greenplumn generic-acc 源码
greenplumn generic-acc 代码
文件路径：/src/include/port/atomics/generic-acc.h
/*-------------------------------------------------------------------------
*
* generic-acc.h
* Atomic operations support when using HPs acc on HPUX
*
* Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* NOTES:
*
* Documentation:
* * inline assembly for Itanium-based HP-UX:
* http://h21007.www2.hp.com/portal/download/files/unprot/Itanium/inline_assem_ERS.pdf
* * Implementing Spinlocks on the Intel (R) Itanium (R) Architecture and PA-RISC
* http://h21007.www2.hp.com/portal/download/files/unprot/itanium/spinlocks.pdf
*
* Itanium only supports a small set of numbers (6, -8, -4, -1, 1, 4, 8, 16)
* for atomic add/sub, so we just implement everything but compare_exchange
* via the compare_exchange fallbacks in atomics/generic.h.
*
* src/include/port/atomics/generic-acc.h
*
* -------------------------------------------------------------------------
*/
#include <machine/sys/inline.h>
#define pg_compiler_barrier_impl() _Asm_sched_fence()
#if defined(HAVE_ATOMICS)
/* IA64 always has 32/64 bit atomics */
#define PG_HAVE_ATOMIC_U32_SUPPORT
typedef struct pg_atomic_uint32
{
volatile uint32 value;
} pg_atomic_uint32;
#define PG_HAVE_ATOMIC_U64_SUPPORT
typedef struct pg_atomic_uint64
{
/*
* Alignment is guaranteed to be 64bit. Search for "Well-behaved
* application restrictions" => "Data alignment and data sharing" on HP's
* website. Unfortunately the URL doesn't seem to stable enough to
* include.
*/
volatile uint64 value;
} pg_atomic_uint64;
#define MINOR_FENCE (_Asm_fence) (_UP_CALL_FENCE | _UP_SYS_FENCE | \
_DOWN_CALL_FENCE | _DOWN_SYS_FENCE )
#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;
_Asm_mov_to_ar(_AREG_CCV, *expected, MINOR_FENCE);
/*
* We want a barrier, not just release/acquire semantics.
*/
_Asm_mf();
/*
* Notes:
* DOWN_MEM_FENCE | _UP_MEM_FENCE prevents reordering by the compiler
*/
current = _Asm_cmpxchg(_SZ_W, /* word */
_SEM_REL,
&ptr->value,
newval, _LDHINT_NONE,
_DOWN_MEM_FENCE | _UP_MEM_FENCE);
ret = current == *expected;
*expected = current;
return ret;
}
#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;
_Asm_mov_to_ar(_AREG_CCV, *expected, MINOR_FENCE);
_Asm_mf();
current = _Asm_cmpxchg(_SZ_D, /* doubleword */
_SEM_REL,
&ptr->value,
newval, _LDHINT_NONE,
_DOWN_MEM_FENCE | _UP_MEM_FENCE);
ret = current == *expected;
*expected = current;
return ret;
}
#undef MINOR_FENCE
#endif /* defined(HAVE_ATOMICS) */
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