[PATCH] AArch64: Add SVE memcpy
Wilco Dijkstra
Wilco.Dijkstra@arm.com
Wed May 25 16:04:26 GMT 2022
Add an initial SVE memcpy implementation. Copies up to 32 bytes use SVE vectors
which improves the random memcpy benchmark significantly.
Enable it for Neoverse V1.
Passes GLIBC testsuite, OK for commit?
---
diff --git a/sysdeps/aarch64/multiarch/Makefile b/sysdeps/aarch64/multiarch/Makefile
index 7500cf1e9369443daed1c5a938903dcff9d0a45e..490aaa0faf1e74fb7014e2ed6b574d92b8b83637 100644
--- a/sysdeps/aarch64/multiarch/Makefile
+++ b/sysdeps/aarch64/multiarch/Makefile
@@ -1,6 +1,6 @@
ifeq ($(subdir),string)
sysdep_routines += memcpy_generic memcpy_advsimd memcpy_thunderx memcpy_thunderx2 \
- memcpy_falkor memcpy_a64fx \
+ memcpy_falkor memcpy_a64fx memcpy_sve \
memset_generic memset_falkor memset_emag memset_kunpeng \
memset_a64fx \
memchr_generic memchr_nosimd \
diff --git a/sysdeps/aarch64/multiarch/ifunc-impl-list.c b/sysdeps/aarch64/multiarch/ifunc-impl-list.c
index 483fbbdb523c9a5b697a9b7f63153d2cefb482ac..e12c1a9fad3c2b1061f3f9d10accfe61ccc5ea50 100644
--- a/sysdeps/aarch64/multiarch/ifunc-impl-list.c
+++ b/sysdeps/aarch64/multiarch/ifunc-impl-list.c
@@ -45,6 +45,7 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
IFUNC_IMPL_ADD (array, i, memcpy, 1, __memcpy_simd)
#if HAVE_AARCH64_SVE_ASM
IFUNC_IMPL_ADD (array, i, memcpy, sve, __memcpy_a64fx)
+ IFUNC_IMPL_ADD (array, i, memcpy, sve, __memcpy_sve)
#endif
IFUNC_IMPL_ADD (array, i, memcpy, 1, __memcpy_generic))
IFUNC_IMPL (i, name, memmove,
@@ -54,6 +55,7 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
IFUNC_IMPL_ADD (array, i, memmove, 1, __memmove_simd)
#if HAVE_AARCH64_SVE_ASM
IFUNC_IMPL_ADD (array, i, memmove, sve, __memmove_a64fx)
+ IFUNC_IMPL_ADD (array, i, memmove, sve, __memmove_sve)
#endif
IFUNC_IMPL_ADD (array, i, memmove, 1, __memmove_generic))
IFUNC_IMPL (i, name, memset,
diff --git a/sysdeps/aarch64/multiarch/memcpy.c b/sysdeps/aarch64/multiarch/memcpy.c
index a476dd548fd04fddcd0b39cc3263866769bb309a..6172fddcb83baf91e78f621cae7cf4dd9aff822a 100644
--- a/sysdeps/aarch64/multiarch/memcpy.c
+++ b/sysdeps/aarch64/multiarch/memcpy.c
@@ -35,6 +35,7 @@ extern __typeof (__redirect_memcpy) __memcpy_thunderx2 attribute_hidden;
extern __typeof (__redirect_memcpy) __memcpy_falkor attribute_hidden;
# if HAVE_AARCH64_SVE_ASM
extern __typeof (__redirect_memcpy) __memcpy_a64fx attribute_hidden;
+extern __typeof (__redirect_memcpy) __memcpy_sve attribute_hidden;
# endif
libc_ifunc (__libc_memcpy,
@@ -45,15 +46,12 @@ libc_ifunc (__libc_memcpy,
: (IS_THUNDERX2 (midr) || IS_THUNDERX2PA (midr)
? __memcpy_thunderx2
: (IS_NEOVERSE_N1 (midr) || IS_NEOVERSE_N2 (midr)
- || IS_NEOVERSE_V1 (midr)
? __memcpy_simd
-# if HAVE_AARCH64_SVE_ASM
- : (IS_A64FX (midr) && sve
- ? __memcpy_a64fx
- : __memcpy_generic))))));
-# else
- : __memcpy_generic)))));
-# endif
+ : (sve && HAVE_AARCH64_SVE_ASM
+ ? (IS_A64FX (midr)
+ ? __memcpy_a64fx
+ : __memcpy_sve)
+ : __memcpy_generic))))));
# undef memcpy
strong_alias (__libc_memcpy, memcpy);
#endif
diff --git a/sysdeps/aarch64/multiarch/memcpy_sve.S b/sysdeps/aarch64/multiarch/memcpy_sve.S
new file mode 100644
index 0000000000000000000000000000000000000000..a70907ec5595114e4da35c54e932279c22e53cc6
--- /dev/null
+++ b/sysdeps/aarch64/multiarch/memcpy_sve.S
@@ -0,0 +1,218 @@
+/* Optimized memcpy for SVE.
