Add SSE4.2 support for strcmp and strncmp on x86-64.

7 files changed, 1714 insertions, 5 deletions

diff --git a/ChangeLog b/ChangeLog
index 08e4b863ef..8ddbd84af5 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,15 @@
+2009-06-22  H.J. Lu  <hongjiu.lu@intel.com>
+
+	* string/strncmp.c (STRNCMP): New.  Defined to strncmp if not
+	defined.
+	(strncmp): Renamed to STRNCMP.
+	* sysdeps/x86_64/multiarch/Makefile (sysdep_routines): Add
+	strncmp-c for string.
+	* sysdeps/x86_64/multiarch/init-arch.h (HAS_SSE4_2): Define.
+	* sysdeps/x86_64/multiarch/strcmp.S: New file.
+	* sysdeps/x86_64/multiarch/strncmp.S: New file.
+	* sysdeps/x86_64/multiarch/strncmp-c.c: New file.
+
 2009-06-19  H.J. Lu  <hongjiu.lu@intel.com>
 
 	* elf/Makefile (distribute): Add ifuncmain1staticpie.c,
diff --git a/string/strncmp.c b/string/strncmp.c
index 1adb2c0ebd..bb0cbfdf65 100644
--- a/string/strncmp.c
+++ b/string/strncmp.c
@@ -21,15 +21,16 @@
 
 #undef strncmp
 
+#ifndef STRNCMP
+#define STRNCMP strncmp
+#endif
+
 /* Compare no more than N characters of S1 and S2,
    returning less than, equal to or greater than zero
    if S1 is lexicographically less than, equal to or
    greater than S2.  */
 int
-strncmp (s1, s2, n)
-     const char *s1;
-     const char *s2;
-     size_t n;
+STRNCMP (const char *s1, const char *s2, size_t n)
 {
   unsigned reg_char c1 = '\0';
   unsigned reg_char c2 = '\0';
@@ -70,4 +71,5 @@ strncmp (s1, s2, n)
 
   return c1 - c2;
 }
-libc_hidden_builtin_def (strncmp)
+
+libc_hidden_builtin_def (STRNCMP)
diff --git a/sysdeps/x86_64/multiarch/Makefile b/sysdeps/x86_64/multiarch/Makefile
index 33d98c36e6..1c35e1ffb4 100644
--- a/sysdeps/x86_64/multiarch/Makefile
+++ b/sysdeps/x86_64/multiarch/Makefile
@@ -2,3 +2,7 @@ ifeq ($(subdir),csu)
 aux += init-arch
 gen-as-const-headers += ifunc-defines.sym
 endif
+
+ifeq ($(subdir),string)
+sysdep_routines += strncmp-c
+endif
diff --git a/sysdeps/x86_64/multiarch/init-arch.h b/sysdeps/x86_64/multiarch/init-arch.h
index f160ba2a94..5c4892de38 100644
--- a/sysdeps/x86_64/multiarch/init-arch.h
+++ b/sysdeps/x86_64/multiarch/init-arch.h
@@ -56,3 +56,6 @@ extern void __init_cpu_features (void) attribute_hidden;
 
 #define HAS_POPCOUNT \
   ((__cpu_features.cpuid[COMMON_CPUID_INDEX_1].ecx & (1 << 23)) != 0)
+
+#define HAS_SSE4_2 \
+  ((__cpu_features.cpuid[COMMON_CPUID_INDEX_1].ecx & (1 << 20)) != 0)
diff --git a/sysdeps/x86_64/multiarch/strcmp.S b/sysdeps/x86_64/multiarch/strcmp.S
new file mode 100644
index 0000000000..8a6aee673a
--- /dev/null
+++ b/sysdeps/x86_64/multiarch/strcmp.S
@@ -0,0 +1,1677 @@
+/* strcmp with SSE4.2
+   Copyright (C) 2009 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.  */
+
+#include <sysdep.h>
+#include <ifunc-defines.h>
+
+#ifdef USE_AS_STRNCMP
+/* Since the counter, %r11, is unsigned, we branch to strcmp_exitz
+   if the new counter > the old one or is 0.  */
+#define UPDATE_STRNCMP_COUNTER				\
+	/* calculate left number to compare */		\
+	lea	-16(%rcx, %r11), %r9;			\
+	cmp	%r9, %r11;				\
+	jb	LABEL(strcmp_exitz);			\
+	test	%r9, %r9;				\
+	je	LABEL(strcmp_exitz);			\
+	mov	%r9, %r11
+
+#define STRCMP_SSE42	__strncmp_sse42
+#define STRCMP_SSE2	__strncmp_sse2
+#define __GI_STRCMP	__GI_strncmp
+#else
+#define UPDATE_STRNCMP_COUNTER
+#ifndef STRCMP
+#define STRCMP		strcmp
+#define STRCMP_SSE42	__strcmp_sse42
+#define STRCMP_SSE2	__strcmp_sse2
+#define __GI_STRCMP	__GI_strcmp
+#endif
+#endif
+
+#ifndef LABEL
+#define LABEL(l) L(l)
+#endif
+
+/* Define multiple versions only for the definition in libc.  Don't
+   define multiple versions for strncmp in static library since we 
+   need strncmp before the initialization happened.  */
+#if (defined SHARED || !defined USE_AS_STRNCMP) && !defined NOT_IN_libc
+	.text
+ENTRY(STRCMP)
+	.type	STRCMP, @gnu_indirect_function
+	cmpl	$0, __cpu_features+KIND_OFFSET(%rip)
+	jne	1f
+	call	__init_cpu_features
+1:	leaq	STRCMP_SSE2(%rip), %rax
+	testl	$(1<<20), __cpu_features+CPUID_OFFSET+COMMON_CPUID_INDEX_1*CPUID_SIZE+CPUID_ECX_OFFSET(%rip)
+	jz	2f
+	leaq	STRCMP_SSE42(%rip), %rax
+2:	ret
+END(STRCMP)
+
+/* We use 0x1a:
+	_SIDD_SBYTE_OPS
+	| _SIDD_CMP_EQUAL_EACH
+	| _SIDD_NEGATIVE_POLARITY
+	| _SIDD_LEAST_SIGNIFICANT
+   on pcmpistri to find out if two 16byte data elements are the same
+   and the offset of the first different byte.  There are 4 cases:
+
+   1. Both 16byte data elements are valid and identical.
+   2. Both 16byte data elements have EOS and identical.
+   3. Both 16byte data elements are valid and they differ at offset X.
+   4. At least one 16byte data element has EOS at offset X.  Two 16byte
+      data elements must differ at or before offset X.
+
+   Here is the table of ECX, CFlag, ZFlag and SFlag for 4 cases:
+
+   case		ECX	CFlag	ZFlag	SFlag
+    1		16	  0	  0	  0
+    2		16	  0	  1	  1
+    3		 X	  1	  0	  0
+    4	       0 <= X	  1	 0/1	 0/1
+
+   We exit from the loop for cases 2, 3 and 4 with jbe which branches
+   when either CFlag or ZFlag is 1.  If CFlag == 0, we return 0 for
+   case 2.  */
+
+	/* Put all SSE 4.2 functions together.  */
+	.section .text.sse4.2,"ax",@progbits
+	.align 	16
+	.type	STRCMP_SSE42, @function
+STRCMP_SSE42:
+	cfi_startproc
+	CALL_MCOUNT
+
+/*
+ * This implementation uses SSE to compare up to 16 bytes at a time.
+ */
+#ifdef USE_AS_STRNCMP
+	test	%rdx, %rdx
+	je	LABEL(strcmp_exitz)
+	cmp	$1, %rdx
+	je	LABEL(Byte0)
+	mov	%rdx, %r11
+#endif
+	mov	%esi, %ecx
+	mov	%edi, %eax
+/* Use 64bit AND here to avoid long NOP padding.  */
+	and	$0x3f, %rcx		/* rsi alignment in cache line */
+	and	$0x3f, %rax		/* rdi alignment in cache line */
+	cmp	$0x30, %ecx
+	ja	LABEL(crosscache)	/* rsi: 16-byte load will cross cache line */
+	cmp	$0x30, %eax
+	ja	LABEL(crosscache)	/* rdi: 16-byte load will cross cache line */
+	movlpd	(%rdi), %xmm1
+	movlpd	(%rsi), %xmm2
+	movhpd	8(%rdi), %xmm1
+	movhpd	8(%rsi), %xmm2
+	pxor	%xmm0, %xmm0		/* clear %xmm0 for null char checks */
+	pcmpeqb	%xmm1, %xmm0		/* Any null chars? */
+	pcmpeqb	%xmm2, %xmm1		/* compare first 16 bytes for equality */
+	psubb	%xmm0, %xmm1		/* packed sub of comparison results*/
+	pmovmskb %xmm1, %edx
+	sub	$0xffff, %edx		/* if first 16 bytes are same, edx == 0xffff */
+	jnz	LABEL(less16bytes)	/* If not, find different value or null char */
+#ifdef USE_AS_STRNCMP
+	sub	$16, %r11
+	jbe	LABEL(strcmp_exitz)	/* finish comparision */
+#endif
+	add	$16, %rsi		/* prepare to search next 16 bytes */
+	add	$16, %rdi		/* prepare to search next 16 bytes */
+
+	/*
+	 * Determine source and destination string offsets from 16-byte alignment.
