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/* Optimized version of the standard memmove() function.
This file is part of the GNU C Library.
Copyright (C) 2000-2024 Free Software Foundation, Inc.
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
<https://www.gnu.org/licenses/>. */
/* Return: dest
Inputs:
in0: dest
in1: src
in2: byte count
The core of the function is the memcpy implementation used in memcpy.S.
When bytes have to be copied backwards, only the easy case, when
all arguments are multiples of 8, is optimised.
In this form, it assumes little endian mode. For big endian mode,
sh1 must be computed using an extra instruction: sub sh1 = 64, sh1
or the UM.be bit should be cleared at the beginning and set at the end. */
#include <sysdep.h>
#undef ret
#define OP_T_THRES 16
#define OPSIZ 8
#define adest r15
#define saved_pr r17
#define saved_lc r18
#define dest r19
#define src r20
#define len r21
#define asrc r22
#define tmp2 r23
#define tmp3 r24
#define tmp4 r25
#define ptable r26
#define ploop56 r27
#define loopaddr r28
#define sh1 r29
#define loopcnt r30
#define value r31
#ifdef GAS_ALIGN_BREAKS_UNWIND_INFO
# define ALIGN(n) { nop 0 }
#else
# define ALIGN(n) .align n
#endif
#define LOOP(shift) \
ALIGN(32); \
.loop##shift##: \
(p[0]) ld8 r[0] = [asrc], 8 ; /* w1 */ \
(p[MEMLAT+1]) st8 [dest] = value, 8 ; \
(p[MEMLAT]) shrp value = r[MEMLAT], r[MEMLAT+1], shift ; \
nop.b 0 ; \
nop.b 0 ; \
br.ctop.sptk .loop##shift ; \
br.cond.sptk .cpyfew ; /* deal with the remaining bytes */
#define MEMLAT 21
#define Nrot (((2*MEMLAT+3) + 7) & ~7)
ENTRY(memmove)
.prologue
alloc r2 = ar.pfs, 3, Nrot - 3, 0, Nrot
.rotr r[MEMLAT + 2], q[MEMLAT + 1]
.rotp p[MEMLAT + 2]
mov ret0 = in0 // return value = dest
.save pr, saved_pr
mov saved_pr = pr // save the predicate registers
.save ar.lc, saved_lc
mov saved_lc = ar.lc // save the loop counter
.body
or tmp3 = in0, in1 ;; // tmp3 = dest | src
or tmp3 = tmp3, in2 // tmp3 = dest | src | len
mov dest = in0 // dest
mov src = in1 // src
mov len = in2 // len
sub tmp2 = r0, in0 // tmp2 = -dest
cmp.eq p6, p0 = in2, r0 // if (len == 0)
(p6) br.cond.spnt .restore_and_exit;;// return dest;
and tmp4 = 7, tmp3 // tmp4 = (dest | src | len) & 7
cmp.le p6, p0 = dest, src // if dest <= src it's always safe
(p6) br.cond.spnt .forward // to copy forward
add tmp3 = src, len;;
cmp.lt p6, p0 = dest, tmp3 // if dest > src && dest < src + len
(p6) br.cond.spnt .backward // we have to copy backward
.forward:
shr.u loopcnt = len, 4 ;; // loopcnt = len / 16
cmp.ne p6, p0 = tmp4, r0 // if ((dest | src | len) & 7 != 0)
(p6) br.cond.sptk .next // goto next;
// The optimal case, when dest, src and len are all multiples of 8
and tmp3 = 0xf, len
mov pr.rot = 1 << 16 // set rotating predicates
mov ar.ec = MEMLAT + 1 ;; // set the epilog counter
cmp.ne p6, p0 = tmp3, r0 // do we have to copy an extra word?
