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Re: RFC: Rewrite x86-64 IFUNC selector in C
On 28/05/2017 13:26, H.J. Lu wrote:
> On Thu, May 25, 2017 at 2:55 PM, Adhemerval Zanella
> <adhemerval.zanella@linaro.org> wrote:
>>
>>
>> On 25/05/2017 18:38, H.J. Lu wrote:
>>> On Thu, May 25, 2017 at 2:25 PM, Erich Elsen <eriche@google.com> wrote:
>>>> Ok, I'll get started then.
>>>>
>>>> Are there any general comments about the attached conversion for
>>>> memcpy? Just so I don't repeat the same wrong thing many times.
>>>
>>> You missed:
>>>
>>> /* Define multiple versions only for the definition in lib and for
>>> DSO. In static binaries we need memcpy before the initialization
>>> happened. */
>>> #if defined SHARED && IS_IN (libc)
>>>
>>> +typedef void * (*memcpy_fn)(void *, const void *, size_t);
>>> +
>>> +extern void * __memcpy_erms(void *dest, const void *src, size_t n);
>>> +extern void * __memcpy_sse2_unaligned(void *dest, const void *src, size_t n);
>>> +extern void * __memcpy_sse2_unaligned_erms(void *dest, const void
>>> *src, size_t n);
>>> +extern void * __memcpy_ssse3(void *dest, const void *src, size_t n);
>>> +extern void * __memcpy_ssse3_back(void *dest, const void *src, size_t n);
>>> +extern void * __memcpy_avx_unaligned(void *dest, const void *src, size_t n);
>>> +extern void * __memcpy_avx_unaligned_erms(void *dest, const void
>>> *src, size_t n);
>>> +extern void * __memcpy_avx512_unaligned(void *dest, const void *src, size_t n);
>>> +extern void * __memcpy_avx512_unaligned_erms(void *dest, const void
>>> *src, size_t n);
>>>
>>> Please use something similar to multiarch/strstr.c:
>>>
>>> /* Redefine strstr so that the compiler won't complain about the type
>>> mismatch with the IFUNC selector in strong_alias, below. */
>>> #undef strstr
>>> #define strstr __redirect_strstr
>>> #include <string.h>
>>> #undef strstr
>>> ...
>>> extern __typeof (__redirect_strstr) __strstr_sse2 attribute_hidden;
>>>
>>> +/* Defined in cacheinfo.c */
>>> +extern long int __x86_shared_cache_size attribute_hidden;
>>> +extern long int __x86_shared_cache_size_half attribute_hidden;
>>> +extern long int __x86_data_cache_size attribute_hidden;
>>> +extern long int __x86_data_cache_size_half attribute_hidden;
>>> +extern long int __x86_shared_non_temporal_threshold attribute_hidden;
>>
>> It seems it will be used not only for memcpy, so I would suggest to add
>> on a common header on multiarch.
>>
>>>
>>> Remove them.
