrword: 332b3a04ed5SBabu Moger subcc %o3, 4, %o3 333b3a04ed5SBabu Moger st %o1, [%o5] ! 4-byte writing loop 334b3a04ed5SBabu Moger bnz,pt %xcc, .wrword 335b3a04ed5SBabu Moger add %o5, 4, %o5 336b3a04ed5SBabu Moger 337b3a04ed5SBabu Moger and %o2, 3, %o2 ! leftover count, if any 338b3a04ed5SBabu Moger 339b3a04ed5SBabu Moger.wrchar: 340b3a04ed5SBabu Moger ! Set the remaining bytes, if any 341b3a04ed5SBabu Moger brz %o2, .exit 342b3a04ed5SBabu Moger nop 343b3a04ed5SBabu Moger.wrfin: 344b3a04ed5SBabu Moger deccc %o2 345b3a04ed5SBabu Moger stb %o1, [%o5] 346b3a04ed5SBabu Moger bgu,pt %xcc, .wrfin 347b3a04ed5SBabu Moger inc %o5 348b3a04ed5SBabu Moger.exit: 349b3a04ed5SBabu Moger retl ! %o0 was preserved 350b3a04ed5SBabu Moger nop 351b3a04ed5SBabu Moger 352b3a04ed5SBabu Moger .size M7memset,.-M7memset 353