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Re: [PATCH] Remove Prefer_SSE_for_memop on x64
- From: Dmitrieva Liubov <liubov dot dmitrieva at gmail dot com>
- To: Ondřej Bílka <neleai at seznam dot cz>
- Cc: libc-alpha at sourceware dot org
- Date: Thu, 7 Mar 2013 12:59:57 +0400
- Subject: Re: [PATCH] Remove Prefer_SSE_for_memop on x64
- References: <20130214213001.GA11656@domone.kolej.mff.cuni.cz><CAHjhQ933bsxCLVv+3ppr_u7YyeRztvHtDUwyhQBsQOPCrrThfQ@mail.gmail.com>
This is an important cleanup. Maintainers, please don't leave it
without attention.
There is unnecessary extra check of sse support, but actually sse
version is always chosen on x86_64.
--
Liubov Dmitrieva
Intel Corporation
2013/2/15 Dmitrieva Liubov <liubov.dmitrieva@gmail.com>:
> Looks good to me.
>
> But I would add a sentence more after "Update" in the Change Log
> entries to clarify what is the update about...
>
> --
> Liubov Dmitrieva
> Intel Corporation
>
>
> 2013/2/15 OndÅej BÃlka <neleai@seznam.cz>:
>> Hello,
>> As I asked in
>> http://www.sourceware.org/ml/libc-alpha/2013-02/msg00203.html
>> nobody objected to keep non-sse memset on x64.
>>
>> This patch removes that implementation and flag Prefer_SSE_for_memop
>> which is always set and only choose sse memset over nonsse one.
>>
>> 2013-02-14 OndÅej BÃlka <neleai@seznam.cz>
>>
>> * sysdeps/x86_64/memset.S: Always define bcopy.
>> * sysdeps/x86_64/multiarch/Makefile: Update.
>> * sysdeps/x86_64/multiarch/ifunc-impl-list.c: Update.
>> * sysdeps/x86_64/multiarch/init-arch.c: Remove Prefer_SSE_for_memop.
>> * sysdeps/x86_64/multiarch/init-arch.h: Likewise.
>> * sysdeps/x86_64/multiarch/bzero.S: Remove.
>> * sysdeps/x86_64/multiarch/memset-x86-64.S: Likewise.
>> * sysdeps/x86_64/multiarch/memset.S: Likewise.
>> * sysdeps/x86_64/multiarch/memset_chk.S: Likewise.
>>
>> ---
>> sysdeps/x86_64/memset.S | 2 +-
>> sysdeps/x86_64/multiarch/Makefile | 2 +-
>> sysdeps/x86_64/multiarch/bzero.S | 28 ----------
>> sysdeps/x86_64/multiarch/ifunc-impl-list.c | 11 ----
>> sysdeps/x86_64/multiarch/init-arch.c | 11 ----
>> sysdeps/x86_64/multiarch/init-arch.h | 4 --
>> sysdeps/x86_64/multiarch/memset-x86-64.S | 19 -------
>> sysdeps/x86_64/multiarch/memset.S | 79 ----------------------------
>> sysdeps/x86_64/multiarch/memset_chk.S | 44 ---------------
>> 9 files changed, 2 insertions(+), 198 deletions(-)
>> delete mode 100644 sysdeps/x86_64/multiarch/bzero.S
>> delete mode 100644 sysdeps/x86_64/multiarch/memset-x86-64.S
>> delete mode 100644 sysdeps/x86_64/multiarch/memset.S
>> delete mode 100644 sysdeps/x86_64/multiarch/memset_chk.S
>>
>> diff --git a/sysdeps/x86_64/memset.S b/sysdeps/x86_64/memset.S
>> index f3a4d44..b393efe 100644
>> --- a/sysdeps/x86_64/memset.S
>> +++ b/sysdeps/x86_64/memset.S
>> @@ -23,7 +23,7 @@
>> #define __STOS_UPPER_BOUNDARY $65536
>>
>> .text
>> -#if !defined NOT_IN_libc && !defined USE_MULTIARCH
>> +#if !defined NOT_IN_libc
>> ENTRY(__bzero)
>> mov %rsi,%rdx /* Adjust parameter. */
>> xorl %esi,%esi /* Fill with 0s. */
>> diff --git a/sysdeps/x86_64/multiarch/Makefile b/sysdeps/x86_64/multiarch/Makefile
>> index dd6c27d..4f7c070 100644
>> --- a/sysdeps/x86_64/multiarch/Makefile
>> +++ b/sysdeps/x86_64/multiarch/Makefile
>> @@ -10,7 +10,7 @@ sysdep_routines += strncat-c stpncpy-c strncpy-c strcmp-ssse3 strncmp-ssse3 \
>> strend-sse4 memcmp-sse4 memcpy-ssse3 mempcpy-ssse3 \
>> memmove-ssse3 memcpy-ssse3-back mempcpy-ssse3-back \
>> memmove-ssse3-back strcasestr-nonascii strcasecmp_l-ssse3 \
>> - strncase_l-ssse3 strlen-sse4 strlen-sse2-no-bsf memset-x86-64 \
>> + strncase_l-ssse3 strlen-sse4 strlen-sse2-no-bsf \
>> strcpy-ssse3 strncpy-ssse3 stpcpy-ssse3 stpncpy-ssse3 \
>> strcpy-sse2-unaligned strncpy-sse2-unaligned \
>> stpcpy-sse2-unaligned stpncpy-sse2-unaligned \
>> diff --git a/sysdeps/x86_64/multiarch/bzero.S b/sysdeps/x86_64/multiarch/bzero.S
>> deleted file mode 100644
>> index 88e96ea..0000000
>> --- a/sysdeps/x86_64/multiarch/bzero.S
>> +++ /dev/null
>> @@ -1,28 +0,0 @@
>> -/* bzero. x86-64 version.
