x86_64: Implement evex512 version of memchr, rawmemchr and wmemchr

This patch implements following evex512 version of string functions.
evex512 version takes up to 30% less cycle as compared to evex,
depending on length and alignment.

- memchr function using 512 bit vectors.
- rawmemchr function using 512 bit vectors.
- wmemchr function using 512 bit vectors.

Code size data:

memchr-evex.o		762 byte
memchr-evex512.o	576 byte (-24%)

rawmemchr-evex.o	461 byte
rawmemchr-evex512.o	412 byte (-11%)

wmemchr-evex.o		794 byte
wmemchr-evex512.o	552 byte (-30%)

Placeholder function, not used by any processor at the moment.

Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>

6 files changed, 346 insertions, 0 deletions

diff --git a/sysdeps/x86_64/multiarch/Makefile b/sysdeps/x86_64/multiarch/Makefile
index df4601c294..e974b1ad97 100644
--- a/sysdeps/x86_64/multiarch/Makefile
+++ b/sysdeps/x86_64/multiarch/Makefile
@@ -4,6 +4,7 @@ sysdep_routines += \
   memchr-avx2 \
   memchr-avx2-rtm \
   memchr-evex \
+  memchr-evex512 \
   memchr-evex-rtm \
   memchr-sse2 \
   memcmp-avx2-movbe \
@@ -36,6 +37,7 @@ sysdep_routines += \
   rawmemchr-avx2 \
   rawmemchr-avx2-rtm \
   rawmemchr-evex \
+  rawmemchr-evex512 \
   rawmemchr-evex-rtm \
   rawmemchr-sse2 \
   stpcpy-avx2 \
@@ -156,6 +158,7 @@ sysdep_routines += \
   wmemchr-avx2 \
   wmemchr-avx2-rtm \
   wmemchr-evex \
+  wmemchr-evex512 \
   wmemchr-evex-rtm \
   wmemchr-sse2 \
   wmemcmp-avx2-movbe \
diff --git a/sysdeps/x86_64/multiarch/ifunc-impl-list.c b/sysdeps/x86_64/multiarch/ifunc-impl-list.c
index 00a91123d3..529c0b0ef0 100644
--- a/sysdeps/x86_64/multiarch/ifunc-impl-list.c
+++ b/sysdeps/x86_64/multiarch/ifunc-impl-list.c
@@ -67,6 +67,11 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
 				     (CPU_FEATURE_USABLE (AVX512VL)
 				      && CPU_FEATURE_USABLE (AVX512BW)
 				      && CPU_FEATURE_USABLE (BMI2)),
+				     __memchr_evex512)
+	      X86_IFUNC_IMPL_ADD_V4 (array, i, memchr,
+				     (CPU_FEATURE_USABLE (AVX512VL)
+				      && CPU_FEATURE_USABLE (AVX512BW)
+				      && CPU_FEATURE_USABLE (BMI2)),
 				     __memchr_evex_rtm)
 	      X86_IFUNC_IMPL_ADD_V3 (array, i, memchr,
 				     (CPU_FEATURE_USABLE (AVX2)
@@ -341,6 +346,11 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
 				     (CPU_FEATURE_USABLE (AVX512VL)
 				      && CPU_FEATURE_USABLE (AVX512BW)
 				      && CPU_FEATURE_USABLE (BMI2)),
+				     __rawmemchr_evex512)
+	      X86_IFUNC_IMPL_ADD_V4 (array, i, rawmemchr,
+				     (CPU_FEATURE_USABLE (AVX512VL)
+				      && CPU_FEATURE_USABLE (AVX512BW)
+				      && CPU_FEATURE_USABLE (BMI2)),
