commit 8ab861d295b90177b89288a2bc95c5de5e4e5bc6
Author: Sunil K Pandey <skpgkp2@gmail.com>
Date: Sun Feb 27 16:39:47 2022 -0800
x86_64: Implement evex512 version of strlen, strnlen, wcslen and wcsnlen
This patch implements following evex512 version of string functions.
Perf gain for evex512 version is up to 50% as compared to evex,
depending on length and alignment.
Placeholder function, not used by any processor at the moment.
- String length function using 512 bit vectors.
- String N length using 512 bit vectors.
- Wide string length using 512 bit vectors.
- Wide string N length using 512 bit vectors.
Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>
(cherry picked from commit 9c66efb86fe384f77435f7e326333fb2e4e10676)
diff --git a/sysdeps/x86_64/multiarch/Makefile b/sysdeps/x86_64/multiarch/Makefile
index 67401162d526f664..4d4ad2a3686b5bc3 100644
--- a/sysdeps/x86_64/multiarch/Makefile
+++ b/sysdeps/x86_64/multiarch/Makefile
@@ -87,6 +87,7 @@ sysdep_routines += \
strlen-avx2 \
strlen-avx2-rtm \
strlen-evex \
+ strlen-evex512 \
strlen-sse2 \
strncase_l-avx2 \
strncase_l-avx2-rtm \
@@ -115,6 +116,7 @@ sysdep_routines += \
strnlen-avx2 \
strnlen-avx2-rtm \
strnlen-evex \
+ strnlen-evex512 \
strnlen-sse2 \
strpbrk-c \
strpbrk-sse2 \
@@ -148,6 +150,7 @@ sysdep_routines += \
wcslen-avx2 \
wcslen-avx2-rtm \
wcslen-evex \
+ wcslen-evex512 \
wcslen-sse2 \
wcslen-sse4_1 \
wcsncmp-avx2 \
@@ -158,6 +161,7 @@ sysdep_routines += \
wcsnlen-avx2-rtm \
wcsnlen-c \
wcsnlen-evex \
+ wcsnlen-evex512 \
wcsnlen-sse4_1 \
wcsrchr-avx2 \
wcsrchr-avx2-rtm \
diff --git a/sysdeps/x86_64/multiarch/ifunc-impl-list.c b/sysdeps/x86_64/multiarch/ifunc-impl-list.c
index d990a7149489efd9..6b75a7106e174bce 100644
--- a/sysdeps/x86_64/multiarch/ifunc-impl-list.c
+++ b/sysdeps/x86_64/multiarch/ifunc-impl-list.c
@@ -317,6 +317,11 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
&& CPU_FEATURE_USABLE (AVX512BW)
&& CPU_FEATURE_USABLE (BMI2)),
__strlen_evex)
+ IFUNC_IMPL_ADD (array, i, strlen,
+ (CPU_FEATURE_USABLE (AVX512VL)
+ && CPU_FEATURE_USABLE (AVX512BW)
+ && CPU_FEATURE_USABLE (BMI2)),
+ __strlen_evex512)
IFUNC_IMPL_ADD (array, i, strlen, 1, __strlen_sse2))
/* Support sysdeps/x86_64/multiarch/strnlen.c. */
@@ -335,6 +340,11 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
&& CPU_FEATURE_USABLE (AVX512BW)
&& CPU_FEATURE_USABLE (BMI2)),
__strnlen_evex)
+ IFUNC_IMPL_ADD (array, i, strnlen,
+ (CPU_FEATURE_USABLE (AVX512VL)
+ && CPU_FEATURE_USABLE (AVX512BW)
+ && CPU_FEATURE_USABLE (BMI2)),
+ __strnlen_evex512)
IFUNC_IMPL_ADD (array, i, strnlen, 1, __strnlen_sse2))
/* Support sysdeps/x86_64/multiarch/stpncpy.c. */
@@ -714,6 +724,11 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
&& CPU_FEATURE_USABLE (AVX512BW)
&& CPU_FEATURE_USABLE (BMI2)),
__wcslen_evex)
+ IFUNC_IMPL_ADD (array, i, wcslen,
+ (CPU_FEATURE_USABLE (AVX512VL)
+ && CPU_FEATURE_USABLE (AVX512BW)
+ && CPU_FEATURE_USABLE (BMI2)),
+ __wcslen_evex512)