+	 * Use relative offset difference between the two to determine which case
+	 * below to use.
+	 */
+	.p2align 4
+LABEL(crosscache):
+	and	$0xfffffffffffffff0, %rsi	/* force %rsi is 16 byte aligned */
+	and	$0xfffffffffffffff0, %rdi	/* force %rdi is 16 byte aligned */
+	mov	$0xffff, %edx			/* for equivalent offset */
+	xor	%r8d, %r8d
+	and	$0xf, %ecx			/* offset of rsi */
+	and	$0xf, %eax			/* offset of rdi */
+	cmp	%eax, %ecx
+	je	LABEL(ashr_0)			/* rsi and rdi relative offset same */
+	ja	LABEL(bigger)
+	mov	%edx, %r8d			/* r8d is offset flag for exit tail */
+	xchg	%ecx, %eax
+	xchg	%rsi, %rdi
+LABEL(bigger):
+	lea	15(%rax), %r9
+	sub	%rcx, %r9
+	lea	LABEL(unaligned_table)(%rip), %r10
+	movslq	(%r10, %r9,4), %r9
+	lea	(%r10, %r9), %r10
+	jmp	*%r10				/* jump to corresponding case */
+
+/*
+ * The following cases will be handled by ashr_0
+ *  rcx(offset of rsi)  rax(offset of rdi)  relative offset  corresponding case
+ *        n(0~15)            n(0~15)           15(15+ n-n)         ashr_0
+ */
+	.p2align 4
+LABEL(ashr_0):
+
+	movdqa	(%rsi), %xmm1
+	pxor	%xmm0, %xmm0			/* clear %xmm0 for null char check */
+	pcmpeqb	%xmm1, %xmm0			/* Any null chars? */
+	pcmpeqb	(%rdi), %xmm1			/* compare 16 bytes for equality */
+	psubb	%xmm0, %xmm1			/* packed sub of comparison results*/
+	pmovmskb %xmm1, %r9d
+	shr	%cl, %edx			/* adjust 0xffff for offset */
+	shr	%cl, %r9d			/* adjust for 16-byte offset */
+	sub	%r9d, %edx
+	/*
+	 * edx must be the same with r9d if in left byte (16-rcx) is equal to
+	 * the start from (16-rax) and no null char was seen.
+	 */
+	jne	LABEL(less32bytes)		/* mismatch or null char */
+	UPDATE_STRNCMP_COUNTER
+	mov	$16, %rcx
+	mov	$16, %r9
+	pxor	%xmm0, %xmm0			/* clear xmm0, may have changed above */
+
+	/*
+	 * Now both strings are aligned at 16-byte boundary. Loop over strings
+	 * checking 32-bytes per iteration.
+	 */
+	mov	%rcx, %rdx	/* only for offset of sse4 instruction loop*/
+	.p2align 4
+LABEL(ashr_0_use_sse4_2):
+	movdqa	(%rdi,%rdx), %xmm0
+	pcmpistri      $0x1a,(%rsi,%rdx), %xmm0
+	lea	16(%rdx), %rdx
+	jbe	LABEL(ashr_0_use_sse4_2_exit)
+#ifdef USE_AS_STRNCMP
+	sub	$16, %r11
+	jbe	LABEL(strcmp_exitz)
+#endif
+
+	movdqa	(%rdi,%rdx), %xmm0
+	pcmpistri      $0x1a,(%rsi,%rdx), %xmm0
+	lea	16(%rdx), %rdx
+	jbe	LABEL(ashr_0_use_sse4_2_exit)
+#ifdef USE_AS_STRNCMP
+	sub	$16, %r11
+	jbe	LABEL(strcmp_exitz)
+#endif
+	jmp	LABEL(ashr_0_use_sse4_2)
+
+
+	.p2align 4
+LABEL(ashr_0_use_sse4_2_exit):
+	jnc	LABEL(strcmp_exitz)
+#ifdef USE_AS_STRNCMP
+	sub	%rcx, %r11
+	jbe	LABEL(strcmp_exitz)
+#endif
+	lea	-16(%rdx, %rcx), %rcx
+	movzbl	(%rdi, %rcx), %eax
+	movzbl	(%rsi, %rcx), %edx
+	sub	%edx, %eax
+	ret
+
+
+
+
+/*
+ * The following cases will be handled by ashr_1
+ * rcx(offset of rsi)  rax(offset of rdi)   relative offset   	corresponding case
+ *        n(15)            n -15            0(15 +(n-15) - n)         ashr_1
+ */
+	.p2align 4
+LABEL(ashr_1):
+	pxor	%xmm0, %xmm0
+	movdqa	(%rdi), %xmm2
+	movdqa	(%rsi), %xmm1
+	pcmpeqb	%xmm1, %xmm0		/* Any null chars? */
+	pslldq	$15, %xmm2		/* shift first string to align with second */
+	pcmpeqb	%xmm1, %xmm2		/* compare 16 bytes for equality */
+	psubb	%xmm0, %xmm2		/* packed sub of comparison results*/
+	pmovmskb %xmm2, %r9d
+	shr	%cl, %edx		/* adjust 0xffff for offset */
+	shr	%cl, %r9d		/* adjust for 16-byte offset */
+	sub	%r9d, %edx
+	jnz	LABEL(less32bytes)	/* mismatch or null char seen */
+	movdqa	(%rdi), %xmm3
+	UPDATE_STRNCMP_COUNTER
+
+	pxor	%xmm0, %xmm0
+	mov	$16, %rcx		/* index for loads*/
+	mov	$1, %r9d		/* byte position left over from less32bytes case */
+	/*
+	 * Setup %r10 value allows us to detect crossing a page boundary.
+	 * When %r10 goes positive we have crossed a page boundary and
+	 * need to do a nibble.
+	 */
+	lea	1(%rdi), %r10
+	and	$0xfff, %r10		/* offset into 4K page */
+	sub	$0x1000, %r10		/* subtract 4K pagesize */
+	mov	%rcx, %rdx	/* only for offset of sse4 instruction loop*/
+
+	.p2align 4
+LABEL(loop_ashr_1_use_sse4_2):
+	add	$16, %r10
+	jg	LABEL(nibble_ashr_1_use_sse4_2)
+
+	movdqa	(%rdi, %rdx), %xmm0
+	palignr $1, -16(%rdi, %rdx), %xmm0
+	pcmpistri	$0x1a,(%rsi,%rdx), %xmm0
+	jbe	LABEL(use_sse4_2_exit)
+#ifdef USE_AS_STRNCMP
+	sub	$16, %r11
+	jbe	LABEL(strcmp_exitz)
+#endif
+
+	add	$16, %rdx
+	add	$16, %r10
+	jg	LABEL(nibble_ashr_1_use_sse4_2)
+
+	movdqa	(%rdi, %rdx), %xmm0
+	palignr $1, -16(%rdi, %rdx), %xmm0
+	pcmpistri	$0x1a,(%rsi,%rdx), %xmm0
+	jbe	LABEL(use_sse4_2_exit)
+#ifdef USE_AS_STRNCMP
+	sub	$16, %r11
+	jbe	LABEL(strcmp_exitz)
+#endif
+	add	$16, %rdx
+	jmp	LABEL(loop_ashr_1_use_sse4_2)
+
+	.p2align 4
+LABEL(nibble_ashr_1_use_sse4_2):
+	sub	$0x1000, %r10
+	movdqa	-16(%rdi, %rdx), %xmm0
+	psrldq	$1, %xmm0
+	pcmpistri      $0x3a,%xmm0, %xmm0
+#ifdef USE_AS_STRNCMP
+	cmp	%r11, %rcx
+	jae	LABEL(nibble_ashr_use_sse4_2_exit)
+#endif
+	cmp	$14, %ecx
+	ja	LABEL(loop_ashr_1_use_sse4_2)
+
+	jmp	LABEL(nibble_ashr_use_sse4_2_exit)
+
+/*
+ * The following cases will be handled by ashr_2
+ * rcx(offset of rsi)  rax(offset of rdi)   relative offset   	corresponding case
+ *        n(14~15)            n -14         1(15 +(n-14) - n)         ashr_2
+ */
+	.p2align 4
+LABEL(ashr_2):
+	pxor	%xmm0, %xmm0
+	movdqa	(%rdi), %xmm2
+	movdqa	(%rsi), %xmm1
+	pcmpeqb	%xmm1, %xmm0
+	pslldq	$14, %xmm2
+	pcmpeqb	%xmm1, %xmm2
+	psubb	%xmm0, %xmm2
+	pmovmskb %xmm2, %r9d
+	shr	%cl, %edx
+	shr	%cl, %r9d
+	sub	%r9d, %edx
+	jnz	LABEL(less32bytes)
+	movdqa	(%rdi), %xmm3
+	UPDATE_STRNCMP_COUNTER
+
+	pxor	%xmm0, %xmm0
+	mov	$16, %rcx	/* index for loads */
+	mov	$2, %r9d	/* byte position left over from less32bytes case */
+	/*
+	 * Setup %r10 value allows us to detect crossing a page boundary.
+	 * When %r10 goes positive we have crossed a page boundary and
+	 * need to do a nibble.
