# define atomic_write_barrier() atomic_thread_fence_release ()
#endif
-
-/* ATOMIC_EXCHANGE_USES_CAS is non-zero if atomic_exchange operations
- are implemented based on a CAS loop; otherwise, this is zero and we assume
- that the atomic_exchange operations could provide better performance
- than a CAS loop. */
-#ifndef ATOMIC_EXCHANGE_USES_CAS
-# error ATOMIC_EXCHANGE_USES_CAS has to be defined.
-#endif
-
#endif /* atomic.h */
int val = 0;
/* We assume that the first try mostly will be successful, thus we use
- atomic_exchange if it is not implemented by a CAS loop (we also assume
- that atomic_exchange can be faster if it succeeds, see
- ATOMIC_EXCHANGE_USES_CAS). Otherwise, we use a weak CAS and not an
- exchange so we bail out after the first failed attempt to change the
- state. For the subsequent attempts we use atomic_compare_and_exchange
- after we observe that the lock is not acquired.
- See also comment in pthread_spin_trylock.
+ atomic_exchange.
We use acquire MO to synchronize-with the release MO store in
pthread_spin_unlock, and thus ensure that prior critical sections
happen-before this critical section. */
-#if ! ATOMIC_EXCHANGE_USES_CAS
- /* Try to acquire the lock with an exchange instruction as this architecture
- has such an instruction and we assume it is faster than a CAS.
- The acquisition succeeds if the lock is not in an acquired state. */
if (__glibc_likely (atomic_exchange_acquire (lock, 1) == 0))
return 0;
-#else
- /* Try to acquire the lock with a CAS instruction as this architecture
- has no exchange instruction. The acquisition succeeds if the lock is not
- acquired. */
- if (__glibc_likely (atomic_compare_exchange_weak_acquire (lock, &val, 1)))
- return 0;
-#endif
do
{
int
__pthread_spin_trylock (pthread_spinlock_t *lock)
{
- /* For the spin try lock, we have the following possibilities:
-
- 1) If we assume that trylock will most likely succeed in practice:
- * We just do an exchange.
-
- 2) If we want to bias towards cases where trylock succeeds, but don't
- rule out contention:
- * If exchange is not implemented by a CAS loop, and exchange is faster
- than CAS, do an exchange.
- * If exchange is implemented by a CAS loop, use a weak CAS and not an
- exchange so we bail out after the first failed attempt to change the state.
-
- 3) If we expect contention to be likely:
- * If CAS always brings the cache line into an exclusive state even if the
- spinlock is already acquired, then load the value first with
- atomic_load_relaxed and test if lock is not acquired. Then do 2).
-
- We assume that 2) is the common case, and that this won't be slower than
- 1) in the common case.
-
- We use acquire MO to synchronize-with the release MO store in
- pthread_spin_unlock, and thus ensure that prior critical sections
- happen-before this critical section. */
-#if ! ATOMIC_EXCHANGE_USES_CAS
- /* Try to acquire the lock with an exchange instruction as this architecture
- has such an instruction and we assume it is faster than a CAS.
- The acquisition succeeds if the lock is not in an acquired state. */
if (atomic_exchange_acquire (lock, 1) == 0)
return 0;
-#else
- /* Try to acquire the lock with a CAS instruction as this architecture
- has no exchange instruction. The acquisition succeeds if the lock is not
- acquired. */
- do
- {
- int val = 0;
- if (atomic_compare_exchange_weak_acquire (lock, &val, 1))
- return 0;
- }
- /* atomic_compare_exchange_weak_acquire can fail spuriously. Whereas
- C++11 and C11 make it clear that trylock operations can fail spuriously,
- POSIX does not explicitly specify this; it only specifies that failing
- synchronization operations do not need to have synchronization effects
- themselves, but a spurious failure is something that could contradict a
- happens-before established earlier (e.g., that we need to observe that
- the lock is acquired). Therefore, we emulate a strong CAS by simply
- checking with a relaxed MO load that the lock is really acquired before
- returning EBUSY; the additional overhead this may cause is on the slow
- path. */
- while (atomic_load_relaxed (lock) == 0);
-#endif
return EBUSY;
}
+++ /dev/null
-/* Copyright (C) 2003-2025 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
- <https://www.gnu.org/licenses/>. */
-
-#ifndef _AARCH64_ATOMIC_MACHINE_H
-#define _AARCH64_ATOMIC_MACHINE_H 1
-
-#define ATOMIC_EXCHANGE_USES_CAS 0
-
-#endif
#include <stdint.h>
-/* XXX Is this actually correct? */
-#define ATOMIC_EXCHANGE_USES_CAS 1
-
#define atomic_write_barrier() __asm ("wmb" : : : "memory");
+++ /dev/null
-/* Low-level functions for atomic operations. ARC version.