 				     __rawmemchr_evex_rtm)
 	      X86_IFUNC_IMPL_ADD_V3 (array, i, rawmemchr,
 				     (CPU_FEATURE_USABLE (AVX2)
@@ -946,6 +956,11 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
 				     (CPU_FEATURE_USABLE (AVX512VL)
 				      && CPU_FEATURE_USABLE (AVX512BW)
 				      && CPU_FEATURE_USABLE (BMI2)),
+				     __wmemchr_evex512)
+	      X86_IFUNC_IMPL_ADD_V4 (array, i, wmemchr,
+				     (CPU_FEATURE_USABLE (AVX512VL)
+				      && CPU_FEATURE_USABLE (AVX512BW)
+				      && CPU_FEATURE_USABLE (BMI2)),
 				     __wmemchr_evex_rtm)
 	      X86_IFUNC_IMPL_ADD_V3 (array, i, wmemchr,
 				     (CPU_FEATURE_USABLE (AVX2)
diff --git a/sysdeps/x86_64/multiarch/memchr-evex-base.S b/sysdeps/x86_64/multiarch/memchr-evex-base.S
new file mode 100644
index 0000000000..6ebc9a66e8
--- /dev/null
+++ b/sysdeps/x86_64/multiarch/memchr-evex-base.S
@@ -0,0 +1,304 @@
+/* Placeholder function, not used by any processor at the moment.
+   Copyright (C) 2022 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
+   <https://www.gnu.org/licenses/>.  */
+
+/* UNUSED. Exists purely as reference implementation.  */
+
+#include <isa-level.h>
+
+#if ISA_SHOULD_BUILD (4)
+
+# include <sysdep.h>
+
+# ifdef USE_AS_WMEMCHR
+#  define CHAR_SIZE	4
+#  define VPBROADCAST   vpbroadcastd
+#  define VPCMPEQ	vpcmpeqd
+#  define VPCMPNE	vpcmpneqd
+#  define VPMINU	vpminud
+#  define VPTESTNM	vptestnmd
+# else
+#  define CHAR_SIZE	1
+#  define VPBROADCAST   vpbroadcastb
+#  define VPCMPEQ	vpcmpeqb
+#  define VPCMPNE	vpcmpneqb
+#  define VPMINU	vpminub
+#  define VPTESTNM	vptestnmb
+# endif
+
+# define PAGE_SIZE	4096
+# define CHAR_PER_VEC	(VEC_SIZE / CHAR_SIZE)
+
+	.section SECTION(.text), "ax", @progbits
+/* Aligning entry point to 64 byte, provides better performance for
+   one vector length string.  */
+ENTRY_P2ALIGN (MEMCHR, 6)
+# ifndef USE_AS_RAWMEMCHR
+	/* Check for zero length.  */
+	test	%RDX_LP, %RDX_LP
+	jz	L(zero)
+
+#  ifdef __ILP32__
+	/* Clear the upper 32 bits.  */
+	movl	%edx, %edx
+#  endif
+# endif
+
+	/* Broadcast CHAR to VMM(1).  */
+	VPBROADCAST %esi, %VMM(1)
+	movl	%edi, %eax
+	andl	$(PAGE_SIZE - 1), %eax
+	cmpl	$(PAGE_SIZE - VEC_SIZE), %eax
+	ja	L(page_cross)
+
+	/* Compare [w]char for null, mask bit will be set for match.  */
+	VPCMPEQ	(%rdi), %VMM(1), %k0
+
+	KMOV	%k0, %VRCX
+# ifndef USE_AS_RAWMEMCHR
+	mov	%rdx, %rsi
+	/* Need to use bsfq here as upper 32 bit of rsi may zero out
+	   for 'bsf %ecx, %esi', if %ecx is 0.  */
+	bsfq	%rcx, %rsi
+	cmp	$CHAR_PER_VEC, %rsi
+	ja	L(align_more)
+#  ifdef USE_AS_WMEMCHR
+	leaq	(%rdi, %rsi, CHAR_SIZE), %rdi