>> - Copyright (C) 2010-2013 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/>. */
>> -
>> -#include <sysdep.h>
>> -#include <init-arch.h>
>> -
>> - .text
>> -ENTRY(__bzero)
>> - mov %rsi,%rdx /* Adjust parameter. */
>> - xorl %esi,%esi /* Fill with 0s. */
>> - jmp __libc_memset /* Branch to IFUNC memset. */
>> -END(__bzero)
>> -weak_alias (__bzero, bzero)
>> diff --git a/sysdeps/x86_64/multiarch/ifunc-impl-list.c b/sysdeps/x86_64/multiarch/ifunc-impl-list.c
>> index 643cb2d..cb4aba3 100644
>> --- a/sysdeps/x86_64/multiarch/ifunc-impl-list.c
>> +++ b/sysdeps/x86_64/multiarch/ifunc-impl-list.c
>> @@ -61,17 +61,6 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
>> __memmove_ssse3)
>> IFUNC_IMPL_ADD (array, i, memmove, 1, __memmove_sse2))
>>
>> - /* Support sysdeps/x86_64/multiarch/memset_chk.S. */
>> - IFUNC_IMPL (i, name, __memset_chk,
>> - IFUNC_IMPL_ADD (array, i, __memset_chk, 1, __memset_chk_sse2)
>> - IFUNC_IMPL_ADD (array, i, __memset_chk, 1,
>> - __memset_chk_x86_64))
>> -
>> - /* Support sysdeps/x86_64/multiarch/memset.S. */
>> - IFUNC_IMPL (i, name, memset,
>> - IFUNC_IMPL_ADD (array, i, memset, 1, __memset_sse2)
>> - IFUNC_IMPL_ADD (array, i, memset, 1, __memset_x86_64))
>> -
>> /* Support sysdeps/x86_64/multiarch/rawmemchr.S. */
>> IFUNC_IMPL (i, name, rawmemchr,
>> IFUNC_IMPL_ADD (array, i, rawmemchr, HAS_SSE4_2,
>> diff --git a/sysdeps/x86_64/multiarch/init-arch.c b/sysdeps/x86_64/multiarch/init-arch.c
>> index 992cbfb..7daaf46 100644
>> --- a/sysdeps/x86_64/multiarch/init-arch.c
>> +++ b/sysdeps/x86_64/multiarch/init-arch.c
>> @@ -58,11 +58,6 @@ __init_cpu_features (void)
>>
>> get_common_indeces (&family, &model);
>>
>> - /* Intel processors prefer SSE instruction for memory/string
>> - routines if they are available. */
>> - __cpu_features.feature[index_Prefer_SSE_for_memop]
>> - |= bit_Prefer_SSE_for_memop;
>> -
>> unsigned int eax = __cpu_features.cpuid[COMMON_CPUID_INDEX_1].eax;
>> unsigned int extended_family = (eax >> 20) & 0xff;
>> unsigned int extended_model = (eax >> 12) & 0xf0;
>> @@ -125,12 +120,6 @@ __init_cpu_features (void)
>>
>> ecx = __cpu_features.cpuid[COMMON_CPUID_INDEX_1].ecx;
>>
>> - /* AMD processors prefer SSE instructions for memory/string routines
>> - if they are available, otherwise they prefer integer instructions. */
>> - if ((ecx & 0x200))
>> - __cpu_features.feature[index_Prefer_SSE_for_memop]
>> - |= bit_Prefer_SSE_for_memop;
>> -
>> unsigned int eax;
>> __cpuid (0x80000000, eax, ebx, ecx, edx);
>> if (eax >= 0x80000001)
>> diff --git a/sysdeps/x86_64/multiarch/init-arch.h b/sysdeps/x86_64/multiarch/init-arch.h
>> index 0aece18..28edbf7 100644
>> --- a/sysdeps/x86_64/multiarch/init-arch.h
>> +++ b/sysdeps/x86_64/multiarch/init-arch.h
>> @@ -18,7 +18,6 @@
>> #define bit_Fast_Rep_String (1 << 0)
