x86-64: Optimize strrchr/wcsrchr with AVX2 hjl/avx2/master

Optimize strrchr/wcsrchr with AVX2 to check 32 bytes with vector
instructions.  It is as fast as SSE2 version for small data sizes
and up to 1X faster for large data sizes on Haswell.  Select AVX2
version on AVX2 machines where vzeroupper is preferred and AVX
unaligned load is fast.

	* sysdeps/x86_64/multiarch/Makefile (sysdep_routines): Add
	strrchr-sse2, strrchr-avx2, wcsrchr-sse2 and wcsrchr-avx2.
	* sysdeps/x86_64/multiarch/ifunc-impl-list.c
	(__libc_ifunc_impl_list): Add tests for __strrchr_avx2,
	__strrchr_sse2, __wcsrchr_avx2 and __wcsrchr_sse2.
	* sysdeps/x86_64/multiarch/strrchr-avx2.S: New file.
	* sysdeps/x86_64/multiarch/strrchr-sse2.S: Likewise.
	* sysdeps/x86_64/multiarch/strrchr.c: Likewise.
	* sysdeps/x86_64/multiarch/wcsrchr-avx2.S: Likewise.
	* sysdeps/x86_64/multiarch/wcsrchr-sse2.S: Likewise.
	* sysdeps/x86_64/multiarch/wcsrchr.c: Likewise.

8 files changed, 368 insertions, 0 deletions

diff --git a/sysdeps/x86_64/multiarch/Makefile b/sysdeps/x86_64/multiarch/Makefile
index 2fa390b3dd..c901704b11 100644
--- a/sysdeps/x86_64/multiarch/Makefile
+++ b/sysdeps/x86_64/multiarch/Makefile
@@ -15,6 +15,7 @@ sysdep_routines += strncat-c stpncpy-c strncpy-c strcmp-ssse3 \
 		   memmove-ssse3-back \
 		   memmove-avx512-no-vzeroupper strcasecmp_l-ssse3 \
 		   strchr-sse2 strchrnul-sse2 strchr-avx2 strchrnul-avx2 \
+		   strrchr-sse2 strrchr-avx2 \
 		   strlen-sse2 strnlen-sse2 strlen-avx2 strnlen-avx2 \
 		   strncase_l-ssse3 strcat-ssse3 strncat-ssse3\
 		   strcpy-ssse3 strncpy-ssse3 stpcpy-ssse3 stpncpy-ssse3 \
@@ -40,6 +41,7 @@ sysdep_routines += wmemcmp-sse4 wmemcmp-ssse3 wmemcmp-c \
 		   wmemchr-sse2 wmemchr-avx2 \
 		   wcscpy-ssse3 wcscpy-c \
 		   wcschr-sse2 wcschr-avx2 \
+		   wcsrchr-sse2 wcsrchr-avx2 \
 		   wcsnlen-sse4_1 wcsnlen-c \
 		   wcslen-sse2 wcslen-avx2 wcsnlen-avx2
 endif
diff --git a/sysdeps/x86_64/multiarch/ifunc-impl-list.c b/sysdeps/x86_64/multiarch/ifunc-impl-list.c
index 5670eb7e9e..81f4d9b7af 100644
--- a/sysdeps/x86_64/multiarch/ifunc-impl-list.c
+++ b/sysdeps/x86_64/multiarch/ifunc-impl-list.c
@@ -251,6 +251,13 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
 			      __strchrnul_avx2)
 	      IFUNC_IMPL_ADD (array, i, strchrnul, 1, __strchrnul_sse2))
 
+  /* Support sysdeps/x86_64/multiarch/strrchr.c.  */
+  IFUNC_IMPL (i, name, strrchr,
+	      IFUNC_IMPL_ADD (array, i, strrchr,
+			      HAS_ARCH_FEATURE (AVX2_Usable),
+			      __strrchr_avx2)
+	      IFUNC_IMPL_ADD (array, i, strrchr, 1, __strrchr_sse2))
+
   /* Support sysdeps/x86_64/multiarch/strcmp.S.  */
   IFUNC_IMPL (i, name, strcmp,
 	      IFUNC_IMPL_ADD (array, i, strcmp, HAS_CPU_FEATURE (SSE4_2),
@@ -342,6 +349,13 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
 			      __wcschr_avx2)
 	      IFUNC_IMPL_ADD (array, i, wcschr, 1, __wcschr_sse2))
 
+  /* Support sysdeps/x86_64/multiarch/wcsrchr.c.  */
+  IFUNC_IMPL (i, name, wcsrchr,
+	      IFUNC_IMPL_ADD (array, i, wcsrchr,
+			      HAS_ARCH_FEATURE (AVX2_Usable),
+			      __wcsrchr_avx2)
+	      IFUNC_IMPL_ADD (array, i, wcsrchr, 1, __wcsrchr_sse2))
+
   /* Support sysdeps/x86_64/multiarch/wcscpy.S.  */
   IFUNC_IMPL (i, name, wcscpy,
 	      IFUNC_IMPL_ADD (array, i, wcscpy, HAS_CPU_FEATURE (SSSE3),
diff --git a/sysdeps/x86_64/multiarch/strrchr-avx2.S b/sysdeps/x86_64/multiarch/strrchr-avx2.S
new file mode 100644
index 0000000000..36ef660b2f
--- /dev/null
+++ b/sysdeps/x86_64/multiarch/strrchr-avx2.S
@@ -0,0 +1,235 @@
+/* strrchr/wcsrchr optimized with AVX2.