- Copyright (C) 2020-2025 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
- <https://www.gnu.org/licenses/>. */
-
-#ifndef _ARC_BITS_ATOMIC_H
-#define _ARC_BITS_ATOMIC_H 1
-
-/* ARC does have legacy atomic EX reg, [mem] instruction but the micro-arch
- is not as optimal as LLOCK/SCOND specially for SMP. */
-#define ATOMIC_EXCHANGE_USES_CAS 1
-
-#endif /* _ARC_BITS_ATOMIC_H */
+++ /dev/null
-/* Atomic operations. Pure ARM version.
- Copyright (C) 2002-2025 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
- <https://www.gnu.org/licenses/>. */
-
-#define ATOMIC_EXCHANGE_USES_CAS 1
+++ /dev/null
-/* Atomic operations. C-SKY version.
- Copyright (C) 2018-2025 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
- <https://www.gnu.org/licenses/>. */
-
-#ifndef __CSKY_ATOMIC_H_
-#define __CSKY_ATOMIC_H_
-
-#define ATOMIC_EXCHANGE_USES_CAS 1
-
-#endif /* atomic-machine.h */
#ifndef _ATOMIC_MACHINE_H
#define _ATOMIC_MACHINE_H 1
-/* We have by default no support for atomic operations. So define
- them non-atomic. If this is a problem somebody will have to come
- up with real definitions. */
-
-/* The only basic operation needed is compare and exchange. */
-#define atomic_compare_and_exchange_val_acq(mem, newval, oldval) \
- ({ __typeof (mem) __gmemp = (mem); \
- __typeof (*mem) __gret = *__gmemp; \
- __typeof (*mem) __gnewval = (newval); \
- \
- if (__gret == (oldval)) \
- *__gmemp = __gnewval; \
- __gret; })
-
-#define atomic_compare_and_exchange_bool_acq(mem, newval, oldval) \
- ({ __typeof (mem) __gmemp = (mem); \
- __typeof (*mem) __gnewval = (newval); \
- \
- *__gmemp == (oldval) ? (*__gmemp = __gnewval, 0) : 1; })
+/* Some macros can be overridden if the architecture requires some specific
+ atomic operations or provides extra optimizations.
+
+ * atomic_max (mem, value): atomically set the maximum value of *mem
+ and value to *mem. Used on malloc statistics collection.
+
+ * atomic_full_barrier: defaults to __atomic_thread_fence (__ATOMIC_SEQ_CST)
+
+ * atomic_read_barrier: defaults to __atomic_thread_fence (__ATOMIC_ACQUIRE)
+
+ * atomic_write_barrier: defaults to __atomic_thread_fence (__ATOMIC_RELEASE)
+
+ * atomic_spin_nop: arch-specific instruction used on pthread spin lock
+ and adaptive mutexes to optimize spin-wait loops.
+*/
#endif /* atomic-machine.h */
+++ /dev/null
-/* Copyright (C) 2003-2025 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
- <https://www.gnu.org/licenses/>. */
-
-#ifndef _ATOMIC_MACHINE_H
-#define _ATOMIC_MACHINE_H 1
-
-/* XXX Is this actually correct? */
-#define ATOMIC_EXCHANGE_USES_CAS 1
-
-#endif
+++ /dev/null
-/* Atomic operations.
- Copyright (C) 2022-2025 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
- <https://www.gnu.org/licenses/>. */
-
-#ifndef _LINUX_LOONGARCH_BITS_ATOMIC_H
-#define _LINUX_LOONGARCH_BITS_ATOMIC_H 1
-
-#define ATOMIC_EXCHANGE_USES_CAS 0
-
-#endif /* bits/atomic.h */
+++ /dev/null
-/* Copyright (C) 2003-2025 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
- <https://www.gnu.org/licenses/>. */
-
-#ifndef _M68K_ATOMIC_MACHINE_H
-#define _M68K_ATOMIC_MACHINE_H 1
-
-#if defined __mc68020__ || defined __mcoldfire__
-/* XXX Is this actually correct? */
-# define ATOMIC_EXCHANGE_USES_CAS 1
-#else
-# error "ISAs does not support atomic operations"
-#endif
-
-#endif
+++ /dev/null
-/* Copyright (C) 2003-2025 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
- <https://www.gnu.org/licenses/>. */
-
-#include <sysdep.h>
-
-/* XXX Is this actually correct? */
-#define ATOMIC_EXCHANGE_USES_CAS 1
+++ /dev/null
-/* Low-level functions for atomic operations. Mips version.