+	 */
+	lea	2(%rdi), %r10
+	and	$0xfff, %r10	/* offset into 4K page */
+	sub	$0x1000, %r10	/* subtract 4K pagesize */
+	mov	%rcx, %rdx	/* only for offset of sse4 instruction loop*/
+
+	.p2align 4
+LABEL(loop_ashr_2_use_sse4_2):
+	add	$16, %r10
+	jg	LABEL(nibble_ashr_2_use_sse4_2)
+
+	movdqa	(%rdi, %rdx), %xmm0
+	palignr $2, -16(%rdi, %rdx), %xmm0
+	pcmpistri	$0x1a,(%rsi,%rdx), %xmm0
+	jbe	LABEL(use_sse4_2_exit)
+#ifdef USE_AS_STRNCMP
+	sub	$16, %r11
+	jbe	LABEL(strcmp_exitz)
+#endif
+
+	add	$16, %rdx
+	add	$16, %r10
+	jg	LABEL(nibble_ashr_2_use_sse4_2)
+
+	movdqa	(%rdi, %rdx), %xmm0
+	palignr $2, -16(%rdi, %rdx), %xmm0
+	pcmpistri	$0x1a,(%rsi,%rdx), %xmm0
+	jbe	LABEL(use_sse4_2_exit)
+#ifdef USE_AS_STRNCMP
+	sub	$16, %r11
+	jbe	LABEL(strcmp_exitz)
+#endif
+	add	$16, %rdx
+	jmp	LABEL(loop_ashr_2_use_sse4_2)
+
+	.p2align 4
+LABEL(nibble_ashr_2_use_sse4_2):
+	sub	$0x1000, %r10
+	movdqa	-16(%rdi, %rdx), %xmm0
+	psrldq	$2, %xmm0
+	pcmpistri      $0x3a,%xmm0, %xmm0
+#ifdef USE_AS_STRNCMP
+	cmp	%r11, %rcx
+	jae	LABEL(nibble_ashr_use_sse4_2_exit)
+#endif
+	cmp	$13, %ecx
+	ja	LABEL(loop_ashr_2_use_sse4_2)
+
+	jmp	LABEL(nibble_ashr_use_sse4_2_exit)
+
+/*
+ * The following cases will be handled by ashr_3
+ *  rcx(offset of rsi)  rax(offset of rdi)  relative offset	 corresponding case
+ *        n(13~15)            n -13         2(15 +(n-13) - n)         ashr_3
+ */
+	.p2align 4
+LABEL(ashr_3):
+	pxor	%xmm0, %xmm0
+	movdqa	(%rdi), %xmm2
+	movdqa	(%rsi), %xmm1
+	pcmpeqb	%xmm1, %xmm0
+	pslldq	$13, %xmm2
+	pcmpeqb	%xmm1, %xmm2
+	psubb	%xmm0, %xmm2
+	pmovmskb %xmm2, %r9d
+	shr	%cl, %edx
+	shr	%cl, %r9d
+	sub	%r9d, %edx
+	jnz	LABEL(less32bytes)
+	movdqa	(%rdi), %xmm3
+
+	UPDATE_STRNCMP_COUNTER
+
+	pxor	%xmm0, %xmm0
+	mov	$16, %rcx	/* index for loads */
+	mov	$3, %r9d	/* byte position left over from less32bytes case */
+	/*
+	 * Setup %r10 value allows us to detect crossing a page boundary.
+	 * When %r10 goes positive we have crossed a page boundary and
+	 * need to do a nibble.
+	 */
+	lea	3(%rdi), %r10
+	and	$0xfff, %r10	/* offset into 4K page */
+	sub	$0x1000, %r10	/* subtract 4K pagesize */
+	mov	%rcx, %rdx	/* only for offset of sse4 instruction loop*/
+
+LABEL(loop_ashr_3_use_sse4_2):
+	add	$16, %r10
+	jg	LABEL(nibble_ashr_3_use_sse4_2)
+
+	movdqa	(%rdi, %rdx), %xmm0
+	palignr $3, -16(%rdi, %rdx), %xmm0
+	pcmpistri	$0x1a,(%rsi,%rdx), %xmm0
+	jbe	LABEL(use_sse4_2_exit)
+#ifdef USE_AS_STRNCMP
+	sub	$16, %r11
+	jbe	LABEL(strcmp_exitz)
+#endif
+
+	add	$16, %rdx
+	add	$16, %r10
+	jg	LABEL(nibble_ashr_3_use_sse4_2)
+
+	movdqa	(%rdi, %rdx), %xmm0
+	palignr $3, -16(%rdi, %rdx), %xmm0
+	pcmpistri	$0x1a,(%rsi,%rdx), %xmm0
+	jbe	LABEL(use_sse4_2_exit)
+#ifdef USE_AS_STRNCMP
+	sub	$16, %r11
+	jbe	LABEL(strcmp_exitz)
+#endif
+	add	$16, %rdx
+	jmp	LABEL(loop_ashr_3_use_sse4_2)
+
+	.p2align 4
+LABEL(nibble_ashr_3_use_sse4_2):
+	sub	$0x1000, %r10
+	movdqa	-16(%rdi, %rdx), %xmm0
+	psrldq	$3, %xmm0
+	pcmpistri      $0x3a,%xmm0, %xmm0
+#ifdef USE_AS_STRNCMP
+	cmp	%r11, %rcx
+	jae	LABEL(nibble_ashr_use_sse4_2_exit)
+#endif
+	cmp	$12, %ecx
+	ja	LABEL(loop_ashr_3_use_sse4_2)
+
+	jmp	LABEL(nibble_ashr_use_sse4_2_exit)
+
+/*
+ * The following cases will be handled by ashr_4
+ *  rcx(offset of rsi)  rax(offset of rdi)  relative offset	 corresponding case
+ *        n(12~15)            n -12         3(15 +(n-12) - n)         ashr_4
+ */
+	.p2align 4
+LABEL(ashr_4):
+	pxor	%xmm0, %xmm0
+	movdqa	(%rdi), %xmm2
+	movdqa	(%rsi), %xmm1
+	pcmpeqb	%xmm1, %xmm0
+	pslldq	$12, %xmm2
+	pcmpeqb	%xmm1, %xmm2
+	psubb	%xmm0, %xmm2
+	pmovmskb %xmm2, %r9d
+	shr	%cl, %edx
+	shr	%cl, %r9d
+	sub	%r9d, %edx
+	jnz	LABEL(less32bytes)
+	movdqa	(%rdi), %xmm3
+
+	UPDATE_STRNCMP_COUNTER
+
+	pxor	%xmm0, %xmm0
+	mov	$16, %rcx	/* index for loads */
+	mov	$4, %r9d	/* byte position left over from less32bytes case */
+	/*
+	 * Setup %r10 value allows us to detect crossing a page boundary.
+	 * When %r10 goes positive we have crossed a page boundary and
+	 * need to do a nibble.
+	 */
+	lea	4(%rdi), %r10
+	and	$0xfff, %r10	/* offset into 4K page */
+	sub	$0x1000, %r10	/* subtract 4K pagesize */
+	mov	%rcx, %rdx	/* only for offset of sse4 instruction loop*/
+
+	.p2align 4
+LABEL(loop_ashr_4_use_sse4_2):
+	add	$16, %r10
+	jg	LABEL(nibble_ashr_4_use_sse4_2)
+
+	movdqa	(%rdi, %rdx), %xmm0
+	palignr $4, -16(%rdi, %rdx), %xmm0
+	pcmpistri	$0x1a,(%rsi,%rdx), %xmm0
+	jbe	LABEL(use_sse4_2_exit)
+#ifdef USE_AS_STRNCMP
+	sub	$16, %r11
+	jbe	LABEL(strcmp_exitz)
+#endif
+
+	add	$16, %rdx
+	add	$16, %r10
+	jg	LABEL(nibble_ashr_4_use_sse4_2)
+
+	movdqa	(%rdi, %rdx), %xmm0
+	palignr $4, -16(%rdi, %rdx), %xmm0
+	pcmpistri	$0x1a,(%rsi,%rdx), %xmm0
+	jbe	LABEL(use_sse4_2_exit)
+#ifdef USE_AS_STRNCMP
+	sub	$16, %r11
+	jbe	LABEL(strcmp_exitz)
+#endif
+	add	$16, %rdx
+	jmp	LABEL(loop_ashr_4_use_sse4_2)
+
+	.p2align 4
+LABEL(nibble_ashr_4_use_sse4_2):
+	sub	$0x1000, %r10
+	movdqa	-16(%rdi, %rdx), %xmm0
+	psrldq	$4, %xmm0
+	pcmpistri      $0x3a,%xmm0, %xmm0
+#ifdef USE_AS_STRNCMP
+	cmp	%r11, %rcx
+	jae	LABEL(nibble_ashr_use_sse4_2_exit)
+#endif
+	cmp	$11, %ecx
+	ja	LABEL(loop_ashr_4_use_sse4_2)
+
+	jmp	LABEL(nibble_ashr_use_sse4_2_exit)
+
+/*
+ * The following cases will be handled by ashr_5
+ *  rcx(offset of rsi)  rax(offset of rdi)        relative offset      corresponding case
+ *        n(11~15)          n - 11      	  4(15 +(n-11) - n)         ashr_5
+ */
+	.p2align 4
+LABEL(ashr_5):
+	pxor	%xmm0, %xmm0
+	movdqa	(%rdi), %xmm2
+	movdqa	(%rsi), %xmm1
+	pcmpeqb	%xmm1, %xmm0
+	pslldq	$11, %xmm2
+	pcmpeqb	%xmm1, %xmm2
+	psubb	%xmm0, %xmm2
+	pmovmskb %xmm2, %r9d
+	shr	%cl, %edx
+	shr	%cl, %r9d
+	sub	%r9d, %edx
+	jnz	LABEL(less32bytes)
+	movdqa	(%rdi), %xmm3
+
+	UPDATE_STRNCMP_COUNTER
+
+	pxor	%xmm0, %xmm0
+	mov	$16, %rcx	/* index for loads */
+	mov	$5, %r9d	/* byte position left over from less32bytes case */
+	/*
+	 * Setup %r10 value allows us to detect crossing a page boundary.
