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Diffstat (limited to 'sysdeps/aarch64/memcpy.S')
| -rw-r--r-- | sysdeps/aarch64/memcpy.S | 176 |
1 files changed, 176 insertions, 0 deletions
diff --git a/sysdeps/aarch64/memcpy.S b/sysdeps/aarch64/memcpy.S new file mode 100644 index 0000000000..caf2ab2e4f --- /dev/null +++ b/sysdeps/aarch64/memcpy.S @@ -0,0 +1,176 @@ +/* Copyright (C) 2012-2014 Free Software Foundation, Inc. + + This file is part of the GNU C Library. + + 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 + <http://www.gnu.org/licenses/>. */ + +/* Assumptions: + * + * ARMv8-a, AArch64 + * Unaligned accesses + * + */ + +#define dstin x0 +#define src x1 +#define count x2 +#define tmp1 x3 +#define tmp1w w3 +#define tmp2 x4 +#define tmp2w w4 +#define tmp3 x5 +#define tmp3w w5 +#define dst x6 + +#define A_l x7 +#define A_h x8 +#define B_l x9 +#define B_h x10 +#define C_l x11 +#define C_h x12 +#define D_l x13 +#define D_h x14 + +#include <sysdep.h> + +ENTRY_ALIGN (memcpy, 6) + + mov dst, dstin + cmp count, #64 + b.ge L(cpy_not_short) + cmp count, #15 + b.le L(tail15tiny) + + /* Deal with small copies quickly by dropping straight into the + * exit block. */ +L(tail63): + /* Copy up to 48 bytes of data. At this point we only need the + * bottom 6 bits of count to be accurate. */ + ands tmp1, count, #0x30 + b.eq L(tail15) + add dst, dst, tmp1 + add src, src, tmp1 + cmp tmp1w, #0x20 + b.eq 1f + b.lt 2f + ldp A_l, A_h, [src, #-48] + stp A_l, A_h, [dst, #-48] +1: + ldp A_l, A_h, [src, #-32] + stp A_l, A_h, [dst, #-32] +2: + ldp A_l, A_h, [src, #-16] + stp A_l, A_h, [dst, #-16] + +L(tail15): + ands count, count, #15 + beq 1f + add src, src, count + ldp A_l, A_h, [src, #-16] + add dst, dst, count + stp A_l, A_h, [dst, #-16] +1: + RET + +L(tail15tiny): + /* Copy up to 15 bytes of data. Does not assume additional data + being copied. */ + tbz count, #3, 1f + ldr tmp1, [src], #8 + str tmp1, [dst], #8 +1: + tbz count, #2, 1f + ldr tmp1w, [src], #4 + str tmp1w, [dst], #4 +1: + tbz count, #1, 1f + ldrh tmp1w, [src], #2 + strh tmp1w, [dst], #2 +1: + tbz count, #0, 1f + ldrb tmp1w, [src] + strb tmp1w, [dst] +1: + RET + +L(cpy_not_short): + /* We don't much care about the alignment of DST, but we want SRC + * to be 128-bit (16 byte) aligned so that we don't cross cache line + * boundaries on both loads and stores. */ + neg tmp2, src + ands tmp2, tmp2, #15 /* Bytes to reach alignment. */ + b.eq 2f + sub count, count, tmp2 + /* Copy more data than needed; it's faster than jumping + * around copying sub-Quadword quantities. We know that + * it can't overrun. */ + ldp A_l, A_h, [src] + add src, src, tmp2 + stp A_l, A_h, [dst] + add dst, dst, tmp2 + /* There may be less than 63 bytes to go now. */ + cmp count, #63 + b.le L(tail63) +2: + subs count, count, #128 + b.ge L(cpy_body_large) + /* Less than 128 bytes to copy, so handle 64 here and then jump + * to the tail. */ + ldp A_l, A_h, [src] + ldp B_l, B_h, [src, #16] + ldp C_l, C_h, [src, #32] + ldp D_l, D_h, [src, #48] + stp A_l, A_h, [dst] + stp B_l, B_h, [dst, #16] + stp C_l, C_h, [dst, #32] + stp D_l, D_h, [dst, #48] + tst count, #0x3f + add src, src, #64 + add dst, dst, #64 + b.ne L(tail63) + RET + + /* Critical loop. Start at a new cache line boundary. Assuming + * 64 bytes per line this ensures the entire loop is in one line. */ + .p2align 6 +L(cpy_body_large): + /* There are at least 128 bytes to copy. */ + ldp A_l, A_h, [src, #0] + sub dst, dst, #16 /* Pre-bias. */ + ldp B_l, B_h, [src, #16] + ldp C_l, C_h, [src, #32] + ldp D_l, D_h, [src, #48]! /* src += 64 - Pre-bias. */ +1: + 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.ge 1b + stp A_l, A_h, [dst, #16] + stp B_l, B_h, [dst, #32] + stp C_l, C_h, [dst, #48] + stp D_l, D_h, [dst, #64] + add src, src, #16 + add dst, dst, #64 + 16 + tst count, #0x3f + b.ne L(tail63) + RET +END (memcpy) +libc_hidden_builtin_def (memcpy) |