commit eb9aa96facc5231e208de0946870f10c21aee9f3
Author: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date: Fri May 13 09:33:30 2022 -0300
x86_64: Remove bzero optimization
Both symbols are marked as legacy in POSIX.1-2001 and removed on
POSIX.1-2008, although the prototypes are defined for _GNU_SOURCE
or _DEFAULT_SOURCE.
GCC also replaces bcopy with a memmove and bzero with memset on default
configuration (to actually get a bzero libc call the code requires
to omit string.h inclusion and built with -fno-builtin), so it is
highly unlikely programs are actually calling libc bzero symbol.
On a recent Linux distro (Ubuntu 22.04), there is no bzero calls
by the installed binaries.
$ cat count_bstring.sh
#!/bin/bash
files=`IFS=':';for i in $PATH; do test -d "$i" && find "$i" -maxdepth 1 -executable -type f; done`
total=0
for file in $files; do
symbols=`objdump -R $file 2>&1`
if [ $? -eq 0 ]; then
ncalls=`echo $symbols | grep -w $1 | wc -l`
((total=total+ncalls))
if [ $ncalls -gt 0 ]; then
echo "$file: $ncalls"
fi
fi
done
echo "TOTAL=$total"
$ ./count_bstring.sh bzero
TOTAL=0
Checked on x86_64-linux-gnu.
(cherry picked from commit 9403b71ae97e3f1a91c796ddcbb4e6f044434734)
diff --git a/sysdeps/x86_64/bzero.S b/sysdeps/x86_64/bzero.S
deleted file mode 100644
index f96d567fd87696af..0000000000000000
--- a/sysdeps/x86_64/bzero.S
+++ /dev/null
@@ -1 +0,0 @@
-/* Implemented in memset.S. */
diff --git a/sysdeps/x86_64/memset.S b/sysdeps/x86_64/memset.S
index 0358210c7ff3a976..2b64741fd10a8ec2 100644
--- a/sysdeps/x86_64/memset.S
+++ b/sysdeps/x86_64/memset.S
@@ -1,4 +1,4 @@
-/* memset/bzero -- set memory area to CH/0
+/* memset -- set memory area to CH/0
Optimized version for x86-64.
Copyright (C) 2002-2021 Free Software Foundation, Inc.
This file is part of the GNU C Library.
@@ -35,9 +35,6 @@
punpcklwd %xmm0, %xmm0; \
pshufd $0, %xmm0, %xmm0
-# define BZERO_ZERO_VEC0() \
- pxor %xmm0, %xmm0
-
# define WMEMSET_SET_VEC0_AND_SET_RETURN(d, r) \
movd d, %xmm0; \
pshufd $0, %xmm0, %xmm0; \
@@ -56,10 +53,6 @@
# define MEMSET_SYMBOL(p,s) memset
#endif
-#ifndef BZERO_SYMBOL
-# define BZERO_SYMBOL(p,s) __bzero
-#endif
-
#ifndef WMEMSET_SYMBOL
# define WMEMSET_CHK_SYMBOL(p,s) p
# define WMEMSET_SYMBOL(p,s) __wmemset
@@ -70,7 +63,6 @@
libc_hidden_builtin_def (memset)
#if IS_IN (libc)
-weak_alias (__bzero, bzero)
libc_hidden_def (__wmemset)
weak_alias (__wmemset, wmemset)
libc_hidden_weak (wmemset)
diff --git a/sysdeps/x86_64/multiarch/Makefile b/sysdeps/x86_64/multiarch/Makefile
index b503e4b81e92a11c..67401162d526f664 100644
--- a/sysdeps/x86_64/multiarch/Makefile
+++ b/sysdeps/x86_64/multiarch/Makefile
@@ -1,7 +1,6 @@
ifeq ($(subdir),string)
sysdep_routines += \
- bzero \
memchr-avx2 \
memchr-avx2-rtm \
memchr-evex \
diff --git a/sysdeps/x86_64/multiarch/bzero.c b/sysdeps/x86_64/multiarch/bzero.c
deleted file mode 100644
index 13e399a9a1fbdeb2..0000000000000000
--- a/sysdeps/x86_64/multiarch/bzero.c
+++ /dev/null
@@ -1,108 +0,0 @@
-/* Multiple versions of bzero.
