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Re: [PATCH RFC] x86:Improve memset with general 64bit instruction
- From: ling dot ma dot program at gmail dot com
- To: neleai at seznam dot cz
- Cc: libc-alpha at sourceware dot org, aj at suse dot com, hjl dot tools at gmail dot com, liubov dot dmitrieva at gmail dot com, Ling Ma <ling dot ml at alibaba-inc dot com>
- Date: Mon, 14 Apr 2014 08:54:26 -0400
- Subject: Re: [PATCH RFC] x86:Improve memset with general 64bit instruction
- Authentication-results: sourceware.org; auth=none
From: Ling Ma <ling.ml@alibaba-inc.com>
In this patch we take advantage of HSW memory bandwidth, manage to
reduce miss branch prediction by avoiding using branch instructions and
force destination to be aligned with avx & avx2 instruction.
According to Ondra suggestion, the version shrinks code size & improve
destination througput,then re-test all cases compared with sse2 memset.
The CPU2006 403.gcc benchmark indicates this patch improves performance
from 23.7% to 57%.
---
ChangeLog | 9 ++
sysdeps/x86_64/multiarch/Makefile | 4 +-
sysdeps/x86_64/multiarch/memset-avx2.S | 195 +++++++++++++++++++++++++++++++++
sysdeps/x86_64/multiarch/memset.S | 58 ++++++++++
sysdeps/x86_64/multiarch/memset_chk.S | 43 ++++++++
5 files changed, 308 insertions(+), 1 deletion(-)
create mode 100644 sysdeps/x86_64/multiarch/memset-avx2.S
create mode 100644 sysdeps/x86_64/multiarch/memset.S
create mode 100644 sysdeps/x86_64/multiarch/memset_chk.S
diff --git a/ChangeLog b/ChangeLog
index ba8980c..9e5c3bb 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+2014-04-04 Ling Ma <ling.ml@alibaba-inc.com>
+
+ * sysdeps/x86_64/multiarch/Makefile: Add memset-avx2
+ * sysdeps/x86_64/multiarch/memset-avx2.S: New file for AVX2 memset
+ * sysdeps/x86_64/multiarch/memset.S: New file for multiple memset
+ versions
+ * sysdeps/x86_64/multiarch/memset_chk.S: New file for multiple memset_chk
+ versions
+
2014-04-04 Sihai Yao <sihai.ysh@alibaba-inc.com>
* sysdeps/x86_64/multiarch/ifunc-defines.sym: Add COMMON_CPU_INDEX_7 and
FEATURE_INDEX_7.
diff --git a/sysdeps/x86_64/multiarch/Makefile b/sysdeps/x86_64/multiarch/Makefile
index 57a3c13..42df96f 100644
--- a/sysdeps/x86_64/multiarch/Makefile
+++ b/sysdeps/x86_64/multiarch/Makefile
@@ -17,7 +17,9 @@ sysdep_routines += strncat-c stpncpy-c strncpy-c strcmp-ssse3 \
strcpy-sse2-unaligned strncpy-sse2-unaligned \
stpcpy-sse2-unaligned stpncpy-sse2-unaligned \
strcat-sse2-unaligned strncat-sse2-unaligned \
- strchr-sse2-no-bsf memcmp-ssse3 strstr-sse2-unaligned
+ strchr-sse2-no-bsf memcmp-ssse3 strstr-sse2-unaligned \
+ memset-avx2
+
ifeq (yes,$(config-cflags-sse4))
sysdep_routines += strcspn-c strpbrk-c strspn-c varshift
CFLAGS-varshift.c += -msse4
diff --git a/sysdeps/x86_64/multiarch/memset-avx2.S b/sysdeps/x86_64/multiarch/memset-avx2.S
new file mode 100644
index 0000000..fea1f5a
--- /dev/null
+++ b/sysdeps/x86_64/multiarch/memset-avx2.S
@@ -0,0 +1,195 @@
+/* memset with AVX2
+ Copyright (C) 2014 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
