--- /dev/null
+/* Set a block of memory to some byte value. For SUN4V M7.
+ Copyright (C) 2017 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+#include <sysdep.h>
+
+#ifndef XCC
+# define XCC xcc
+#endif
+ .register %g2, #scratch
+ .register %g3, #scratch
+
+/* The algorithm is as follows :
+ *
+ * For small 7 or fewer bytes stores, bytes will be stored.
+ *
+ * For less than 32 bytes stores, align the address on 4 byte boundary.
+ * Then store as many 4-byte chunks, followed by trailing bytes.
+ *
+ * For sizes greater than 32 bytes, align the address on 8 byte boundary.
+ * if (count >= 64) {
+ * store 8-bytes chunks to align the address on 64 byte boundary
+ * if (value to be set is zero && count >= MIN_ZERO) {
+ * Using BIS stores, set the first long word of each
+ * 64-byte cache line to zero which will also clear the
+ * other seven long words of the cache line.
+ * }
+ * else if (count >= MIN_LOOP) {
+ * Using BIS stores, set the first long word of each of
+ * ST_CHUNK cache lines (64 bytes each) before the main
+ * loop is entered.
+ * In the main loop, continue pre-setting the first long
+ * word of each cache line ST_CHUNK lines in advance while
+ * setting the other seven long words (56 bytes) of each
+ * cache line until fewer than ST_CHUNK*64 bytes remain.
+ * Then set the remaining seven long words of each cache
+ * line that has already had its first long word set.
+ * }
+ * store remaining data in 64-byte chunks until less than
+ * 64 bytes remain.
+ * }
+ * Store as many 8-byte chunks, followed by trailing bytes.
+ *
+ *
+ * BIS = Block Init Store
+ * Doing the advance store of the first element of the cache line
+ * initiates the displacement of a cache line while only using a single
+ * instruction in the pipeline. That avoids various pipeline delays,
+ * such as filling the miss buffer. The performance effect is
+ * similar to prefetching for normal stores.
+ * The special case for zero fills runs faster and uses fewer instruction
+ * cycles than the normal memset loop.
+ *
+ * We only use BIS for memset of greater than MIN_LOOP bytes because a sequence
+ * BIS stores must be followed by a membar #StoreStore. The benefit of
+ * the BIS store must be balanced against the cost of the membar operation.
+ */
+
+/*
+ * ASI_STBI_P marks the cache line as "least recently used"
+ * which means if many threads are active, it has a high chance
+ * of being pushed out of the cache between the first initializing
+ * store and the final stores.
+ * Thus, we use ASI_STBIMRU_P which marks the cache line as
+ * "most recently used" for all but the last store to the cache line.
+ */
+
+#define ASI_BLK_INIT_QUAD_LDD_P 0xe2
+#define ASI_ST_BLK_INIT_MRU_P 0xf2
+
+#define ASI_STBI_P ASI_BLK_INIT_QUAD_LDD_P
+#define ASI_STBIMRU_P ASI_ST_BLK_INIT_MRU_P
+
+#define ST_CHUNK 24 /* multiple of 4 due to loop unrolling */
+#define MIN_LOOP (ST_CHUNK)*64
+#define MIN_ZERO 256
+
+#define EX_ST(x) x
