Add x86_64 memset optimized for AVX2

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.

The CPU2006 403.gcc benchmark indicates this patch improves performance
from 26% to 59%.

	* sysdeps/x86_64/multiarch/Makefile: Add memset-avx2.
	* sysdeps/x86_64/multiarch/memset-avx2.S: New file.
	* sysdeps/x86_64/multiarch/memset.S: Likewise.
	* sysdeps/x86_64/multiarch/memset_chk.S: Likewise.
	* sysdeps/x86_64/multiarch/rtld-memset.S: Likewise.

5 files changed, 275 insertions, 1 deletions

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..b45f8a0
--- /dev/null
+++ b/sysdeps/x86_64/multiarch/memset-avx2.S
@@ -0,0 +1,168 @@
+/* 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
+	lea	(%rdi, %rdx), %rsi
+	mov	%rdi, %rax
+	vpshufb	%xmm0, %xmm1, %xmm0
+	cmp	$16, %rdx
+	jb	L(less_16bytes)
+	cmp	$256, %rdx
+	jae	L(256bytesormore)
+	cmp	$128, %dl
+	jb	L(less_128bytes)
+	vmovdqu	%xmm0, (%rdi)
+	vmovdqu %xmm0, 0x10(%rdi)
+	vmovdqu %xmm0, 0x20(%rdi)
+	vmovdqu %xmm0, 0x30(%rdi)
+	vmovdqu %xmm0, 0x40(%rdi)
+	vmovdqu %xmm0, 0x50(%rdi)
+	vmovdqu %xmm0, 0x60(%rdi)
+	vmovdqu %xmm0, 0x70(%rdi)
+	vmovdqu %xmm0, -0x80(%rsi)
+	vmovdqu %xmm0, -0x70(%rsi)
+	vmovdqu %xmm0, -0x60(%rsi)
+	vmovdqu %xmm0, -0x50(%rsi)
+	vmovdqu %xmm0, -0x40(%rsi)
+	vmovdqu %xmm0, -0x30(%rsi)
+	vmovdqu %xmm0, -0x20(%rsi)
+	vmovdqu %xmm0, -0x10(%rsi)
+	ret
+
+	.p2align 4
+L(less_128bytes):
+	cmp	$64, %dl
+	jb	L(less_64bytes)
+	vmovdqu %xmm0, (%rdi)
+	vmovdqu %xmm0, 0x10(%rdi)
+	vmovdqu %xmm0, 0x20(%rdi)
+	vmovdqu %xmm0, 0x30(%rdi)
+	vmovdqu %xmm0, -0x40(%rsi)
+	vmovdqu %xmm0, -0x30(%rsi)
+	vmovdqu %xmm0, -0x20(%rsi)
+	vmovdqu %xmm0, -0x10(%rsi)
+	ret
+
+	.p2align 4
+L(less_64bytes):
+	cmp	$32, %dl
+	jb	L(less_32bytes)
+	vmovdqu %xmm0, (%rdi)
+	vmovdqu %xmm0, 0x10(%rdi)
+	vmovdqu %xmm0, -0x20(%rsi)
+	vmovdqu %xmm0, -0x10(%rsi)
+	ret
+
+	.p2align 4
+L(less_32bytes):
+	vmovdqu %xmm0, (%rdi)
+	vmovdqu %xmm0, -0x10(%rsi)
+	ret
+
+	.p2align 4
+L(less_16bytes):
+	cmp	$8, %dl
+	jb	L(less_8bytes)
+	vmovq %xmm0, (%rdi)
+	vmovq %xmm0, -0x08(%rsi)
+	ret
+
+	.p2align 4
+L(less_8bytes):
+	vmovd	%xmm0, %ecx
+	cmp	$4, %dl
+	jb	L(less_4bytes)
+	mov	%ecx, (%rdi)
+	mov	%ecx, -0x04(%rsi)
+	ret
+
+	.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
+	and	$-0x20, %rdi
+	add	$0x20, %rdi
+	vmovdqu	%ymm0, (%rax)
+	sub	%rdi, %rax
+	lea	-0x80(%rax, %rdx), %rcx
+	cmp	$4096, %rcx
+	ja	L(gobble_data)
+L(gobble_128_loop):
+	vmovdqa	%ymm0, (%rdi)
+	vmovdqa	%ymm0, 0x20(%rdi)
+	vmovdqa	%ymm0, 0x40(%rdi)
+	vmovdqa	%ymm0, 0x60(%rdi)
+	sub	$-0x80, %rdi
+	add	$-0x80, %ecx
+	jb	L(gobble_128_loop)
+	mov	%rsi, %rax
+	vmovdqu	%ymm0, -0x80(%rsi)
+	vmovdqu	%ymm0, -0x60(%rsi)
+	vmovdqu	%ymm0, -0x40(%rsi)
+	vmovdqu	%ymm0, -0x20(%rsi)
+	sub	%rdx, %rax
+	vzeroupper
+	ret
+
+	.p2align 4
+L(gobble_data):
+	sub	$-0x80, %rcx
+	vmovd	%xmm0, %eax
+	rep	stosb
+	mov	%rsi, %rax
+	sub	%rdx, %rax
+	vzeroupper
+	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..3113d1c
--- /dev/null
+++ b/sysdeps/x86_64/multiarch/memset.S
@@ -0,0 +1,59 @@
+/* Multiple versions of memset
+   All versions must be listed in ifunc-impl-list.c.
+   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..2182780
--- /dev/null
+++ b/sysdeps/x86_64/multiarch/memset_chk.S
@@ -0,0 +1,44 @@
+/* Multiple versions of memset_chk
+   All versions must be listed in ifunc-impl-list.c.
+   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
diff --git a/sysdeps/x86_64/multiarch/rtld-memset.S b/sysdeps/x86_64/multiarch/rtld-memset.S
new file mode 100644
index 0000000..8092aa0
--- /dev/null
+++ b/sysdeps/x86_64/multiarch/rtld-memset.S
@@ -0,0 +1 @@
+#include "../rtld-memset.S"