>>> static void * select_memcpy_impl(void) {
>>> + const struct cpu_features* cpu_features_struct_p = __get_cpu_features ();
>>> +
>>> + if (CPU_FEATURES_ARCH_P(cpu_features_struct_p, Prefer_ERMS)) {
>>> + return __memcpy_erms;
>>> + }
>>> +
>>> + if (CPU_FEATURES_ARCH_P(cpu_features_struct_p, AVX512F_Usable)) {
>>> + if (CPU_FEATURES_ARCH_P(cpu_features_struct_p, Prefer_No_VZEROUPPER))
>>> + return __memcpy_avx512_unaligned_erms;
>>> + return __memcpy_avx512_unaligned;
>>> + }
>>> +
>>> + if (CPU_FEATURES_ARCH_P(cpu_features_struct_p, AVX_Fast_Unaligned_Load)) {
>>> + if (CPU_FEATURES_CPU_P(cpu_features_struct_p, ERMS)) {
>>> + return __memcpy_avx_unaligned_erms;
>>> +
>>> + }
>>> + return __memcpy_avx_unaligned;
>>> + }
>>> + else {
>>> + if (CPU_FEATURES_ARCH_P(cpu_features_struct_p, Fast_Unaligned_Copy)) {
>>> + if (CPU_FEATURES_CPU_P(cpu_features_struct_p, ERMS)) {
>>> + return __memcpy_sse2_unaligned_erms;
>>> +
>>> + }
>>> + return __memcpy_sse2_unaligned;
>>> + }
>>> + else {
>>> + if (!CPU_FEATURES_CPU_P(cpu_features_struct_p, SSSE3)) {
>>> + return __memcpy_sse2_unaligned;
>>> +
>>> + }
>>> + if (CPU_FEATURES_ARCH_P(cpu_features_struct_p, Fast_Copy_Backward)) {
>>> + return __memcpy_ssse3_back;
>>> +
>>> + }
>>> + return __memcpy_ssse3;
>>> + }
>>> + }
>>> +}
>>>
>>> Please
>>>
>>> 1. Fix formatting.
>>> 2. Remove unnecessary {}.
>>> 3. Don't use "else".
>>>
>>> +void *__new_memcpy(void *dest, const void *src, size_t n)
>>> + __attribute__ ((ifunc ("select_memcpy_impl")));
>>>
>>> Use "typeof" here.
>>
>> We have the libc_ifunc{_redirect} to handle the __attribute__ ((ifunc)) support
>> from compiler. I think you can use:
>>
>> # include <string.h>
>>
>> // extern __typeof (memcpy) __memcpy_<each supported one> attribute_hidden;
>>
>> static void *memcpy_selector (void)
>> {
>> // fill me.
>> }
>>
>> libc_ifunc_hidden (memcpy, memcpy, memcpy_selector);
>> libc_hidden_def (memcpy)
>
> Here is my take. It only covers memcpy and mempcpy. Please
> extend it to memmove as well as *_chk functions.
>
I think we can simplify it further and use the already existent ifunc macros on
libc-symbols.h. Also, for memmove I think we can organize the code better (at
least for ifunc) and build a extra object with a more meaningful name. I used
your logic for the ifunc selection and extended for memmove as well.
diff --git a/sysdeps/x86_64/multiarch/Makefile b/sysdeps/x86_64/multiarch/Makefile
index 3736f54..b6179aa 100644
--- a/sysdeps/x86_64/multiarch/Makefile
+++ b/sysdeps/x86_64/multiarch/Makefile
@@ -7,6 +7,7 @@ ifeq ($(subdir),string)
sysdep_routines += strncat-c stpncpy-c strncpy-c strcmp-ssse3 \
strcmp-sse2-unaligned strncmp-ssse3 \
memcmp-sse4 memcpy-ssse3 \
+ mem-impls \
memmove-ssse3 \
memcpy-ssse3-back \
memmove-ssse3-back \
diff --git a/sysdeps/x86_64/multiarch/memmove.S b/sysdeps/x86_64/multiarch/mem-impls.S
similarity index 52%
rename from sysdeps/x86_64/multiarch/memmove.S
rename to sysdeps/x86_64/multiarch/mem-impls.S
index 8c534e8..5e74fa0 100644
--- a/sysdeps/x86_64/multiarch/memmove.S
+++ b/sysdeps/x86_64/multiarch/mem-impls.S
@@ -1,6 +1,5 @@
-/* Multiple versions of memmove
- All versions must be listed in ifunc-impl-list.c.
- Copyright (C) 2016-2017 Free Software Foundation, Inc.
+/* Multiple versions of memmove, memcpy, and mempcpy.
