Improve 64 bit strcat functions with SSE2/SSSE3

18 files changed, 1523 insertions, 321 deletions

diff --git a/ChangeLog b/ChangeLog
index 0932ae59e4..e3dc2ee88f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,32 @@
+2011-07-15  Liubov Dmitrieva  <liubov.dmitrieva@intel.com>
+
+	* sysdeps/x86_64/multiarch/Makefile (sysdep_routines): Add
+	strcat-ssse3 strcat-sse2-unaligned strncat-ssse3
+	strncat-sse2-unaligned strncat-c strlen-sse2-pminub
+	* sysdeps/x86_64/multiarch/strcat-sse2-unaligned.S: New file.
+	* sysdeps/x86_64/multiarch/strcat.S: New file.
+	* sysdeps/x86_64/multiarch/strncat.S: New file.
+	* sysdeps/x86_64/multiarch/strncat-c.c: New file.
+	* sysdeps/x86_64/multiarch/strcat-ssse3.S: New file.
+	* sysdeps/x86_64/multiarch/strncat-sse2-unaligned.S: New file.
+	* sysdeps/x86_64/multiarch/strncat-ssse3.S: New file.
+	* sysdeps/x86_64/multiarch/strcpy-ssse3.S
+	(USE_AS_STRCAT): Define.
+	Add strcat and strncat support.
+	* sysdeps/x86_64/multiarch/strlen-no-bsf.S: Likewise.
+	* sysdeps/x86_64/multiarch/strcpy-sse2-unaligned.S: Likewise.
+	* sysdeps/x86_64/multiarch/strlen-sse2-pminub.S: New file.
+	* string/strncat.c: Update.
+	(USE_AS_STRNCAT): Define.
+	* sysdeps/x86_64/multiarch/init-arch.c (__init_cpu_features):
+	Turn on bit_Prefer_PMINUB_for_stringop for Intel Core i3, i5
+	and i7.
+	* sysdeps/x86_64/multiarch/init-arch.h
+	(bit_Prefer_PMINUB_for_stringop): New.
+	(index_Prefer_PMINUB_for_stringop): Likewise.
+	* sysdeps/x86_64/multiarch/strlen.S (strlen): Check
+	bit_Prefer_PMINUB_for_stringop.
+
 2011-07-19  Ulrich Drepper  <drepper@gmail.com>
 
 	* crypt/sha512.h (struct sha512_ctx): Move buffer into union and add
diff --git a/NEWS b/NEWS
index f3cead3dba..fb2c15ec43 100644
--- a/NEWS
+++ b/NEWS
@@ -1,4 +1,4 @@
-GNU C Library NEWS -- history of user-visible changes.  2011-7-6
+GNU C Library NEWS -- history of user-visible changes.  2011-7-19
 Copyright (C) 1992-2009, 2010, 2011 Free Software Foundation, Inc.
 See the end for copying conditions.
 
@@ -23,6 +23,9 @@ Version 2.15
 
 * Improved strcpy, strncpy, stpcpy, stpncpy for SSE2 and SSSE3 on x86-64.
   Contributed by HJ Lu.
+
+* Improved strcat and strncat on x86-64.
+  Contributed by Liubov Dmitrieva.
 
 Version 2.14
 
diff --git a/string/strncat.c b/string/strncat.c
index 2e2de11508..72d9d697ac 100644
--- a/string/strncat.c
+++ b/string/strncat.c
@@ -24,10 +24,12 @@
 typedef char reg_char;
 #endif
 
-#undef strncat
+#ifndef STRNCAT
+# define STRNCAT  strncat
+#endif
 
 char *
-strncat (s1, s2, n)
+STRNCAT (s1, s2, n)
      char *s1;
      const char *s2;
      size_t n;
diff --git a/sysdeps/x86_64/multiarch/Makefile b/sysdeps/x86_64/multiarch/Makefile
index 88410b395a..c959dd195f 100644
--- a/sysdeps/x86_64/multiarch/Makefile
+++ b/sysdeps/x86_64/multiarch/Makefile
@@ -5,14 +5,16 @@ endif
 
 ifeq ($(subdir),string)
 
