From 1b6634e6bb89e9127e025433e9562dbc0e0c8fde Mon Sep 17 00:00:00 2001
From: Anton Youdkevitch <anton.youdkevitch@bell-sw.com>
Date: Wed, 10 Apr 2019 15:18:00 +0000
Subject: [PATCH] [AARCH64] thunderx2 memmove performance improvements
Used SIMD load/store instead of GPR for overlapping
forward move.
Reused existing memcpy implementation for small or
overlapping backward move.
Fixed the existing memcpy implementation to allow it
to deal with the overlapping case.
Simplified loop tails in the memcpy implementation -
use branchless overlapping sequence of fixed length
load/stores instead of branching depending on the
size.
---
sysdeps/aarch64/multiarch/ifunc-impl-list.c | 1 +
sysdeps/aarch64/multiarch/memcpy_thunderx2.S | 372 ++++++++-------------------
sysdeps/aarch64/multiarch/memmove.c | 5 +-
3 files changed, 119 insertions(+), 259 deletions(-)
@@ -45,6 +45,7 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
IFUNC_IMPL_ADD (array, i, memcpy, 1, __memcpy_generic))
IFUNC_IMPL (i, name, memmove,
IFUNC_IMPL_ADD (array, i, memmove, 1, __memmove_thunderx)
+ IFUNC_IMPL_ADD (array, i, memmove, 1, __memmove_thunderx2)
IFUNC_IMPL_ADD (array, i, memmove, 1, __memmove_falkor)
IFUNC_IMPL_ADD (array, i, memmove, 1, __memmove_generic))
IFUNC_IMPL (i, name, memset,
@@ -85,16 +85,14 @@
#if IS_IN (libc)
#undef MEMCPY
-#undef MEMMOVE
#define MEMCPY __memcpy_thunderx2
+#undef MEMMOVE
#define MEMMOVE __memmove_thunderx2
-/* Moves 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.
- Overlapping large forward memmoves use a loop that copies backwards.
+/* Overlapping large forward memmoves use a loop that copies backwards.
+ Otherwise memcpy is used. Small moves branch to memcopy16 directly.
+ The longer memcpy cases fall through to the memcpy head.
*/
ENTRY_ALIGN (MEMMOVE, 6)
@@ -103,188 +101,14 @@ ENTRY_ALIGN (MEMMOVE, 6)
DELOUSE (1)
DELOUSE (2)
+ add srcend, src, count
+ cmp count, 16
+ b.ls L(memcopy16)
sub tmp1, dstin, src
cmp count, 96
ccmp tmp1, count, 2, hi
b.lo L(move_long)
- prfm PLDL1KEEP, [src]
- add srcend, src, count
- add dstend, dstin, count
- cmp count, 16
- b.ls L(copy16)
- cmp count, 96
- b.hi L(copy_long)
-
- /* Medium copies: 17..96 bytes. */
- sub tmp1, count, 1
- ldp A_l, A_h, [src]
- tbnz tmp1, 6, L(copy96)
- ldp D_l, D_h, [srcend, -16]
- tbz tmp1, 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
-
- .p2align 4
- /* Small copies: 0..16 bytes. */
-L(copy16):
- cmp count, 8
- b.lo 1f
- ldr A_l, [src]
- ldr A_h, [srcend, -8]
- str A_l, [dstin]
- str A_h, [dstend, -8]
- ret
- .p2align 4
-1:
- tbz count, 2, 1f
- ldr A_lw, [src]
- ldr A_hw, [srcend, -4]
- str A_lw, [dstin]
- str A_hw, [dstend, -4]
- ret
-
- /* Copy 0..3 bytes. Use a branchless sequence that copies the same
- byte 3 times if count==1, or the 2nd byte twice if count==2. */
-1:
- cbz count, 2f
- lsr tmp1, count, 1
- ldrb A_lw, [src]
- ldrb A_hw, [srcend, -1]
- ldrb B_lw, [src, tmp1]
- strb A_lw, [dstin]
- strb B_lw, [dstin, tmp1]
- strb A_hw, [dstend, -1]
-2: 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 L(last64)
-L(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 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 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, [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 (MEMMOVE)
libc_hidden_builtin_def (MEMMOVE)
@@ -293,18 +117,15 @@ libc_hidden_builtin_def (MEMMOVE)
medium copies of 17..96 bytes which are fully unrolled. Large copies
of more than 96 bytes align the destination and use load-and-merge
approach in the case src and dst addresses are unaligned not evenly,
- so that, loads and stores are always aligned.