+ 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
@@ -17,57 +16,6 @@
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 and for
- DSO. */
-#if IS_IN (libc)
- .text
-ENTRY(__libc_memmove)
- .type __libc_memmove, @gnu_indirect_function
- LOAD_RTLD_GLOBAL_RO_RDX
- lea __memmove_erms(%rip), %RAX_LP
- HAS_ARCH_FEATURE (Prefer_ERMS)
- jnz 2f
- HAS_ARCH_FEATURE (Prefer_No_AVX512)
- jnz 1f
- HAS_ARCH_FEATURE (AVX512F_Usable)
- jz 1f
- lea __memmove_avx512_no_vzeroupper(%rip), %RAX_LP
- HAS_ARCH_FEATURE (Prefer_No_VZEROUPPER)
- jnz 2f
- lea __memmove_avx512_unaligned_erms(%rip), %RAX_LP
- HAS_CPU_FEATURE (ERMS)
- jnz 2f
- lea __memmove_avx512_unaligned(%rip), %RAX_LP
- ret
-1: lea __memmove_avx_unaligned(%rip), %RAX_LP
- HAS_ARCH_FEATURE (AVX_Fast_Unaligned_Load)
- jz L(Fast_Unaligned_Load)
- HAS_CPU_FEATURE (ERMS)
- jz 2f
- lea __memmove_avx_unaligned_erms(%rip), %RAX_LP
- ret
-L(Fast_Unaligned_Load):
- lea __memmove_sse2_unaligned(%rip), %RAX_LP
- HAS_ARCH_FEATURE (Fast_Unaligned_Copy)
- jz L(SSSE3)
- HAS_CPU_FEATURE (ERMS)
- jz 2f
- lea __memmove_sse2_unaligned_erms(%rip), %RAX_LP
- ret
-L(SSSE3):
- HAS_CPU_FEATURE (SSSE3)
- jz 2f
- lea __memmove_ssse3_back(%rip), %RAX_LP
- HAS_ARCH_FEATURE (Fast_Copy_Backward)
- jnz 2f
- lea __memmove_ssse3(%rip), %RAX_LP
-2: ret
-END(__libc_memmove)
-#endif
-
#if IS_IN (libc)
# define MEMMOVE_SYMBOL(p,s) p##_sse2_##s
@@ -82,15 +30,16 @@ libc_hidden_ver (__mempcpy_sse2_unaligned, __mempcpy)
The speedup we get from using SSE2 instructions is likely eaten away
by the indirect call in the PLT. */
# define libc_hidden_builtin_def
+# else
+strong_alias (__memmove_sse2_unaligned, memmove)
# endif
-strong_alias (__libc_memmove, memmove)
#endif
#if !defined SHARED || !IS_IN (libc)
weak_alias (__mempcpy, mempcpy)
#endif
-#include "../memmove.S"
+#include <sysdeps/x86_64/memmove.S>
#if defined SHARED && IS_IN (libc)
# include <shlib-compat.h>
diff --git a/sysdeps/x86_64/multiarch/memcpy.S b/sysdeps/x86_64/multiarch/memcpy.S
deleted file mode 100644
index af27703..0000000
--- a/sysdeps/x86_64/multiarch/memcpy.S
+++ /dev/null
@@ -1,75 +0,0 @@
-/* Multiple versions of memcpy
- All versions must be listed in ifunc-impl-list.c.
- Copyright (C) 2010-2017 Free Software Foundation, Inc.
- Contributed by Intel Corporation.
