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aarch64: Optimized memset for Kunpeng processor.
Due to the branch prediction issue of Kunpeng processor, we found memset_generic has poor performance on middle sizes setting, and so we reconstructed the logic, expanded the loop by 4 times in set_long to solve the problem, even when setting below 1K sizes have benefit. Another change is that DZ_ZVA seems no work when setting zero, so we discarded it and used set_long to set zero instead. Fewer branches and predictions also make the zero case have slightly improvement. Checked on aarch64-linux-gnu. Reviewed-by: Wilco Dijkstra <Wilco.Dijkstra@arm.com>
This commit is contained in:
Xuelei Zhang
Adhemerval Zanella
parent
c2150769d0
commit
525de033a9
@ -1,7 +1,7 @@
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ifeq ($(subdir),string)
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sysdep_routines += memcpy_generic memcpy_thunderx memcpy_thunderx2 \
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memcpy_falkor memmove_falkor \
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memset_generic memset_falkor memset_emag \
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memset_generic memset_falkor memset_emag memset_kunpeng \
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memchr_generic memchr_nosimd \
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strlen_generic strlen_asimd
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endif
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@ -53,6 +53,7 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
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can do a comparative analysis with __memset_generic. */
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IFUNC_IMPL_ADD (array, i, memset, (zva_size == 64), __memset_falkor)
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IFUNC_IMPL_ADD (array, i, memset, (zva_size == 64), __memset_emag)
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IFUNC_IMPL_ADD (array, i, memset, 1, __memset_kunpeng)
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IFUNC_IMPL_ADD (array, i, memset, 1, __memset_generic))
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IFUNC_IMPL (i, name, memchr,
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IFUNC_IMPL_ADD (array, i, memchr, 1, __memchr_nosimd)
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@ -30,10 +30,13 @@ extern __typeof (__redirect_memset) __libc_memset;
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extern __typeof (__redirect_memset) __memset_falkor attribute_hidden;
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extern __typeof (__redirect_memset) __memset_emag attribute_hidden;
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extern __typeof (__redirect_memset) __memset_kunpeng attribute_hidden;
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extern __typeof (__redirect_memset) __memset_generic attribute_hidden;
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libc_ifunc (__libc_memset,
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((IS_FALKOR (midr) || IS_PHECDA (midr)) && zva_size == 64
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IS_KUNPENG (midr)
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?__memset_kunpeng
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: ((IS_FALKOR (midr) || IS_PHECDA (midr)) && zva_size == 64
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? __memset_falkor
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: (IS_EMAG (midr) && zva_size == 64
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? __memset_emag
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113
sysdeps/aarch64/multiarch/memset_kunpeng.S
Normal file
113
sysdeps/aarch64/multiarch/memset_kunpeng.S
Normal file
@ -0,0 +1,113 @@
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/* Optimized memset for Huawei Kunpeng processor.
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Copyright (C) 2012-2019 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library. If not, see
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<https://www.gnu.org/licenses/>. */
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#include <sysdep.h>
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#include <sysdeps/aarch64/memset-reg.h>
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#if IS_IN (libc)
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# define MEMSET __memset_kunpeng
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/* Assumptions:
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*
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* ARMv8-a, AArch64, unaligned accesses
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*
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*/
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ENTRY_ALIGN (MEMSET, 6)
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DELOUSE (0)
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DELOUSE (2)
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dup v0.16B, valw
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add dstend, dstin, count
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cmp count, 128
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b.hs L(set_long)
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cmp count, 16
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b.lo L(less16)
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/* Set 16..127 bytes. */
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str q0, [dstin]
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tbnz count, 6, L(set127)
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str q0, [dstend, -16]
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tbz count, 5, 1f
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str q0, [dstin, 16]
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str q0, [dstend, -32]
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1: ret
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.p2align 4
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/* Set 64..127 bytes. Write 64 bytes from the start and
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64 bytes from the end. */
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L(set127):
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stp q0, q0, [dstin, 16]
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str q0, [dstin, 48]
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stp q0, q0, [dstend, -64]
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stp q0, q0, [dstend, -32]
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ret
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.p2align 4
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/* Set 0..15 bytes. */
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L(less16):
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tbz count, 3, L(less8)
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str d0, [dstin]
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str d0, [dstend, -8]
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ret
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L(less8):
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tbz count, 2, 2f
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str s0, [dstin]
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str s0, [dstend, -4]
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ret
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2: cbz count, 3f
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str b0, [dstin]
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tbz count, 1, 3f
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str h0, [dstend, -2]
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3: ret
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.p2align 4
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L(set_long):
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bic dst, dstin, 15
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str q0, [dstin]
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sub count, dstend, dst /* Count is 16 too large. */
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sub dst, dst, 16 /* Dst is biased by -32. */
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sub count, count, 64 + 16 + 1 /* Adjust count and bias for loop. */
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1: stp q0, q0, [dst, 32]
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stp q0, q0, [dst, 64]!
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subs count, count, 64
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b.lo 1f
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stp q0, q0, [dst, 32]
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stp q0, q0, [dst, 64]!
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subs count, count, 64
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b.lo 1f
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stp q0, q0, [dst, 32]
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stp q0, q0, [dst, 64]!
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subs count, count, 64
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b.lo 1f
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stp q0, q0, [dst, 32]
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stp q0, q0, [dst, 64]!
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subs count, count, 64
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b.hs 1b
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1: stp q0, q0, [dstend, -64]
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stp q0, q0, [dstend, -32]
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ret
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END (MEMSET)
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libc_hidden_builtin_def (MEMSET)
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#endif
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