+   Copyright (C) 2017 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/>.  */
+
+#if IS_IN (libc)
+
+# include <sysdep.h>
+
+# ifndef STRRCHR
+#  define STRRCHR	__strrchr_avx2
+# endif
+
+# ifdef USE_AS_WCSRCHR
+#  define VPBROADCAST	vpbroadcastd
+#  define VPCMPEQ	vpcmpeqd
+# else
+#  define VPBROADCAST	vpbroadcastb
+#  define VPCMPEQ	vpcmpeqb
+# endif
+
+# ifndef VZEROUPPER
+#  define VZEROUPPER	vzeroupper
+# endif
+
+# define VEC_SIZE	32
+
+	.section .text.avx,"ax",@progbits
+ENTRY (STRRCHR)
+	movd	%esi, %xmm4
+	movl	%edi, %ecx
+	/* Broadcast CHAR to YMM4.  */
+	VPBROADCAST %xmm4, %ymm4
+	vpxor	%ymm0, %ymm0, %ymm0
+
+	/* Check if we may cross page boundary with one vector load.  */
+	andl	$(2 * VEC_SIZE - 1), %ecx
+	cmpl	$VEC_SIZE, %ecx
+	ja	L(cros_page_boundary)
+
+	vmovdqu	(%rdi), %ymm1
+	VPCMPEQ	%ymm1, %ymm0, %ymm2
+	VPCMPEQ	%ymm1, %ymm4, %ymm3
+	vpmovmskb %ymm2, %ecx
+	vpmovmskb %ymm3, %eax
+	addq	$VEC_SIZE, %rdi
+
+	testl	%eax, %eax
+	jnz	L(first_vec)
+
+	testl	%ecx, %ecx
+	jnz	L(return_null)
+
+	andq	$-VEC_SIZE, %rdi
+	xorl	%edx, %edx
+	jmp	L(aligned_loop)
+
+	.p2align 4
+L(first_vec):
+	/* Check if there is a nul CHAR.  */
+	testl	%ecx, %ecx
+	jnz	L(char_and_nul_in_first_vec)
+
+	/* Remember the match and keep searching.  */
+	movl	%eax, %edx
+	movq	%rdi, %rsi
+	andq	$-VEC_SIZE, %rdi
+	jmp	L(aligned_loop)
+
+	.p2align 4
+L(cros_page_boundary):
+	andl	$(VEC_SIZE - 1), %ecx
+	andq	$-VEC_SIZE, %rdi
+	vmovdqa	(%rdi), %ymm1
+	VPCMPEQ	%ymm1, %ymm0, %ymm2
+	VPCMPEQ	%ymm1, %ymm4, %ymm3
+	vpmovmskb %ymm2, %edx
+	vpmovmskb %ymm3, %eax
+	shrl	%cl, %edx
+	shrl	%cl, %eax
+	addq	$VEC_SIZE, %rdi
+
+	/* Check if there is a CHAR.  */
+	testl	%eax, %eax
+	jnz	L(found_char)
+
+	testl	%edx, %edx
+	jnz	L(return_null)
+
+	jmp	L(aligned_loop)
+
+	.p2align 4
+L(found_char):
+	testl	%edx, %edx
+	jnz	L(char_and_nul)
+
+	/* Remember the match and keep searching.  */
+	movl	%eax, %edx
+	leaq	(%rdi, %rcx), %rsi
+
+	.p2align 4
+L(aligned_loop):
+	vmovdqa	(%rdi), %ymm1
+	VPCMPEQ	%ymm1, %ymm0, %ymm2
+	addq	$VEC_SIZE, %rdi
+	VPCMPEQ	%ymm1, %ymm4, %ymm3
+	vpmovmskb %ymm2, %ecx
+	vpmovmskb %ymm3, %eax
+	orl	%eax, %ecx
+	jnz	L(char_nor_null)
+
+	vmovdqa	(%rdi), %ymm1
+	VPCMPEQ	%ymm1, %ymm0, %ymm2
+	add	$VEC_SIZE, %rdi
+	VPCMPEQ	%ymm1, %ymm4, %ymm3
+	vpmovmskb %ymm2, %ecx
+	vpmovmskb %ymm3, %eax
+	orl	%eax, %ecx
+	jnz	L(char_nor_null)
+
+	vmovdqa	(%rdi), %ymm1
+	VPCMPEQ	%ymm1, %ymm0, %ymm2