- All versions must be listed in ifunc-impl-list.c.
- 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/>. */
-
-/* Define multiple versions only for the definition in libc. */
-#if IS_IN (libc)
-# define __bzero __redirect___bzero
-# include <string.h>
-# undef __bzero
-
-/* OPTIMIZE1 definition required for bzero patch. */
-# define OPTIMIZE1(name) EVALUATOR1 (SYMBOL_NAME, name)
-# define SYMBOL_NAME __bzero
-# include <init-arch.h>
-
-extern __typeof (REDIRECT_NAME) OPTIMIZE1 (sse2_unaligned)
- attribute_hidden;
-extern __typeof (REDIRECT_NAME) OPTIMIZE1 (sse2_unaligned_erms)
- attribute_hidden;
-extern __typeof (REDIRECT_NAME) OPTIMIZE1 (avx2_unaligned) attribute_hidden;
-extern __typeof (REDIRECT_NAME) OPTIMIZE1 (avx2_unaligned_erms)
- attribute_hidden;
-extern __typeof (REDIRECT_NAME) OPTIMIZE1 (avx2_unaligned_rtm)
- attribute_hidden;
-extern __typeof (REDIRECT_NAME) OPTIMIZE1 (avx2_unaligned_erms_rtm)
- attribute_hidden;
-extern __typeof (REDIRECT_NAME) OPTIMIZE1 (evex_unaligned)
- attribute_hidden;
-extern __typeof (REDIRECT_NAME) OPTIMIZE1 (evex_unaligned_erms)
- attribute_hidden;
-extern __typeof (REDIRECT_NAME) OPTIMIZE1 (avx512_unaligned)
- attribute_hidden;
-extern __typeof (REDIRECT_NAME) OPTIMIZE1 (avx512_unaligned_erms)
- attribute_hidden;
-
-static inline void *
-IFUNC_SELECTOR (void)
-{
- const struct cpu_features* cpu_features = __get_cpu_features ();
-
- if (CPU_FEATURE_USABLE_P (cpu_features, AVX512F)
- && !CPU_FEATURES_ARCH_P (cpu_features, Prefer_No_AVX512))
- {
- if (CPU_FEATURE_USABLE_P (cpu_features, AVX512VL)
- && CPU_FEATURE_USABLE_P (cpu_features, AVX512BW)
- && CPU_FEATURE_USABLE_P (cpu_features, BMI2))
- {
- if (CPU_FEATURE_USABLE_P (cpu_features, ERMS))
- return OPTIMIZE1 (avx512_unaligned_erms);
-
- return OPTIMIZE1 (avx512_unaligned);
- }
- }
-
- if (CPU_FEATURE_USABLE_P (cpu_features, AVX2))
- {
- if (CPU_FEATURE_USABLE_P (cpu_features, AVX512VL)
- && CPU_FEATURE_USABLE_P (cpu_features, AVX512BW)
- && CPU_FEATURE_USABLE_P (cpu_features, BMI2))
- {
- if (CPU_FEATURE_USABLE_P (cpu_features, ERMS))
- return OPTIMIZE1 (evex_unaligned_erms);
-
- return OPTIMIZE1 (evex_unaligned);
- }
-
- if (CPU_FEATURE_USABLE_P (cpu_features, RTM))
- {
- if (CPU_FEATURE_USABLE_P (cpu_features, ERMS))
- return OPTIMIZE1 (avx2_unaligned_erms_rtm);
-
- return OPTIMIZE1 (avx2_unaligned_rtm);
- }
-
- if (!CPU_FEATURES_ARCH_P (cpu_features, Prefer_No_VZEROUPPER))
- {
- if (CPU_FEATURE_USABLE_P (cpu_features, ERMS))
- return OPTIMIZE1 (avx2_unaligned_erms);
-
- return OPTIMIZE1 (avx2_unaligned);
- }
- }
-