+#define EX_RETVAL(x) x
+#define STORE_ASI(src,addr) stxa src, [addr] ASI_STBIMRU_P
+#define STORE_INIT(src,addr) stxa src, [addr] ASI_STBI_P
+
+#if IS_IN (libc)
+
+ .text
+ .align 32
+
+ENTRY(__bzero_niagara7)
+ /* bzero (dst, size) */
+ mov %o1, %o2
+ mov 0, %o1
+ /* fall through into memset code */
+END(__bzero_niagara7)
+
+ENTRY(__memset_niagara7)
+ /* memset (src, c, size) */
+ mov %o0, %o5 /* copy sp1 before using it */
+ cmp %o2, 7 /* if small counts, just write bytes */
+ bleu,pn %XCC, .Lwrchar
+ and %o1, 0xff, %o1 /* o1 is (char)c */
+
+ sll %o1, 8, %o3
+ or %o1, %o3, %o1 /* now o1 has 2 bytes of c */
+ sll %o1, 16, %o3
+ cmp %o2, 32
+ blu,pn %XCC, .Lwdalign
+ or %o1, %o3, %o1 /* now o1 has 4 bytes of c */
+
+ sllx %o1, 32, %o3
+ or %o1, %o3, %o1 /* now o1 has 8 bytes of c */
+
+.Ldbalign:
+ andcc %o5, 7, %o3 /* is sp1 aligned on a 8 byte bound? */
+ bz,pt %XCC, .Lblkalign /* already long word aligned */
+ sub %o3, 8, %o3 /* -(bytes till long word aligned) */
+
+ add %o2, %o3, %o2 /* update o2 with new count */
+ /* Set -(%o3) bytes till sp1 long word aligned */
+1: stb %o1, [%o5] /* there is at least 1 byte to set */
+ inccc %o3 /* byte clearing loop */
+ bl,pt %XCC, 1b
+ inc %o5
+
+ /* Now sp1 is long word aligned (sp1 is found in %o5) */
+.Lblkalign:
+ cmp %o2, 64 /* check if there are 64 bytes to set */
+ blu,pn %XCC, .Lwrshort
+ mov %o2, %o3
+
+ andcc %o5, 63, %o3 /* is sp1 block aligned? */
+ bz,pt %XCC, .Lblkwr /* now block aligned */
+ sub %o3, 64, %o3 /* o3 is -(bytes till block aligned) */
+ add %o2, %o3, %o2 /* o2 is the remainder */
+
+ /* Store -(%o3) bytes till dst is block (64 byte) aligned. */
+ /* Use long word stores. */
+ /* Recall that dst is already long word aligned */
+1:
+ addcc %o3, 8, %o3
+ stx %o1, [%o5]
+ bl,pt %XCC, 1b
+ add %o5, 8, %o5
+
+ /* Now sp1 is block aligned */
+.Lblkwr:
+ andn %o2, 63, %o4 /* calculate size of blocks in bytes */
+ brz,pn %o1, .Lwrzero /* special case if c == 0 */
+ and %o2, 63, %o3 /* %o3 = bytes left after blk stores */
+
+ cmp %o4, MIN_LOOP /* check for enough bytes to set */
+ blu,pn %XCC, .Lshort_set /* to justify cost of membar */
+ nop /* must be > pre-cleared lines */
+
+ /* initial cache-clearing stores */
+ /* get store pipeline moving */
+
+/* Primary memset loop for large memsets */
+.Lwr_loop:
+ mov ST_CHUNK, %g1
+.Lwr_loop_start:
+ subcc %g1, 4, %g1
+ EX_ST(STORE_ASI(%o1,%o5))
+ add %o5, 64, %o5
+ EX_ST(STORE_ASI(%o1,%o5))
+ add %o5, 64, %o5
+ EX_ST(STORE_ASI(%o1,%o5))
+ add %o5, 64, %o5
+ EX_ST(STORE_ASI(%o1,%o5))
+ bgu %XCC, .Lwr_loop_start
+ add %o5, 64, %o5
+
+ sub %o5, ST_CHUNK*64, %o5 /* reset %o5 */
+ mov ST_CHUNK, %g1
+ sub %o5, 8, %o5 /* adjust %o5 for ASI store */
+
+.Lwr_loop_rest:
+ stx %o1,[%o5+8+8]
+ sub %o4, 64, %o4
+ stx %o1,[%o5+16+8]
+ subcc %g1, 1, %g1
+ stx %o1,[%o5+24+8]
+ stx %o1,[%o5+32+8]
+ stx %o1,[%o5+40+8]
+ add %o5, 64, %o5
+ stx %o1,[%o5-8]
+ bgu %XCC, .Lwr_loop_rest
+ EX_ST(STORE_INIT(%o1,%o5))
+
