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211 lines
5.0 KiB
ArmAsm
211 lines
5.0 KiB
ArmAsm
/* Optimized memcpy for SVE.
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Copyright (C) 2021-2024 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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/* Assumptions:
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*
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* ARMv8-a, AArch64, Advanced SIMD, SVE, 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 dst x3
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#define srcend x4
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#define dstend x5
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#define tmp1 x6
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#define vlen x6
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#define A_q q0
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#define B_q q1
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#define C_q q2
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#define D_q q3
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#define E_q q4
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#define F_q q5
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#define G_q q6
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#define H_q q7
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/* This implementation supports both memcpy and memmove and shares most code.
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It uses unaligned accesses and branchless sequences to keep the code small,
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simple and improve performance.
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Copies are split into 3 main cases: small copies of up to 32 bytes, medium
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copies of up to 128 bytes, and large copies. The overhead of the overlap
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check in memmove is negligible since it is only required for large copies.
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Large copies use a software pipelined loop processing 64 bytes per iteration.
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The source pointer is 16-byte aligned to minimize unaligned accesses.
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The loop tail is handled by always copying 64 bytes from the end.
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*/
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#if HAVE_AARCH64_SVE_ASM
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.arch armv8.2-a+sve
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ENTRY (__memcpy_sve)
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PTR_ARG (0)
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PTR_ARG (1)
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SIZE_ARG (2)
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cmp count, 128
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b.hi L(copy_long)
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cntb vlen
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cmp count, vlen, lsl 1
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b.hi L(copy32_128)
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whilelo p0.b, xzr, count
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whilelo p1.b, vlen, count
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ld1b z0.b, p0/z, [src, 0, mul vl]
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ld1b z1.b, p1/z, [src, 1, mul vl]
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st1b z0.b, p0, [dstin, 0, mul vl]
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st1b z1.b, p1, [dstin, 1, mul vl]
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ret
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/* Medium copies: 33..128 bytes. */
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L(copy32_128):
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add srcend, src, count
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add dstend, dstin, count
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ldp A_q, B_q, [src]
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ldp C_q, D_q, [srcend, -32]
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cmp count, 64
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b.hi L(copy128)
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stp A_q, B_q, [dstin]
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stp C_q, D_q, [dstend, -32]
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ret
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/* Copy 65..128 bytes. */
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L(copy128):
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ldp E_q, F_q, [src, 32]
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cmp count, 96
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b.ls L(copy96)
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ldp G_q, H_q, [srcend, -64]
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stp G_q, H_q, [dstend, -64]
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L(copy96):
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stp A_q, B_q, [dstin]
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stp E_q, F_q, [dstin, 32]
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stp C_q, D_q, [dstend, -32]
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ret
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.p2align 4
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/* Copy more than 128 bytes. */
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L(copy_long):
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add srcend, src, count
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add dstend, dstin, count
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/* Copy 16 bytes and then align src to 16-byte alignment. */
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ldr D_q, [src]
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and tmp1, src, 15
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bic src, src, 15
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sub dst, dstin, tmp1
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add count, count, tmp1 /* Count is now 16 too large. */
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ldp A_q, B_q, [src, 16]
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str D_q, [dstin]
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ldp C_q, D_q, [src, 48]
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subs count, count, 128 + 16 /* Test and readjust count. */
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b.ls L(copy64_from_end)
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L(loop64):
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stp A_q, B_q, [dst, 16]
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ldp A_q, B_q, [src, 80]
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stp C_q, D_q, [dst, 48]
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ldp C_q, D_q, [src, 112]
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add src, src, 64
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add dst, dst, 64
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subs count, count, 64
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b.hi L(loop64)
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/* Write the last iteration and copy 64 bytes from the end. */
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L(copy64_from_end):
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ldp E_q, F_q, [srcend, -64]
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stp A_q, B_q, [dst, 16]
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ldp A_q, B_q, [srcend, -32]
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stp C_q, D_q, [dst, 48]
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stp E_q, F_q, [dstend, -64]
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stp A_q, B_q, [dstend, -32]
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ret
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END (__memcpy_sve)
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ENTRY (__memmove_sve)
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PTR_ARG (0)
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PTR_ARG (1)
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SIZE_ARG (2)
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cmp count, 128
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b.hi L(move_long)
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cntb vlen
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cmp count, vlen, lsl 1
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b.hi L(copy32_128)
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whilelo p0.b, xzr, count
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whilelo p1.b, vlen, count
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ld1b z0.b, p0/z, [src, 0, mul vl]
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ld1b z1.b, p1/z, [src, 1, mul vl]
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st1b z0.b, p0, [dstin, 0, mul vl]
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st1b z1.b, p1, [dstin, 1, mul vl]
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ret
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.p2align 4
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L(move_long):
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add srcend, src, count
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add dstend, dstin, count
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/* Only use backward copy if there is an overlap. */
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sub tmp1, dstin, src
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cbz tmp1, L(return)
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cmp tmp1, count
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b.hs L(copy_long)
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/* Large backwards copy for overlapping copies.
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Copy 16 bytes and then align srcend to 16-byte alignment. */
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ldr D_q, [srcend, -16]
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and tmp1, srcend, 15
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bic srcend, srcend, 15
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sub count, count, tmp1
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ldp A_q, B_q, [srcend, -32]
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str D_q, [dstend, -16]
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ldp C_q, D_q, [srcend, -64]
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sub dstend, dstend, tmp1
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subs count, count, 128
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b.ls L(copy64_from_start)
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L(loop64_backwards):
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str B_q, [dstend, -16]
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str A_q, [dstend, -32]
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ldp A_q, B_q, [srcend, -96]
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str D_q, [dstend, -48]
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str C_q, [dstend, -64]!
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ldp C_q, D_q, [srcend, -128]
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sub srcend, srcend, 64
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subs count, count, 64
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b.hi L(loop64_backwards)
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/* Write the last iteration and copy 64 bytes from the start. */
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L(copy64_from_start):
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ldp E_q, F_q, [src, 32]
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stp A_q, B_q, [dstend, -32]
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ldp A_q, B_q, [src]
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stp C_q, D_q, [dstend, -64]
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stp E_q, F_q, [dstin, 32]
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stp A_q, B_q, [dstin]
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L(return):
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ret
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END (__memmove_sve)
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#endif
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