/* Single-thread optimization definitions.  Linux version.

   Copyright (C) 2017-2018 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 <tls.h>

#include <nptl/pthreadP.h>

/* The default way to check if the process is single thread is by using the

   pthread_t 'multiple_threads' field.  However for some architectures it

   is faster to either use an extra field on TCB or global varibles

   (the TCB field is also used on x86 for some single-thread atomic

   optimizations).

   The ABI might define SINGLE_THREAD_BY_GLOBAL to enable the single

   thread check to use global variables instead of the pthread_t

   field.  */

#ifdef SINGLE_THREAD_BY_GLOBAL

# if IS_IN (libc)

extern int __libc_multiple_threads;

#  define SINGLE_THREAD_P \

  __glibc_likely (__libc_multiple_threads == 0)

# elif IS_IN (libpthread)

extern int __pthread_multiple_threads;

#  define SINGLE_THREAD_P \

  __glibc_likely (__pthread_multiple_threads == 0)

# elif IS_IN (librt)

#   define SINGLE_THREAD_P					\

  __glibc_likely (THREAD_GETMEM (THREAD_SELF,			\

				 header.multiple_threads) == 0)

# else

/* For rtld, et cetera.  */

#  define SINGLE_THREAD_P (1)

# endif

#else /* SINGLE_THREAD_BY_GLOBAL  */

# if IS_IN (libc) || IS_IN (libpthread) || IS_IN (librt)

#   define SINGLE_THREAD_P					\

  __glibc_likely (THREAD_GETMEM (THREAD_SELF,			\

				 header.multiple_threads) == 0)

# else

/* For rtld, et cetera.  */

#  define SINGLE_THREAD_P (1)

# endif

#endif /* SINGLE_THREAD_BY_GLOBAL  */

#define RTLD_SINGLE_THREAD_P \

  __glibc_likely (THREAD_GETMEM (THREAD_SELF, \

				 header.multiple_threads) == 0)