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177 lines
4.1 KiB
ArmAsm
177 lines
4.1 KiB
ArmAsm
/* Copyright (C) 2012-2016 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library. If not, see
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<http://www.gnu.org/licenses/>. */
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/* Assumptions:
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*
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* ARMv8-a, AArch64
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* Unaligned accesses
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*
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*/
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#define dstin x0
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#define src x1
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#define count x2
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#define tmp1 x3
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#define tmp1w w3
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#define tmp2 x4
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#define tmp2w w4
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#define tmp3 x5
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#define tmp3w w5
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#define dst x6
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#define A_l x7
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#define A_h x8
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#define B_l x9
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#define B_h x10
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#define C_l x11
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#define C_h x12
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#define D_l x13
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#define D_h x14
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#include <sysdep.h>
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ENTRY_ALIGN (memcpy, 6)
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mov dst, dstin
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cmp count, #64
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b.ge L(cpy_not_short)
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cmp count, #15
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b.le L(tail15tiny)
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/* Deal with small copies quickly by dropping straight into the
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* exit block. */
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L(tail63):
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/* Copy up to 48 bytes of data. At this point we only need the
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* bottom 6 bits of count to be accurate. */
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ands tmp1, count, #0x30
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b.eq L(tail15)
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add dst, dst, tmp1
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add src, src, tmp1
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cmp tmp1w, #0x20
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b.eq 1f
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b.lt 2f
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ldp A_l, A_h, [src, #-48]
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stp A_l, A_h, [dst, #-48]
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1:
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ldp A_l, A_h, [src, #-32]
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stp A_l, A_h, [dst, #-32]
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2:
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ldp A_l, A_h, [src, #-16]
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stp A_l, A_h, [dst, #-16]
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L(tail15):
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ands count, count, #15
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beq 1f
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add src, src, count
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ldp A_l, A_h, [src, #-16]
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add dst, dst, count
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stp A_l, A_h, [dst, #-16]
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1:
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RET
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L(tail15tiny):
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/* Copy up to 15 bytes of data. Does not assume additional data
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being copied. */
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tbz count, #3, 1f
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ldr tmp1, [src], #8
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str tmp1, [dst], #8
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1:
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tbz count, #2, 1f
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ldr tmp1w, [src], #4
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str tmp1w, [dst], #4
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1:
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tbz count, #1, 1f
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ldrh tmp1w, [src], #2
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strh tmp1w, [dst], #2
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1:
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tbz count, #0, 1f
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ldrb tmp1w, [src]
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strb tmp1w, [dst]
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1:
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RET
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L(cpy_not_short):
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/* We don't much care about the alignment of DST, but we want SRC
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* to be 128-bit (16 byte) aligned so that we don't cross cache line
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* boundaries on both loads and stores. */
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neg tmp2, src
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ands tmp2, tmp2, #15 /* Bytes to reach alignment. */
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b.eq 2f
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sub count, count, tmp2
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/* Copy more data than needed; it's faster than jumping
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* around copying sub-Quadword quantities. We know that
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* it can't overrun. */
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ldp A_l, A_h, [src]
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add src, src, tmp2
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stp A_l, A_h, [dst]
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add dst, dst, tmp2
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/* There may be less than 63 bytes to go now. */
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cmp count, #63
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b.le L(tail63)
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2:
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subs count, count, #128
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b.ge L(cpy_body_large)
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/* Less than 128 bytes to copy, so handle 64 here and then jump
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* to the tail. */
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ldp A_l, A_h, [src]
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ldp B_l, B_h, [src, #16]
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ldp C_l, C_h, [src, #32]
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ldp D_l, D_h, [src, #48]
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stp A_l, A_h, [dst]
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stp B_l, B_h, [dst, #16]
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stp C_l, C_h, [dst, #32]
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stp D_l, D_h, [dst, #48]
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tst count, #0x3f
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add src, src, #64
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add dst, dst, #64
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b.ne L(tail63)
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RET
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/* Critical loop. Start at a new cache line boundary. Assuming
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* 64 bytes per line this ensures the entire loop is in one line. */
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.p2align 6
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L(cpy_body_large):
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/* There are at least 128 bytes to copy. */
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ldp A_l, A_h, [src, #0]
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sub dst, dst, #16 /* Pre-bias. */
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ldp B_l, B_h, [src, #16]
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ldp C_l, C_h, [src, #32]
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ldp D_l, D_h, [src, #48]! /* src += 64 - Pre-bias. */
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1:
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stp A_l, A_h, [dst, #16]
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ldp A_l, A_h, [src, #16]
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stp B_l, B_h, [dst, #32]
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ldp B_l, B_h, [src, #32]
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stp C_l, C_h, [dst, #48]
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ldp C_l, C_h, [src, #48]
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stp D_l, D_h, [dst, #64]!
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ldp D_l, D_h, [src, #64]!
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subs count, count, #64
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b.ge 1b
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stp A_l, A_h, [dst, #16]
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stp B_l, B_h, [dst, #32]
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stp C_l, C_h, [dst, #48]
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stp D_l, D_h, [dst, #64]
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add src, src, #16
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add dst, dst, #64 + 16
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tst count, #0x3f
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b.ne L(tail63)
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RET
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END (memcpy)
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libc_hidden_builtin_def (memcpy)
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