-sysdep_routines += stpncpy-c strncpy-c strcmp-ssse3 strncmp-ssse3 \
+sysdep_routines += strncat-c stpncpy-c strncpy-c strcmp-ssse3 strncmp-ssse3 \
 		   strend-sse4 memcmp-sse4 memcpy-ssse3 mempcpy-ssse3 \
 		   memmove-ssse3 memcpy-ssse3-back mempcpy-ssse3-back \
 		   memmove-ssse3-back strcasestr-nonascii strcasecmp_l-ssse3 \
 		   strncase_l-ssse3 strlen-sse4 strlen-no-bsf memset-x86-64 \
 		   strcpy-ssse3 strncpy-ssse3 stpcpy-ssse3 stpncpy-ssse3 \
 		   strcpy-sse2-unaligned strncpy-sse2-unaligned \
-		   stpcpy-sse2-unaligned stpncpy-sse2-unaligned
+		   stpcpy-sse2-unaligned stpncpy-sse2-unaligned \
+		   strcat-sse2-unaligned strncat-sse2-unaligned \
+		   strcat-ssse3 strncat-ssse3 strlen-sse2-pminub
 ifeq (yes,$(config-cflags-sse4))
 sysdep_routines += strcspn-c strpbrk-c strspn-c strstr-c strcasestr-c varshift
 CFLAGS-varshift.c += -msse4
diff --git a/sysdeps/x86_64/multiarch/init-arch.c b/sysdeps/x86_64/multiarch/init-arch.c
index 81b2378467..0a145ca259 100644
--- a/sysdeps/x86_64/multiarch/init-arch.c
+++ b/sysdeps/x86_64/multiarch/init-arch.c
@@ -97,18 +97,22 @@ __init_cpu_features (void)
 	    case 0x2c:
 	    case 0x2e:
 	    case 0x2f:
-	      /* Rep string instructions, copy backward and unaligned loads
-		 are fast on Intel Core i3, i5 and i7.  */
+	      /* Rep string instructions, copy backward, unaligned loads
+		 and pminub are fast on Intel Core i3, i5 and i7.  */
 #if index_Fast_Rep_String != index_Fast_Copy_Backward
 # error index_Fast_Rep_String != index_Fast_Copy_Backward
 #endif
 #if index_Fast_Rep_String != index_Fast_Unaligned_Load
 # error index_Fast_Rep_String != index_Fast_Unaligned_Load
 #endif
+#if index_Fast_Rep_String != index_Prefer_PMINUB_for_stringop
+# error index_Fast_Rep_String != index_Prefer_PMINUB_for_stringop
+#endif
 	      __cpu_features.feature[index_Fast_Rep_String]
 		|= (bit_Fast_Rep_String
 		    | bit_Fast_Copy_Backward
-		    | bit_Fast_Unaligned_Load);
+		    | bit_Fast_Unaligned_Load
+		    | bit_Prefer_PMINUB_for_stringop);
 	      break;
 	    }
 	}
diff --git a/sysdeps/x86_64/multiarch/init-arch.h b/sysdeps/x86_64/multiarch/init-arch.h
index addf5f3dde..6cfdbddc4e 100644
--- a/sysdeps/x86_64/multiarch/init-arch.h
+++ b/sysdeps/x86_64/multiarch/init-arch.h
@@ -21,6 +21,7 @@
 #define bit_Slow_BSF			(1 << 2)
 #define bit_Prefer_SSE_for_memop	(1 << 3)
 #define bit_Fast_Unaligned_Load		(1 << 4)
+#define bit_Prefer_PMINUB_for_stringop	(1 << 5)
 
 #ifdef	__ASSEMBLER__
 
@@ -41,6 +42,7 @@
 # define index_Slow_BSF			FEATURE_INDEX_1*FEATURE_SIZE
 # define index_Prefer_SSE_for_memop	FEATURE_INDEX_1*FEATURE_SIZE
 # define index_Fast_Unaligned_Load	FEATURE_INDEX_1*FEATURE_SIZE
+# define index_Prefer_PMINUB_for_stringop FEATURE_INDEX_1*FEATURE_SIZE
 