+ Copyright (C) 2021-2022 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
+ <https://www.gnu.org/licenses/>. */
+
+#include <sysdep.h>
+
+/* Assumptions:
+ *
+ * ARMv8-a, AArch64, Advanced SIMD, SVE, unaligned accesses.
+ *
+ */
+
+#define dstin x0
+#define src x1
+#define count x2
+#define dst x3
+#define srcend x4
+#define dstend x5
+#define tmp1 x6
+#define vlen x6
+
+#define A_q q0
+#define B_q q1
+#define C_q q2
+#define D_q q3
+#define E_q q4
+#define F_q q5
+#define G_q q6
+#define H_q q7
+
+/* This implementation supports both memcpy and memmove and shares most code.
+ It uses unaligned accesses and branchless sequences to keep the code small,
+ simple and improve performance.
+
+ Copies are split into 3 main cases: small copies of up to 32 bytes, medium
+ copies of up to 128 bytes, and large copies. The overhead of the overlap
+ check in memmove is negligible since it is only required for large copies.
+
+ Large copies use a software pipelined loop processing 64 bytes per iteration.
+ The source pointer is 16-byte aligned to minimize unaligned accesses.
+ The loop tail is handled by always copying 64 bytes from the end.
+*/
+
+#if HAVE_AARCH64_SVE_ASM
+
+ .arch armv8.2-a+sve
+
+ENTRY (__memcpy_sve)
+ PTR_ARG (0)
+ PTR_ARG (1)
+ SIZE_ARG (2)
+
+ cmp count, 128
+ b.hi L(copy_long)
+ cmp count, 32
+ b.hi L(copy32_128)
+
+ whilelo p0.b, xzr, count
+ cntb vlen
+ tbnz vlen, 4, L(vlen128)
+ ld1b z0.b, p0/z, [src]
+ st1b z0.b, p0, [dstin]
+ ret
+
+ /* Medium copies: 33..128 bytes. */
+L(copy32_128):
+ add srcend, src, count
+ add dstend, dstin, count
+ ldp A_q, B_q, [src]
+ ldp C_q, D_q, [srcend, -32]
+ cmp count, 64
+ b.hi L(copy128)
+ stp A_q, B_q, [dstin]
+ stp C_q, D_q, [dstend, -32]
+ ret
+
+ /* Copy 65..128 bytes. */
+L(copy128):
+ ldp E_q, F_q, [src, 32]
+ cmp count, 96
+ b.ls L(copy96)
+ ldp G_q, H_q, [srcend, -64]
+ stp G_q, H_q, [dstend, -64]
+L(copy96):
+ stp A_q, B_q, [dstin]
+ stp E_q, F_q, [dstin, 32]
+ stp C_q, D_q, [dstend, -32]
+ ret
+
+L(vlen128):
+ whilelo p1.b, vlen, count
+ ld1b z0.b, p0/z, [src, 0, mul vl]
+ ld1b z1.b, p1/z, [src, 1, mul vl]
+ st1b z0.b, p0, [dstin, 0, mul vl]
+ st1b z1.b, p1, [dstin, 1, mul vl]
+ ret
+
+ .p2align 4
+ /* Copy more than 128 bytes. */
+L(copy_long):
+ add srcend, src, count
+ add dstend, dstin, count
+
+ /* Copy 16 bytes and then align src to 16-byte alignment. */
+ ldr D_q, [src]
+ and tmp1, src, 15
+ bic src, src, 15
+ sub dst, dstin, tmp1
+ add count, count, tmp1 /* Count is now 16 too large. */
+ ldp A_q, B_q, [src, 16]
+ str D_q, [dstin]
+ ldp C_q, D_q, [src, 48]
+ subs count, count, 128 + 16 /* Test and readjust count. */
+ b.ls L(copy64_from_end)
+L(loop64):
+ stp A_q, B_q, [dst, 16]
+ ldp A_q, B_q, [src, 80]
+ stp C_q, D_q, [dst, 48]
+ ldp C_q, D_q, [src, 112]
+ add src, src, 64
+ add dst, dst, 64
+ subs count, count, 64
+ b.hi L(loop64)
+