IFUNC_IMPL_ADD (array, i, wcslen,
CPU_FEATURE_USABLE (SSE4_1),
__wcslen_sse4_1)
@@ -735,6 +750,11 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
&& CPU_FEATURE_USABLE (AVX512BW)
&& CPU_FEATURE_USABLE (BMI2)),
__wcsnlen_evex)
+ IFUNC_IMPL_ADD (array, i, wcsnlen,
+ (CPU_FEATURE_USABLE (AVX512VL)
+ && CPU_FEATURE_USABLE (AVX512BW)
+ && CPU_FEATURE_USABLE (BMI2)),
+ __wcsnlen_evex512)
IFUNC_IMPL_ADD (array, i, wcsnlen,
CPU_FEATURE_USABLE (SSE4_1),
__wcsnlen_sse4_1)
diff --git a/sysdeps/x86_64/multiarch/strlen-evex-base.S b/sysdeps/x86_64/multiarch/strlen-evex-base.S
new file mode 100644
index 0000000000000000..278c899691d89ba7
--- /dev/null
+++ b/sysdeps/x86_64/multiarch/strlen-evex-base.S
@@ -0,0 +1,302 @@
+/* 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/>. */
+
+#if IS_IN (libc)
+
+# include <sysdep.h>
+
+# ifdef USE_AS_WCSLEN
+# define VPCMP vpcmpd
+# define VPTESTN vptestnmd
+# define VPMINU vpminud
+# define CHAR_SIZE 4
+# else
+# define VPCMP vpcmpb
+# define VPTESTN vptestnmb
+# define VPMINU vpminub
+# define CHAR_SIZE 1
+# endif
+
+# define XMM0 xmm16
+# define PAGE_SIZE 4096
+# define CHAR_PER_VEC (VEC_SIZE / CHAR_SIZE)
+
+# if VEC_SIZE == 64
+# define KMOV kmovq
+# define KORTEST kortestq
+# define RAX rax
+# define RCX rcx
+# define RDX rdx
+# define SHR shrq
+# define TEXTSUFFIX evex512
+# define VMM0 zmm16
+# define VMM1 zmm17
+# define VMM2 zmm18
+# define VMM3 zmm19
+# define VMM4 zmm20
+# define VMOVA vmovdqa64
+# elif VEC_SIZE == 32
+/* Currently Unused. */
+# define KMOV kmovd
+# define KORTEST kortestd
+# define RAX eax
+# define RCX ecx
+# define RDX edx
+# define SHR shrl
+# define TEXTSUFFIX evex256
+# define VMM0 ymm16
+# define VMM1 ymm17
+# define VMM2 ymm18
+# define VMM3 ymm19
+# define VMM4 ymm20
+# define VMOVA vmovdqa32
+# endif
+
+ .section .text.TEXTSUFFIX, "ax", @progbits
+/* Aligning entry point to 64 byte, provides better performance for
+ one vector length string. */
+ENTRY_P2ALIGN (STRLEN, 6)
+# ifdef USE_AS_STRNLEN
+ /* Check zero length. */
+ test %RSI_LP, %RSI_LP
+ jz L(ret_max)
+# ifdef __ILP32__
+ /* Clear the upper 32 bits. */
+ movl %esi, %esi
+# endif
+# endif
+
+ movl %edi, %eax
+ vpxorq %XMM0, %XMM0, %XMM0
+ 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. */
+ VPCMP $0, (%rdi), %VMM0, %k0
+ KMOV %k0, %RAX
+ test %RAX, %RAX
+ jz L(align_more)
+
+ bsf %RAX, %RAX
+# ifdef USE_AS_STRNLEN
+ cmpq %rsi, %rax
+ cmovnb %rsi, %rax
+# endif
+ ret
+
+ /* At this point vector max length reached. */
+# ifdef USE_AS_STRNLEN
+ .p2align 4,,3
+L(ret_max):
+ movq %rsi, %rax
+ ret
+# endif
+
+L(align_more):
+ leaq VEC_SIZE(%rdi), %rax
+ /* Align rax to VEC_SIZE. */
+ andq $-VEC_SIZE, %rax
+# ifdef USE_AS_STRNLEN
+ movq %rax, %rdx
+ subq %rdi, %rdx
+# ifdef USE_AS_WCSLEN
+ SHR $2, %RDX
+# endif
+ /* At this point rdx contains [w]chars already compared. */
+ subq %rsi, %rdx
+ jae L(ret_max)
+ negq %rdx
+ /* At this point rdx contains number of w[char] needs to go.