 #else	/* __ASSEMBLER__ */
 
diff --git a/sysdeps/x86_64/multiarch/strcat-sse2-unaligned.S b/sysdeps/x86_64/multiarch/strcat-sse2-unaligned.S
new file mode 100644
index 0000000000..1150281fe4
--- /dev/null
+++ b/sysdeps/x86_64/multiarch/strcat-sse2-unaligned.S
@@ -0,0 +1,55 @@
+/* strcat with SSE2
+   Copyright (C) 2011 Free Software Foundation, Inc.
+   Contributed by Intel Corporation.
+   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, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+#ifndef NOT_IN_libc
+
+# include <sysdep.h>
+
+# ifndef STRCAT
+#  define STRCAT  __strcat_sse2_unaligned
+# endif
+
+# define USE_AS_STRCAT
+
+.text
+ENTRY (STRCAT)
+	mov	%rdi, %r9
+# ifdef USE_AS_STRNCAT
+	mov	%rdx, %r8
+# endif
+
+# define RETURN  jmp L(StartStrcpyPart)
+# include "strlen-sse2-pminub.S"
+# undef RETURN
+
+L(StartStrcpyPart):
+	lea	(%r9, %rax), %rdi
+	mov	%rsi, %rcx
+	mov	%r9, %rax      /* save result */
+
+# ifdef USE_AS_STRNCAT
+	test	%r8, %r8
+	jz	L(ExitZero)
+#  define USE_AS_STRNCPY
+# endif
+
+# include "strcpy-sse2-unaligned.S"
+#endif
+
diff --git a/sysdeps/x86_64/multiarch/strcat-ssse3.S b/sysdeps/x86_64/multiarch/strcat-ssse3.S
new file mode 100644
index 0000000000..66736a7087
--- /dev/null
+++ b/sysdeps/x86_64/multiarch/strcat-ssse3.S
@@ -0,0 +1,559 @@
+/* strcat with SSSE3
+   Copyright (C) 2011 Free Software Foundation, Inc.
+   Contributed by Intel Corporation.
+   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, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+#ifndef NOT_IN_libc
+
+# include <sysdep.h>
+
+# ifndef STRCAT
+#  define STRCAT  __strcat_ssse3
+# endif
+
+# define USE_AS_STRCAT
+
+.text
+ENTRY (STRCAT)
+# ifdef USE_AS_STRNCAT
+	mov	%rdx, %r8
+# endif
+
+# define RETURN  jmp L(StartStrcpyPart)
+# include "strlen-no-bsf.S"
+
+# undef RETURN
+
+L(StartStrcpyPart):
+	mov	%rsi, %rcx
+	lea	(%rdi, %rax), %rdx
+# ifdef USE_AS_STRNCAT
+	test	%r8, %r8
+	jz	L(StrncatExit0)
+	cmp	$8, %r8
+	jbe	L(StrncatExit8Bytes)
+# endif
+	cmpb	$0, (%rcx)
+	jz	L(Exit1)
+	cmpb	$0, 1(%rcx)
+	jz	L(Exit2)
+	cmpb	$0, 2(%rcx)
+	jz	L(Exit3)
+	cmpb	$0, 3(%rcx)
