//===----------------------------------------------------------------------===// // // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. // See https://llvm.org/LICENSE.txt for license information. // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception // //===----------------------------------------------------------------------===// /// /// \file /// This file contains assembly-optimized implementations of Scalable Matrix /// Extension (SME) compatible memcpy and memmove functions. /// /// These implementations depend on unaligned access support. /// /// Routines taken from libc/AOR_v20.02/string/aarch64. /// //===----------------------------------------------------------------------===// #include "../assembly.h" // // __arm_sc_memcpy / __arm_sc_memmove // #define dstin x0 #define src x1 #define count x2 #define dst x3 #define srcend1 x4 #define dstend1 x5 #define A_l x6 #define A_lw w6 #define A_h x7 #define B_l x8 #define B_lw w8 #define B_h x9 #define C_l x10 #define C_lw w10 #define C_h x11 #define D_l x12 #define D_h x13 #define E_l x14 #define E_h x15 #define F_l x16 #define F_h x17 #define G_l count #define G_h dst #define H_l src #define H_h srcend1 #define tmp1 x14 /* This implementation handles overlaps and supports both memcpy and memmove from a single entry point. It uses unaligned accesses and branchless sequences to keep the code small, simple and improve performance. Copies are split into 3 main cases: small copies of up to 32 bytes, medium copies of up to 128 bytes, and large copies. The overhead of the overlap check is negligible since it is only required for large copies. Large copies use a software pipelined loop processing 64 bytes per iteration. The destination pointer is 16-byte aligned to minimize unaligned accesses. The loop tail is handled by always copying 64 bytes from the end. */ DEFINE_COMPILERRT_FUNCTION(__arm_sc_memcpy) add srcend1, src, count add dstend1, dstin, count cmp count, 128 b.hi 7f // copy_long cmp count, 32 b.hi 4f // copy32_128 /* Small copies: 0..32 bytes. */ cmp count, 16 b.lo 0f // copy16 ldp A_l, A_h, [src] ldp D_l, D_h, [srcend1, -16] stp A_l, A_h, [dstin] stp D_l, D_h, [dstend1, -16] ret /* Copy 8-15 bytes. */ 0: // copy16 tbz count, 3, 1f // copy8 ldr A_l, [src] ldr A_h, [srcend1, -8] str A_l, [dstin] str A_h, [dstend1, -8] ret .p2align 3 /* Copy 4-7 bytes. */ 1: // copy8 tbz count, 2, 2f // copy4 ldr A_lw, [src] ldr B_lw, [srcend1, -4] str A_lw, [dstin] str B_lw, [dstend1, -4] ret /* Copy 0..3 bytes using a branchless sequence. */ 2: // copy4 cbz count, 3f // copy0 lsr tmp1, count, 1 ldrb A_lw, [src] ldrb C_lw, [srcend1, -1] ldrb B_lw, [src, tmp1] strb A_lw, [dstin] strb B_lw, [dstin, tmp1] strb C_lw, [dstend1, -1] 3: // copy0 ret .p2align 4 /* Medium copies: 33..128 bytes. */ 4: // copy32_128 ldp A_l, A_h, [src] ldp B_l, B_h, [src, 16] ldp C_l, C_h, [srcend1, -32] ldp D_l, D_h, [srcend1, -16] cmp count, 64 b.hi 5f // copy128 stp A_l, A_h, [dstin] stp B_l, B_h, [dstin, 16] stp C_l, C_h, [dstend1, -32] stp