glibc/sysdeps/x86/init-arch.h

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/* This file is part of the GNU C Library.
Copyright (C) 2008-2021 Free Software Foundation, Inc.
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
Prefer https to http for gnu.org and fsf.org URLs Also, change sources.redhat.com to sourceware.org. This patch was automatically generated by running the following shell script, which uses GNU sed, and which avoids modifying files imported from upstream: sed -ri ' s,(http|ftp)(://(.*\.)?(gnu|fsf|sourceware)\.org($|[^.]|\.[^a-z])),https\2,g s,(http|ftp)(://(.*\.)?)sources\.redhat\.com($|[^.]|\.[^a-z]),https\2sourceware.org\4,g ' \ $(find $(git ls-files) -prune -type f \ ! -name '*.po' \ ! -name 'ChangeLog*' \ ! -path COPYING ! -path COPYING.LIB \ ! -path manual/fdl-1.3.texi ! -path manual/lgpl-2.1.texi \ ! -path manual/texinfo.tex ! -path scripts/config.guess \ ! -path scripts/config.sub ! -path scripts/install-sh \ ! -path scripts/mkinstalldirs ! -path scripts/move-if-change \ ! -path INSTALL ! -path locale/programs/charmap-kw.h \ ! -path po/libc.pot ! -path sysdeps/gnu/errlist.c \ ! '(' -name configure \ -execdir test -f configure.ac -o -f configure.in ';' ')' \ ! '(' -name preconfigure \ -execdir test -f preconfigure.ac ';' ')' \ -print) and then by running 'make dist-prepare' to regenerate files built from the altered files, and then executing the following to cleanup: chmod a+x sysdeps/unix/sysv/linux/riscv/configure # Omit irrelevant whitespace and comment-only changes, # perhaps from a slightly-different Autoconf version. git checkout -f \ sysdeps/csky/configure \ sysdeps/hppa/configure \ sysdeps/riscv/configure \ sysdeps/unix/sysv/linux/csky/configure # Omit changes that caused a pre-commit check to fail like this: # remote: *** error: sysdeps/powerpc/powerpc64/ppc-mcount.S: trailing lines git checkout -f \ sysdeps/powerpc/powerpc64/ppc-mcount.S \ sysdeps/unix/sysv/linux/s390/s390-64/syscall.S # Omit change that caused a pre-commit check to fail like this: # remote: *** error: sysdeps/sparc/sparc64/multiarch/memcpy-ultra3.S: last line does not end in newline git checkout -f sysdeps/sparc/sparc64/multiarch/memcpy-ultra3.S
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<https://www.gnu.org/licenses/>. */
#include <ldsodefs.h>
#include <ifunc-init.h>
#include <isa.h>
Detect and select i586/i686 implementation at run-time We detect i586 and i686 features at run-time by checking CX8 and CMOV CPUID features bits. We can use these information to select the best implementation in ix86 multiarch. HAS_I586/HAS_I686 is true if i586/i686 instructions are available on the processor. Due to the reordering and the other nifty extensions in i686, it is not really good to use heavily i586 optimized code on an i686. It's better to use i486 code if it isn't an i586. USE_I586/USE_I686 is true if i586/i686 implementation should be used for the processor. USE_I586 is true only if i686 instructions aren't available. If i686 instructions are available, we always choose i686 or i486 implementation, in that order, and we never choose i586 implementation for i686-class processors. * sysdeps/i386/init-arch.h: New file. * sysdeps/i386/i586/init-arch.h: Likewise. * sysdeps/i386/i686/init-arch.h: Likewise. * sysdeps/x86/cpu-features.c (init_cpu_features): Set bit_I586 bit if CX8 is available. Set bit_I686 bit if CMOV is available. * sysdeps/x86/cpu-features.h (bit_I586): New. (bit_I686): Likewise. (bit_CX8): Likewise. (bit_CMOV): Likewise. (index_CX8): Likewise. (index_CMOV): Likewise. (index_I586): Likewise. (index_I686): Likewise. (reg_CX8): Likewise. (reg_CMOV): Likewise. (HAS_I586): Defined as HAS_ARCH_FEATURE (I586) if i586 isn't available at compile-time. (HAS_I686): Defined as HAS_ARCH_FEATURE (I686) if i686 isn't available at compile-time. * sysdeps/x86/init-arch.h (USE_I586): New macro. (USE_I686): Likewise.
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#ifndef __x86_64__
/* Due to the reordering and the other nifty extensions in i686, it is
not really good to use heavily i586 optimized code on an i686. It's
better to use i486 code if it isn't an i586. */
# if MINIMUM_ISA == 686
# define USE_I586 0
# define USE_I686 1
# else
# define USE_I586 (HAS_ARCH_FEATURE (I586) && !HAS_ARCH_FEATURE (I686))
# define USE_I686 HAS_ARCH_FEATURE (I686)
# endif
#endif