- 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 and for
- DSO. In static binaries we need memcpy before the initialization
- happened. */
-#if defined SHARED && IS_IN (libc)
- .text
-ENTRY(__new_memcpy)
- .type __new_memcpy, @gnu_indirect_function
- LOAD_RTLD_GLOBAL_RO_RDX
- lea __memcpy_erms(%rip), %RAX_LP
- HAS_ARCH_FEATURE (Prefer_ERMS)
- jnz 2f
- HAS_ARCH_FEATURE (Prefer_No_AVX512)
- jnz 1f
- HAS_ARCH_FEATURE (AVX512F_Usable)
- jz 1f
- lea __memcpy_avx512_no_vzeroupper(%rip), %RAX_LP
- HAS_ARCH_FEATURE (Prefer_No_VZEROUPPER)
- jnz 2f
- lea __memcpy_avx512_unaligned_erms(%rip), %RAX_LP
- HAS_CPU_FEATURE (ERMS)
- jnz 2f
- lea __memcpy_avx512_unaligned(%rip), %RAX_LP
- ret
-1: lea __memcpy_avx_unaligned(%rip), %RAX_LP
- HAS_ARCH_FEATURE (AVX_Fast_Unaligned_Load)
- jz L(Fast_Unaligned_Load)
- HAS_CPU_FEATURE (ERMS)
- jz 2f
- lea __memcpy_avx_unaligned_erms(%rip), %RAX_LP
- ret
-L(Fast_Unaligned_Load):
- lea __memcpy_sse2_unaligned(%rip), %RAX_LP
- HAS_ARCH_FEATURE (Fast_Unaligned_Copy)
- jz L(SSSE3)
- HAS_CPU_FEATURE (ERMS)
- jz 2f
- lea __memcpy_sse2_unaligned_erms(%rip), %RAX_LP
- ret
-L(SSSE3):
- HAS_CPU_FEATURE (SSSE3)
- jz 2f
- lea __memcpy_ssse3_back(%rip), %RAX_LP
- HAS_ARCH_FEATURE (Fast_Copy_Backward)
- jnz 2f
- lea __memcpy_ssse3(%rip), %RAX_LP
-2: ret
-END(__new_memcpy)
-
-# undef memcpy
-# include <shlib-compat.h>
-versioned_symbol (libc, __new_memcpy, memcpy, GLIBC_2_14);
-#endif
diff --git a/sysdeps/x86_64/multiarch/memcpy.c b/sysdeps/x86_64/multiarch/memcpy.c
new file mode 100644
index 0000000..ad1b31f
--- /dev/null
+++ b/sysdeps/x86_64/multiarch/memcpy.c
@@ -0,0 +1,35 @@
+/* Multiple version of memcpy.
+ All versions must be listed in ifunc-impl-list.c.
+ 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 defined SHARED && IS_IN (libc)
+
+# define memcpy __redirect_memcpy
+# include <string.h>
+# undef memcpy
+
+# define SYMBOL_NAME memcpy
+# include "memifunc.h"
+
+extern __typeof (__redirect_memcpy) __new_memcpy;
+
+libc_ifunc (__new_memcpy, memcpy_ifunc_selector ());
+
+# include <shlib-compat.h>
+versioned_symbol (libc, __new_memcpy, memcpy, GLIBC_2_14);
+#endif
diff --git a/sysdeps/x86_64/multiarch/memifunc.h b/sysdeps/x86_64/multiarch/memifunc.h
new file mode 100644
index 0000000..894b4a0
--- /dev/null
+++ b/sysdeps/x86_64/multiarch/memifunc.h
@@ -0,0 +1,95 @@
+/* Common definition for memcpy, mempcpy, and memmove implementation.
+ All versions must be listed in ifunc-impl-list.c.
