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Diffstat (limited to 'src/include/port/atomics/generic-gcc.h')
| -rw-r--r-- | src/include/port/atomics/generic-gcc.h | 236 |
1 files changed, 236 insertions, 0 deletions
diff --git a/src/include/port/atomics/generic-gcc.h b/src/include/port/atomics/generic-gcc.h new file mode 100644 index 00000000000..23fa2a6ebb8 --- /dev/null +++ b/src/include/port/atomics/generic-gcc.h @@ -0,0 +1,236 @@ +/*------------------------------------------------------------------------- + * + * generic-gcc.h + * Atomic operations, implemented using gcc (or compatible) intrinsics. + * + * Portions Copyright (c) 1996-2014, PostgreSQL Global Development Group + * Portions Copyright (c) 1994, Regents of the University of California + * + * NOTES: + * + * Documentation: + * * Legacy __sync Built-in Functions for Atomic Memory Access + * http://gcc.gnu.org/onlinedocs/gcc-4.8.2/gcc/_005f_005fsync-Builtins.html + * * Built-in functions for memory model aware atomic operations + * http://gcc.gnu.org/onlinedocs/gcc-4.8.2/gcc/_005f_005fatomic-Builtins.html + * + * src/include/port/atomics/generic-gcc.h + * + *------------------------------------------------------------------------- + */ + +/* intentionally no include guards, should only be included by atomics.h */ +#ifndef INSIDE_ATOMICS_H +#error "should be included via atomics.h" +#endif + +/* + * icc provides all the same intrinsics but doesn't understand gcc's inline asm + */ +#if defined(__INTEL_COMPILER) +/* NB: Yes, __memory_barrier() is actually just a compiler barrier */ +#define pg_compiler_barrier_impl() __memory_barrier() +#else +#define pg_compiler_barrier_impl() __asm__ __volatile__("" ::: "memory") +#endif + +/* + * If we're on GCC 4.1.0 or higher, we should be able to get a memory barrier + * out of this compiler built-in. But we prefer to rely on platform specific + * definitions where possible, and use this only as a fallback. + */ +#if !defined(pg_memory_barrier_impl) +# if defined(HAVE_GCC__ATOMIC_INT64_CAS) +# define pg_memory_barrier_impl() __atomic_thread_fence(__ATOMIC_SEQ_CST) +# elif (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 1)) +# define pg_memory_barrier_impl() __sync_synchronize() +# endif +#endif /* !defined(pg_memory_barrier_impl) */ + +#if !defined(pg_read_barrier_impl) && defined(HAVE_GCC__ATOMIC_INT64_CAS) +/* acquire semantics include read barrier semantics */ +# define pg_read_barrier_impl() __atomic_thread_fence(__ATOMIC_ACQUIRE) +#endif + +#if !defined(pg_write_barrier_impl) && defined(HAVE_GCC__ATOMIC_INT64_CAS) +/* release semantics include write barrier semantics */ +# define pg_write_barrier_impl() __atomic_thread_fence(__ATOMIC_RELEASE) +#endif + +#ifdef HAVE_ATOMICS + +/* generic gcc based atomic flag implementation */ +#if !defined(PG_HAVE_ATOMIC_FLAG_SUPPORT) \ + && (defined(HAVE_GCC__SYNC_INT32_TAS) || defined(HAVE_GCC__SYNC_CHAR_TAS)) + +#define PG_HAVE_ATOMIC_FLAG_SUPPORT +typedef struct pg_atomic_flag +{ + /* some platforms only have a 8 bit wide TAS */ +#ifdef HAVE_GCC__SYNC_CHAR_TAS + volatile char value; +#else + /* but an int works on more platforms */ + volatile int value; +#endif +} pg_atomic_flag; + +#endif /* !ATOMIC_FLAG_SUPPORT && SYNC_INT32_TAS */ + +/* generic gcc based atomic uint32 implementation */ +#if !defined(PG_HAVE_ATOMIC_U32_SUPPORT) \ + && (defined(HAVE_GCC__ATOMIC_INT32_CAS) || defined(HAVE_GCC__SYNC_INT32_CAS)) + +#define PG_HAVE_ATOMIC_U32_SUPPORT +typedef struct pg_atomic_uint32 +{ + volatile uint32 value; +} pg_atomic_uint32; + +#endif /* defined(HAVE_GCC__ATOMIC_INT32_CAS) || defined(HAVE_GCC__SYNC_INT32_CAS) */ + +/* generic gcc based atomic uint64 implementation */ +#if !defined(PG_HAVE_ATOMIC_U64_SUPPORT) \ + && !defined(PG_DISABLE_64_BIT_ATOMICS) \ + && (defined(HAVE_GCC__ATOMIC_INT64_CAS) || defined(HAVE_GCC__SYNC_INT64_CAS)) + +#define PG_HAVE_ATOMIC_U64_SUPPORT + +typedef struct pg_atomic_uint64 +{ + volatile uint64 value; +} pg_atomic_uint64; + +#endif /* defined(HAVE_GCC__ATOMIC_INT64_CAS) || defined(HAVE_GCC__SYNC_INT64_CAS) */ + +/* + * Implementation follows. Inlined or directly included from atomics.c + */ +#if defined(PG_USE_INLINE) || defined(ATOMICS_INCLUDE_DEFINITIONS) + +#if !defined(PG_HAVE_ATOMIC_TEST_SET_FLAG) && \ + (defined(HAVE_GCC__SYNC_CHAR_TAS) || defined(HAVE_GCC__SYNC_INT32_TAS)) +#define PG_HAVE_ATOMIC_TEST_SET_FLAG +static inline bool +pg_atomic_test_set_flag_impl(volatile pg_atomic_flag *ptr) +{ + /* NB: only a acquire barrier, not a full one */ + /* some platform only support a 1 here */ + return __sync_lock_test_and_set(&ptr->value, 1) == 0; +} +#endif /* !defined(PG_HAVE_ATOMIC_TEST_SET_FLAG) && defined(HAVE_GCC__SYNC_*_TAS) */ + +#ifndef PG_HAVE_ATOMIC_UNLOCKED_TEST_FLAG +#define PG_HAVE_ATOMIC_UNLOCKED_TEST_FLAG +static inline bool +pg_atomic_unlocked_test_flag_impl(volatile pg_atomic_flag *ptr) +{ + return ptr->value == 0; +} +#endif + +#ifndef PG_HAVE_ATOMIC_CLEAR_FLAG +#define PG_HAVE_ATOMIC_CLEAR_FLAG +static inline void +pg_atomic_clear_flag_impl(volatile pg_atomic_flag *ptr) +{ + /* + * XXX: It would be nicer to use __sync_lock_release here, but gcc insists + * on making that an atomic op which is far to expensive and a stronger + * guarantee than what we actually need. + */ + pg_write_barrier_impl(); + ptr->value = 0; +} +#endif + +#ifndef PG_HAVE_ATOMIC_INIT_FLAG +#define PG_HAVE_ATOMIC_INIT_FLAG +static inline void +pg_atomic_init_flag_impl(volatile pg_atomic_flag *ptr) +{ + pg_atomic_clear_flag_impl(ptr); +} +#endif + +/* prefer __atomic, it has a better API */ +#if !defined(PG_HAVE_ATOMIC_COMPARE_EXCHANGE_U32) && defined(HAVE_GCC__ATOMIC_INT32_CAS) +#define PG_HAVE_ATOMIC_COMPARE_EXCHANGE_U32 +static inline bool +pg_atomic_compare_exchange_u32_impl(volatile pg_atomic_uint32 *ptr, + uint32 *expected, uint32 newval) +{ + /* FIXME: we can probably use a lower consistency model */ + return __atomic_compare_exchange_n(&ptr->value, expected, newval, false, + __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST); +} +#endif + +#if !defined(PG_HAVE_ATOMIC_COMPARE_EXCHANGE_U32) && defined(HAVE_GCC__SYNC_INT32_CAS) +#define PG_HAVE_ATOMIC_COMPARE_EXCHANGE_U32 +static inline bool +pg_atomic_compare_exchange_u32_impl(volatile pg_atomic_uint32 *ptr, + uint32 *expected, uint32 newval) +{ + bool ret; + uint32 current; + current = __sync_val_compare_and_swap(&ptr->value, *expected, newval); + ret = current == *expected; + *expected = current; + return ret; +} +#endif + +#if !defined(PG_HAVE_ATOMIC_FETCH_ADD_U32) && defined(HAVE_GCC__SYNC_INT32_CAS) +#define PG_HAVE_ATOMIC_FETCH_ADD_U32 +static inline uint32 +pg_atomic_fetch_add_u32_impl(volatile pg_atomic_uint32 *ptr, int32 add_) +{ + return __sync_fetch_and_add(&ptr->value, add_); +} +#endif + + +#if !defined(PG_DISABLE_64_BIT_ATOMICS) + +#if !defined(PG_HAVE_ATOMIC_COMPARE_EXCHANGE_U64) && defined(HAVE_GCC__ATOMIC_INT64_CAS) +#define PG_HAVE_ATOMIC_COMPARE_EXCHANGE_U64 +static inline bool +pg_atomic_compare_exchange_u64_impl(volatile pg_atomic_uint64 *ptr, + uint64 *expected, uint64 newval) +{ + return __atomic_compare_exchange_n(&ptr->value, expected, newval, false, + __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST); +} +#endif + +#if !defined(PG_HAVE_ATOMIC_COMPARE_EXCHANGE_U64) && defined(HAVE_GCC__SYNC_INT64_CAS) +#define PG_HAVE_ATOMIC_COMPARE_EXCHANGE_U64 +static inline bool +pg_atomic_compare_exchange_u64_impl(volatile pg_atomic_uint64 *ptr, + uint64 *expected, uint64 newval) +{ + bool ret; + uint64 current; + current = __sync_val_compare_and_swap(&ptr->value, *expected, newval); + ret = current == *expected; + *expected = current; + return ret; +} +#endif + +#if !defined(PG_HAVE_ATOMIC_FETCH_ADD_U64) && defined(HAVE_GCC__SYNC_INT64_CAS) +#define PG_HAVE_ATOMIC_FETCH_ADD_U64 +static inline uint64 +pg_atomic_fetch_add_u64_impl(volatile pg_atomic_uint64 *ptr, int64 add_) +{ + return __sync_fetch_and_add(&ptr->value, add_); +} +#endif + +#endif /* !defined(PG_DISABLE_64_BIT_ATOMICS) */ + +#endif /* defined(PG_USE_INLINE) || defined(ATOMICS_INCLUDE_DEFINITIONS) */ + +#endif /* defined(HAVE_ATOMICS) */ + |