+	jz	L(Exit4)
+	cmpb	$0, 4(%rcx)
+	jz	L(Exit5)
+	cmpb	$0, 5(%rcx)
+	jz	L(Exit6)
+	cmpb	$0, 6(%rcx)
+	jz	L(Exit7)
+	cmpb	$0, 7(%rcx)
+	jz	L(Exit8)
+	cmpb	$0, 8(%rcx)
+	jz	L(Exit9)
+# ifdef USE_AS_STRNCAT
+	cmp	$16, %r8
+	jb	L(StrncatExit15Bytes)
+# endif
+	cmpb	$0, 9(%rcx)
+	jz	L(Exit10)
+	cmpb	$0, 10(%rcx)
+	jz	L(Exit11)
+	cmpb	$0, 11(%rcx)
+	jz	L(Exit12)
+	cmpb	$0, 12(%rcx)
+	jz	L(Exit13)
+	cmpb	$0, 13(%rcx)
+	jz	L(Exit14)
+	cmpb	$0, 14(%rcx)
+	jz	L(Exit15)
+	cmpb	$0, 15(%rcx)
+	jz	L(Exit16)
+# ifdef USE_AS_STRNCAT
+	cmp	$16, %r8
+	je	L(StrncatExit16)
+#  define USE_AS_STRNCPY
+# endif
+
+# include "strcpy-ssse3.S"
+
+	.p2align 4
+L(CopyFrom1To16Bytes):
+	add	%rsi, %rdx
+	add	%rsi, %rcx
+
+	test	%al, %al
+	jz	L(ExitHigh)
+	test	$0x01, %al
+	jnz	L(Exit1)
+	test	$0x02, %al
+	jnz	L(Exit2)
+	test	$0x04, %al
+	jnz	L(Exit3)
+	test	$0x08, %al
+	jnz	L(Exit4)
+	test	$0x10, %al
+	jnz	L(Exit5)
+	test	$0x20, %al
+	jnz	L(Exit6)
+	test	$0x40, %al
+	jnz	L(Exit7)
+	movlpd	(%rcx), %xmm0
+	movlpd	%xmm0, (%rdx)
+	mov	%rdi, %rax
+	ret
+
+	.p2align 4
+L(ExitHigh):
+	test	$0x01, %ah
+	jnz	L(Exit9)
+	test	$0x02, %ah
+	jnz	L(Exit10)
+	test	$0x04, %ah
+	jnz	L(Exit11)
+	test	$0x08, %ah
+	jnz	L(Exit12)
+	test	$0x10, %ah
+	jnz	L(Exit13)
+	test	$0x20, %ah
+	jnz	L(Exit14)
+	test	$0x40, %ah
+	jnz	L(Exit15)
+	movlpd	(%rcx), %xmm0
+	movlpd	8(%rcx), %xmm1
+	movlpd	%xmm0, (%rdx)
+	movlpd	%xmm1, 8(%rdx)
+	mov	%rdi, %rax
+	ret
+
+	.p2align 4
+L(StrncatExit1):
+	xor	%ah, %ah
+	movb	%ah, 1(%rdx)
+L(Exit1):
+	movb	(%rcx), %al
+	movb	%al, (%rdx)
+	mov	%rdi, %rax
+	ret
+
+	.p2align 4
+L(StrncatExit2):
+	xor	%ah, %ah
+	movb	%ah, 2(%rdx)
+L(Exit2):
+	movw	(%rcx), %ax
+	movw	%ax, (%rdx)
+	mov	%rdi, %rax
+	ret
+
+	.p2align 4
+L(StrncatExit3):
+	xor	%ah, %ah
+	movb	%ah, 3(%rdx)
+L(Exit3):
+	movw	(%rcx), %ax
+	movw	%ax, (%rdx)
+	movb	2(%rcx), %al
+	movb	%al, 2(%rdx)
+	mov	%rdi, %rax
+	ret
+
+	.p2align 4
+L(StrncatExit4):
+	xor	%ah, %ah
+	movb	%ah, 4(%rdx)
+L(Exit4):
+	mov	(%rcx), %eax
+	mov	%eax, (%rdx)
+	mov	%rdi, %rax
+	ret
+
+	.p2align 4
+L(StrncatExit5):
+	xor	%ah, %ah
+	movb	%ah, 5(%rdx)
+L(Exit5):
+	mov	(%rcx), %eax