+	addq	$VEC_SIZE, %rdi
+	VPCMPEQ	%ymm1, %ymm4, %ymm3
+	vpmovmskb %ymm2, %ecx
+	vpmovmskb %ymm3, %eax
+	orl	%eax, %ecx
+	jnz	L(char_nor_null)
+
+	vmovdqa	(%rdi), %ymm1
+	VPCMPEQ	%ymm1, %ymm0, %ymm2
+	addq	$VEC_SIZE, %rdi
+	VPCMPEQ	%ymm1, %ymm4, %ymm3
+	vpmovmskb %ymm2, %ecx
+	vpmovmskb %ymm3, %eax
+	orl	%eax, %ecx
+	jz	L(aligned_loop)
+
+	.p2align 4
+L(char_nor_null):
+	/* Find a CHAR or a nul CHAR in a loop.  */
+	testl	%eax, %eax
+	jnz	L(match)
+L(return_value):
+	testl	%edx, %edx
+	jz	L(return_null)
+	movl	%edx, %eax
+	movq	%rsi, %rdi
+
+# ifdef USE_AS_WCSRCHR
+	/* Keep the first bit for each matching CHAR for bsr.  */
+	andl	$0x11111111, %eax
+# endif
+	bsrl	%eax, %eax
+	leaq	-VEC_SIZE(%rdi, %rax), %rax
+	VZEROUPPER
+	ret
+
+	.p2align 4
+L(match):
+	/* Find a CHAR.  Check if there is a nul CHAR.  */
+	vpmovmskb %ymm2, %ecx
+	testl	%ecx, %ecx
+	jnz	L(find_nul)
+
+	/* Remember the match and keep searching.  */
+	movl	%eax, %edx
+	movq	%rdi, %rsi
+	jmp	L(aligned_loop)
+
+	.p2align 4
+L(find_nul):
+# ifdef USE_AS_WCSRCHR
+	/* Keep the first bit for each matching CHAR for bsr.  */
+	andl	$0x11111111, %ecx
+	andl	$0x11111111, %eax
+# endif
+	/* Mask out any matching bits after the nul CHAR.  */
+	movl	%ecx, %r8d
+	subl	$1, %r8d
+	xorl	%ecx, %r8d
+	andl	%r8d, %eax
+	testl	%eax, %eax
+	/* If there is no CHAR here, return the remembered one.  */
+	jz	L(return_value)
+	bsrl	%eax, %eax
+	leaq	-VEC_SIZE(%rdi, %rax), %rax
+	VZEROUPPER
+	ret
+
+	.p2align 4
+L(char_and_nul):
+	/* Find both a CHAR and a nul CHAR.  */
+	addq	%rcx, %rdi
+	movl	%edx, %ecx
+L(char_and_nul_in_first_vec):
+# ifdef USE_AS_WCSRCHR
+	/* Keep the first bit for each matching CHAR for bsr.  */
+	andl	$0x11111111, %ecx
+	andl	$0x11111111, %eax
+# endif
+	/* Mask out any matching bits after the nul CHAR.  */
+	movl	%ecx, %r8d
+	subl	$1, %r8d
+	xorl	%ecx, %r8d
+	andl	%r8d, %eax
+	testl	%eax, %eax
+	/* Return null pointer if the nul CHAR comes first.  */
+	jz	L(return_null)
+	bsrl	%eax, %eax
+	leaq	-VEC_SIZE(%rdi, %rax), %rax
+	VZEROUPPER
+	ret
+
+	.p2align 4
+L(return_null):
+	xorl	%eax, %eax
+	VZEROUPPER
+	ret
+
+END (STRRCHR)
+#endif
diff --git a/sysdeps/x86_64/multiarch/strrchr-sse2.S b/sysdeps/x86_64/multiarch/strrchr-sse2.S
new file mode 100644
index 0000000000..6479d17915
--- /dev/null
+++ b/sysdeps/x86_64/multiarch/strrchr-sse2.S
@@ -0,0 +1,28 @@
+/* strrchr optimized with SSE2.
