diff options
Diffstat (limited to 'libc')
| -rw-r--r-- | libc/arch-arm64/generic/bionic/memcpy_base.S | 295 |
1 files changed, 162 insertions, 133 deletions
diff --git a/libc/arch-arm64/generic/bionic/memcpy_base.S b/libc/arch-arm64/generic/bionic/memcpy_base.S index c5d42ce1d..82431a36b 100644 --- a/libc/arch-arm64/generic/bionic/memcpy_base.S +++ b/libc/arch-arm64/generic/bionic/memcpy_base.S @@ -1,4 +1,4 @@ -/* Copyright (c) 2012, Linaro Limited +/* Copyright (c) 2012-2013, Linaro Limited All rights reserved. Redistribution and use in source and binary forms, with or without @@ -22,158 +22,187 @@ DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE - OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. -*/ + OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ + +/* + * Copyright (c) 2015 ARM Ltd + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. The name of the company may not be used to endorse or promote + * products derived from this software without specific prior written + * permission. + * + * THIS SOFTWARE IS PROVIDED BY ARM LTD ``AS IS'' AND ANY EXPRESS OR IMPLIED + * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF + * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. + * IN NO EVENT SHALL ARM LTD BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, + * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED + * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR + * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF + * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING + * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS + * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ /* Assumptions: * - * ARMv8-a, AArch64 - * Unaligned accesses + * ARMv8-a, AArch64, unaligned accesses. * */ +#include <private/bionic_asm.h> + #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 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 B_l x8 +#define B_h x9 +#define C_l x10 +#define C_h x11 +#define D_l x12 +#define D_h x13 +#define E_l src +#define E_h count +#define F_l srcend +#define F_h dst +#define tmp1 x9 -#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 +#define L(l) .L ## l - mov dst, dstin - cmp count, #64 - b.ge .Lcpy_not_short - cmp count, #15 - b.le .Ltail15tiny +/* Copies are split into 3 main cases: small copies of up to 16 bytes, + medium copies of 17..96 bytes which are fully unrolled. Large copies + of more than 96 bytes align the destination and use an unrolled loop + processing 64 bytes per iteration. + Small and medium copies read all data before writing, allowing any + kind of overlap, and memmove tailcalls memcpy for these cases as + well as non-overlapping copies. +*/ - /* Deal with small copies quickly by dropping straight into the - * exit block. */ -.Ltail63: - /* 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 .Ltail15 - 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] + add srcend, src, count + add dstend, dstin, count + cmp count, 96 + b.hi L(copy_long) + cmp count, 16 + b.hs L(copy_medium) -.Ltail15: - 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: + /* Small copies: 0..16 bytes. */ +L(copy16): + tbz count, 3, 1f + ldr A_l, [src] + ldr A_h, [srcend, -8] + str A_l, [dstin] + str A_h, [dstend, -8] ret - -.Ltail15tiny: - /* 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 + tbz count, 2, 1f + ldr A_lw, [src] + ldr A_hw, [srcend, -4] + str A_lw, [dstin] + str A_hw, [dstend, -4] + ret + .p2align 4 1: - tbz count, #0, 1f - ldrb tmp1w, [src] - strb tmp1w, [dst] + cbz count, 2f + ldrb A_lw, [src] + tbz count, 1, 1f + ldrh A_hw, [srcend, -2] + strh A_hw, [dstend, -2] +1: strb A_lw, [dstin] +2: ret + + .p2align 4 + /* Medium copies: 17..96 bytes. */ +L(copy_medium): + ldp A_l, A_h, [src] + tbnz count, 6, L(copy96) + ldp D_l, D_h, [srcend, -16] + tbz count, 5, 1f + ldp B_l, B_h, [src, 16] + ldp C_l, C_h, [srcend, -32] + stp B_l, B_h, [dstin, 16] + stp C_l, C_h, [dstend, -32] 1: + stp A_l, A_h, [dstin] + stp D_l, D_h, [dstend, -16] ret -.Lcpy_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 .Ltail63 -2: - subs count, count, #128 - b.ge .Lcpy_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 .Ltail63 + .p2align 4 + /* Copy 64..96 bytes. Copy 64 bytes from the start and + 32 bytes from the end. */ +L(copy96): + ldp B_l, B_h, [src, 16] + ldp C_l, C_h, [src, 32] + ldp D_l, D_h, [src, 48] + ldp E_l, E_h, [srcend, -32] + ldp F_l, F_h, [srcend, -16] + stp A_l, A_h, [dstin] + stp B_l, B_h, [dstin, 16] + stp C_l, C_h, [dstin, 32] + stp D_l, D_h, [dstin, 48] + stp E_l, E_h, [dstend, -32] + stp F_l, F_h, [dstend, -16] 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 -.Lcpy_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. */ + /* Align DST to 16 byte alignment so that we don't cross cache line + boundaries on both loads and stores. There are at least 96 bytes + to copy, so copy 16 bytes unaligned and then align. The loop + copies 64 bytes per iteration and prefetches one iteration ahead. */ + + .p2align 4 +L(copy_long): + and tmp1, dstin, 15 + bic dst, dstin, 15 + ldp D_l, D_h, [src] + 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 2f 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 .Ltail63 + 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 1b + + /* 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. */ +2: + ldp E_l, E_h, [srcend, -64] + stp A_l, A_h, [dst, 16] + ldp A_l, A_h, [srcend, -48] + stp B_l, B_h, [dst, 32] + ldp B_l, B_h, [srcend, -32] + stp C_l, C_h, [dst, 48] + ldp C_l, C_h, [srcend, -16] + stp D_l, D_h, [dst, 64] + stp E_l, E_h, [dstend, -64] + stp A_l, A_h, [dstend, -48] + stp B_l, B_h, [dstend, -32] + stp C_l, C_h, [dstend, -16] ret |