+ Copyright (C) 2016-2017 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/>. */
+
+/* memcpy, mempcpy, and memmove share the same logic for ifunc selection. */
+
+#include <cpu-features.h>
+#include <ldsodefs.h>
+
+#define PASTER1(x,y) x ## _ ## y
+#define EVALUATOR1(x,y) PASTER1(x,y)
+#define PASTER2(x,y) __ ## x ## _ ## y
+#define EVALUATOR2(x,y) PASTER2(x,y)
+
+/* Basically set '__redirect_<symbol>' to use as type definition,
+ '__<symbol>_<variant>' as the optimized implementation and
+ '<symbol>_ifunc_selector' as the IFUNC selector. */
+#define REDIRECT_NAME EVALUATOR1(__redirect, SYMBOL_NAME)
+#define OPTIMIZE(name) EVALUATOR2(SYMBOL_NAME, name)
+#define IFUNC_NAME EVALUATOR1(SYMBOL_NAME, ifunc_selector)
+
+extern __typeof (REDIRECT_NAME) OPTIMIZE(erms) attribute_hidden;
+extern __typeof (REDIRECT_NAME) OPTIMIZE(sse2_unaligned)
+ attribute_hidden;
+extern __typeof (REDIRECT_NAME) OPTIMIZE(sse2_unaligned_erms)
+ attribute_hidden;
+extern __typeof (REDIRECT_NAME) OPTIMIZE(ssse3) attribute_hidden;
+extern __typeof (REDIRECT_NAME) OPTIMIZE(ssse3_back) attribute_hidden;
+extern __typeof (REDIRECT_NAME) OPTIMIZE(avx_unaligned) attribute_hidden;
+extern __typeof (REDIRECT_NAME) OPTIMIZE(avx_unaligned_erms)
+ attribute_hidden;
+extern __typeof (REDIRECT_NAME) OPTIMIZE(avx512_unaligned)
+ attribute_hidden;
+extern __typeof (REDIRECT_NAME) OPTIMIZE(avx512_unaligned_erms)
+ attribute_hidden;
+extern __typeof (REDIRECT_NAME) OPTIMIZE(avx512_no_vzeroupper)
+ attribute_hidden;
+
+static inline void *
+IFUNC_NAME (void)
+{
+ const struct cpu_features* cpu_features = __get_cpu_features ();
+
+ if (CPU_FEATURES_ARCH_P (cpu_features, Prefer_ERMS))
+ return OPTIMIZE(erms);
+
+ if (CPU_FEATURES_ARCH_P (cpu_features, AVX512F_Usable)
+ && !CPU_FEATURES_ARCH_P (cpu_features, Prefer_No_AVX512))
+ {
+ if (CPU_FEATURES_ARCH_P (cpu_features, Prefer_No_VZEROUPPER))
+ return OPTIMIZE(avx512_no_vzeroupper);
+
+ if (CPU_FEATURES_CPU_P (cpu_features, ERMS))
+ return OPTIMIZE(avx512_unaligned_erms);
+
+ return OPTIMIZE(avx512_unaligned);
+ }
+
+ if (CPU_FEATURES_ARCH_P (cpu_features, AVX_Fast_Unaligned_Load))
+ {
+ if (CPU_FEATURES_CPU_P (cpu_features, ERMS))
+ return OPTIMIZE(avx_unaligned_erms);
+
+ return OPTIMIZE(avx_unaligned);
+ }
+
+ if (!CPU_FEATURES_CPU_P (cpu_features, SSSE3)
+ || CPU_FEATURES_ARCH_P (cpu_features, Fast_Unaligned_Copy))
+ {
+ if (CPU_FEATURES_CPU_P (cpu_features, ERMS))
+ return OPTIMIZE(sse2_unaligned_erms);
+
+ return OPTIMIZE(sse2_unaligned);
+ }
+
+ if (CPU_FEATURES_ARCH_P (cpu_features, Fast_Copy_Backward))
+ return OPTIMIZE(ssse3_back);
+
+ return OPTIMIZE(ssse3);
+}
diff --git a/sysdeps/x86_64/multiarch/memmove.c b/sysdeps/x86_64/multiarch/memmove.c
new file mode 100644
index 0000000..76372fc
--- /dev/null
+++ b/sysdeps/x86_64/multiarch/memmove.c
@@ -0,0 +1,33 @@
+/* Multiple version of memmmove.
+ All versions must be listed in ifunc-impl-list.c.