+#  else
+	addq	%rsi, %rdi
+#  endif
+	xor	%eax, %eax
+	cmp	%rsi, %rdx
+	cmova	%rdi, %rax
+# else
+	bsf     %VRCX, %VRAX
+	jz	L(align_more)
+	add	%rdi, %rax
+# endif
+	ret
+
+	.p2align 5,,5
+L(page_cross):
+	movl	%eax, %ecx
+	andl	$(VEC_SIZE - 1), %ecx
+# ifdef USE_AS_WMEMCHR
+	shrl	$2, %ecx
+# endif
+	xorq	%rdi, %rax
+	VPCMPEQ (PAGE_SIZE - VEC_SIZE)(%rax), %VMM(1), %k0
+	KMOV    %k0, %VRSI
+	shr	%cl, %VRSI
+# ifndef USE_AS_RAWMEMCHR
+	jnz	L(page_cross_end)
+	movl	$CHAR_PER_VEC, %eax
+	sub	%ecx, %eax
+	cmp	%rax, %rdx
+	ja	L(align_more)
+# else
+	jz	L(align_more)
+# endif
+
+L(page_cross_end):
+# ifndef USE_AS_RAWMEMCHR
+	bsf	%VRSI, %VRCX
+	jz	L(zero)
+	leaq	(%rdi, %rcx, CHAR_SIZE), %rdi
+	xor	%eax, %eax
+	cmp	%rcx, %rdx
+	cmova	%rdi, %rax
+# else
+	bsf	%VRSI, %VRAX
+	add	%rdi, %rax
+# endif
+	ret
+
+# ifndef USE_AS_RAWMEMCHR
+L(zero):
+	xorl	%eax, %eax
+	ret
+# endif
+
+L(ret_vec_x2):
+	subq	$-VEC_SIZE, %rdi
+L(ret_vec_x1):
+	bsf     %VRAX, %VRAX
+# ifndef USE_AS_RAWMEMCHR
+	cmp	%rax, %rdx
+	jbe	L(zero)
+# endif
+# ifdef USE_AS_WMEMCHR
+	leaq	(%rdi, %rax, CHAR_SIZE), %rax
+# else
+	add	%rdi, %rax
+# endif
+	ret
+
+	.p2align 5,,5
+L(align_more):
+# ifndef USE_AS_RAWMEMCHR
+	mov	%rdi, %rax
+# endif
+	subq	$-VEC_SIZE, %rdi
+	/* Align rdi to VEC_SIZE.  */
+	andq	$-VEC_SIZE, %rdi
+
+# ifndef USE_AS_RAWMEMCHR
+	subq	%rdi, %rax
+#  ifdef USE_AS_WMEMCHR
+	sar	$2, %rax
+#  endif
+	addq	%rax, %rdx
+# endif
+
+	/* Loop unroll 4 times for 4 vector loop.  */
+	VPCMPEQ	(%rdi), %VMM(1), %k0
+
+	KMOV	%k0, %VRAX
+	test	%VRAX, %VRAX
+	jnz	L(ret_vec_x1)
+
+# ifndef USE_AS_RAWMEMCHR
+	subq	$CHAR_PER_VEC, %rdx
+	jbe	L(zero)
+# endif
+
+	VPCMPEQ	VEC_SIZE(%rdi), %VMM(1), %k0
+
+	KMOV	%k0, %VRAX
+	test	%VRAX, %VRAX
+	jnz	L(ret_vec_x2)
+
+# ifndef USE_AS_RAWMEMCHR
+	subq	$CHAR_PER_VEC, %rdx
+	jbe	L(zero)
+# endif
+
+	VPCMPEQ	(VEC_SIZE * 2)(%rdi), %VMM(1), %k0
+
+	KMOV	%k0, %VRAX
+	test	%VRAX, %VRAX
+	jnz	L(ret_vec_x3)
+
+# ifndef USE_AS_RAWMEMCHR
+	subq	$CHAR_PER_VEC, %rdx
+	jbe	L(zero)
+# endif
+
+	VPCMPEQ	(VEC_SIZE * 3)(%rdi), %VMM(1), %k0
+
+	KMOV	%k0, %VRAX
+	test	%VRAX, %VRAX
+	jnz	L(ret_vec_x4)
+
+# ifndef USE_AS_RAWMEMCHR
+	subq	$CHAR_PER_VEC, %rdx
+	jbe	L(zero)
+	/* Save pointer to find alignment adjustment.  */
+	movq	%rdi, %rax
+# endif
+	/* Align address to VEC_SIZE * 4 for loop.  */
+	andq	$-(VEC_SIZE * 4), %rdi
+
+	/* Add alignment difference to rdx.  */
+# ifndef USE_AS_RAWMEMCHR
+	subq	%rdi, %rax
+#  ifdef USE_AS_WMEMCHR
+	shr	$2, %VRAX
+#  endif
+	addq	%rax, %rdx
+# endif
+
+	/* 4 vector loop.  */
+	.p2align 5,,11
+L(loop):
+
+	VPCMPNE	(VEC_SIZE * 4)(%rdi), %VMM(1), %k1