>> #define bit_Fast_Copy_Backward (1 << 1)
>> #define bit_Slow_BSF (1 << 2)
>> -#define bit_Prefer_SSE_for_memop (1 << 3)
>> #define bit_Fast_Unaligned_Load (1 << 4)
>> #define bit_Prefer_PMINUB_for_stringop (1 << 5)
>> #define bit_AVX_Usable (1 << 6)
>> @@ -58,7 +57,6 @@
>> # define index_Fast_Rep_String FEATURE_INDEX_1*FEATURE_SIZE
>> # define index_Fast_Copy_Backward FEATURE_INDEX_1*FEATURE_SIZE
>> # define index_Slow_BSF FEATURE_INDEX_1*FEATURE_SIZE
>> -# define index_Prefer_SSE_for_memop FEATURE_INDEX_1*FEATURE_SIZE
>> # define index_Fast_Unaligned_Load FEATURE_INDEX_1*FEATURE_SIZE
>> # define index_Prefer_PMINUB_for_stringop FEATURE_INDEX_1*FEATURE_SIZE
>> # define index_AVX_Usable FEATURE_INDEX_1*FEATURE_SIZE
>> @@ -157,7 +155,6 @@ extern const struct cpu_features *__get_cpu_features (void)
>> # define index_Fast_Rep_String FEATURE_INDEX_1
>> # define index_Fast_Copy_Backward FEATURE_INDEX_1
>> # define index_Slow_BSF FEATURE_INDEX_1
>> -# define index_Prefer_SSE_for_memop FEATURE_INDEX_1
>> # define index_Fast_Unaligned_Load FEATURE_INDEX_1
>> # define index_AVX_Usable FEATURE_INDEX_1
>> # define index_FMA_Usable FEATURE_INDEX_1
>> @@ -169,7 +166,6 @@ extern const struct cpu_features *__get_cpu_features (void)
>> # define HAS_FAST_REP_STRING HAS_ARCH_FEATURE (Fast_Rep_String)
>> # define HAS_FAST_COPY_BACKWARD HAS_ARCH_FEATURE (Fast_Copy_Backward)
>> # define HAS_SLOW_BSF HAS_ARCH_FEATURE (Slow_BSF)
>> -# define HAS_PREFER_SSE_FOR_MEMOP HAS_ARCH_FEATURE (Prefer_SSE_for_memop)
>> # define HAS_FAST_UNALIGNED_LOAD HAS_ARCH_FEATURE (Fast_Unaligned_Load)
>> # define HAS_AVX HAS_ARCH_FEATURE (AVX_Usable)
>> # define HAS_FMA HAS_ARCH_FEATURE (FMA_Usable)
>> diff --git a/sysdeps/x86_64/multiarch/memset-x86-64.S b/sysdeps/x86_64/multiarch/memset-x86-64.S
>> deleted file mode 100644
>> index 551d105..0000000
>> --- a/sysdeps/x86_64/multiarch/memset-x86-64.S
>> +++ /dev/null
>> @@ -1,19 +0,0 @@
>> -#include <sysdep.h>
>> -
>> -#ifndef NOT_IN_libc
>> -# undef ENTRY_CHK
>> -# define ENTRY_CHK(name) \
>> - .type __memset_chk_x86_64, @function; \
>> - .globl __memset_chk_x86_64; \
>> - .p2align 4; \
>> - __memset_chk_x86_64: cfi_startproc; \
>> - CALL_MCOUNT
>> -# undef END_CHK
>> -# define END_CHK(name) \
>> - cfi_endproc; .size __memset_chk_x86_64, .-__memset_chk_x86_64
>> -
>> -# undef libc_hidden_builtin_def
>> -# define libc_hidden_builtin_def(name)
>> -# define memset __memset_x86_64
>> -# include "../memset.S"
>> -#endif
>> diff --git a/sysdeps/x86_64/multiarch/memset.S b/sysdeps/x86_64/multiarch/memset.S
>> deleted file mode 100644
>> index 7f673fa..0000000
>> --- a/sysdeps/x86_64/multiarch/memset.S
>> +++ /dev/null
>> @@ -1,79 +0,0 @@
>> -/* Multiple versions of memset
>> - All versions must be listed in ifunc-impl-list.c.