D_l, D_h, [dstend1, -16] ret .p2align 4 /* Copy 65..128 bytes. */ 5: // copy128 ldp E_l, E_h, [src, 32] ldp F_l, F_h, [src, 48] cmp count, 96 b.ls 6f // copy96 ldp G_l, G_h, [srcend1, -64] ldp H_l, H_h, [srcend1, -48] stp G_l, G_h, [dstend1, -64] stp H_l, H_h, [dstend1, -48] 6: // copy96 stp A_l, A_h, [dstin] stp B_l, B_h, [dstin, 16] stp E_l, E_h, [dstin, 32] stp F_l, F_h, [dstin, 48] stp C_l, C_h, [dstend1, -32] stp D_l, D_h, [dstend1, -16] ret .p2align 4 /* Copy more than 128 bytes. */ 7: // copy_long /* Use backwards copy if there is an overlap. */ sub tmp1, dstin, src cbz tmp1, 3b // copy0 cmp tmp1, count b.lo 10f //copy_long_backwards /* Copy 16 bytes and then align dst to 16-byte alignment. */ ldp D_l, D_h, [src] and tmp1, dstin, 15 bic dst, dstin, 15 sub src, src, tmp1 add count, count, tmp1 /* Count is now 16 too large. */ ldp A_l, A_h, [src, 16] stp D_l, D_h, [dstin] ldp B_l, B_h, [src, 32] ldp C_l, C_h, [src, 48] ldp D_l, D_h, [src, 64]! subs count, count, 128 + 16 /* Test and readjust count. */ b.ls 9f // copy64_from_end 8: // loop64 stp A_l, A_h, [dst, 16] ldp A_l, A_h, [src, 16] stp B_l, B_h, [dst, 32] ldp B_l, B_h, [src, 32] stp C_l, C_h, [dst, 48] ldp C_l, C_h, [src, 48] stp D_l, D_h, [dst, 64]! ldp D_l, D_h, [src, 64]! subs count, count, 64 b.hi 8b // loop64 /* Write the last iteration and copy 64 bytes from the end. */ 9: // copy64_from_end ldp E_l, E_h, [srcend1, -64] stp A_l, A_h, [dst, 16] ldp A_l, A_h, [srcend1, -48] stp B_l, B_h, [dst, 32] ldp B_l, B_h, [srcend1, -32] stp C_l, C_h, [dst, 48] ldp C_l, C_h, [srcend1, -16] stp D_l, D_h, [dst, 64] stp E_l, E_h, [dstend1, -64] stp A_l, A_h, [dstend1, -48] stp B_l, B_h, [dstend1, -32] stp C_l, C_h, [dstend1, -16] ret .p2align 4 /* Large backwards copy for overlapping copies. Copy 16 bytes and then align dst to 16-byte alignment. */ 10: // copy_long_backwards ldp D_l, D_h, [srcend1, -16] and tmp1, dstend1, 15 sub srcend1, srcend1, tmp1 sub count, count, tmp1 ldp A_l, A_h, [srcend1, -16] stp D_l, D_h, [dstend1, -16] ldp B_l, B_h, [srcend1, -32] ldp C_l, C_h, [srcend1, -48] ldp D_l, D_h, [srcend1, -64]! sub dstend1, dstend1, tmp1 subs count, count, 128 b.ls 12f // copy64_from_start 11: // loop64_backwards stp A_l, A_h, [dstend1, -16] ldp A_l, A_h, [srcend1, -16] stp B_l, B_h, [dstend1, -32] ldp B_l, B_h, [srcend1, -32] stp C_l, C_h, [dstend1, -48] ldp C_l, C_h, [srcend1, -48] stp D_l, D_h, [dstend1, -64]! ldp D_l, D_h, [srcend1, -64]! subs count, count, 64 b.hi 11b // loop64_backwards /* Write the last iteration and copy 64 bytes from the start. */ 12: // copy64_from_start ldp G_l, G_h, [src, 48] stp A_l, A_h, [dstend1, -16] ldp A_l, A_h, [src, 32] stp B_l, B_h, [dstend1, -32] ldp B_l, B_h, [src, 16] stp C_l, C_h, [dstend1, -48] ldp C_l, C_h, [src] stp D_l, D_h, [dstend1, -64] stp G_l, G_h, [dstin, 48] stp A_l, A_h, [dstin, 32] stp B_l, B_h, [dstin, 16] stp C_l, C_h, [dstin] ret END_COMPILERRT_FUNCTION(__arm_sc_memcpy) DEFINE_COMPILERRT_FUNCTION_ALIAS(__arm_sc_memmove, __arm_sc_memcpy)