- Large copies use an unrolled loop processing 64 bytes per iteration.
- The current optimized memcpy implementation is not compatible with
- memmove and is separated from it completely.
-
- memcpy implementation below is not compatible with memmove
- because of pipelined loads/stores, which are faster, but they
- can't be used in the case of overlapping memmove arrays */
+ so that, actual loads and stores are always aligned.
+ Large copies use the loops processing 64 bytes per iteration for
+ unaligned case and 128 bytes per iteration for aligned ones.
+*/
#define MEMCPY_PREFETCH_LDR 640
ENTRY (MEMCPY)
+
DELOUSE (0)
DELOUSE (1)
DELOUSE (2)
@@ -373,29 +194,26 @@ L(bytes_0_to_8):
/* Copy 0..3 bytes. Use a branchless sequence that copies the same
byte 3 times if count==1, or the 2nd byte twice if count==2. */
L(bytes_0_to_3):
- cbz count, L(end)
+ cbz count, 1f
lsr tmp1, count, 1
ldrb A_lw, [src]
ldrb A_hw, [srcend, -1]
add dstend, dstin, count
ldrb B_lw, [src, tmp1]
- strb A_lw, [dstin]
strb B_lw, [dstin, tmp1]
strb A_hw, [dstend, -1]
-L(end):
+ strb A_lw, [dstin]
+1:
ret
.p2align 4
L(memcpy_copy96):
/* Copying 65..96 bytes. A_q (first 16 bytes) and
- E_q(last 16 bytes) are already loaded.
-
- The size is large enough to benefit from aligned
- loads */
+ E_q(last 16 bytes) are already loaded. The size
+ is large enough to benefit from aligned loads */
bic src, src, 15
ldp B_q, C_q, [src]
- str A_q, [dstin]
/* Loaded 64 bytes, second 16-bytes chunk can be
overlapping with the first chunk by tmp1 bytes.
Stored 16 bytes. */
@@ -408,44 +226,47 @@ L(memcpy_copy96):
b.gt L(copy96_medium)
ldr D_q, [src, 32]
stp B_q, C_q, [dst, 16]
- str E_q, [dstend, -16]
str D_q, [dst, 48]
+ str A_q, [dstin]
+ str E_q, [dstend, -16]
ret
.p2align 4
L(copy96_medium):
- ldp D_q, A_q, [src, 32]
- str B_q, [dst, 16]
+ ldp D_q, G_q, [src, 32]
cmp count, 96
b.gt L(copy96_large)
- str E_q, [dstend, -16]
+ str B_q, [dst, 16]
stp C_q, D_q, [dst, 32]
- str A_q, [dst, 64]
+ str G_q, [dst, 64]
+ str A_q, [dstin]
+ str E_q, [dstend, -16]
ret
L(copy96_large):
ldr F_q, [src, 64]
+ str B_q, [dst, 16]
stp C_q, D_q, [dst, 32]