+	 * When %r10 goes positive we have crossed a page boundary and
+	 * need to do a nibble.
+	 */
+	lea	5(%rdi), %r10
+	and	$0xfff, %r10	/* offset into 4K page */
+	sub	$0x1000, %r10	/* subtract 4K pagesize */
+	mov	%rcx, %rdx	/* only for offset of sse4 instruction loop*/
+
+	.p2align 4
+LABEL(loop_ashr_5_use_sse4_2):
+	add	$16, %r10
+	jg	LABEL(nibble_ashr_5_use_sse4_2)
+
+	movdqa	(%rdi, %rdx), %xmm0
+	palignr $5, -16(%rdi, %rdx), %xmm0
+	pcmpistri	$0x1a,(%rsi,%rdx), %xmm0
+	jbe	LABEL(use_sse4_2_exit)
+#ifdef USE_AS_STRNCMP
+	sub	$16, %r11
+	jbe	LABEL(strcmp_exitz)
+#endif
+
+	add	$16, %rdx
+	add	$16, %r10
+	jg	LABEL(nibble_ashr_5_use_sse4_2)
+
+	movdqa	(%rdi, %rdx), %xmm0
+
+	palignr $5, -16(%rdi, %rdx), %xmm0
+	pcmpistri	$0x1a,(%rsi,%rdx), %xmm0
+	jbe	LABEL(use_sse4_2_exit)
+#ifdef USE_AS_STRNCMP
+	sub	$16, %r11
+	jbe	LABEL(strcmp_exitz)
+#endif
+	add	$16, %rdx
+	jmp	LABEL(loop_ashr_5_use_sse4_2)
+
+	.p2align 4
+LABEL(nibble_ashr_5_use_sse4_2):
+	sub	$0x1000, %r10
+	movdqa	-16(%rdi, %rdx), %xmm0
+	psrldq	$5, %xmm0
+	pcmpistri      $0x3a,%xmm0, %xmm0
+#ifdef USE_AS_STRNCMP
+	cmp	%r11, %rcx
+	jae	LABEL(nibble_ashr_use_sse4_2_exit)
+#endif
+	cmp	$10, %ecx
+	ja	LABEL(loop_ashr_5_use_sse4_2)
+
+	jmp	LABEL(nibble_ashr_use_sse4_2_exit)
+
+/*
+ * The following cases will be handled by ashr_6
+ *  rcx(offset of rsi)  rax(offset of rdi)        relative offset      corresponding case
+ *        n(10~15)          n - 10      	  5(15 +(n-10) - n)         ashr_6
+ */
+	.p2align 4
+LABEL(ashr_6):
+	pxor	%xmm0, %xmm0
+	movdqa	(%rdi), %xmm2
+	movdqa	(%rsi), %xmm1
+	pcmpeqb	%xmm1, %xmm0
+	pslldq	$10, %xmm2
+	pcmpeqb	%xmm1, %xmm2
+	psubb	%xmm0, %xmm2
+	pmovmskb %xmm2, %r9d
+	shr	%cl, %edx
+	shr	%cl, %r9d
+	sub	%r9d, %edx
+	jnz	LABEL(less32bytes)
+	movdqa	(%rdi), %xmm3
+
+	UPDATE_STRNCMP_COUNTER
+
+	pxor	%xmm0, %xmm0
+	mov	$16, %rcx	/* index for loads */
+	mov	$6, %r9d	/* byte position left over from less32bytes case */
+	/*
+	 * Setup %r10 value allows us to detect crossing a page boundary.
+	 * When %r10 goes positive we have crossed a page boundary and
+	 * need to do a nibble.
+	 */
+	lea	6(%rdi), %r10
+	and	$0xfff, %r10	/* offset into 4K page */
+	sub	$0x1000, %r10	/* subtract 4K pagesize */
+	mov	%rcx, %rdx	/* only for offset of sse4 instruction loop*/
+
+	.p2align 4
+LABEL(loop_ashr_6_use_sse4_2):
+	add	$16, %r10
+	jg	LABEL(nibble_ashr_6_use_sse4_2)
+
+	movdqa	(%rdi, %rdx), %xmm0
+	palignr $6, -16(%rdi, %rdx), %xmm0
+	pcmpistri	$0x1a,(%rsi,%rdx), %xmm0
+	jbe	LABEL(use_sse4_2_exit)
+#ifdef USE_AS_STRNCMP
+	sub	$16, %r11
+	jbe	LABEL(strcmp_exitz)
+#endif
+
+	add	$16, %rdx
+	add	$16, %r10
+	jg	LABEL(nibble_ashr_6_use_sse4_2)
+
+	movdqa	(%rdi, %rdx), %xmm0
+	palignr $6, -16(%rdi, %rdx), %xmm0
+	pcmpistri	$0x1a,(%rsi,%rdx), %xmm0
+	jbe	LABEL(use_sse4_2_exit)
+#ifdef USE_AS_STRNCMP
+	sub	$16, %r11
+	jbe	LABEL(strcmp_exitz)
+#endif
+	add	$16, %rdx
+	jmp	LABEL(loop_ashr_6_use_sse4_2)
+
+	.p2align 4
+LABEL(nibble_ashr_6_use_sse4_2):
+	sub	$0x1000, %r10
+	movdqa	-16(%rdi, %rdx), %xmm0
+	psrldq	$6, %xmm0
+	pcmpistri      $0x3a,%xmm0, %xmm0
+#ifdef USE_AS_STRNCMP
+	cmp	%r11, %rcx
+	jae	LABEL(nibble_ashr_use_sse4_2_exit)
+#endif
+	cmp	$9, %ecx
+	ja	LABEL(loop_ashr_6_use_sse4_2)
+
+	jmp	LABEL(nibble_ashr_use_sse4_2_exit)
+
+/*
+ * The following cases will be handled by ashr_7
+ *  rcx(offset of rsi)  rax(offset of rdi)        relative offset      corresponding case
+ *        n(9~15)          n - 9      	        6(15 +(n - 9) - n)         ashr_7
+ */
+	.p2align 4
+LABEL(ashr_7):
+	pxor	%xmm0, %xmm0
+	movdqa	(%rdi), %xmm2
+	movdqa	(%rsi), %xmm1
+	pcmpeqb	%xmm1, %xmm0
+	pslldq	$9, %xmm2
+	pcmpeqb	%xmm1, %xmm2
+	psubb	%xmm0, %xmm2
+	pmovmskb %xmm2, %r9d
+	shr	%cl, %edx
+	shr	%cl, %r9d
+	sub	%r9d, %edx
+	jnz	LABEL(less32bytes)
+	movdqa	(%rdi), %xmm3
+
+	UPDATE_STRNCMP_COUNTER
+
+	pxor	%xmm0, %xmm0
+	mov	$16, %rcx	/* index for loads */
+	mov	$7, %r9d	/* byte position left over from less32bytes case */
+	/*
+	 * Setup %r10 value allows us to detect crossing a page boundary.
+	 * When %r10 goes positive we have crossed a page boundary and
+	 * need to do a nibble.