+	mov	%eax, (%rdx)
+	movb	4(%rcx), %al
+	movb	%al, 4(%rdx)
+	mov	%rdi, %rax
+	ret
+
+	.p2align 4
+L(StrncatExit6):
+	xor	%ah, %ah
+	movb	%ah, 6(%rdx)
+L(Exit6):
+	mov	(%rcx), %eax
+	mov	%eax, (%rdx)
+	movw	4(%rcx), %ax
+	movw	%ax, 4(%rdx)
+	mov	%rdi, %rax
+	ret
+
+	.p2align 4
+L(StrncatExit7):
+	xor	%ah, %ah
+	movb	%ah, 7(%rdx)
+L(Exit7):
+	mov	(%rcx), %eax
+	mov	%eax, (%rdx)
+	mov	3(%rcx), %eax
+	mov	%eax, 3(%rdx)
+	mov	%rdi, %rax
+	ret
+
+	.p2align 4
+L(StrncatExit8):
+	xor	%ah, %ah
+	movb	%ah, 8(%rdx)
+L(Exit8):
+	movlpd	(%rcx), %xmm0
+	movlpd	%xmm0, (%rdx)
+	mov	%rdi, %rax
+	ret
+
+	.p2align 4
+L(StrncatExit9):
+	xor	%ah, %ah
+	movb	%ah, 9(%rdx)
+L(Exit9):
+	movlpd	(%rcx), %xmm0
+	movlpd	%xmm0, (%rdx)
+	movb	8(%rcx), %al
+	movb	%al, 8(%rdx)
+	mov	%rdi, %rax
+	ret
+
+	.p2align 4
+L(StrncatExit10):
+	xor	%ah, %ah
+	movb	%ah, 10(%rdx)
+L(Exit10):
+	movlpd	(%rcx), %xmm0
+	movlpd	%xmm0, (%rdx)
+	movw	8(%rcx), %ax
+	movw	%ax, 8(%rdx)
+	mov	%rdi, %rax
+	ret
+
+	.p2align 4
+L(StrncatExit11):
+	xor	%ah, %ah
+	movb	%ah, 11(%rdx)
+L(Exit11):
+	movlpd	(%rcx), %xmm0
+	movlpd	%xmm0, (%rdx)
+	mov	7(%rcx), %eax
+	mov	%eax, 7(%rdx)
+	mov	%rdi, %rax
+	ret
+
+	.p2align 4
+L(StrncatExit12):
+	xor	%ah, %ah
+	movb	%ah, 12(%rdx)
+L(Exit12):
+	movlpd	(%rcx), %xmm0
+	movlpd	%xmm0, (%rdx)
+	mov	8(%rcx), %eax
+	mov	%eax, 8(%rdx)
+	mov	%rdi, %rax
+	ret
+
+	.p2align 4
+L(StrncatExit13):
+	xor	%ah, %ah
+	movb	%ah, 13(%rdx)
+L(Exit13):
+	movlpd	(%rcx), %xmm0
+	movlpd	%xmm0, (%rdx)
+	movlpd	5(%rcx), %xmm1
+	movlpd	%xmm1, 5(%rdx)
+	mov	%rdi, %rax
+	ret
+
+	.p2align 4
+L(StrncatExit14):
+	xor	%ah, %ah
+	movb	%ah, 14(%rdx)
+L(Exit14):
+	movlpd	(%rcx), %xmm0
+	movlpd	%xmm0, (%rdx)
+	movlpd	6(%rcx), %xmm1
+	movlpd	%xmm1, 6(%rdx)
+	mov	%rdi, %rax
+	ret
+
+	.p2align 4
+L(StrncatExit15):
+	xor	%ah, %ah
+	movb	%ah, 15(%rdx)
+L(Exit15):
+	movlpd	(%rcx), %xmm0
+	movlpd	%xmm0, (%rdx)
+	movlpd	7(%rcx), %xmm1
+	movlpd	%xmm1, 7(%rdx)
+	mov	%rdi, %rax
+	ret
+
+	.p2align 4
+L(StrncatExit16):
+	xor	%ah, %ah
+	movb	%ah, 16(%rdx)
+L(Exit16):
+	movlpd	(%rcx), %xmm0
+	movlpd	8(%rcx), %xmm1
+	movlpd	%xmm0, (%rdx)