+ <http://www.gnu.org/licenses/>. */
+
+#include <sysdep.h>
+
+#if !defined NOT_IN_libc
+
+#include "asm-syntax.h"
+#ifndef MEMSET
+# define MEMSET __memset_avx2
+# define MEMSET_CHK __memset_chk_avx2
+#endif
+
+ .section .text.avx2,"ax",@progbits
+#if defined PIC
+ENTRY (MEMSET_CHK)
+ cmpq %rdx, %rcx
+ jb HIDDEN_JUMPTARGET (__chk_fail)
+END (MEMSET_CHK)
+#endif
+
+ENTRY (MEMSET)
+ vpxor %xmm0, %xmm0, %xmm0
+ vmovd %esi, %xmm1
+ mov %rdi, %rsi
+ mov %rdi, %rax
+ vpshufb %xmm0, %xmm1, %xmm0
+ cmp $256, %rdx
+ ja L(256bytesormore)
+ add %rdx, %rsi
+ vmovd %xmm0, %rcx
+ cmp $128, %edx
+ jb L(less_128bytes)
+ vmovups %xmm0, (%rdi)
+ vmovups %xmm0, 0x10(%rdi)
+ vmovups %xmm0, 0x20(%rdi)
+ vmovups %xmm0, 0x30(%rdi)
+ vmovups %xmm0, 0x40(%rdi)
+ vmovups %xmm0, 0x50(%rdi)
+ vmovups %xmm0, 0x60(%rdi)
+ vmovups %xmm0, 0x70(%rdi)
+ vmovups %xmm0, -0x80(%rsi)
+ vmovups %xmm0, -0x70(%rsi)
+ vmovups %xmm0, -0x60(%rsi)
+ vmovups %xmm0, -0x50(%rsi)
+ vmovups %xmm0, -0x40(%rsi)
+ vmovups %xmm0, -0x30(%rsi)
+ vmovups %xmm0, -0x20(%rsi)
+ vmovups %xmm0, -0x10(%rsi)
+ ret
+
+ .p2align 4
+L(less_128bytes):
+ cmp $64, %dl
+ jb L(less_64bytes)
+ vmovups %xmm0, (%rdi)
+ vmovups %xmm0, 0x10(%rdi)
+ vmovups %xmm0, 0x20(%rdi)
+ vmovups %xmm0, 0x30(%rdi)
+ vmovups %xmm0, -0x40(%rsi)
+ vmovups %xmm0, -0x30(%rsi)
+ vmovups %xmm0, -0x20(%rsi)
+ vmovups %xmm0, -0x10(%rsi)
+ ret
+
+ .p2align 4
+L(less_64bytes):
+ cmp $32, %dl
+ jb L(less_32bytes)
+ vmovups %xmm0, (%rdi)
+ vmovups %xmm0, 0x10(%rdi)
+ vmovups %xmm0, -0x20(%rsi)
+ vmovups %xmm0, -0x10(%rsi)
+ ret
+
+ .p2align 4
+L(less_32bytes):
+ cmp $16, %dl
+ jb L(less_16bytes)
+ vmovups %xmm0, (%rdi)
+ vmovups %xmm0, -0x10(%rsi)
+ ret
+ .p2align 4
+L(less_16bytes):
+ cmp $8, %dl
+ jb L(less_8bytes)
+ mov %rcx, (%rdi)
+ mov %rcx, -0x08(%rsi)
+ ret
+
+ .p2align 4
+L(less_8bytes):
+ cmp $4, %dl
+ jb L(less_4bytes)
+ mov %ecx, (%rdi)
+ mov %ecx, -0x04(%rsi)
+
+ .p2align 4
+L(less_4bytes):
+ cmp $2, %dl
+ jb L(less_2bytes)
+ mov %cx, (%rdi)
+ mov %cx, -0x02(%rsi)
+ ret
+ .p2align 4
+L(less_2bytes):
+ cmp $1, %dl
+ jb L(less_1bytes)
+ mov %cl, (%rdi)
+L(less_1bytes):
+ ret
+
+ .p2align 4
+L(256bytesormore):
+ vinserti128 $1, %xmm0, %ymm0, %ymm0
+ mov $0x80, %rcx
+ add %rdx, %rsi
+ mov %rdi, %r9
+ vmovups %ymm0, (%rdi)
+ and $-0x20, %rdi
+ add $32, %rdi
+ sub %rdi, %r9
+ add %r9, %rdx
+ cmp $4096, %rdx
+ ja L(gobble_data)
+ sub %ecx, %edx
+L(gobble_128_loop):
+ vmovaps %ymm0, (%rdi)
+ vmovaps %ymm0, 0x20(%rdi)
+ vmovaps %ymm0, 0x40(%rdi)
+ vmovaps %ymm0, 0x60(%rdi)
+ add %rcx, %rdi
+ sub %ecx, %edx
+ jae L(gobble_128_loop)
+ vmovups %ymm0, -0x80(%rsi)
+ vmovups %ymm0, -0x60(%rsi)
+ vmovups %ymm0, -0x40(%rsi)
+ vmovups %ymm0, -0x20(%rsi)
+ vzeroupper
+ ret
+
+ .p2align 4
+L(gobble_data):
+#ifdef SHARED_CACHE_SIZE_HALF
+ mov $SHARED_CACHE_SIZE_HALF, %r9
+#else
+ mov __x86_shared_cache_size_half(%rip), %r9
+#endif
+ shl $4, %r9
+ cmp %r9, %rdx
+ ja L(gobble_big_data)
+ mov %rax, %rsi
+ vmovd %xmm0, %eax
+ mov %rdx, %rcx