- if (CPU_FEATURE_USABLE_P (cpu_features, ERMS))
- return OPTIMIZE1 (sse2_unaligned_erms);
-
- return OPTIMIZE1 (sse2_unaligned);
-}
-
-libc_ifunc_redirected (__redirect___bzero, __bzero, IFUNC_SELECTOR ());
-
-weak_alias (__bzero, bzero)
-#endif
diff --git a/sysdeps/x86_64/multiarch/ifunc-impl-list.c b/sysdeps/x86_64/multiarch/ifunc-impl-list.c
index e5e48b36c3175e68..d990a7149489efd9 100644
--- a/sysdeps/x86_64/multiarch/ifunc-impl-list.c
+++ b/sysdeps/x86_64/multiarch/ifunc-impl-list.c
@@ -280,48 +280,6 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
__memset_avx512_no_vzeroupper)
)
- /* Support sysdeps/x86_64/multiarch/bzero.c. */
- IFUNC_IMPL (i, name, bzero,
- IFUNC_IMPL_ADD (array, i, bzero, 1,
- __bzero_sse2_unaligned)
- IFUNC_IMPL_ADD (array, i, bzero, 1,
- __bzero_sse2_unaligned_erms)
- IFUNC_IMPL_ADD (array, i, bzero,
- CPU_FEATURE_USABLE (AVX2),
- __bzero_avx2_unaligned)
- IFUNC_IMPL_ADD (array, i, bzero,
- CPU_FEATURE_USABLE (AVX2),
- __bzero_avx2_unaligned_erms)
- IFUNC_IMPL_ADD (array, i, bzero,
- (CPU_FEATURE_USABLE (AVX2)
- && CPU_FEATURE_USABLE (RTM)),
- __bzero_avx2_unaligned_rtm)
- IFUNC_IMPL_ADD (array, i, bzero,
- (CPU_FEATURE_USABLE (AVX2)
- && CPU_FEATURE_USABLE (RTM)),
- __bzero_avx2_unaligned_erms_rtm)
- IFUNC_IMPL_ADD (array, i, bzero,
- (CPU_FEATURE_USABLE (AVX512VL)
- && CPU_FEATURE_USABLE (AVX512BW)
- && CPU_FEATURE_USABLE (BMI2)),
- __bzero_evex_unaligned)
- IFUNC_IMPL_ADD (array, i, bzero,
- (CPU_FEATURE_USABLE (AVX512VL)
- && CPU_FEATURE_USABLE (AVX512BW)
- && CPU_FEATURE_USABLE (BMI2)),
- __bzero_evex_unaligned_erms)
- IFUNC_IMPL_ADD (array, i, bzero,
- (CPU_FEATURE_USABLE (AVX512VL)
- && CPU_FEATURE_USABLE (AVX512BW)
- && CPU_FEATURE_USABLE (BMI2)),
- __bzero_avx512_unaligned_erms)
- IFUNC_IMPL_ADD (array, i, bzero,
- (CPU_FEATURE_USABLE (AVX512VL)
- && CPU_FEATURE_USABLE (AVX512BW)
- && CPU_FEATURE_USABLE (BMI2)),
- __bzero_avx512_unaligned)
- )
-
/* Support sysdeps/x86_64/multiarch/rawmemchr.c. */
IFUNC_IMPL (i, name, rawmemchr,
IFUNC_IMPL_ADD (array, i, rawmemchr,
diff --git a/sysdeps/x86_64/multiarch/memset-avx2-unaligned-erms-rtm.S b/sysdeps/x86_64/multiarch/memset-avx2-unaligned-erms-rtm.S
index 5a5ee6f67299400b..8ac3e479bba488be 100644
--- a/sysdeps/x86_64/multiarch/memset-avx2-unaligned-erms-rtm.S
+++ b/sysdeps/x86_64/multiarch/memset-avx2-unaligned-erms-rtm.S
@@ -5,7 +5,6 @@
#define SECTION(p) p##.avx.rtm
#define MEMSET_SYMBOL(p,s) p##_avx2_##s##_rtm
-#define BZERO_SYMBOL(p,s) p##_avx2_##s##_rtm
#define WMEMSET_SYMBOL(p,s) p##_avx2_##s##_rtm
#include "memset-avx2-unaligned-erms.S"