+	 */
+	lea	7(%rdi), %r10
+	and	$0xfff, %r10	/* offset into 4K page */
+	sub	$0x1000, %r10	/* subtract 4K pagesize */
+	mov	%rcx, %rdx	/* only for offset of sse4 instruction loop*/
+
+	.p2align 4
+LABEL(loop_ashr_7_use_sse4_2):
+	add	$16, %r10
+	jg	LABEL(nibble_ashr_7_use_sse4_2)
+
+	movdqa	(%rdi, %rdx), %xmm0
+	palignr $7, -16(%rdi, %rdx), %xmm0
+	pcmpistri	$0x1a,(%rsi,%rdx), %xmm0
+	jbe	LABEL(use_sse4_2_exit)
+#ifdef USE_AS_STRNCMP
+	sub	$16, %r11
+	jbe	LABEL(strcmp_exitz)
+#endif
+
+	add	$16, %rdx
+	add	$16, %r10
+	jg	LABEL(nibble_ashr_7_use_sse4_2)
+
+	movdqa	(%rdi, %rdx), %xmm0
+	palignr $7, -16(%rdi, %rdx), %xmm0
+	pcmpistri	$0x1a,(%rsi,%rdx), %xmm0
+	jbe	LABEL(use_sse4_2_exit)
+#ifdef USE_AS_STRNCMP
+	sub	$16, %r11
+	jbe	LABEL(strcmp_exitz)
+#endif
+	add	$16, %rdx
+	jmp	LABEL(loop_ashr_7_use_sse4_2)
+
+	.p2align 4
+LABEL(nibble_ashr_7_use_sse4_2):
+	sub	$0x1000, %r10
+	movdqa	-16(%rdi, %rdx), %xmm0
+	psrldq	$7, %xmm0
+	pcmpistri      $0x3a,%xmm0, %xmm0
+#ifdef USE_AS_STRNCMP
+	cmp	%r11, %rcx
+	jae	LABEL(nibble_ashr_use_sse4_2_exit)
+#endif
+	cmp	$8, %ecx
+	ja	LABEL(loop_ashr_7_use_sse4_2)
+
+	jmp	LABEL(nibble_ashr_use_sse4_2_exit)
+
+/*
+ *  The following cases will be handled by ashr_8
+ *  rcx(offset of rsi)  rax(offset of rdi)        relative offset	 corresponding case
+ *        n(8~15)          n - 8      	        7(15 +(n - 8) - n)         ashr_8
+ */
+	.p2align 4
+LABEL(ashr_8):
+	pxor	%xmm0, %xmm0
+	movdqa	(%rdi), %xmm2
+	movdqa	(%rsi), %xmm1
+	pcmpeqb	%xmm1, %xmm0
+	pslldq	$8, %xmm2
+	pcmpeqb	%xmm1, %xmm2
+	psubb	%xmm0, %xmm2
+	pmovmskb %xmm2, %r9d
+	shr	%cl, %edx
+	shr	%cl, %r9d
+	sub	%r9d, %edx
+	jnz	LABEL(less32bytes)
+	movdqa	(%rdi), %xmm3
+
+	UPDATE_STRNCMP_COUNTER
+
+	pxor	%xmm0, %xmm0
+	mov	$16, %rcx	/* index for loads */
+	mov	$8, %r9d	/* byte position left over from less32bytes case */
+	/*
+	 * Setup %r10 value allows us to detect crossing a page boundary.
+	 * When %r10 goes positive we have crossed a page boundary and
+	 * need to do a nibble.
+	 */
+	lea	8(%rdi), %r10
+	and	$0xfff, %r10	/* offset into 4K page */
+	sub	$0x1000, %r10	/* subtract 4K pagesize */
+	mov	%rcx, %rdx	/* only for offset of sse4 instruction loop*/
+
+	.p2align 4
+LABEL(loop_ashr_8_use_sse4_2):
+	add	$16, %r10
+	jg	LABEL(nibble_ashr_8_use_sse4_2)
+
+	movdqa	(%rdi, %rdx), %xmm0
+	palignr $8, -16(%rdi, %rdx), %xmm0
+	pcmpistri	$0x1a,(%rsi,%rdx), %xmm0
+	jbe	LABEL(use_sse4_2_exit)
+#ifdef USE_AS_STRNCMP
+	sub	$16, %r11
+	jbe	LABEL(strcmp_exitz)
+#endif
+
+	add	$16, %rdx
+	add	$16, %r10
+	jg	LABEL(nibble_ashr_8_use_sse4_2)
+
+	movdqa	(%rdi, %rdx), %xmm0
+	palignr $8, -16(%rdi, %rdx), %xmm0
+	pcmpistri	$0x1a,(%rsi,%rdx), %xmm0
+	jbe	LABEL(use_sse4_2_exit)
+#ifdef USE_AS_STRNCMP
+	sub	$16, %r11
+	jbe	LABEL(strcmp_exitz)
+#endif
+	add	$16, %rdx
+	jmp	LABEL(loop_ashr_8_use_sse4_2)
+
+	.p2align 4
+LABEL(nibble_ashr_8_use_sse4_2):
+	sub	$0x1000, %r10
+	movdqa	-16(%rdi, %rdx), %xmm0
+	psrldq	$8, %xmm0
+	pcmpistri      $0x3a,%xmm0, %xmm0
+#ifdef USE_AS_STRNCMP
+	cmp	%r11, %rcx
+	jae	LABEL(nibble_ashr_use_sse4_2_exit)
+#endif
+	cmp	$7, %ecx
+	ja	LABEL(loop_ashr_8_use_sse4_2)
+
+	jmp	LABEL(nibble_ashr_use_sse4_2_exit)
+
+/*
+ *  The following cases will be handled by ashr_9
+ *  rcx(offset of rsi)  rax(offset of rdi)        relative offset	 corresponding case
+ *        n(7~15)          n - 7      	        8(15 +(n - 7) - n)         ashr_9
+ */
+	.p2align 4
+LABEL(ashr_9):
+	pxor	%xmm0, %xmm0
+	movdqa	(%rdi), %xmm2
+	movdqa	(%rsi), %xmm1
+	pcmpeqb	%xmm1, %xmm0
+	pslldq	$7, %xmm2
+	pcmpeqb	%xmm1, %xmm2
+	psubb	%xmm0, %xmm2
+	pmovmskb %xmm2, %r9d
+	shr	%cl, %edx
+	shr	%cl, %r9d
+	sub	%r9d, %edx
+	jnz	LABEL(less32bytes)
+	movdqa	(%rdi), %xmm3
+
+	UPDATE_STRNCMP_COUNTER
+
+	pxor	%xmm0, %xmm0
+	mov	$16, %rcx	/* index for loads */
+	mov	$9, %r9d	/* byte position left over from less32bytes case */
+	/*
+	 * Setup %r10 value allows us to detect crossing a page boundary.
+	 * When %r10 goes positive we have crossed a page boundary and
+	 * need to do a nibble.
+	 */
+	lea	9(%rdi), %r10
+	and	$0xfff, %r10	/* offset into 4K page */
+	sub	$0x1000, %r10	/* subtract 4K pagesize */
+	mov	%rcx, %rdx	/* only for offset of sse4 instruction loop*/
+
+	.p2align 4
+LABEL(loop_ashr_9_use_sse4_2):
+	add	$16, %r10
+	jg	LABEL(nibble_ashr_9_use_sse4_2)
+
+	movdqa	(%rdi, %rdx), %xmm0
+
+	palignr $9, -16(%rdi, %rdx), %xmm0
+	pcmpistri	$0x1a,(%rsi,%rdx), %xmm0
+	jbe	LABEL(use_sse4_2_exit)
+#ifdef USE_AS_STRNCMP
+	sub	$16, %r11
+	jbe	LABEL(strcmp_exitz)
+#endif
+
+	add	$16, %rdx
+	add	$16, %r10
+	jg	LABEL(nibble_ashr_9_use_sse4_2)
+
+	movdqa	(%rdi, %rdx), %xmm0
+	palignr $9, -16(%rdi, %rdx), %xmm0
+	pcmpistri	$0x1a,(%rsi,%rdx), %xmm0
+	jbe	LABEL(use_sse4_2_exit)
+#ifdef USE_AS_STRNCMP
+	sub	$16, %r11
+	jbe	LABEL(strcmp_exitz)
+#endif
+	add	$16, %rdx
+	jmp	LABEL(loop_ashr_9_use_sse4_2)
+
+	.p2align 4
+LABEL(nibble_ashr_9_use_sse4_2):
+	sub	$0x1000, %r10
+	movdqa	-16(%rdi, %rdx), %xmm0
+	psrldq	$9, %xmm0
+	pcmpistri      $0x3a,%xmm0, %xmm0
+#ifdef USE_AS_STRNCMP
+	cmp	%r11, %rcx
+	jae	LABEL(nibble_ashr_use_sse4_2_exit)
+#endif
+	cmp	$6, %ecx
+	ja	LABEL(loop_ashr_9_use_sse4_2)
+
+	jmp	LABEL(nibble_ashr_use_sse4_2_exit)
+
+/*
+ *  The following cases will be handled by ashr_10
+ *  rcx(offset of rsi)  rax(offset of rdi)        relative offset	 corresponding case
+ *        n(6~15)          n - 6      	        9(15 +(n - 6) - n)         ashr_10
+ */
+	.p2align 4
+LABEL(ashr_10):
+	pxor	%xmm0, %xmm0
+	movdqa	(%rdi), %xmm2
+	movdqa	(%rsi), %xmm1
+	pcmpeqb	%xmm1, %xmm0
+	pslldq	$6, %xmm2
+	pcmpeqb	%xmm1, %xmm2
+	psubb	%xmm0, %xmm2
+	pmovmskb %xmm2, %r9d
+	shr	%cl, %edx
+	shr	%cl, %r9d
+	sub	%r9d, %edx
+	jnz	LABEL(less32bytes)
+	movdqa	(%rdi), %xmm3
+
+	UPDATE_STRNCMP_COUNTER
+
+	pxor	%xmm0, %xmm0
+	mov	$16, %rcx	/* index for loads */
+	mov	$10, %r9d	/* byte position left over from less32bytes case */
+	/*
+	 * Setup %r10 value allows us to detect crossing a page boundary.
+	 * When %r10 goes positive we have crossed a page boundary and
+	 * need to do a nibble.