+	vpxorq  (VEC_SIZE * 5)(%rdi), %VMM(1), %VMM(2)
+	vpxorq  (VEC_SIZE * 6)(%rdi), %VMM(1), %VMM(3)
+	VPCMPEQ (VEC_SIZE * 7)(%rdi), %VMM(1), %k3
+	VPMINU  %VMM(2), %VMM(3), %VMM(3){%k1}{z}
+	VPTESTNM %VMM(3), %VMM(3), %k2
+
+	subq	$-(VEC_SIZE * 4), %rdi
+	KORTEST	%k2, %k3
+# ifdef USE_AS_RAWMEMCHR
+	jz	L(loop)
+# else
+	jnz	L(loopend)
+	subq	$(CHAR_PER_VEC * 4), %rdx
+	ja	L(loop)
+L(zero_2):
+	xor	%eax, %eax
+	ret
+# endif
+
+L(loopend):
+	VPCMPEQ	(%rdi), %VMM(1), %k1
+	KMOV	%k1, %VRAX
+	test	%VRAX, %VRAX
+	jnz	L(ret_vec_x1)
+
+# ifndef USE_AS_RAWMEMCHR
+	subq	$CHAR_PER_VEC, %rdx
+	jbe	L(zero_2)
+# endif
+
+	VPCMPEQ	VEC_SIZE(%rdi), %VMM(1), %k1
+	KMOV	%k1, %VRAX
+	test	%VRAX, %VRAX
+	jnz	L(ret_vec_x2)
+
+# ifndef USE_AS_RAWMEMCHR
+	subq	$CHAR_PER_VEC, %rdx
+	jbe	L(zero_2)
+# endif
+
+	VPCMPEQ	(VEC_SIZE * 2)(%rdi), %VMM(1), %k1
+	KMOV	%k1, %VRAX
+	test	%VRAX, %VRAX
+	jnz	L(ret_vec_x3)
+
+# ifndef USE_AS_RAWMEMCHR
+	subq	$CHAR_PER_VEC, %rdx
+	jbe	L(zero_2)
+# endif
+
+	/* At this point null [w]char must be in the fourth vector so no
+	   need to check.  */
+	KMOV	%k3, %VRAX
+
+L(ret_vec_x4):
+	bsf	%VRAX, %VRAX
+# ifndef USE_AS_RAWMEMCHR
+	cmp	%rax, %rdx
+	jbe	L(zero)
+# endif
+	leaq	(VEC_SIZE * 3)(%rdi, %rax, CHAR_SIZE), %rax
+	ret
+
+	.p2align 5,,5
+L(ret_vec_x3):
+	bsf	%VRAX, %VRAX
+# ifndef USE_AS_RAWMEMCHR
+	cmp	%rax, %rdx
+	jbe	L(zero)
+# endif
+	leaq	(VEC_SIZE * 2)(%rdi, %rax, CHAR_SIZE), %rax
+	ret
+
+END (MEMCHR)
+#endif
diff --git a/sysdeps/x86_64/multiarch/memchr-evex512.S b/sysdeps/x86_64/multiarch/memchr-evex512.S
new file mode 100644
index 0000000000..002f8c8489
--- /dev/null
+++ b/sysdeps/x86_64/multiarch/memchr-evex512.S
@@ -0,0 +1,8 @@
+# ifndef MEMCHR
+#  define MEMCHR       __memchr_evex512
+# endif
+
+#include "x86-evex512-vecs.h"
+#include "reg-macros.h"
+
+#include "memchr-evex-base.S"
diff --git a/sysdeps/x86_64/multiarch/rawmemchr-evex512.S b/sysdeps/x86_64/multiarch/rawmemchr-evex512.S
new file mode 100644
index 0000000000..302d3cb055
--- /dev/null
+++ b/sysdeps/x86_64/multiarch/rawmemchr-evex512.S
@@ -0,0 +1,7 @@
+#ifndef RAWMEMCHR
+# define RAWMEMCHR	__rawmemchr_evex512
+#endif
+#define USE_AS_RAWMEMCHR	1
+#define MEMCHR	RAWMEMCHR
+
+#include "memchr-evex512.S"
diff --git a/sysdeps/x86_64/multiarch/wmemchr-evex512.S b/sysdeps/x86_64/multiarch/wmemchr-evex512.S
new file mode 100644
index 0000000000..78ec4ee5ad
--- /dev/null
+++ b/sysdeps/x86_64/multiarch/wmemchr-evex512.S
@@ -0,0 +1,9 @@
+#ifndef WMEMCHR
+# define WMEMCHR	__wmemchr_evex512
+#endif
+
+#define MEMCHR	WMEMCHR
+#define USE_AS_WMEMCHR	1
+
+#define USE_WIDE_CHAR	1
+#include "memchr-evex512.S"