diff --git a/sysdeps/x86_64/multiarch/memset-avx2-unaligned-erms.S b/sysdeps/x86_64/multiarch/memset-avx2-unaligned-erms.S
index a093a2831f3dfa0d..c0bf2875d03d51ab 100644
--- a/sysdeps/x86_64/multiarch/memset-avx2-unaligned-erms.S
+++ b/sysdeps/x86_64/multiarch/memset-avx2-unaligned-erms.S
@@ -14,9 +14,6 @@
vmovd d, %xmm0; \
movq r, %rax;
-# define BZERO_ZERO_VEC0() \
- vpxor %xmm0, %xmm0, %xmm0
-
# define WMEMSET_SET_VEC0_AND_SET_RETURN(d, r) \
MEMSET_SET_VEC0_AND_SET_RETURN(d, r)
@@ -32,9 +29,6 @@
# ifndef MEMSET_SYMBOL
# define MEMSET_SYMBOL(p,s) p##_avx2_##s
# endif
-# ifndef BZERO_SYMBOL
-# define BZERO_SYMBOL(p,s) p##_avx2_##s
-# endif
# ifndef WMEMSET_SYMBOL
# define WMEMSET_SYMBOL(p,s) p##_avx2_##s
# endif
diff --git a/sysdeps/x86_64/multiarch/memset-avx512-unaligned-erms.S b/sysdeps/x86_64/multiarch/memset-avx512-unaligned-erms.S
index 727c92133a15900f..5241216a77bf72b7 100644
--- a/sysdeps/x86_64/multiarch/memset-avx512-unaligned-erms.S
+++ b/sysdeps/x86_64/multiarch/memset-avx512-unaligned-erms.S
@@ -19,9 +19,6 @@
vpbroadcastb d, %VEC0; \
movq r, %rax
-# define BZERO_ZERO_VEC0() \
- vpxorq %XMM0, %XMM0, %XMM0
-
# define WMEMSET_SET_VEC0_AND_SET_RETURN(d, r) \
vpbroadcastd d, %VEC0; \
movq r, %rax
diff --git a/sysdeps/x86_64/multiarch/memset-evex-unaligned-erms.S b/sysdeps/x86_64/multiarch/memset-evex-unaligned-erms.S
index 5d8fa78f05476b10..637002150659123c 100644
--- a/sysdeps/x86_64/multiarch/memset-evex-unaligned-erms.S
+++ b/sysdeps/x86_64/multiarch/memset-evex-unaligned-erms.S
@@ -19,9 +19,6 @@
vpbroadcastb d, %VEC0; \
movq r, %rax
-# define BZERO_ZERO_VEC0() \
- vpxorq %XMM0, %XMM0, %XMM0
-
# define WMEMSET_SET_VEC0_AND_SET_RETURN(d, r) \
vpbroadcastd d, %VEC0; \
movq r, %rax
diff --git a/sysdeps/x86_64/multiarch/memset-sse2-unaligned-erms.S b/sysdeps/x86_64/multiarch/memset-sse2-unaligned-erms.S
index 2951f7f5f70e274a..c47f3a9c955508a2 100644
--- a/sysdeps/x86_64/multiarch/memset-sse2-unaligned-erms.S
+++ b/sysdeps/x86_64/multiarch/memset-sse2-unaligned-erms.S
@@ -22,7 +22,6 @@
#if IS_IN (libc)
# define MEMSET_SYMBOL(p,s) p##_sse2_##s
-# define BZERO_SYMBOL(p,s) MEMSET_SYMBOL (p, s)
# define WMEMSET_SYMBOL(p,s) p##_sse2_##s
# ifdef SHARED
diff --git a/sysdeps/x86_64/multiarch/memset-vec-unaligned-erms.S b/sysdeps/x86_64/multiarch/memset-vec-unaligned-erms.S
index d9c577fb5ff9700f..abc12d9cda1b3843 100644
--- a/sysdeps/x86_64/multiarch/memset-vec-unaligned-erms.S
+++ b/sysdeps/x86_64/multiarch/memset-vec-unaligned-erms.S
@@ -1,5 +1,5 @@
-/* memset/bzero with unaligned store and rep stosb
- Copyright (C) 2016-2021 Free Software Foundation, Inc.