+ stp G_q, F_q, [dst, 64]
+ str A_q, [dstin]
str E_q, [dstend, -16]
- stp A_q, F_q, [dst, 64]
ret
.p2align 4
L(memcopy_long):
bic src, src, 15
ldp B_q, C_q, [src], #32
- str A_q, [dstin]
sub dst, dstin, tmp1
add count, count, tmp1
add dst, dst, 16
and tmp1, dst, 15
ldp D_q, E_q, [src], #32
- str B_q, [dst], #16
+ str A_q, [dstin]
/* Already loaded 64+16 bytes. Check if at
least 64 more bytes left */
subs count, count, 64+64+16
- b.lt L(loop128_exit2)
+ b.lt L(loop128_exit0)
cmp count, MEMCPY_PREFETCH_LDR + 64 + 32
b.lt L(loop128)
cbnz tmp1, L(dst_unaligned)
@@ -454,66 +275,59 @@ L(memcopy_long):
.p2align 4
L(loop128_prefetch):
- str C_q, [dst], #16
prfm pldl1strm, [src, MEMCPY_PREFETCH_LDR]
- str D_q, [dst], #16
ldp F_q, G_q, [src], #32
- str E_q, [dst], #16
- ldp H_q, A_q, [src], #32
- str F_q, [dst], #16
+ stp B_q, C_q, [dst], #32
+ ldp H_q, I_q, [src], #32
prfm pldl1strm, [src, MEMCPY_PREFETCH_LDR]
- str G_q, [dst], #16
ldp B_q, C_q, [src], #32
- str H_q, [dst], #16
+ stp D_q, E_q, [dst], #32
ldp D_q, E_q, [src], #32
- stp A_q, B_q, [dst], #32
+ stp F_q, G_q, [dst], #32
+ stp H_q, I_q, [dst], #32
subs count, count, 128
b.ge L(loop128_prefetch)
-L(preloop128):
add count, count, MEMCPY_PREFETCH_LDR + 64 + 32
.p2align 4
L(loop128):
ldp F_q, G_q, [src], #32
- str C_q, [dst], #16
- ldp B_q, A_q, [src], #32
- str D_q, [dst], #16
- stp E_q, F_q, [dst], #32
- stp G_q, B_q, [dst], #32
+ ldp H_q, I_q, [src], #32
+ stp B_q, C_q, [dst], #32
+ stp D_q, E_q, [dst], #32
subs count, count, 64
b.lt L(loop128_exit1)
-L(loop128_proceed):
ldp B_q, C_q, [src], #32
- str A_q, [dst], #16
ldp D_q, E_q, [src], #32
- str B_q, [dst], #16
+ stp F_q, G_q, [dst], #32
+ stp H_q, I_q, [dst], #32
subs count, count, 64
b.ge L(loop128)
-
- .p2align 4
-L(loop128_exit2):
- stp C_q, D_q, [dst], #32
- str E_q, [dst], #16
- b L(copy_long_check32);
-
+L(loop128_exit0):
+ ldp F_q, G_q, [srcend, -64]
+ ldp H_q, I_q, [srcend, -32]
+ stp B_q, C_q, [dst], #32
+ stp D_q, E_q, [dst]
+ stp F_q, G_q, [dstend, -64]
+ stp H_q, I_q, [dstend, -32]
+ ret
L(loop128_exit1):
- /* A_q is still not stored and 0..63 bytes left,
- so, count is -64..-1.