+	 */
+	lea	10(%rdi), %r10
+	and	$0xfff, %r10	/* offset into 4K page */
+	sub	$0x1000, %r10	/* subtract 4K pagesize */
+	mov	%rcx, %rdx	/* only for offset of sse4 instruction loop*/
+
+	.p2align 4
+LABEL(loop_ashr_10_use_sse4_2):
+	add	$16, %r10
+	jg	LABEL(nibble_ashr_10_use_sse4_2)
+
+	movdqa	(%rdi, %rdx), %xmm0
+	palignr $10, -16(%rdi, %rdx), %xmm0
+	pcmpistri	$0x1a,(%rsi,%rdx), %xmm0
+	jbe	LABEL(use_sse4_2_exit)
+#ifdef USE_AS_STRNCMP
+	sub	$16, %r11
+	jbe	LABEL(strcmp_exitz)
+#endif
+
+	add	$16, %rdx
+	add	$16, %r10
+	jg	LABEL(nibble_ashr_10_use_sse4_2)
+
+	movdqa	(%rdi, %rdx), %xmm0
+	palignr $10, -16(%rdi, %rdx), %xmm0
+	pcmpistri	$0x1a,(%rsi,%rdx), %xmm0
+	jbe	LABEL(use_sse4_2_exit)
+#ifdef USE_AS_STRNCMP
+	sub	$16, %r11
+	jbe	LABEL(strcmp_exitz)
+#endif
+	add	$16, %rdx
+	jmp	LABEL(loop_ashr_10_use_sse4_2)
+
+	.p2align 4
+LABEL(nibble_ashr_10_use_sse4_2):
+	sub	$0x1000, %r10
+	movdqa	-16(%rdi, %rdx), %xmm0
+	psrldq	$10, %xmm0
+	pcmpistri      $0x3a,%xmm0, %xmm0
+#ifdef USE_AS_STRNCMP
+	cmp	%r11, %rcx
+	jae	LABEL(nibble_ashr_use_sse4_2_exit)
+#endif
+	cmp	$5, %ecx
+	ja	LABEL(loop_ashr_10_use_sse4_2)
+
+	jmp	LABEL(nibble_ashr_use_sse4_2_exit)
+
+/*
+ *  The following cases will be handled by ashr_11
+ *  rcx(offset of rsi)  rax(offset of rdi)        relative offset	 corresponding case
+ *        n(5~15)          n - 5      	        10(15 +(n - 5) - n)         ashr_11
+ */
+	.p2align 4
+LABEL(ashr_11):
+	pxor	%xmm0, %xmm0
+	movdqa	(%rdi), %xmm2
+	movdqa	(%rsi), %xmm1
+	pcmpeqb	%xmm1, %xmm0
+	pslldq	$5, %xmm2
+	pcmpeqb	%xmm1, %xmm2
+	psubb	%xmm0, %xmm2
+	pmovmskb %xmm2, %r9d
+	shr	%cl, %edx
+	shr	%cl, %r9d
+	sub	%r9d, %edx
+	jnz	LABEL(less32bytes)
+	movdqa	(%rdi), %xmm3
+
+	UPDATE_STRNCMP_COUNTER
+
+	pxor	%xmm0, %xmm0
+	mov	$16, %rcx	/* index for loads */
+	mov	$11, %r9d	/* byte position left over from less32bytes case */
+	/*
+	 * Setup %r10 value allows us to detect crossing a page boundary.
+	 * When %r10 goes positive we have crossed a page boundary and
+	 * need to do a nibble.
+	 */
+	lea	11(%rdi), %r10
+	and	$0xfff, %r10	/* offset into 4K page */
+	sub	$0x1000, %r10	/* subtract 4K pagesize */
+	mov	%rcx, %rdx	/* only for offset of sse4 instruction loop*/
+
+	.p2align 4
+LABEL(loop_ashr_11_use_sse4_2):
+	add	$16, %r10
+	jg	LABEL(nibble_ashr_11_use_sse4_2)
+
+	movdqa	(%rdi, %rdx), %xmm0
+	palignr $11, -16(%rdi, %rdx), %xmm0
+	pcmpistri	$0x1a,(%rsi,%rdx), %xmm0
+	jbe	LABEL(use_sse4_2_exit)
+#ifdef USE_AS_STRNCMP
+	sub	$16, %r11
+	jbe	LABEL(strcmp_exitz)
+#endif
+
+	add	$16, %rdx
+	add	$16, %r10
+	jg	LABEL(nibble_ashr_11_use_sse4_2)
+
+	movdqa	(%rdi, %rdx), %xmm0
+	palignr $11, -16(%rdi, %rdx), %xmm0
+	pcmpistri	$0x1a,(%rsi,%rdx), %xmm0
+	jbe	LABEL(use_sse4_2_exit)
+#ifdef USE_AS_STRNCMP
+	sub	$16, %r11
+	jbe	LABEL(strcmp_exitz)
+#endif
+	add	$16, %rdx
+	jmp	LABEL(loop_ashr_11_use_sse4_2)
+
+	.p2align 4
+LABEL(nibble_ashr_11_use_sse4_2):
+	sub	$0x1000, %r10
+	movdqa	-16(%rdi, %rdx), %xmm0
+	psrldq	$11, %xmm0
+	pcmpistri      $0x3a,%xmm0, %xmm0
+#ifdef USE_AS_STRNCMP
+	cmp	%r11, %rcx
+	jae	LABEL(nibble_ashr_use_sse4_2_exit)
+#endif
+	cmp	$4, %ecx
+	ja	LABEL(loop_ashr_11_use_sse4_2)
+
+	jmp	LABEL(nibble_ashr_use_sse4_2_exit)
+
+/*
+ *  The following cases will be handled by ashr_12
+ *  rcx(offset of rsi)  rax(offset of rdi)        relative offset	 corresponding case
+ *        n(4~15)          n - 4      	        11(15 +(n - 4) - n)         ashr_12
+ */
+	.p2align 4
+LABEL(ashr_12):
+	pxor	%xmm0, %xmm0
+	movdqa	(%rdi), %xmm2
+	movdqa	(%rsi), %xmm1
+	pcmpeqb	%xmm1, %xmm0
+	pslldq	$4, %xmm2
+	pcmpeqb	%xmm1, %xmm2
+	psubb	%xmm0, %xmm2
+	pmovmskb %xmm2, %r9d
+	shr	%cl, %edx
+	shr	%cl, %r9d
+	sub	%r9d, %edx
+	jnz	LABEL(less32bytes)
+	movdqa	(%rdi), %xmm3
+
+	UPDATE_STRNCMP_COUNTER
+
+	pxor	%xmm0, %xmm0
+	mov	$16, %rcx	/* index for loads */
+	mov	$12, %r9d	/* byte position left over from less32bytes case */
+	/*
+	 * Setup %r10 value allows us to detect crossing a page boundary.
+	 * When %r10 goes positive we have crossed a page boundary and
+	 * need to do a nibble.
+	 */
+	lea	12(%rdi), %r10
+	and	$0xfff, %r10	/* offset into 4K page */
+	sub	$0x1000, %r10	/* subtract 4K pagesize */
+	mov	%rcx, %rdx	/* only for offset of sse4 instruction loop*/
+
+	.p2align 4
+LABEL(loop_ashr_12_use_sse4_2):
+	add	$16, %r10
+	jg	LABEL(nibble_ashr_12_use_sse4_2)
+
+	movdqa	(%rdi, %rdx), %xmm0
+	palignr $12, -16(%rdi, %rdx), %xmm0
+	pcmpistri	$0x1a,(%rsi,%rdx), %xmm0
+	jbe	LABEL(use_sse4_2_exit)
+#ifdef USE_AS_STRNCMP
+	sub	$16, %r11
+	jbe	LABEL(strcmp_exitz)
+#endif
+
+	add	$16, %rdx
+	add	$16, %r10
+	jg	LABEL(nibble_ashr_12_use_sse4_2)
+
+	movdqa	(%rdi, %rdx), %xmm0
+	palignr $12, -16(%rdi, %rdx), %xmm0
+	pcmpistri	$0x1a,(%rsi,%rdx), %xmm0
+	jbe	LABEL(use_sse4_2_exit)
+#ifdef USE_AS_STRNCMP
+	sub	$16, %r11
+	jbe	LABEL(strcmp_exitz)
+#endif
+	add	$16, %rdx
+	jmp	LABEL(loop_ashr_12_use_sse4_2)
+
+	.p2align 4
+LABEL(nibble_ashr_12_use_sse4_2):
+	sub	$0x1000, %r10
+	movdqa	-16(%rdi, %rdx), %xmm0
+	psrldq	$12, %xmm0
+	pcmpistri      $0x3a,%xmm0, %xmm0
+#ifdef USE_AS_STRNCMP
+	cmp	%r11, %rcx
+	jae	LABEL(nibble_ashr_use_sse4_2_exit)
+#endif
+	cmp	$3, %ecx
+	ja	LABEL(loop_ashr_12_use_sse4_2)
+
+	jmp	LABEL(nibble_ashr_use_sse4_2_exit)
+
+/*
+ *  The following cases will be handled by ashr_13
+ *  rcx(offset of rsi)  rax(offset of rdi)        relative offset	 corresponding case
+ *        n(3~15)          n - 3      	        12(15 +(n - 3) - n)         ashr_13
+ */
+	.p2align 4
+LABEL(ashr_13):
+	pxor	%xmm0, %xmm0
+	movdqa	(%rdi), %xmm2
+	movdqa	(%rsi), %xmm1
+	pcmpeqb	%xmm1, %xmm0
+	pslldq	$3, %xmm2
+	pcmpeqb	%xmm1, %xmm2
+	psubb	%xmm0, %xmm2
+	pmovmskb %xmm2, %r9d
+	shr	%cl, %edx
+	shr	%cl, %r9d
+	sub	%r9d, %edx
+	jnz	LABEL(less32bytes)
+	movdqa	(%rdi), %xmm3
+
+	UPDATE_STRNCMP_COUNTER
+
+	pxor	%xmm0, %xmm0
+	mov	$16, %rcx	/* index for loads */
+	mov	$13, %r9d	/* byte position left over from less32bytes case */
+	/*
+	 * Setup %r10 value allows us to detect crossing a page boundary.
