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[/] [openrisc/] [trunk/] [gnu-dev/] [or1k-gcc/] [libitm/] [stmlock.h] - Rev 746
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/* Copyright (C) 2009, 2011 Free Software Foundation, Inc. Contributed by Richard Henderson <rth@redhat.com>. This file is part of the GNU Transactional Memory Library (libitm). Libitm is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version. Libitm 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 General Public License for more details. Under Section 7 of GPL version 3, you are granted additional permissions described in the GCC Runtime Library Exception, version 3.1, as published by the Free Software Foundation. You should have received a copy of the GNU General Public License and a copy of the GCC Runtime Library Exception along with this program; see the files COPYING3 and COPYING.RUNTIME respectively. If not, see <http://www.gnu.org/licenses/>. */ #ifndef LIBITM_STMLOCK_H #define LIBITM_STMLOCK_H 1 namespace GTM HIDDEN { /* A versioned write lock on a cacheline. This must be wide enough to store a pointer, and preferably wide enough to avoid overflowing the version counter. Thus we use a "word", which should be 64-bits on 64-bit systems even when their pointer size is forced smaller. */ typedef gtm_word gtm_stmlock; /* This has to be the same size as gtm_stmlock, we just use this name for documentation purposes. */ typedef gtm_word gtm_version; /* The maximum value a version number can have. This is a consequence of having the low bit of gtm_stmlock reserved for the owned bit. */ #define GTM_VERSION_MAX (~(gtm_version)0 >> 1) /* A value that may be used to indicate "uninitialized" for a version. */ #define GTM_VERSION_INVALID (~(gtm_version)0) /* This bit is set when the write lock is held. When set, the balance of the bits in the lock is a pointer that references STM backend specific data; it is up to the STM backend to determine if this thread holds the lock. If this bit is clear, the balance of the bits are the last version number committed to the cacheline. */ static inline bool gtm_stmlock_owned_p (gtm_stmlock lock) { return lock & 1; } static inline gtm_stmlock gtm_stmlock_set_owned (void *data) { return (gtm_stmlock)(uintptr_t)data | 1; } static inline void * gtm_stmlock_get_addr (gtm_stmlock lock) { return (void *)((uintptr_t)lock & ~(uintptr_t)1); } static inline gtm_version gtm_stmlock_get_version (gtm_stmlock lock) { return lock >> 1; } static inline gtm_stmlock gtm_stmlock_set_version (gtm_version ver) { return ver << 1; } /* We use a fixed set of locks for all memory, hashed into the following table. */ #define LOCK_ARRAY_SIZE (1024 * 1024) extern gtm_stmlock gtm_stmlock_array[LOCK_ARRAY_SIZE]; static inline gtm_stmlock * gtm_get_stmlock (const gtm_cacheline *addr) { size_t idx = ((uintptr_t) addr / CACHELINE_SIZE) % LOCK_ARRAY_SIZE; return gtm_stmlock_array + idx; } /* The current global version number. */ extern atomic<gtm_version> gtm_clock; static inline gtm_version gtm_get_clock (void) { atomic_thread_fence(memory_order_release); return gtm_clock.load(memory_order_acquire); } static inline gtm_version gtm_inc_clock (void) { /* ??? Here we have a choice, the pre-inc operator mapping to __atomic_add_fetch with memory_order_seq_cst, or fetch_add with memory_order_acq_rel plus another separate increment. We really ought to recognize and optimize fetch_op(x) op x... */ gtm_version r = ++gtm_clock; /* ??? Ought to handle wraparound for 32-bit. */ if (sizeof(r) < 8 && r > GTM_VERSION_MAX) abort (); return r; } } // namespace GTM #endif // LIBITM_STMLOCK_H
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