- Check if less than 32 bytes left (count < -32) */
- str A_q, [dst], #16
-L(copy_long_check32):
- cmn count, 64
- b.eq L(copy_long_done)
- cmn count, 32
- b.le L(copy_long_last32)
- ldp B_q, C_q, [src]
- stp B_q, C_q, [dst]
-
-L(copy_long_last32):
- ldp F_q, G_q, [srcend, -32]
- stp F_q, G_q, [dstend, -32]
+ ldp B_q, C_q, [srcend, -64]
+ ldp D_q, E_q, [srcend, -32]
+ stp F_q, G_q, [dst], #32
+ stp H_q, I_q, [dst]
+ stp B_q, C_q, [dstend, -64]
+ stp D_q, E_q, [dstend, -32]
+ ret
-L(copy_long_done):
+L(dst_unaligned_tail):
+ ldp C_q, D_q, [srcend, -64]
+ ldp E_q, F_q, [srcend, -32]
+ stp A_q, B_q, [dst], #32
+ stp H_q, I_q, [dst], #16
+ str G_q, [dst, tmp1]
+ stp C_q, D_q, [dstend, -64]
+ stp E_q, F_q, [dstend, -32]
ret
L(dst_unaligned):
@@ -542,17 +356,20 @@ L(dst_unaligned):
/* Store the 16 bytes to dst and align dst for further
operations, several bytes will be stored at this
address once more */
- str C_q, [dst], #16
+
ldp F_q, G_q, [src], #32
+ stp B_q, C_q, [dst], #32
bic dst, dst, 15
- subs count, count, 32
+ sub count, count, 32
adrp tmp2, L(ext_table)
add tmp2, tmp2, :lo12:L(ext_table)
add tmp2, tmp2, tmp1, LSL #2
ldr tmp3w, [tmp2]
add tmp2, tmp2, tmp3w, SXTW
br tmp2
-.p2align 4 ;\
+
+.p2align 4
+ /* to make the loop in each chunk 16-bytes aligned */
nop
#define EXT_CHUNK(shft) \
L(ext_size_ ## shft):;\
@@ -573,7 +390,7 @@ L(ext_size_ ## shft):;\
b.ge 1b;\
2:;\
ext I_v.16b, F_v.16b, G_v.16b, 16-shft;\
- b L(ext_tail);
+ b L(dst_unaligned_tail);
EXT_CHUNK(1)
EXT_CHUNK(2)
@@ -591,12 +408,51 @@ EXT_CHUNK(13)
EXT_CHUNK(14)
EXT_CHUNK(15)
-L(ext_tail):
- stp A_q, B_q, [dst], #32
- stp H_q, I_q, [dst], #16
- add dst, dst, tmp1
- str G_q, [dst], #16
- b L(copy_long_check32)
+L(move_long):
+ .p2align 4
+1:
+ cbz tmp1, 3f
+
+ add srcend, src, count
+ add dstend, dstin, count
+
+ and tmp1, srcend, 15
+ ldr D_q, [srcend, -16]
+ sub srcend, srcend, tmp1
+ sub count, count, tmp1
+ ldp A_q, B_q, [srcend, -32]
+ str D_q, [dstend, -16]
+ ldp C_q, D_q, [srcend, -64]!
+ sub dstend, dstend, tmp1
+ subs count, count, 128
+ b.ls 2f
+
+ .p2align 4
+1:
+ subs count, count, 64
+ stp A_q, B_q, [dstend, -32]
+ ldp A_q, B_q, [srcend, -32]
+ stp C_q, D_q, [dstend, -64]!
+ ldp C_q, D_q, [srcend, -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:
+ ldr G_q, [src, 48]
+ str B_q, [dstend, -16]
+ ldr B_q, [src, 32]
+ str A_q, [dstend, -32]
+ ldr A_q, [src, 16]
+ str D_q, [dstend, -48]
+ ldr D_q, [src]
+ str C_q, [dstend, -64]
+ str G_q, [dstin, 48]
+ str B_q, [dstin, 32]
+ str A_q, [dstin, 16]
+ str D_q, [dstin]
+3: ret
END (MEMCPY)
@@ -30,6 +30,7 @@ extern __typeof (__redirect_memmove) __libc_memmove;
extern __typeof (__redirect_memmove) __memmove_generic attribute_hidden;
extern __typeof (__redirect_memmove) __memmove_thunderx attribute_hidden;
+extern __typeof (__redirect_memmove) __memmove_thunderx2 attribute_hidden;
extern __typeof (__redirect_memmove) __memmove_falkor attribute_hidden;
libc_ifunc (__libc_memmove,
@@ -37,7 +38,9 @@ libc_ifunc (__libc_memmove,
? __memmove_thunderx
: (IS_FALKOR (midr) || IS_PHECDA (midr)
? __memmove_falkor
- : __memmove_generic)));
+ : (IS_THUNDERX2 (midr) || IS_THUNDERX2PA (midr)
+ ? __memmove_thunderx2
+ : __memmove_generic))));
# undef memmove
strong_alias (__libc_memmove, memmove);
--
2.7.4