+ Copyright (C) 2016-2017 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 defined SHARED && IS_IN (libc)
+
+# define memmove __redirect_memmove
+# include <string.h>
+# undef memmove
+
+# define SYMBOL_NAME memmove
+# include "memifunc.h"
+
+extern __typeof (__redirect_memmove) __libc_memmove;
+
+libc_ifunc (__libc_memmove, memmove_ifunc_selector ());
+strong_alias (__libc_memmove, memmove);
+#endif
diff --git a/sysdeps/x86_64/multiarch/mempcpy.S b/sysdeps/x86_64/multiarch/mempcpy.S
deleted file mode 100644
index b8b2b28..0000000
--- a/sysdeps/x86_64/multiarch/mempcpy.S
+++ /dev/null
@@ -1,73 +0,0 @@
-/* Multiple versions of mempcpy
- All versions must be listed in ifunc-impl-list.c.
- Copyright (C) 2010-2017 Free Software Foundation, Inc.
- Contributed by Intel Corporation.
- 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 and for
- DSO. In static binaries we need mempcpy before the initialization
- happened. */
-#if defined SHARED && IS_IN (libc)
- .text
-ENTRY(__mempcpy)
- .type __mempcpy, @gnu_indirect_function
- LOAD_RTLD_GLOBAL_RO_RDX
- lea __mempcpy_erms(%rip), %RAX_LP
- HAS_ARCH_FEATURE (Prefer_ERMS)
- jnz 2f
- HAS_ARCH_FEATURE (Prefer_No_AVX512)
- jnz 1f
- HAS_ARCH_FEATURE (AVX512F_Usable)
- jz 1f
- lea __mempcpy_avx512_no_vzeroupper(%rip), %RAX_LP
- HAS_ARCH_FEATURE (Prefer_No_VZEROUPPER)
- jnz 2f
- lea __mempcpy_avx512_unaligned_erms(%rip), %RAX_LP
- HAS_CPU_FEATURE (ERMS)
- jnz 2f
- lea __mempcpy_avx512_unaligned(%rip), %RAX_LP
- ret
-1: lea __mempcpy_avx_unaligned(%rip), %RAX_LP
- HAS_ARCH_FEATURE (AVX_Fast_Unaligned_Load)
- jz L(Fast_Unaligned_Load)
- HAS_CPU_FEATURE (ERMS)
- jz 2f
- lea __mempcpy_avx_unaligned_erms(%rip), %RAX_LP
- ret
-L(Fast_Unaligned_Load):
- lea __mempcpy_sse2_unaligned(%rip), %RAX_LP
- HAS_ARCH_FEATURE (Fast_Unaligned_Copy)
- jz L(SSSE3)
- HAS_CPU_FEATURE (ERMS)
- jz 2f
- lea __mempcpy_sse2_unaligned_erms(%rip), %RAX_LP
- ret
-L(SSSE3):
- HAS_CPU_FEATURE (SSSE3)
- jz 2f
- lea __mempcpy_ssse3_back(%rip), %RAX_LP
- HAS_ARCH_FEATURE (Fast_Copy_Backward)
- jnz 2f
- lea __mempcpy_ssse3(%rip), %RAX_LP
-2: ret
-END(__mempcpy)
-
-weak_alias (__mempcpy, mempcpy)
-#endif
diff --git a/sysdeps/x86_64/multiarch/mempcpy.c b/sysdeps/x86_64/multiarch/mempcpy.c
new file mode 100644
index 0000000..e59bde2
--- /dev/null
+++ b/sysdeps/x86_64/multiarch/mempcpy.c
@@ -0,0 +1,34 @@
+/* Multiple version of mempcpy.
+ All versions must be listed in ifunc-impl-list.c.
+ 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 defined SHARED && IS_IN (libc)
+
+# define mempcpy __redirect_mempcpy
+# define __mempcpy __redirect___mempcpy
+# include <string.h>
+# undef mempcpy
+# undef __mempcpy
+
+# define SYMBOL_NAME mempcpy
+# include "memifunc.h"
+
+libc_ifunc_redirected (__redirect_mempcpy, __mempcpy,
+ mempcpy_ifunc_selector ());
+weak_alias (__mempcpy, mempcpy)
+#endif
--
2.7.4