diff options
Diffstat (limited to 'sysdeps/aarch64/multiarch/memcpy_falkor.S')
| -rw-r--r-- | sysdeps/aarch64/multiarch/memcpy_falkor.S | 187 |
1 files changed, 187 insertions, 0 deletions
diff --git a/sysdeps/aarch64/multiarch/memcpy_falkor.S b/sysdeps/aarch64/multiarch/memcpy_falkor.S new file mode 100644 index 0000000000..3708281147 --- /dev/null +++ b/sysdeps/aarch64/multiarch/memcpy_falkor.S @@ -0,0 +1,187 @@ +/* Optimized memcpy for Qualcomm Falkor processor. + Copyright (C) 2017 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/>. */ + +#include <sysdep.h> + +/* Assumptions: + * + * ARMv8-a, AArch64, falkor, unaligned accesses. + * + */ + +#define dstin x0 +#define src x1 +#define count x2 +#define dst x3 +#define srcend x4 +#define dstend x5 +#define A_l x6 +#define A_lw w6 +#define A_h x7 +#define A_hw w7 +#define tmp1 x14 + +/* Copies are split into 3 main cases: + + 1. Small copies of up to 32 bytes + 2. Medium copies of 33..128 bytes which are fully unrolled + 3. Large copies of more than 128 bytes. + + Large copies align the sourceto a quad word and use an unrolled loop + processing 64 bytes per iteration. + + FALKOR-SPECIFIC DESIGN: + + The smallest copies (32 bytes or less) focus on optimal pipeline usage, + which is why the redundant copies of 0-3 bytes have been replaced with + conditionals, since the former would unnecessarily break across multiple + issue groups. The medium copy group has been enlarged to 128 bytes since + bumping up the small copies up to 32 bytes allows us to do that without + cost and also allows us the reduce the size of the prep code before loop64. + + All copies are done only via two registers r6 and r7. This is to ensure + that all loads hit a single hardware prefetcher which can get correctly + trained to prefetch a single stream. + + The non-temporal stores help optimize cache utilization. +*/ + +#if IS_IN (libc) +ENTRY_ALIGN (__memcpy_falkor, 6) + + cmp count, 32 + add srcend, src, count + add dstend, dstin, count + b.ls L(copy32) + ldp A_l, A_h, [src] + cmp count, 128 + stp A_l, A_h, [dstin] + b.hi L(copy_long) + + /* Medium copies: 33..128 bytes. */ + sub tmp1, count, 1 + ldp A_l, A_h, [src, 16] + stp A_l, A_h, [dstin, 16] + tbz tmp1, 6, 1f + ldp A_l, A_h, [src, 32] + stp A_l, A_h, [dstin, 32] + ldp A_l, A_h, [src, 48] + stp A_l, A_h, [dstin, 48] + ldp A_l, A_h, [srcend, -64] + stp A_l, A_h, [dstend, -64] + ldp A_l, A_h, [srcend, -48] + stp A_l, A_h, [dstend, -48] +1: + ldp A_l, A_h, [srcend, -32] + stp A_l, A_h, [dstend, -32] + ldp A_l, A_h, [srcend, -16] + stp A_l, A_h, [dstend, -16] + ret + + .p2align 4 + /* Small copies: 0..32 bytes. */ +L(copy32): + /* 16-32 */ + cmp count, 16 + b.lo 1f + ldp A_l, A_h, [src] + stp A_l, A_h, [dstin] + ldp A_l, A_h, [srcend, -16] + stp A_l, A_h, [dstend, -16] + ret + .p2align 4 +1: + /* 8-15 */ + tbz count, 3, 1f + ldr A_l, [src] + str A_l, [dstin] + ldr A_l, [srcend, -8] + str A_l, [dstend, -8] + ret + .p2align 4 +1: + /* 4-7 */ + tbz count, 2, 1f + ldr A_lw, [src] + str A_lw, [dstin] + ldr A_lw, [srcend, -4] + str A_lw, [dstend, -4] + ret + .p2align 4 +1: + /* 2-3 */ + tbz count, 1, 1f + ldrh A_lw, [src] + strh A_lw, [dstin] + ldrh A_lw, [srcend, -2] + strh A_lw, [dstend, -2] + ret + .p2align 4 +1: + /* 0-1 */ + tbz count, 0, 1f + ldrb A_lw, [src] + strb A_lw, [dstin] +1: + ret + + /* Align SRC to 16 bytes and copy; that way at least one of the + accesses is aligned throughout the copy sequence. + + The count is off by 0 to 15 bytes, but this is OK because we trim + off the last 64 bytes to copy off from the end. Due to this the + loop never runs out of bounds. */ + .p2align 6 +L(copy_long): + sub count, count, 64 + 16 + and tmp1, src, 15 + bic src, src, 15 + sub dst, dstin, tmp1 + add count, count, tmp1 + +L(loop64): + ldp A_l, A_h, [src, 16]! + stnp A_l, A_h, [dst, 16] + ldp A_l, A_h, [src, 16]! + subs count, count, 64 + stnp A_l, A_h, [dst, 32] + ldp A_l, A_h, [src, 16]! + stnp A_l, A_h, [dst, 48] + ldp A_l, A_h, [src, 16]! + stnp A_l, A_h, [dst, 64] + add dst, dst, 64 + b.hi L(loop64) + + /* Write the last full set of 64 bytes. The remainder is at most 64 + bytes, so it is safe to always copy 64 bytes from the end even if + there is just 1 byte left. */ +L(last64): + ldp A_l, A_h, [srcend, -64] + stnp A_l, A_h, [dstend, -64] + ldp A_l, A_h, [srcend, -48] + stnp A_l, A_h, [dstend, -48] + ldp A_l, A_h, [srcend, -32] + stnp A_l, A_h, [dstend, -32] + ldp A_l, A_h, [srcend, -16] + stnp A_l, A_h, [dstend, -16] + ret + +END (__memcpy_falkor) +libc_hidden_builtin_def (__memcpy_falkor) +#endif |