+	 * When %r10 goes positive we have crossed a page boundary and
+	 * need to do a nibble.
+	 */
+	lea	13(%rdi), %r10
+	and	$0xfff, %r10	/* offset into 4K page */
+	sub	$0x1000, %r10	/* subtract 4K pagesize */
+
+	mov	%rcx, %rdx	/* only for offset of sse4 instruction loop*/
+
+	.p2align 4
+LABEL(loop_ashr_13_use_sse4_2):
+	add	$16, %r10
+	jg	LABEL(nibble_ashr_13_use_sse4_2)
+
+	movdqa	(%rdi, %rdx), %xmm0
+	palignr $13, -16(%rdi, %rdx), %xmm0
+	pcmpistri	$0x1a,(%rsi,%rdx), %xmm0
+	jbe	LABEL(use_sse4_2_exit)
+#ifdef USE_AS_STRNCMP
+	sub	$16, %r11
+	jbe	LABEL(strcmp_exitz)
+#endif
+
+	add	$16, %rdx
+	add	$16, %r10
+	jg	LABEL(nibble_ashr_13_use_sse4_2)
+
+	movdqa	(%rdi, %rdx), %xmm0
+	palignr $13, -16(%rdi, %rdx), %xmm0
+	pcmpistri	$0x1a,(%rsi,%rdx), %xmm0
+	jbe	LABEL(use_sse4_2_exit)
+#ifdef USE_AS_STRNCMP
+	sub	$16, %r11
+	jbe	LABEL(strcmp_exitz)
+#endif
+	add	$16, %rdx
+	jmp	LABEL(loop_ashr_13_use_sse4_2)
+
+	.p2align 4
+LABEL(nibble_ashr_13_use_sse4_2):
+	sub	$0x1000, %r10
+	movdqa	-16(%rdi, %rdx), %xmm0
+	psrldq	$13, %xmm0
+	pcmpistri      $0x3a,%xmm0, %xmm0
+#ifdef USE_AS_STRNCMP
+	cmp	%r11, %rcx
+	jae	LABEL(nibble_ashr_use_sse4_2_exit)
+#endif
+	cmp	$2, %ecx
+	ja	LABEL(loop_ashr_13_use_sse4_2)
+
+	jmp	LABEL(nibble_ashr_use_sse4_2_exit)
+
+/*
+ *  The following cases will be handled by ashr_14
+ *  rcx(offset of rsi)  rax(offset of rdi)        relative offset	 corresponding case
+ *        n(2~15)          n - 2      	        13(15 +(n - 2) - n)         ashr_14
+ */
+	.p2align 4
+LABEL(ashr_14):
+	pxor	%xmm0, %xmm0
+	movdqa	(%rdi), %xmm2
+	movdqa	(%rsi), %xmm1
+	pcmpeqb	%xmm1, %xmm0
+	pslldq  $2, %xmm2
+	pcmpeqb	%xmm1, %xmm2
+	psubb	%xmm0, %xmm2
+	pmovmskb %xmm2, %r9d
+	shr	%cl, %edx
+	shr	%cl, %r9d
+	sub	%r9d, %edx
+	jnz	LABEL(less32bytes)
+	movdqa	(%rdi), %xmm3
+
+	UPDATE_STRNCMP_COUNTER
+
+	pxor	%xmm0, %xmm0
+	mov	$16, %rcx	/* index for loads */
+	mov	$14, %r9d	/* byte position left over from less32bytes case */
+	/*
+	 * Setup %r10 value allows us to detect crossing a page boundary.
+	 * When %r10 goes positive we have crossed a page boundary and
+	 * need to do a nibble.
+	 */
+	lea	14(%rdi), %r10
+	and	$0xfff, %r10	/* offset into 4K page */
+	sub	$0x1000, %r10	/* subtract 4K pagesize */
+
+	mov	%rcx, %rdx	/* only for offset of sse4 instruction loop*/
+
+	.p2align 4
+LABEL(loop_ashr_14_use_sse4_2):
+	add	$16, %r10
+	jg	LABEL(nibble_ashr_14_use_sse4_2)
+
+	movdqa	(%rdi, %rdx), %xmm0
+	palignr $14, -16(%rdi, %rdx), %xmm0
+	pcmpistri	$0x1a,(%rsi,%rdx), %xmm0
+	jbe	LABEL(use_sse4_2_exit)
+#ifdef USE_AS_STRNCMP
+	sub	$16, %r11
+	jbe	LABEL(strcmp_exitz)
+#endif
+
+	add	$16, %rdx
+	add	$16, %r10
+	jg	LABEL(nibble_ashr_14_use_sse4_2)
+
+	movdqa	(%rdi, %rdx), %xmm0
+	palignr $14, -16(%rdi, %rdx), %xmm0
+	pcmpistri	$0x1a,(%rsi,%rdx), %xmm0
+	jbe	LABEL(use_sse4_2_exit)
+#ifdef USE_AS_STRNCMP
+	sub	$16, %r11
+	jbe	LABEL(strcmp_exitz)
+#endif
+	add	$16, %rdx
+	jmp	LABEL(loop_ashr_14_use_sse4_2)
+
+	.p2align 4
+LABEL(nibble_ashr_14_use_sse4_2):
+	sub	$0x1000, %r10
+	movdqa	-16(%rdi, %rdx), %xmm0
+	psrldq	$14, %xmm0
+	pcmpistri      $0x3a,%xmm0, %xmm0
+#ifdef USE_AS_STRNCMP
+	cmp	%r11, %rcx
+	jae	LABEL(nibble_ashr_use_sse4_2_exit)
+#endif
+	cmp	$1, %ecx
+	ja	LABEL(loop_ashr_14_use_sse4_2)
+
+	jmp	LABEL(nibble_ashr_use_sse4_2_exit)
+
+/*
+ *  The following cases will be handled by ashr_15
+ *  rcx(offset of rsi)  rax(offset of rdi)        relative offset	 corresponding case
+ *        n(1~15)          n - 1      	        14(15 +(n - 1) - n)         ashr_15
+ */
+	.p2align 4
+LABEL(ashr_15):
+	pxor	%xmm0, %xmm0
+	movdqa	(%rdi), %xmm2
+	movdqa	(%rsi), %xmm1
+	pcmpeqb	%xmm1, %xmm0
+	pslldq	$1, %xmm2
+	pcmpeqb	%xmm1, %xmm2
+	psubb	%xmm0, %xmm2
+	pmovmskb %xmm2, %r9d
+	shr	%cl, %edx
+	shr	%cl, %r9d
+	sub	%r9d, %edx
+	jnz	LABEL(less32bytes)
+
+	movdqa	(%rdi), %xmm3
+
+	UPDATE_STRNCMP_COUNTER
+
+	pxor	%xmm0, %xmm0
+	mov	$16, %rcx	/* index for loads */
+	mov	$15, %r9d	/* byte position left over from less32bytes case */
+	/*
+	 * Setup %r10 value allows us to detect crossing a page boundary.
+	 * When %r10 goes positive we have crossed a page boundary and
+	 * need to do a nibble.
+	 */
+	lea	15(%rdi), %r10
+	and	$0xfff, %r10	/* offset into 4K page */
+
+	sub	$0x1000, %r10	/* subtract 4K pagesize */
+
+	mov	%rcx, %rdx	/* only for offset of sse4 instruction loop*/
+
+	.p2align 4
+LABEL(loop_ashr_15_use_sse4_2):
+	add	$16, %r10
+	jg	LABEL(nibble_ashr_15_use_sse4_2)
+
+	movdqa	(%rdi, %rdx), %xmm0
+	palignr $15, -16(%rdi, %rdx), %xmm0
+	pcmpistri      $0x1a,(%rsi,%rdx), %xmm0
+	jbe	LABEL(use_sse4_2_exit)
+#ifdef USE_AS_STRNCMP
+	sub	$16, %r11
+	jbe	LABEL(strcmp_exitz)
+#endif
+
+	add	$16, %rdx
+	add	$16, %r10
+	jg	LABEL(nibble_ashr_15_use_sse4_2)
+
+	movdqa	(%rdi, %rdx), %xmm0
+	palignr $15, -16(%rdi, %rdx), %xmm0
+	pcmpistri      $0x1a,(%rsi,%rdx), %xmm0
+	jbe	LABEL(use_sse4_2_exit)
+#ifdef USE_AS_STRNCMP
+	sub	$16, %r11
+	jbe	LABEL(strcmp_exitz)
+#endif
+	add	$16, %rdx
+	jmp	LABEL(loop_ashr_15_use_sse4_2)
+
+	.p2align 4
+LABEL(nibble_ashr_15_use_sse4_2):
+	sub	$0x1000, %r10
+	movdqa	-16(%rdi, %rdx), %xmm0
+	psrldq	$15, %xmm0
+	pcmpistri      $0x3a,%xmm0, %xmm0
+#ifdef USE_AS_STRNCMP
+	cmp	%r11, %rcx
+	jae	LABEL(nibble_ashr_use_sse4_2_exit)
+#endif
+	cmp	$0, %ecx
+	ja	LABEL(loop_ashr_15_use_sse4_2)
+
+LABEL(nibble_ashr_use_sse4_2_exit):
+	pcmpistri      $0x1a,(%rsi,%rdx), %xmm0
+	.p2align 4
+LABEL(use_sse4_2_exit):
+	jnc	LABEL(strcmp_exitz)
+#ifdef USE_AS_STRNCMP
+	sub	%rcx, %r11
+	jbe	LABEL(strcmp_exitz)
+#endif
+	add	%rcx, %rdx
+	lea	-16(%rdi, %r9), %rdi
+	movzbl	(%rdi, %rdx), %eax
+	movzbl	(%rsi, %rdx), %edx
+	test	%r8d, %r8d
+	jz	LABEL(use_sse4_2_ret)
+	xchg	%eax, %edx
+LABEL(use_sse4_2_ret):
+	sub	%edx, %eax
+	ret
+
+	.p2align 4
+LABEL(aftertail):
+	pcmpeqb	%xmm3, %xmm1
+	psubb	%xmm0, %xmm1
+	pmovmskb %xmm1, %edx
+	not	%edx
+
+	.p2align 4
+LABEL(exit):
+	lea	-16(%r9, %rcx), %rax	/* locate the exact offset for rdi */
+LABEL(less32bytes):
+	lea	(%rdi, %rax), %rdi	/* locate the exact address for first operand(rdi) */
+	lea	(%rsi, %rcx), %rsi	/* locate the exact address for second operand(rsi) */
+	test	%r8d, %r8d
+	jz	LABEL(ret)
+	xchg	%rsi, %rdi		/* recover original order according to flag(%r8d) */
+
+	.p2align 4
+LABEL(ret):
+LABEL(less16bytes):
+	/*
+	 * Check to see if BSF is fast on this processor. If not, use a different
+	 * exit tail.