+/* memset with unaligned store and rep stosb
+ Copyright (C) 2016-2022 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
@@ -26,10 +26,6 @@
#include <sysdep.h>
-#ifndef BZERO_SYMBOL
-# define BZERO_SYMBOL(p,s) MEMSET_SYMBOL (p, s)
-#endif
-
#ifndef MEMSET_CHK_SYMBOL
# define MEMSET_CHK_SYMBOL(p,s) MEMSET_SYMBOL(p, s)
#endif
@@ -134,31 +130,6 @@ ENTRY (WMEMSET_SYMBOL (__wmemset, unaligned))
END (WMEMSET_SYMBOL (__wmemset, unaligned))
#endif
-ENTRY (BZERO_SYMBOL(__bzero, unaligned))
-#if VEC_SIZE > 16
- BZERO_ZERO_VEC0 ()
-#endif
- mov %RDI_LP, %RAX_LP
- mov %RSI_LP, %RDX_LP
-#ifndef USE_LESS_VEC_MASK_STORE
- xorl %esi, %esi
-#endif
- cmp $VEC_SIZE, %RDX_LP
- jb L(less_vec_no_vdup)
-#ifdef USE_LESS_VEC_MASK_STORE
- xorl %esi, %esi
-#endif
-#if VEC_SIZE <= 16
- BZERO_ZERO_VEC0 ()
-#endif
- cmp $(VEC_SIZE * 2), %RDX_LP
- ja L(more_2x_vec)
- /* From VEC and to 2 * VEC. No branch when size == VEC_SIZE. */
- VMOVU %VEC(0), (%rdi)
- VMOVU %VEC(0), (VEC_SIZE * -1)(%rdi, %rdx)
- VZEROUPPER_RETURN
-END (BZERO_SYMBOL(__bzero, unaligned))
-
#if defined SHARED && IS_IN (libc)
ENTRY_CHK (MEMSET_CHK_SYMBOL (__memset_chk, unaligned))
cmp %RDX_LP, %RCX_LP
@@ -216,31 +187,6 @@ END (__memset_erms)
END (MEMSET_SYMBOL (__memset, erms))
# endif
-ENTRY_P2ALIGN (BZERO_SYMBOL(__bzero, unaligned_erms), 6)
-# if VEC_SIZE > 16
- BZERO_ZERO_VEC0 ()
-# endif
- mov %RDI_LP, %RAX_LP
- mov %RSI_LP, %RDX_LP
-# ifndef USE_LESS_VEC_MASK_STORE
- xorl %esi, %esi
-# endif
- cmp $VEC_SIZE, %RDX_LP
- jb L(less_vec_no_vdup)
-# ifdef USE_LESS_VEC_MASK_STORE
- xorl %esi, %esi
-# endif
-# if VEC_SIZE <= 16
- BZERO_ZERO_VEC0 ()
-# endif
- cmp $(VEC_SIZE * 2), %RDX_LP
- ja L(stosb_more_2x_vec)
- /* From VEC and to 2 * VEC. No branch when size == VEC_SIZE. */
- VMOVU %VEC(0), (%rdi)
- VMOVU %VEC(0), (VEC_SIZE * -1)(%rdi, %rdx)
- VZEROUPPER_RETURN
-END (BZERO_SYMBOL(__bzero, unaligned_erms))
-
# if defined SHARED && IS_IN (libc)
ENTRY_CHK (MEMSET_CHK_SYMBOL (__memset_chk, unaligned_erms))
cmp %RDX_LP, %RCX_LP
@@ -282,7 +228,6 @@ L(last_2x_vec):
#ifdef USE_LESS_VEC_MASK_STORE
.p2align 4,, 10
L(less_vec):
-L(less_vec_no_vdup):
L(less_vec_from_wmemset):
/* Less than 1 VEC. */
# if VEC_SIZE != 16 && VEC_SIZE != 32 && VEC_SIZE != 64
@@ -430,9 +375,6 @@ L(less_vec):
xmm). This is only does anything for AVX2. */
MEMSET_VDUP_TO_VEC0_LOW ()
L(less_vec_from_wmemset):
-#if VEC_SIZE > 16
-L(less_vec_no_vdup):
-#endif
#endif
L(cross_page):
#if VEC_SIZE > 32
@@ -445,9 +387,6 @@ L(cross_page):
#endif
#ifndef USE_XMM_LESS_VEC
MOVQ %XMM0, %SET_REG64
-#endif
-#if VEC_SIZE <= 16
-L(less_vec_no_vdup):
#endif
cmpl $8, %edx
jge L(between_8_15)