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113 lines
2.6 KiB
ArmAsm
113 lines
2.6 KiB
ArmAsm
/* Optimized memset for AmpereComputing emag processor.
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Copyright (C) 2018-2024 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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<https://www.gnu.org/licenses/>. */
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#include <sysdep.h>
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#include "memset-reg.h"
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/* Assumptions:
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*
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* ARMv8-a, AArch64, unaligned accesses
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*
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*/
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ENTRY (__memset_emag)
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PTR_ARG (0)
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SIZE_ARG (2)
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bfi valw, valw, 8, 8
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bfi valw, valw, 16, 16
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bfi val, val, 32, 32
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add dstend, dstin, count
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cmp count, 96
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b.hi L(set_long)
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cmp count, 16
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b.hs L(set_medium)
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/* Set 0..15 bytes. */
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tbz count, 3, 1f
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str val, [dstin]
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str val, [dstend, -8]
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ret
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.p2align 3
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1: tbz count, 2, 2f
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str valw, [dstin]
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str valw, [dstend, -4]
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ret
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2: cbz count, 3f
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strb valw, [dstin]
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tbz count, 1, 3f
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strh valw, [dstend, -2]
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3: ret
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.p2align 3
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/* Set 16..96 bytes. */
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L(set_medium):
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stp val, val, [dstin]
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tbnz count, 6, L(set96)
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stp val, val, [dstend, -16]
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tbz count, 5, 1f
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stp val, val, [dstin, 16]
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stp val, val, [dstend, -32]
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1: ret
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.p2align 4
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/* Set 64..96 bytes. Write 64 bytes from the start and
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32 bytes from the end. */
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L(set96):
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stp val, val, [dstin, 16]
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stp val, val, [dstin, 32]
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stp val, val, [dstin, 48]
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stp val, val, [dstend, -32]
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stp val, val, [dstend, -16]
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ret
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.p2align 4
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L(set_long):
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stp val, val, [dstin]
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bic dst, dstin, 15
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/* Small-size or non-zero memset does not use DC ZVA. */
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sub count, dstend, dst
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/*
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* Adjust count and bias for loop. By subtracting extra 1 from count,
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* it is easy to use tbz instruction to check whether loop tailing
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* count is less than 33 bytes, so as to bypass 2 unnecessary stps.
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*/
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sub count, count, 64+16+1
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1: stp val, val, [dst, 16]
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stp val, val, [dst, 32]
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stp val, val, [dst, 48]
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stp val, val, [dst, 64]!
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subs count, count, 64
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b.hs 1b
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tbz count, 5, 1f /* Remaining count is less than 33 bytes? */
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stp val, val, [dst, 16]
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stp val, val, [dst, 32]
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1: stp val, val, [dstend, -32]
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stp val, val, [dstend, -16]
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ret
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END (__memset_emag)
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