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1626a1cfcd
GCC 9 has gained an enhancement to help detect attribute mismatches between alias declarations and their targets. It consists of a new warning, -Wattribute-alias, an enhancement to an existing warning, -Wmissing-attributes, and a new attribute called copy. The purpose of the warnings is to help identify either possible bugs (an alias declared with more restrictive attributes than its target promises) or optimization or diagnostic opportunities (an alias target missing some attributes that it could be declared with that might benefit analysis and code generation). The purpose of the new attribute is to easily apply (almost) the same set of attributes to one declaration as those already present on another. As expected (and intended) the enhancement triggers warnings for many alias declarations in Glibc code. This change, tested on x86_64-linux, avoids all instances of the new warnings by making use of the attribute where appropriate. To fully benefit from the enhancement Glibc will need to be compiled with -Wattribute-alias=2 and remaining warnings reviewed and dealt with (there are a couple of thousand but most should be straightforward to deal with). ChangeLog: * include/libc-symbols.h (__attribute_copy__): Define macro unless it's already defined. (_strong_alias): Use __attribute_copy__. (_weak_alias, __hidden_ver1, __hidden_nolink2): Same. * misc/sys/cdefs.h (__attribute_copy__): New macro. * sysdeps/x86_64/multiarch/memchr.c (memchr): Use __attribute_copy__. * sysdeps/x86_64/multiarch/memcmp.c (memcmp): Same. * sysdeps/x86_64/multiarch/mempcpy.c (mempcpy): Same. * sysdeps/x86_64/multiarch/memset.c (memset): Same. * sysdeps/x86_64/multiarch/stpcpy.c (stpcpy): Same. * sysdeps/x86_64/multiarch/strcat.c (strcat): Same. * sysdeps/x86_64/multiarch/strchr.c (strchr): Same. * sysdeps/x86_64/multiarch/strcmp.c (strcmp): Same. * sysdeps/x86_64/multiarch/strcpy.c (strcpy): Same. * sysdeps/x86_64/multiarch/strcspn.c (strcspn): Same. * sysdeps/x86_64/multiarch/strlen.c (strlen): Same. * sysdeps/x86_64/multiarch/strncmp.c (strncmp): Same. * sysdeps/x86_64/multiarch/strncpy.c (strncpy): Same. * sysdeps/x86_64/multiarch/strnlen.c (strnlen): Same. * sysdeps/x86_64/multiarch/strpbrk.c (strpbrk): Same. * sysdeps/x86_64/multiarch/strrchr.c (strrchr): Same. * sysdeps/x86_64/multiarch/strspn.c (strspn): Same.
61 lines
2.1 KiB
C
61 lines
2.1 KiB
C
/* Multiple versions of strncmp.
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All versions must be listed in ifunc-impl-list.c.
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Copyright (C) 2017-2018 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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/* Define multiple versions only for the definition in libc. */
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#if IS_IN (libc)
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# define strncmp __redirect_strncmp
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# include <string.h>
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# undef strncmp
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# define SYMBOL_NAME strncmp
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# include <init-arch.h>
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extern __typeof (REDIRECT_NAME) OPTIMIZE (sse2) attribute_hidden;
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extern __typeof (REDIRECT_NAME) OPTIMIZE (ssse3) attribute_hidden;
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extern __typeof (REDIRECT_NAME) OPTIMIZE (sse42) attribute_hidden;
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extern __typeof (REDIRECT_NAME) OPTIMIZE (avx2) attribute_hidden;
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static inline void *
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IFUNC_SELECTOR (void)
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{
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const struct cpu_features* cpu_features = __get_cpu_features ();
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if (!CPU_FEATURES_ARCH_P (cpu_features, Prefer_No_VZEROUPPER)
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&& CPU_FEATURES_ARCH_P (cpu_features, AVX2_Usable)
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&& CPU_FEATURES_ARCH_P (cpu_features, AVX_Fast_Unaligned_Load))
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return OPTIMIZE (avx2);
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if (CPU_FEATURES_CPU_P (cpu_features, SSE4_2)
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&& !CPU_FEATURES_ARCH_P (cpu_features, Slow_SSE4_2))
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return OPTIMIZE (sse42);
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if (CPU_FEATURES_CPU_P (cpu_features, SSSE3))
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return OPTIMIZE (ssse3);
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return OPTIMIZE (sse2);
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}
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libc_ifunc_redirected (__redirect_strncmp, strncmp, IFUNC_SELECTOR ());
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# ifdef SHARED
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__hidden_ver1 (strncmp, __GI_strncmp, __redirect_strncmp)
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__attribute__ ((visibility ("hidden"))) __attribute_copy__ (strncmp);
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# endif
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#endif
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