>> - Copyright (C) 2010-2013 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/>. */
>> -
>> -#include <sysdep.h>
>> -#include <init-arch.h>
>> -
>> -/* Define multiple versions only for the definition in lib. */
>> -#ifndef NOT_IN_libc
>> -ENTRY(memset)
>> - .type memset, @gnu_indirect_function
>> - cmpl $0, __cpu_features+KIND_OFFSET(%rip)
>> - jne 1f
>> - call __init_cpu_features
>> -1: leaq __memset_x86_64(%rip), %rax
>> - testl $bit_Prefer_SSE_for_memop, __cpu_features+FEATURE_OFFSET+index_Prefer_SSE_for_memop(%rip)
>> - jz 2f
>> - leaq __memset_sse2(%rip), %rax
>> -2: ret
>> -END(memset)
>> -
>> -/* Define internal IFUNC memset for bzero. */
>> - .globl __libc_memset
>> - .hidden __libc_memset
>> - __libc_memset = memset
>> -
>> -# define USE_SSE2 1
>> -
>> -# undef ENTRY
>> -# define ENTRY(name) \
>> - .type __memset_sse2, @function; \
>> - .globl __memset_sse2; \
>> - .p2align 4; \
>> - __memset_sse2: cfi_startproc; \
>> - CALL_MCOUNT
>> -# undef END
>> -# define END(name) \
>> - cfi_endproc; .size __memset_sse2, .-__memset_sse2
>> -
>> -# undef ENTRY_CHK
>> -# define ENTRY_CHK(name) \
>> - .type __memset_chk_sse2, @function; \
>> - .globl __memset_chk_sse2; \
>> - .p2align 4; \
>> - __memset_chk_sse2: cfi_startproc; \
>> - CALL_MCOUNT
>> -# undef END_CHK
>> -# define END_CHK(name) \
>> - cfi_endproc; .size __memset_chk_sse2, .-__memset_chk_sse2
>> -
>> -# ifdef SHARED
>> -# undef libc_hidden_builtin_def
>> -/* It doesn't make sense to send libc-internal memset calls through a PLT.
>> - The speedup we get from using GPR instruction is likely eaten away
>> - by the indirect call in the PLT. */
>> -# define libc_hidden_builtin_def(name) \
>> - .globl __GI_memset; __GI_memset = __memset_sse2
>> -# endif
>> -
>> -# undef strong_alias
>> -# define strong_alias(original, alias)
>> -#endif
>> -
>> -#include "../memset.S"
>> diff --git a/sysdeps/x86_64/multiarch/memset_chk.S b/sysdeps/x86_64/multiarch/memset_chk.S
>> deleted file mode 100644
>> index 55e2635..0000000
>> --- a/sysdeps/x86_64/multiarch/memset_chk.S
>> +++ /dev/null
>> @@ -1,44 +0,0 @@
>> -/* Multiple versions of __memset_chk
>> - All versions must be listed in ifunc-impl-list.c.
>> - Copyright (C) 2010-2013 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/>. */
>> -
>> -#include <sysdep.h>
>> -#include <init-arch.h>
>> -
>> -/* Define multiple versions only for the definition in lib. */
>> -#ifndef NOT_IN_libc
>> -# ifdef SHARED
>> -ENTRY(__memset_chk)
>> - .type __memset_chk, @gnu_indirect_function
>> - cmpl $0, __cpu_features+KIND_OFFSET(%rip)
>> - jne 1f
>> - call __init_cpu_features
>> -1: leaq __memset_chk_x86_64(%rip), %rax
>> - testl $bit_Prefer_SSE_for_memop, __cpu_features+FEATURE_OFFSET+index_Prefer_SSE_for_memop(%rip)
>> - jz 2f
>> - leaq __memset_chk_sse2(%rip), %rax
>> -2: ret
>> -END(__memset_chk)
>> -
>> -strong_alias (__memset_chk, __memset_zero_constant_len_parameter)
>> - .section .gnu.warning.__memset_zero_constant_len_parameter
>> - .string "memset used with constant zero length parameter; this could be due to transposed parameters"
>> -# else
>> -# include "../memset_chk.S"
>> -# endif
>> -#endif
>> --
>> 1.7.4.4
>>