+   Copyright (C) 2017 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/>.  */
+
+#if IS_IN (libc)
+# define strrchr __strrchr_sse2
+
+# undef weak_alias
+# define weak_alias(strrchr, rindex)
+# undef libc_hidden_builtin_def
+# define libc_hidden_builtin_def(strrchr)
+#endif
+
+#include "../strrchr.S"
diff --git a/sysdeps/x86_64/multiarch/strrchr.c b/sysdeps/x86_64/multiarch/strrchr.c
new file mode 100644
index 0000000000..0375ae6dae
--- /dev/null
+++ b/sysdeps/x86_64/multiarch/strrchr.c
@@ -0,0 +1,34 @@
+/* Multiple versions of strrchr.
+   Copyright (C) 2017 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/>.  */
+
+/* Define multiple versions only for the definition in libc.  */
+#if IS_IN (libc)
+# define strrchr __redirect_strrchr
+# include <string.h>
+# undef strrchr
+
+# define SYMBOL_NAME strrchr
+# include "ifunc-avx2.h"
+
+libc_ifunc_redirected (__redirect_strrchr, strrchr, IFUNC_SELECTOR ());
+weak_alias (strrchr, rindex);
+# ifdef SHARED
+__hidden_ver1 (strrchr, __GI_strrchr, __redirect_strrchr)
+  __attribute__((visibility ("hidden")));
+# endif
+#endif
diff --git a/sysdeps/x86_64/multiarch/wcsrchr-avx2.S b/sysdeps/x86_64/multiarch/wcsrchr-avx2.S
new file mode 100644
index 0000000000..cf8a239ab2
--- /dev/null
+++ b/sysdeps/x86_64/multiarch/wcsrchr-avx2.S
@@ -0,0 +1,3 @@
+#define STRRCHR __wcsrchr_avx2
+#define USE_AS_WCSRCHR 1
+#include "strrchr-avx2.S"
diff --git a/sysdeps/x86_64/multiarch/wcsrchr-sse2.S b/sysdeps/x86_64/multiarch/wcsrchr-sse2.S
new file mode 100644
index 0000000000..0ac1b1356c
--- /dev/null
+++ b/sysdeps/x86_64/multiarch/wcsrchr-sse2.S
@@ -0,0 +1,23 @@
+/* wcsrchr optimized with SSE2.
+   Copyright (C) 2017 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/>.  */
+
+#if IS_IN (libc)
+# define wcsrchr __wcsrchr_sse2
+#endif
+
+#include "../wcsrchr.S"
diff --git a/sysdeps/x86_64/multiarch/wcsrchr.c b/sysdeps/x86_64/multiarch/wcsrchr.c
new file mode 100644
index 0000000000..b39218f6bd
--- /dev/null
+++ b/sysdeps/x86_64/multiarch/wcsrchr.c
@@ -0,0 +1,29 @@
+/* Multiple versions of wcsrchr.
+   Copyright (C) 2017 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/>.  */
+
+/* Define multiple versions only for the definition in libc.  */
+#if IS_IN (libc)
+# define wcsrchr __redirect_wcsrchr
+# include <wchar.h>
+# undef wcsrchr
+
+# define SYMBOL_NAME wcsrchr
+# include "ifunc-avx2.h"
+
+libc_ifunc_redirected (__redirect_wcsrchr, wcsrchr, IFUNC_SELECTOR ());
+#endif