+ Now onwards rdx will keep decrementing with each compare. */
+# endif
+
+ /* Loop unroll 4 times for 4 vector loop. */
+ VPCMP $0, (%rax), %VMM0, %k0
+ KMOV %k0, %RCX
+ test %RCX, %RCX
+ jnz L(ret_vec_x1)
+
+# ifdef USE_AS_STRNLEN
+ subq $CHAR_PER_VEC, %rdx
+ jbe L(ret_max)
+# endif
+
+ VPCMP $0, VEC_SIZE(%rax), %VMM0, %k0
+ KMOV %k0, %RCX
+ test %RCX, %RCX
+ jnz L(ret_vec_x2)
+
+# ifdef USE_AS_STRNLEN
+ subq $CHAR_PER_VEC, %rdx
+ jbe L(ret_max)
+# endif
+
+ VPCMP $0, (VEC_SIZE * 2)(%rax), %VMM0, %k0
+ KMOV %k0, %RCX
+ test %RCX, %RCX
+ jnz L(ret_vec_x3)
+
+# ifdef USE_AS_STRNLEN
+ subq $CHAR_PER_VEC, %rdx
+ jbe L(ret_max)
+# endif
+
+ VPCMP $0, (VEC_SIZE * 3)(%rax), %VMM0, %k0
+ KMOV %k0, %RCX
+ test %RCX, %RCX
+ jnz L(ret_vec_x4)
+
+# ifdef USE_AS_STRNLEN
+ subq $CHAR_PER_VEC, %rdx
+ jbe L(ret_max)
+ /* Save pointer before 4 x VEC_SIZE alignment. */
+ movq %rax, %rcx
+# endif
+
+ /* Align address to VEC_SIZE * 4 for loop. */
+ andq $-(VEC_SIZE * 4), %rax
+
+# ifdef USE_AS_STRNLEN
+ subq %rax, %rcx
+# ifdef USE_AS_WCSLEN
+ SHR $2, %RCX
+# endif
+ /* rcx contains number of [w]char will be recompared due to
+ alignment fixes. rdx must be incremented by rcx to offset
+ alignment adjustment. */
+ addq %rcx, %rdx
+ /* Need jump as we don't want to add/subtract rdx for first
+ iteration of 4 x VEC_SIZE aligned loop. */
+ jmp L(loop_entry)
+# endif
+
+ .p2align 4,,11
+L(loop):
+# ifdef USE_AS_STRNLEN
+ subq $(CHAR_PER_VEC * 4), %rdx
+ jbe L(ret_max)
+L(loop_entry):
+# endif
+ /* VPMINU and VPCMP combination provide better performance as
+ compared to alternative combinations. */
+ VMOVA (VEC_SIZE * 4)(%rax), %VMM1
+ VPMINU (VEC_SIZE * 5)(%rax), %VMM1, %VMM2
+ VMOVA (VEC_SIZE * 6)(%rax), %VMM3
+ VPMINU (VEC_SIZE * 7)(%rax), %VMM3, %VMM4
+
+ VPTESTN %VMM2, %VMM2, %k0
+ VPTESTN %VMM4, %VMM4, %k1
+
+ subq $-(VEC_SIZE * 4), %rax
+ KORTEST %k0, %k1
+ jz L(loop)
+
+ VPTESTN %VMM1, %VMM1, %k2
+ KMOV %k2, %RCX
+ test %RCX, %RCX
+ jnz L(ret_vec_x1)
+
+ KMOV %k0, %RCX
+ /* At this point, if k0 is non zero, null char must be in the
+ second vector. */
+ test %RCX, %RCX
+ jnz L(ret_vec_x2)
+
+ VPTESTN %VMM3, %VMM3, %k3
+ KMOV %k3, %RCX
+ test %RCX, %RCX
+ jnz L(ret_vec_x3)
+ /* At this point null [w]char must be in the fourth vector so no
+ need to check. */
+ KMOV %k1, %RCX
+
+ /* Fourth, third, second vector terminating are pretty much
+ same, implemented this way to avoid branching and reuse code
+ from pre loop exit condition. */
+L(ret_vec_x4):
+ bsf %RCX, %RCX
+ subq %rdi, %rax
+# ifdef USE_AS_WCSLEN
+ subq $-(VEC_SIZE * 3), %rax