adds loopcnt = -1, loopcnt;; // --loopcnt
(p6) ld8 value = [src], 8;;
(p6) st8 [dest] = value, 8 // copy the "odd" word
mov ar.lc = loopcnt // set the loop counter
cmp.eq p6, p0 = 8, len
(p6) br.cond.spnt .restore_and_exit;;// the one-word special case
adds adest = 8, dest // set adest one word ahead of dest
adds asrc = 8, src ;; // set asrc one word ahead of src
nop.b 0 // get the "golden" alignment for
nop.b 0 // the next loop
.l0:
(p[0]) ld8 r[0] = [src], 16
(p[0]) ld8 q[0] = [asrc], 16
(p[MEMLAT]) st8 [dest] = r[MEMLAT], 16
(p[MEMLAT]) st8 [adest] = q[MEMLAT], 16
br.ctop.dptk .l0 ;;
mov pr = saved_pr, -1 // restore the predicate registers
mov ar.lc = saved_lc // restore the loop counter
br.ret.sptk.many b0
.next:
cmp.ge p6, p0 = OP_T_THRES, len // is len <= OP_T_THRES
and loopcnt = 7, tmp2 // loopcnt = -dest % 8
(p6) br.cond.spnt .cpyfew // copy byte by byte
;;
cmp.eq p6, p0 = loopcnt, r0
(p6) br.cond.sptk .dest_aligned
sub len = len, loopcnt // len -= -dest % 8
adds loopcnt = -1, loopcnt // --loopcnt
;;
mov ar.lc = loopcnt
.l1: // copy -dest % 8 bytes
ld1 value = [src], 1 // value = *src++
;;
st1 [dest] = value, 1 // *dest++ = value
br.cloop.dptk .l1
.dest_aligned:
and sh1 = 7, src // sh1 = src % 8
and tmp2 = -8, len // tmp2 = len & -OPSIZ
and asrc = -8, src // asrc = src & -OPSIZ -- align src
shr.u loopcnt = len, 3 // loopcnt = len / 8
and len = 7, len;; // len = len % 8
adds loopcnt = -1, loopcnt // --loopcnt
addl tmp4 = @ltoff(.table), gp
addl tmp3 = @ltoff(.loop56), gp
mov ar.ec = MEMLAT + 1 // set EC
mov pr.rot = 1 << 16;; // set rotating predicates
mov ar.lc = loopcnt // set LC
cmp.eq p6, p0 = sh1, r0 // is the src aligned?
(p6) br.cond.sptk .src_aligned
add src = src, tmp2 // src += len & -OPSIZ
shl sh1 = sh1, 3 // sh1 = 8 * (src % 8)
ld8 ploop56 = [tmp3] // ploop56 = &loop56
ld8 ptable = [tmp4];; // ptable = &table
add tmp3 = ptable, sh1;; // tmp3 = &table + sh1
mov ar.ec = MEMLAT + 1 + 1 // one more pass needed
ld8 tmp4 = [tmp3];; // tmp4 = loop offset
sub loopaddr = ploop56,tmp4 // loopadd = &loop56 - loop offset
ld8 r[1] = [asrc], 8;; // w0
mov b6 = loopaddr;;
br b6 // jump to the appropriate loop
LOOP(8)
LOOP(16)
LOOP(24)
LOOP(32)
LOOP(40)
LOOP(48)
LOOP(56)
.src_aligned:
.l3:
(p[0]) ld8 r[0] = [src], 8
(p[MEMLAT]) st8 [dest] = r[MEMLAT], 8
br.ctop.dptk .l3
.cpyfew:
cmp.eq p6, p0 = len, r0 // is len == 0 ?
adds len = -1, len // --len;
(p6) br.cond.spnt .restore_and_exit ;;
mov ar.lc = len
.l4:
ld1 value = [src], 1
;;
st1 [dest] = value, 1
br.cloop.dptk .l4 ;;
.restore_and_exit:
mov pr = saved_pr, -1 // restore the predicate registers
mov ar.lc = saved_lc // restore the loop counter
br.ret.sptk.many b0
// In the case of a backward copy, optimise only the case when everything
// is a multiple of 8, otherwise copy byte by byte. The backward copy is
// used only when the blocks are overlapping and dest > src.
.backward:
shr.u loopcnt = len, 3 // loopcnt = len / 8
add src = src, len // src points one byte past the end
add dest = dest, len ;; // dest points one byte past the end
mov ar.ec = MEMLAT + 1 // set the epilog counter
mov pr.rot = 1 << 16 // set rotating predicates
adds loopcnt = -1, loopcnt // --loopcnt
cmp.ne p6, p0 = tmp4, r0 // if ((dest | src | len) & 7 != 0)
(p6) br.cond.sptk .bytecopy ;; // copy byte by byte backward
adds src = -8, src // src points to the last word
adds dest = -8, dest // dest points to the last word
mov ar.lc = loopcnt;; // set the loop counter
.l5:
(p[0]) ld8 r[0] = [src], -8
(p[MEMLAT]) st8 [dest] = r[MEMLAT], -8
br.ctop.dptk .l5
br.cond.sptk .restore_and_exit
.bytecopy:
adds src = -1, src // src points to the last byte
adds dest = -1, dest // dest points to the last byte
adds loopcnt = -1, len;; // loopcnt = len - 1
mov ar.lc = loopcnt;; // set the loop counter
.l6:
(p[0]) ld1 r[0] = [src], -1
(p[MEMLAT]) st1 [dest] = r[MEMLAT], -1
br.ctop.dptk .l6
br.cond.sptk .restore_and_exit
END(memmove)
.rodata
.align 8
.table:
data8 0 // dummy entry
data8 .loop56 - .loop8
data8 .loop56 - .loop16
data8 .loop56 - .loop24
data8 .loop56 - .loop32
data8 .loop56 - .loop40
data8 .loop56 - .loop48
data8 .loop56 - .loop56
libc_hidden_builtin_def (memmove)
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