+	movlpd	%xmm1, 8(%rdx)
+	mov	%rdi, %rax
+	ret
+
+# ifdef USE_AS_STRNCPY
+
+	.p2align 4
+L(CopyFrom1To16BytesCase2):
+	add	$16, %r8
+	add	%rsi, %rcx
+	lea	(%rsi, %rdx), %rsi
+	lea	-9(%r8), %rdx
+	and	$1<<7, %dh
+	or	%al, %dh
+	test	%dh, %dh
+	lea	(%rsi), %rdx
+	jz	L(ExitHighCase2)
+
+	test	$0x01, %al
+	jnz	L(Exit1)
+	cmp	$1, %r8
+	je	L(StrncatExit1)
+	test	$0x02, %al
+	jnz	L(Exit2)
+	cmp	$2, %r8
+	je	L(StrncatExit2)
+	test	$0x04, %al
+	jnz	L(Exit3)
+	cmp	$3, %r8
+	je	L(StrncatExit3)
+	test	$0x08, %al
+	jnz	L(Exit4)
+	cmp	$4, %r8
+	je	L(StrncatExit4)
+	test	$0x10, %al
+	jnz	L(Exit5)
+	cmp	$5, %r8
+	je	L(StrncatExit5)
+	test	$0x20, %al
+	jnz	L(Exit6)
+	cmp	$6, %r8
+	je	L(StrncatExit6)
+	test	$0x40, %al
+	jnz	L(Exit7)
+	cmp	$7, %r8
+	je	L(StrncatExit7)
+	movlpd	(%rcx), %xmm0
+	movlpd	%xmm0, (%rdx)
+	lea	7(%rdx), %rax
+	cmpb	$1, (%rax)
+	sbb	$-1, %rax
+	xor	%cl, %cl
+	movb	%cl, (%rax)
+	mov	%rdi, %rax
+	ret
+
+	.p2align 4
+L(ExitHighCase2):
+	test	$0x01, %ah
+	jnz	L(Exit9)
+	cmp	$9, %r8
+	je	L(StrncatExit9)
+	test	$0x02, %ah
+	jnz	L(Exit10)
+	cmp	$10, %r8
+	je	L(StrncatExit10)
+	test	$0x04, %ah
+	jnz	L(Exit11)
+	cmp	$11, %r8
+	je	L(StrncatExit11)
+	test	$0x8, %ah
+	jnz	L(Exit12)
+	cmp	$12, %r8
+	je	L(StrncatExit12)
+	test	$0x10, %ah
+	jnz	L(Exit13)
+	cmp	$13, %r8
+	je	L(StrncatExit13)
+	test	$0x20, %ah
+	jnz	L(Exit14)
+	cmp	$14, %r8
+	je	L(StrncatExit14)
+	test	$0x40, %ah
+	jnz	L(Exit15)
+	cmp	$15, %r8
+	je	L(StrncatExit15)
+	movlpd	(%rcx), %xmm0
+	movlpd	%xmm0, (%rdx)
+	movlpd	8(%rcx), %xmm1
+	movlpd	%xmm1, 8(%rdx)
+	mov	%rdi, %rax
+	ret
+
+L(CopyFrom1To16BytesCase2OrCase3):
+	test	%rax, %rax
+	jnz	L(CopyFrom1To16BytesCase2)
+
+	.p2align 4
+L(CopyFrom1To16BytesCase3):
+	add	$16, %r8
+	add	%rsi, %rdx
+	add	%rsi, %rcx
+
+	cmp	$8, %r8
+	ja	L(ExitHighCase3)
+	cmp	$1, %r8
+	je	L(StrncatExit1)
+	cmp	$2, %r8
+	je	L(StrncatExit2)
+	cmp	$3, %r8
+	je	L(StrncatExit3)
+	cmp	$4, %r8
+	je	L(StrncatExit4)
+	cmp	$5, %r8
+	je	L(StrncatExit5)
+	cmp	$6, %r8
+	je	L(StrncatExit6)
+	cmp	$7, %r8
+	je	L(StrncatExit7)
+	movlpd	(%rcx), %xmm0
+	movlpd	%xmm0, (%rdx)
+	xor	%ah, %ah
+	movb	%ah, 8(%rdx)
+	mov