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

diff --git a/ChangeLog b/ChangeLog
index a2323fa..6c540a7 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,13 @@
+2013-05-20  Ondřej Bílka  <neleai@seznam.cz>
+
+       * sysdeps/x86_64/multiarch/memcpy-sse2-unaligned.S: New file.
+       * sysdeps/x86_64/multiarch/memcpy.S (__new_memcpy): Add
+       __memcpy_sse2_unaligned ifunc selection.
+       * sysdeps/x86_64/multiarch/Makefile (sysdep_routines):
+       Add memcpy-sse2-unaligned.S.
+       * sysdeps/x86_64/multiarch/ifunc-impl-list.c (__libc_ifunc_impl_list):
+       Add: __memcpy_sse2_unaligned.
+
 2013-05-19  Joseph Myers  <joseph@codesourcery.com>
 
        [BZ #15490]

diff --git a/sysdeps/x86_64/multiarch/Makefile b/sysdeps/x86_64/multiarch/Makefile
index 86787ee..203d16e 100644 (file)
--- a/sysdeps/x86_64/multiarch/Makefile
+++ b/sysdeps/x86_64/multiarch/Makefile
@@ -7,7 +7,7 @@ endif
 ifeq ($(subdir),string)
 
 sysdep_routines += strncat-c stpncpy-c strncpy-c strcmp-ssse3 strncmp-ssse3 \
-                  strend-sse4 memcmp-sse4 memcpy-ssse3 mempcpy-ssse3 \
+                  strend-sse4 memcmp-sse4 memcpy-ssse3 memcpy-sse2-unaligned mempcpy-ssse3 \
                   memmove-ssse3 memcpy-ssse3-back mempcpy-ssse3-back \
                   memmove-ssse3-back strcasestr-nonascii strcasecmp_l-ssse3 \
                   strncase_l-ssse3 strcat-ssse3 strncat-ssse3\

diff --git a/sysdeps/x86_64/multiarch/ifunc-impl-list.c b/sysdeps/x86_64/multiarch/ifunc-impl-list.c
index 05315fd..28d3579 100644 (file)
--- a/sysdeps/x86_64/multiarch/ifunc-impl-list.c
+++ b/sysdeps/x86_64/multiarch/ifunc-impl-list.c
@@ -227,6 +227,7 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
              IFUNC_IMPL_ADD (array, i, memcpy, HAS_SSSE3,
                              __memcpy_ssse3_back)
              IFUNC_IMPL_ADD (array, i, memcpy, HAS_SSSE3, __memcpy_ssse3)
+             IFUNC_IMPL_ADD (array, i, memcpy, 1, __memcpy_sse2_unaligned)
              IFUNC_IMPL_ADD (array, i, memcpy, 1, __memcpy_sse2))
 
   /* Support sysdeps/x86_64/multiarch/mempcpy_chk.S.  */

diff --git a/sysdeps/x86_64/multiarch/memcpy-sse2-unaligned.S b/sysdeps/x86_64/multiarch/memcpy-sse2-unaligned.S
new file mode 100644 (file)
index 0000000..efdfea2
--- /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)

diff --git a/sysdeps/x86_64/multiarch/memcpy.S b/sysdeps/x86_64/multiarch/memcpy.S
index b452f53..a1e5031 100644 (file)
--- a/sysdeps/x86_64/multiarch/memcpy.S
+++ b/sysdeps/x86_64/multiarch/memcpy.S
@@ -33,13 +33,14 @@ ENTRY(__new_memcpy)
        jne     1f
        call    __init_cpu_features
 1:     leaq    __memcpy_sse2(%rip), %rax
-       testl   $bit_SSSE3, __cpu_features+CPUID_OFFSET+index_SSSE3(%rip)
-       jz      2f
-       leaq    __memcpy_ssse3(%rip), %rax
-       testl   $bit_Fast_Copy_Backward, __cpu_features+FEATURE_OFFSET+index_Fast_Copy_Backward(%rip)
-       jz      2f
-       leaq    __memcpy_ssse3_back(%rip), %rax
-2:     ret
+       testl   $bit_Slow_BSF, __cpu_features+FEATURE_OFFSET+index_Slow_BSF(%rip)
+       jnz     2f
+       leaq    __memcpy_sse2_unaligned(%rip), %rax
+       ret
+2:     testl   $bit_SSSE3, __cpu_features+CPUID_OFFSET+index_SSSE3(%rip)
+       jz 3f
+       leaq    __memcpy_ssse3(%rip), %rax
+3:     ret
 END(__new_memcpy)
 
 # undef ENTRY