Faster memcpy on x64.

We add new memcpy version that uses unaligned loads which are fast
on modern processors. This allows second improvement which is avoiding
computed jump which is relatively expensive operation.

Tests available here:
http://kam.mff.cuni.cz/~ondra/memcpy_profile_result27_04_13.tar.bz2

1 files changed, 175 insertions, 0 deletions

diff --git a/sysdeps/x86_64/multiarch/memcpy-sse2-unaligned.S b/sysdeps/x86_64/multiarch/memcpy-sse2-unaligned.S
new file mode 100644
index 0000000000..efdfea238f
--- /dev/null
+++ b/sysdeps/x86_64/multiarch/memcpy-sse2-unaligned.S
@@ -0,0 +1,175 @@
+/* memcpy with unaliged loads
+   Copyright (C) 2013 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 "asm-syntax.h"
+
+#ifndef ALIGN
+# define ALIGN(n)	.p2align n
+#endif
+
+
+ENTRY(__memcpy_sse2_unaligned)
+	movq	%rsi, %rax
+	leaq	(%rdx,%rdx), %rcx
+	subq	%rdi, %rax
+	subq	%rdx, %rax
+	cmpq	%rcx, %rax
+	jb	L(overlapping)
+	cmpq	$16, %rdx
+	jbe	L(less_16)
+	movdqu	(%rsi), %xmm8
+	cmpq	$32, %rdx
+	movdqu	%xmm8, (%rdi)
+	movdqu	-16(%rsi,%rdx), %xmm8
+	movdqu	%xmm8, -16(%rdi,%rdx)
+	ja	.L31
+L(return):
+	movq	%rdi, %rax
+	ret
+	.p2align 4,,10
+	ALIGN(4)
+.L31:
+	movdqu	16(%rsi), %xmm8
+	cmpq	$64, %rdx
+	movdqu	%xmm8, 16(%rdi)
+	movdqu	-32(%rsi,%rdx), %xmm8
+	movdqu	%xmm8, -32(%rdi,%rdx)
+	jbe	L(return)
+	movdqu	32(%rsi), %xmm8
+	cmpq	$128, %rdx
+	movdqu	%xmm8, 32(%rdi)
+	movdqu	-48(%rsi,%rdx), %xmm8
+	movdqu	%xmm8, -48(%rdi,%rdx)
+	movdqu	48(%rsi), %xmm8
+	movdqu	%xmm8, 48(%rdi)
+	movdqu	-64(%rsi,%rdx), %xmm8
+	movdqu	%xmm8, -64(%rdi,%rdx)
+	jbe	L(return)
+	leaq	64(%rdi), %rcx
+	addq	%rdi, %rdx
+	andq	$-64, %rdx
+	andq	$-64, %rcx
+	movq	%rcx, %rax
+	subq	%rdi, %rax
+	addq	%rax, %rsi
+	cmpq	%rdx, %rcx
+	je	L(return)
+	movq	%rsi, %r10
+	subq	%rcx, %r10
+	leaq	16(%r10), %r9
+	leaq	32(%r10), %r8
+	leaq	48(%r10), %rax
+	.p2align 4,,10
+	ALIGN(4)
+L(loop):
+	movdqu	(%rcx,%r10), %xmm8
+	movdqa	%xmm8, (%rcx)
+	movdqu	(%rcx,%r9), %xmm8
+	movdqa	%xmm8, 16(%rcx)
+	movdqu	(%rcx,%r8), %xmm8
+	movdqa	%xmm8, 32(%rcx)
+	movdqu	(%rcx,%rax), %xmm8
+	movdqa	%xmm8, 48(%rcx)
+	addq	$64, %rcx
+	cmpq	%rcx, %rdx
+	jne	L(loop)
+	jmp	L(return)
+L(overlapping):
+	cmpq	%rsi, %rdi
+	jae	.L3
+	testq	%rdx, %rdx
+	.p2align 4,,5
+	je	L(return)
+	movq	%rdx, %r9
+	leaq	16(%rsi), %rcx
+	leaq	16(%rdi), %r8
+	shrq	$4, %r9
+	movq	%r9, %rax
+	salq	$4, %rax
+	cmpq	%rcx, %rdi
+	setae	%cl
+	cmpq	%r8, %rsi
+	setae	%r8b
+	orl	%r8d, %ecx
+	cmpq	$15, %rdx
+	seta	%r8b
+	testb	%r8b, %cl
+	je	.L16
+	testq	%rax, %rax
+	je	.L16
+	xorl	%ecx, %ecx
+	xorl	%r8d, %r8d
+.L7:
+	movdqu	(%rsi,%rcx), %xmm8
+	addq	$1, %r8
+	movdqu	%xmm8, (%rdi,%rcx)
+	addq	$16, %rcx
+	cmpq	%r8, %r9
+	ja	.L7
+	cmpq	%rax, %rdx
+	je	L(return)
+.L21:
+	movzbl	(%rsi,%rax), %ecx
+	movb	%cl, (%rdi,%rax)
+	addq	$1, %rax
+	cmpq	%rax, %rdx
+	ja	.L21
+	jmp	L(return)
+L(less_16):
+	testb	$24, %dl
+	jne	L(between_9_16)
+	testb	$4, %dl
+	.p2align 4,,5
+	jne	L(between_5_8)
+	testq	%rdx, %rdx
+	.p2align 4,,2
+	je	L(return)
+	movzbl	(%rsi), %eax
+	testb	$2, %dl
+	movb	%al, (%rdi)
+	je	L(return)
+	movzwl	-2(%rsi,%rdx), %eax
+	movw	%ax, -2(%rdi,%rdx)
+	jmp	L(return)
+.L3:
+	leaq	-1(%rdx), %rax
+	.p2align 4,,10
+	ALIGN(4)
+.L11:
+	movzbl	(%rsi,%rax), %edx
+	movb	%dl, (%rdi,%rax)
+	subq	$1, %rax
+	jmp	.L11
+L(between_9_16):
+	movq	(%rsi), %rax
+	movq	%rax, (%rdi)
+	movq	-8(%rsi,%rdx), %rax
+	movq	%rax, -8(%rdi,%rdx)
+	jmp	L(return)
+.L16:
+	xorl	%eax, %eax
+	jmp	.L21
+L(between_5_8):
+	movl	(%rsi), %eax
+	movl	%eax, (%rdi)
+	movl	-4(%rsi,%rdx), %eax
+	movl	%eax, -4(%rdi,%rdx)
+	jmp	L(return)
+END(__memcpy_sse2_unaligned)