+ /* Write the last iteration and copy 64 bytes from the end. */
+L(copy64_from_end):
+ ldp E_q, F_q, [srcend, -64]
+ stp A_q, B_q, [dst, 16]
+ ldp A_q, B_q, [srcend, -32]
+ stp C_q, D_q, [dst, 48]
+ stp E_q, F_q, [dstend, -64]
+ stp A_q, B_q, [dstend, -32]
+ ret
+
+END (__memcpy_sve)
+libc_hidden_builtin_def (__memcpy_sve)
+
+
+ENTRY (__memmove_sve)
+ PTR_ARG (0)
+ PTR_ARG (1)
+ SIZE_ARG (2)
+
+ cmp count, 128
+ b.hi L(move_long)
+ cmp count, 32
+ b.hi L(copy32_128)
+
+ whilelo p0.b, xzr, count
+ cntb vlen
+ tbnz vlen, 4, L(vlen128)
+ ld1b z0.b, p0/z, [src]
+ st1b z0.b, p0, [dstin]
+ ret
+
+ .p2align 4
+L(move_long):
+ add srcend, src, count
+ add dstend, dstin, count
+ /* Only use backward copy if there is an overlap. */
+ sub tmp1, dstin, src
+ cbz tmp1, L(return)
+ cmp tmp1, count
+ b.hs L(copy_long)
+
+ /* Large backwards copy for overlapping copies.
+ Copy 16 bytes and then align srcend to 16-byte alignment. */
+ ldr D_q, [srcend, -16]
+ and tmp1, srcend, 15
+ bic srcend, srcend, 15
+ 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 L(copy64_from_start)
+
+L(loop64_backwards):
+ str B_q, [dstend, -16]
+ str A_q, [dstend, -32]
+ ldp A_q, B_q, [srcend, -96]
+ str D_q, [dstend, -48]
+ str C_q, [dstend, -64]!
+ ldp C_q, D_q, [srcend, -128]
+ sub srcend, srcend, 64
+ subs count, count, 64
+ b.hi L(loop64_backwards)
+
+ /* Write the last iteration and copy 64 bytes from the start. */
+L(copy64_from_start):
+ ldp E_q, F_q, [src, 32]
+ stp A_q, B_q, [dstend, -32]
+ ldp A_q, B_q, [src]
+ stp C_q, D_q, [dstend, -64]
+ stp E_q, F_q, [dstin, 32]
+ stp A_q, B_q, [dstin]
+L(return):
+ ret
+
+END (__memmove_sve)
+libc_hidden_builtin_def (__memmove_sve)
+#endif
diff --git a/sysdeps/aarch64/multiarch/memmove.c b/sysdeps/aarch64/multiarch/memmove.c
index 4f7d7eedfd943d1b6a54e90dc973406b30cc8db9..8713932d719fd2f31ac8914d28f586548770936e 100644
--- a/sysdeps/aarch64/multiarch/memmove.c
+++ b/sysdeps/aarch64/multiarch/memmove.c
@@ -35,6 +35,7 @@ extern __typeof (__redirect_memmove) __memmove_thunderx2 attribute_hidden;
extern __typeof (__redirect_memmove) __memmove_falkor attribute_hidden;
# if HAVE_AARCH64_SVE_ASM
extern __typeof (__redirect_memmove) __memmove_a64fx attribute_hidden;
+extern __typeof (__redirect_memmove) __memmove_sve attribute_hidden;
# endif
libc_ifunc (__libc_memmove,
@@ -45,15 +46,12 @@ libc_ifunc (__libc_memmove,
: (IS_THUNDERX2 (midr) || IS_THUNDERX2PA (midr)
? __memmove_thunderx2
: (IS_NEOVERSE_N1 (midr) || IS_NEOVERSE_N2 (midr)
- || IS_NEOVERSE_V1 (midr)
? __memmove_simd
-# if HAVE_AARCH64_SVE_ASM
- : (IS_A64FX (midr) && sve
- ? __memmove_a64fx
- : __memmove_generic))))));
-# else
- : __memmove_generic)))));
-# endif
+ : (sve && HAVE_AARCH64_SVE_ASM
+ ? (IS_A64FX (midr)
+ ? __memmove_a64fx
+ : __memmove_sve)
+ : __memmove_generic))))));
# undef memmove
strong_alias (__libc_memmove, memmove);
#endif
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