- Copyright (C) 2005-2025 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
- <https://www.gnu.org/licenses/>. */
-
-#ifndef _MIPS_ATOMIC_MACHINE_H
-#define _MIPS_ATOMIC_MACHINE_H 1
-
-#include <sgidefs.h>
-
-#if _MIPS_SIM == _ABIO32 && __mips < 2
-#define MIPS_PUSH_MIPS2 ".set mips2\n\t"
-#else
-#define MIPS_PUSH_MIPS2
-#endif
-
-/* MIPS is an LL/SC machine. However, XLP has a direct atomic exchange
- instruction which will be used by __atomic_exchange_n. */
-#ifdef _MIPS_ARCH_XLP
-# define ATOMIC_EXCHANGE_USES_CAS 0
-#else
-# define ATOMIC_EXCHANGE_USES_CAS 1
-#endif
-
-#endif /* atomic-machine.h */
+++ /dev/null
-/* Atomic operations. OpenRISC version.
- Copyright (C) 2022-2025 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
- <https://www.gnu.org/licenses/>. */
-
-#ifndef __OR1K_ATOMIC_H_
-#define __OR1K_ATOMIC_H_
-
-#define ATOMIC_EXCHANGE_USES_CAS 1
-
-#endif /* atomic-machine.h */
+++ /dev/null
-/* Atomic operations. PowerPC Common version.
- Copyright (C) 2003-2025 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
- <https://www.gnu.org/licenses/>. */
-
-#ifndef _POWERPC_ATOMIC_MACHINE_H
-#define _POWERPC_ATOMIC_MACHINE_H 1
-
-#define ATOMIC_EXCHANGE_USES_CAS 1
-
-/* Used on pthread_spin_{try}lock. */
-#define __ARCH_ACQ_INSTR "isync"
-#if defined _ARCH_PWR6 || defined _ARCH_PWR6X
-# define MUTEX_HINT_ACQ ",1"
-# define MUTEX_HINT_REL ",0"
-#else
-# define MUTEX_HINT_ACQ
-# define MUTEX_HINT_REL
-#endif
-
-#endif
#include "pthreadP.h"
#include <shlib-compat.h>
+#define __ARCH_ACQ_INSTR "isync"
+#if defined _ARCH_PWR6 || defined _ARCH_PWR6X
+# define MUTEX_HINT_ACQ ",1"
+# define MUTEX_HINT_REL ",0"
+#else
+# define MUTEX_HINT_ACQ
+# define MUTEX_HINT_REL
+#endif
+
int
__pthread_spin_lock (pthread_spinlock_t *lock)
{
#include "pthreadP.h"
#include <shlib-compat.h>
+#define __ARCH_ACQ_INSTR "isync"
+#if defined _ARCH_PWR6 || defined _ARCH_PWR6X
+# define MUTEX_HINT_ACQ ",1"
+# define MUTEX_HINT_REL ",0"
+#else
+# define MUTEX_HINT_ACQ
+# define MUTEX_HINT_REL
+#endif
+
int
__pthread_spin_trylock (pthread_spinlock_t *lock)
{
#ifdef __riscv_atomic
-# define ATOMIC_EXCHANGE_USES_CAS 0
-
/* Miscellaneous. */
# define asm_amo(which, ordering, mem, value) ({ \
+++ /dev/null
-/* Copyright (C) 2003-2025 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
- <https://www.gnu.org/licenses/>. */
-
-#define ATOMIC_EXCHANGE_USES_CAS 1
+++ /dev/null
-/* Atomic operations used inside libc. Linux/SH version.
- Copyright (C) 2003-2025 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
- <https://www.gnu.org/licenses/>. */
-
-/* XXX Is this actually correct? */
-#define ATOMIC_EXCHANGE_USES_CAS 1
#ifndef _ATOMIC_MACHINE_H
#define _ATOMIC_MACHINE_H 1
-/* XXX Is this actually correct? */
-#define ATOMIC_EXCHANGE_USES_CAS __HAVE_64B_ATOMICS
-
#ifdef __sparc_v9__
# define atomic_full_barrier() \
__asm __volatile ("membar #LoadLoad | #LoadStore" \
#ifndef _X86_ATOMIC_MACHINE_H
#define _X86_ATOMIC_MACHINE_H 1
-#define ATOMIC_EXCHANGE_USES_CAS 0
-
#define atomic_spin_nop() __asm ("pause")
#endif /* atomic-machine.h */
projects / thirdparty / glibc.git / commitdiff