+ add %o5, 8, %o5 /* restore %o5 offset */
+
+ /* If more than ST_CHUNK*64 bytes remain to set, continue */
+ /* setting the first long word of each cache line in advance */
+ /* to keep the store pipeline moving. */
+
+ cmp %o4, ST_CHUNK*64
+ bge,pt %XCC, .Lwr_loop_start
+ mov ST_CHUNK, %g1
+
+ brz,a,pn %o4, .Lasi_done
+ nop
+
+ sub %o5, 8, %o5 /* adjust %o5 for ASI store */
+.Lwr_loop_small:
+ add %o5, 8, %o5 /* adjust %o5 for ASI store */
+ EX_ST(STORE_ASI(%o1,%o5))
+ stx %o1,[%o5+8]
+ stx %o1,[%o5+16]
+ stx %o1,[%o5+24]
+ stx %o1,[%o5+32]
+ subcc %o4, 64, %o4
+ stx %o1,[%o5+40]
+ add %o5, 56, %o5
+ stx %o1,[%o5-8]
+ bgu,pt %XCC, .Lwr_loop_small
+ EX_ST(STORE_INIT(%o1,%o5))
+
+ ba .Lasi_done
+ add %o5, 8, %o5 /* restore %o5 offset */
+
+/* Special case loop for zero fill memsets */
+/* For each 64 byte cache line, single STBI to first element */
+/* clears line */
+.Lwrzero:
+ cmp %o4, MIN_ZERO /* check if enough bytes to set */
+ /* to pay %asi + membar cost */
+ blu %XCC, .Lshort_set
+ nop
+ sub %o4, 256, %o4
+
+.Lwrzero_loop:
+ mov 64, %g3
+ EX_ST(STORE_INIT(%o1,%o5))
+ subcc %o4, 256, %o4
+ EX_ST(STORE_INIT(%o1,%o5+%g3))
+ add %o5, 256, %o5
+ sub %g3, 192, %g3
+ EX_ST(STORE_INIT(%o1,%o5+%g3))
+ add %g3, 64, %g3
+ bge,pt %XCC, .Lwrzero_loop
+ EX_ST(STORE_INIT(%o1,%o5+%g3))
+ add %o4, 256, %o4
+
+ brz,pn %o4, .Lbsi_done
+ nop
+.Lwrzero_small:
+ EX_ST(STORE_INIT(%o1,%o5))
+ subcc %o4, 64, %o4
+ bgu,pt %XCC, .Lwrzero_small
+ add %o5, 64, %o5
+
+.Lasi_done:
+.Lbsi_done:
+ membar #StoreStore /* required by use of BSI */
+
+.Lshort_set:
+ cmp %o4, 64 /* check if 64 bytes to set */
+ blu %XCC, 5f
+ nop
+4: /* set final blocks of 64 bytes */
+ stx %o1, [%o5]
+ stx %o1, [%o5+8]
+ stx %o1, [%o5+16]
+ stx %o1, [%o5+24]
+ subcc %o4, 64, %o4
+ stx %o1, [%o5+32]
+ stx %o1, [%o5+40]
+ add %o5, 64, %o5
+ stx %o1, [%o5-16]
+ bgu,pt %XCC, 4b
+ stx %o1, [%o5-8]
+
+5:
+ /* Set the remaining long words */
+.Lwrshort:
+ subcc %o3, 8, %o3 /* Can we store any long words? */
+ blu,pn %XCC, .Lwrchars
+ and %o2, 7, %o2 /* calc bytes left after long words */
+6:
+ subcc %o3, 8, %o3
+ stx %o1, [%o5] /* store the long words */
+ bgeu,pt %XCC, 6b
+ add %o5, 8, %o5
+
+.Lwrchars: /* check for extra chars */
+ brnz %o2, .Lwrfin
+ nop
+ retl
+ nop
+
+.Lwdalign:
+ andcc %o5, 3, %o3 /* is sp1 aligned on a word boundary */
+ bz,pn %XCC, .Lwrword
+ andn %o2, 3, %o3 /* create word sized count in %o3 */
+
+ dec %o2 /* decrement count */
+ stb %o1, [%o5] /* clear a byte */
+ b .Lwdalign
+ inc %o5 /* next byte */
+
+.Lwrword:
+ subcc %o3, 4, %o3
+ st %o1, [%o5] /* 4-byte writing loop */
+ bnz,pt %XCC, .Lwrword
+ add %o5, 4, %o5
+ and %o2, 3, %o2 /* leftover count, if any */
+
+.Lwrchar:
+ /* Set the remaining bytes, if any */
+ brz %o2, .Lexit
+ nop
+.Lwrfin:
+ deccc %o2
+ stb %o1, [%o5]
+ bgu,pt %XCC, .Lwrfin
+ inc %o5
+.Lexit:
+ retl /* %o0 was preserved */
+ nop
+END(__memset_niagara7)
+#endif
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