+ shrq $2, %rax
+ addq %rcx, %rax
+# else
+ leaq (VEC_SIZE * 3)(%rcx, %rax), %rax
+# endif
+# ifdef USE_AS_STRNLEN
+ cmpq %rsi, %rax
+ cmovnb %rsi, %rax
+# endif
+ ret
+
+L(ret_vec_x3):
+ bsf %RCX, %RCX
+ subq %rdi, %rax
+# ifdef USE_AS_WCSLEN
+ subq $-(VEC_SIZE * 2), %rax
+ shrq $2, %rax
+ addq %rcx, %rax
+# else
+ leaq (VEC_SIZE * 2)(%rcx, %rax), %rax
+# endif
+# ifdef USE_AS_STRNLEN
+ cmpq %rsi, %rax
+ cmovnb %rsi, %rax
+# endif
+ ret
+
+L(ret_vec_x2):
+ subq $-VEC_SIZE, %rax
+L(ret_vec_x1):
+ bsf %RCX, %RCX
+ subq %rdi, %rax
+# ifdef USE_AS_WCSLEN
+ shrq $2, %rax
+# endif
+ addq %rcx, %rax
+# ifdef USE_AS_STRNLEN
+ cmpq %rsi, %rax
+ cmovnb %rsi, %rax
+# endif
+ ret
+
+L(page_cross):
+ movl %eax, %ecx
+# ifdef USE_AS_WCSLEN
+ andl $(VEC_SIZE - 1), %ecx
+ sarl $2, %ecx
+# endif
+ /* ecx contains number of w[char] to be skipped as a result
+ of address alignment. */
+ xorq %rdi, %rax
+ VPCMP $0, (PAGE_SIZE - VEC_SIZE)(%rax), %VMM0, %k0
+ KMOV %k0, %RAX
+ /* Ignore number of character for alignment adjustment. */
+ SHR %cl, %RAX
+ jz L(align_more)
+
+ bsf %RAX, %RAX
+# ifdef USE_AS_STRNLEN
+ cmpq %rsi, %rax
+ cmovnb %rsi, %rax
+# endif
+ ret
+
+END (STRLEN)
+#endif
diff --git a/sysdeps/x86_64/multiarch/strlen-evex512.S b/sysdeps/x86_64/multiarch/strlen-evex512.S
new file mode 100644
index 0000000000000000..116f8981c8954e2e
--- /dev/null
+++ b/sysdeps/x86_64/multiarch/strlen-evex512.S
@@ -0,0 +1,7 @@
+#ifndef STRLEN
+# define STRLEN __strlen_evex512
+#endif
+
+#define VEC_SIZE 64
+
+#include "strlen-evex-base.S"
diff --git a/sysdeps/x86_64/multiarch/strnlen-evex512.S b/sysdeps/x86_64/multiarch/strnlen-evex512.S
new file mode 100644
index 0000000000000000..0b7f220214a7c33c
--- /dev/null
+++ b/sysdeps/x86_64/multiarch/strnlen-evex512.S
@@ -0,0 +1,4 @@
+#define STRLEN __strnlen_evex512
+#define USE_AS_STRNLEN 1
+
+#include "strlen-evex512.S"
diff --git a/sysdeps/x86_64/multiarch/wcslen-evex512.S b/sysdeps/x86_64/multiarch/wcslen-evex512.S
new file mode 100644
index 0000000000000000..f59c372b78b4fb8c
--- /dev/null
+++ b/sysdeps/x86_64/multiarch/wcslen-evex512.S
@@ -0,0 +1,4 @@
+#define STRLEN __wcslen_evex512
+#define USE_AS_WCSLEN 1
+
+#include "strlen-evex512.S"
diff --git a/sysdeps/x86_64/multiarch/wcsnlen-evex512.S b/sysdeps/x86_64/multiarch/wcsnlen-evex512.S
new file mode 100644
index 0000000000000000..73dcf2f210a85aac
--- /dev/null
+++ b/sysdeps/x86_64/multiarch/wcsnlen-evex512.S
@@ -0,0 +1,5 @@
+#define STRLEN __wcsnlen_evex512
+#define USE_AS_WCSLEN 1
+#define USE_AS_STRNLEN 1
+
+#include "strlen-evex512.S"