diff options
Diffstat (limited to 'sysdeps/aarch64/memcpy.S')
| -rw-r--r-- | sysdeps/aarch64/memcpy.S | 348 |
1 files changed, 208 insertions, 140 deletions
diff --git a/sysdeps/aarch64/memcpy.S b/sysdeps/aarch64/memcpy.S index 442f390426..c256828af7 100644 --- a/sysdeps/aarch64/memcpy.S +++ b/sysdeps/aarch64/memcpy.S @@ -16,161 +16,229 @@ License along with the GNU C Library. If not, see <http://www.gnu.org/licenses/>. */ +#include <sysdep.h> + /* Assumptions: * - * ARMv8-a, AArch64 - * Unaligned accesses + * 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 +#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 G_l count +#define G_h dst +#define tmp1 x14 -#include <sysdep.h> +/* 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. + In order to share code with memmove, small and medium copies read all + data before writing, allowing any kind of overlap. So small, medium + and large backwards memmoves are handled by falling through into memcpy. + Overlapping large forward memmoves use a loop that copies backwards. +*/ -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 +ENTRY_ALIGN (memmove, 6) + + sub tmp1, dstin, src + cmp count, 96 + ccmp tmp1, count, 2, hi + b.lo L(move_long) + + /* Common case falls through into memcpy. */ +END (memmove) +libc_hidden_builtin_def (memmove) +ENTRY (memcpy) + + add srcend, src, count + add dstend, dstin, count + cmp count, 96 + b.hi L(copy_long) + cmp count, 16 + b.hs L(copy_medium) + + /* 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 1: - tbz count, #2, 1f - ldr tmp1w, [src], #4 - str tmp1w, [dst], #4 + 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, #1, 1f - ldrh tmp1w, [src], #2 - strh tmp1w, [dst], #2 + 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: - tbz count, #0, 1f - ldrb tmp1w, [src] - strb tmp1w, [dst] + stp A_l, A_h, [dstin] + stp D_l, D_h, [dstend, -16] + ret + + .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 + + /* 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: - 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) + 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: - 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. */ + 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 + + .p2align 4 +L(move_long): + cbz tmp1, 3f + + add srcend, src, count + add dstend, dstin, count + + /* Align dstend 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. */ + + and tmp1, dstend, 15 + ldp D_l, D_h, [srcend, -16] + sub srcend, srcend, tmp1 + sub count, count, tmp1 + ldp A_l, A_h, [srcend, -16] + stp D_l, D_h, [dstend, -16] + ldp B_l, B_h, [srcend, -32] + ldp C_l, C_h, [srcend, -48] + ldp D_l, D_h, [srcend, -64]! + sub dstend, dstend, tmp1 + subs count, count, 128 + b.ls 2f + + nop 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 + stp A_l, A_h, [dstend, -16] + ldp A_l, A_h, [srcend, -16] + stp B_l, B_h, [dstend, -32] + ldp B_l, B_h, [srcend, -32] + stp C_l, C_h, [dstend, -48] + ldp C_l, C_h, [srcend, -48] + stp D_l, D_h, [dstend, -64]! + ldp D_l, D_h, [srcend, -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 start even if + there is just 1 byte left. */ +2: + ldp G_l, G_h, [src, 48] + stp A_l, A_h, [dstend, -16] + ldp A_l, A_h, [src, 32] + stp B_l, B_h, [dstend, -32] + ldp B_l, B_h, [src, 16] + stp C_l, C_h, [dstend, -48] + ldp C_l, C_h, [src] + stp D_l, D_h, [dstend, -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] +3: ret + END (memcpy) libc_hidden_builtin_def (memcpy) |