+	 */
+	bsf	%rdx, %rdx		/* find and store bit index in %rdx */
+
+#ifdef USE_AS_STRNCMP
+	sub	%rdx, %r11
+	jbe	LABEL(strcmp_exitz)
+#endif
+	xor	%ecx, %ecx		/* clear %ecx */
+	xor	%eax, %eax		/* clear %eax */
+
+	movb	(%rsi, %rdx), %cl
+	movb	(%rdi, %rdx), %al
+
+	sub	%ecx, %eax
+	ret
+
+LABEL(strcmp_exitz):
+	xor	%eax, %eax
+	ret
+
+	.p2align 4
+LABEL(Byte0):
+	/*
+	 * never need to handle byte 0 for strncmpy
+#ifdef USE_AS_STRNCMP
+	sub	$0, %r11
+	jbe	LABEL(strcmp_exitz)
+#endif
+	*/
+	movzx	(%rsi), %ecx
+	movzx	(%rdi), %eax
+
+	sub	%ecx, %eax
+	ret
+
+	.p2align 4
+LABEL(Byte1):
+
+#ifdef USE_AS_STRNCMP
+	sub	$1, %r11
+	jbe	LABEL(strcmp_exitz)
+#endif
+	movzx	1(%rsi), %ecx
+	movzx	1(%rdi), %eax
+
+	sub	%ecx, %eax
+	ret
+
+	.p2align 4
+LABEL(Byte2):
+
+#ifdef USE_AS_STRNCMP
+	sub	$2, %r11
+	jbe	LABEL(strcmp_exitz)
+#endif
+	movzx	2(%rsi), %ecx
+	movzx	2(%rdi), %eax
+
+	sub	%ecx, %eax
+	ret
+
+	.p2align 4
+LABEL(Byte3):
+
+#ifdef USE_AS_STRNCMP
+	sub	$3, %r11
+	jbe	LABEL(strcmp_exitz)
+#endif
+	movzx	3(%rsi), %ecx
+	movzx	3(%rdi), %eax
+
+	sub	%ecx, %eax
+	ret
+
+	.p2align 4
+LABEL(Byte4):
+
+#ifdef USE_AS_STRNCMP
+	sub	$4, %r11
+	jbe	LABEL(strcmp_exitz)
+#endif
+	movzx	4(%rsi), %ecx
+	movzx	4(%rdi), %eax
+
+	sub	%ecx, %eax
+	ret
+
+	.p2align 4
+LABEL(Byte5):
+
+#ifdef USE_AS_STRNCMP
+	sub	$5, %r11
+	jbe	LABEL(strcmp_exitz)
+#endif
+	movzx	5(%rsi), %ecx
+	movzx	5(%rdi), %eax
+
+	sub	%ecx, %eax
+	ret
+
+	.p2align 4
+LABEL(Byte6):
+
+#ifdef USE_AS_STRNCMP
+	sub	$6, %r11
+	jbe	LABEL(strcmp_exitz)
+#endif
+	movzx	6(%rsi), %ecx
+	movzx	6(%rdi), %eax
+
+	sub	%ecx, %eax
+	ret
+
+	.p2align 4
+LABEL(next_8_bytes):
+	add	$8, %rdi
+	add	$8, %rsi
+#ifdef USE_AS_STRNCMP
+	sub	$8, %r11
+	jbe	LABEL(strcmp_exitz)
+#endif
+	test	$0x01, %dh
+	jnz	LABEL(Byte0)
+
+	test	$0x02, %dh
+	jnz	LABEL(Byte1)
+
+	test	$0x04, %dh
+	jnz	LABEL(Byte2)
+
+	test	$0x08, %dh
+	jnz	LABEL(Byte3)
+
+	test	$0x10, %dh
+	jnz	LABEL(Byte4)
+
+	test	$0x20, %dh
+	jnz	LABEL(Byte5)
+
+	test	$0x40, %dh
+	jnz	LABEL(Byte6)
+
+#ifdef USE_AS_STRNCMP
+	sub	$7, %r11
+	jbe	LABEL(strcmp_exitz)
+#endif
+	movzx	7(%rsi), %ecx
+	movzx	7(%rdi), %eax
+
+	sub	%ecx, %eax
+	ret
+	cfi_endproc
+	.size	STRCMP_SSE42, .-STRCMP_SSE42
+
+	/* Put all SSE 4.2 functions together.  */
+	.section .rodata.sse4.2,"a",@progbits
+	.p2align 4
+LABEL(unaligned_table):
+	.int	LABEL(ashr_1) - LABEL(unaligned_table)
+	.int	LABEL(ashr_2) - LABEL(unaligned_table)
+	.int	LABEL(ashr_3) - LABEL(unaligned_table)
+	.int	LABEL(ashr_4) - LABEL(unaligned_table)
+	.int	LABEL(ashr_5) - LABEL(unaligned_table)
+	.int	LABEL(ashr_6) - LABEL(unaligned_table)
+	.int	LABEL(ashr_7) - LABEL(unaligned_table)
+	.int	LABEL(ashr_8) - LABEL(unaligned_table)
+	.int	LABEL(ashr_9) - LABEL(unaligned_table)
+	.int	LABEL(ashr_10) - LABEL(unaligned_table)
+	.int	LABEL(ashr_11) - LABEL(unaligned_table)
+	.int	LABEL(ashr_12) - LABEL(unaligned_table)
+	.int	LABEL(ashr_13) - LABEL(unaligned_table)
+	.int	LABEL(ashr_14) - LABEL(unaligned_table)
+	.int	LABEL(ashr_15) - LABEL(unaligned_table)
+	.int	LABEL(ashr_0) - LABEL(unaligned_table)
+
+
+# undef ENTRY
+# define ENTRY(name) \
+	.type STRCMP_SSE2, @function; \
+	STRCMP_SSE2: cfi_startproc; \
+	CALL_MCOUNT
+# undef END
+# define END(name) \
+	cfi_endproc; .size STRCMP_SSE2, .-STRCMP_SSE2
+# undef libc_hidden_builtin_def
+/* It doesn't make sense to send libc-internal strcmp calls through a PLT.
+   The speedup we get from using SSE4.2 instruction is likely eaten away
+   by the indirect call in the PLT.  */
+# define libc_hidden_builtin_def(name) \
+	.globl __GI_STRCMP; __GI_STRCMP = STRCMP_SSE2
+#endif
+
+#ifndef USE_AS_STRNCMP
+#include "../strcmp.S"
+#endif
diff --git a/sysdeps/x86_64/multiarch/strncmp-c.c b/sysdeps/x86_64/multiarch/strncmp-c.c
new file mode 100644
index 0000000000..d4f74a418d
--- /dev/null
+++ b/sysdeps/x86_64/multiarch/strncmp-c.c
@@ -0,0 +1,8 @@
+#ifdef SHARED
+#define STRNCMP __strncmp_sse2
+#undef libc_hidden_builtin_def
+#define libc_hidden_builtin_def(name) \
+  __hidden_ver1 (__strncmp_sse2, __GI_strncmp, __strncmp_sse2);
+#endif
+
+#include "strncmp.c"
diff --git a/sysdeps/x86_64/multiarch/strncmp.S b/sysdeps/x86_64/multiarch/strncmp.S
new file mode 100644
index 0000000000..0af34e7f15
--- /dev/null
+++ b/sysdeps/x86_64/multiarch/strncmp.S
@@ -0,0 +1,3 @@
+#define STRCMP strncmp
+#define USE_AS_STRNCMP
+#include "strcmp.S"