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 a2323faff481fa27e31aa34e11267a09e4103c8f..6c540a7e23c168878e477c1992514a43142b76b1 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 86787ee6eac5932f5551bf6212987739de8eab06..203d16eed32816ecd472846e5c89ccd72dd20b18 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 05315fdd7a95e2f6441fc9c1f76cdb4ebbe9c44c..28d35793c56b1942f7fd0f9c49209dac813f5aa8 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 b452f5304bcc5aa141cdecd55305e163b7495e3f..a1e5031376302a07a6f955feafa6fcde6acffdd3 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