+ rep stosb
+ mov %rsi, %rax
+ vzeroupper
+ ret
+
+ .p2align 4
+L(gobble_big_data):
+ sub %rcx, %rdx
+L(gobble_big_data_loop):
+ vmovntdq %ymm0, (%rdi)
+ vmovntdq %ymm0, 0x20(%rdi)
+ vmovntdq %ymm0, 0x40(%rdi)
+ vmovntdq %ymm0, 0x60(%rdi)
+ add %rcx, %rdi
+ sub %rcx, %rdx
+ jae L(gobble_big_data_loop)
+ vmovups %ymm0, -0x80(%rsi)
+ vmovups %ymm0, -0x60(%rsi)
+ vmovups %ymm0, -0x40(%rsi)
+ vmovups %ymm0, -0x20(%rsi)
+ vzeroupper
+ sfence
+ ret
+
+END (MEMSET)
+#endif
diff --git a/sysdeps/x86_64/multiarch/memset.S b/sysdeps/x86_64/multiarch/memset.S
new file mode 100644
index 0000000..03132db
--- /dev/null
+++ b/sysdeps/x86_64/multiarch/memset.S
@@ -0,0 +1,58 @@
+/* Multiple versions of memset
+ Copyright (C) 2014 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
+ <http://www.gnu.org/licenses/>. */
+
+#include <sysdep.h>
+#include <shlib-compat.h>
+#include <init-arch.h>
+
+/* Define multiple versions only for the definition in lib. */
+#ifndef NOT_IN_libc
+ENTRY(memset)
+ .type memset, @gnu_indirect_function
+ cmpl $0, __cpu_features+KIND_OFFSET(%rip)
+ jne 1f
+ call __init_cpu_features
+1: leaq __memset_sse2(%rip), %rax
+ testl $bit_AVX2_Usable, __cpu_features+FEATURE_OFFSET+index_AVX2_Usable(%rip)
+ jz 2f
+ leaq __memset_avx2(%rip), %rax
+2: ret
+END(memset)
+#endif
+
+#if !defined NOT_IN_libc
+# undef memset
+# define memset __memset_sse2
+
+# undef __memset_chk
+# define __memset_chk __memset_chk_sse2
+
+# ifdef SHARED
+# undef libc_hidden_builtin_def
+/* It doesn't make sense to send libc-internal memset calls through a PLT.
+ The speedup we get from using GPR instruction is likely eaten away
+ by the indirect call in the PLT. */
+# define libc_hidden_builtin_def(name) \
+ .globl __GI_memset; __GI_memset = __memset_sse2
+# endif
+
+# undef strong_alias
+# define strong_alias(original, alias)
+#endif
+
+#include "../memset.S"
diff --git a/sysdeps/x86_64/multiarch/memset_chk.S b/sysdeps/x86_64/multiarch/memset_chk.S
new file mode 100644
index 0000000..aeae56f
--- /dev/null
+++ b/sysdeps/x86_64/multiarch/memset_chk.S
@@ -0,0 +1,43 @@
+/* Multiple versions of memset_chk
+ Copyright (C) 2014 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
+ <http://www.gnu.org/licenses/>. */
+
+#include <sysdep.h>
+#include <init-arch.h>
+
+/* Define multiple versions only for the definition in lib. */
+#ifndef NOT_IN_libc
+# ifdef SHARED
+ENTRY(__memset_chk)
+ .type __memset_chk, @gnu_indirect_function
+ cmpl $0, __cpu_features+KIND_OFFSET(%rip)
+ jne 1f
+ call __init_cpu_features
+1: leaq __memset_chk_sse2(%rip), %rax
+ testl $bit_AVX2_Usable, __cpu_features+FEATURE_OFFSET+index_AVX2_Usable(%rip)
+ jz 2f
+ leaq __memset_chk_avx2(%rip), %rax
+2: ret
+END(__memset_chk)
+
+strong_alias (__memset_chk, __memset_zero_constant_len_parameter)
+ .section .gnu.warning.__memset_zero_constant_len_parameter
+ .string "memset used with constant zero length parameter; this could be due to transposed parameters"
+# else
+# include "../memset_chk.S"
+# endif
+#endif
--
1.8.1.4