/*
* %CopyrightBegin%
*
* Copyright Ericsson AB 2011. All Rights Reserved.
*
* The contents of this file are subject to the Erlang Public License,
* Version 1.1, (the "License"); you may not use this file except in
* compliance with the License. You should have received a copy of the
* Erlang Public License along with this software. If not, it can be
* retrieved online at http://www.erlang.org/.
*
* Software distributed under the License is distributed on an "AS IS"
* basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
* the License for the specific language governing rights and limitations
* under the License.
*
* %CopyrightEnd%
*/
/*
* Description: Memory barriers for x86/x86-64
* Author: Rickard Green
*/
#ifndef ETHR_X86_MEMBAR_H__
#define ETHR_X86_MEMBAR_H__
#define ETHR_LoadLoad (1 << 0)
#define ETHR_LoadStore (1 << 1)
#define ETHR_StoreLoad (1 << 2)
#define ETHR_StoreStore (1 << 3)
#define ETHR_NO_SSE2_MEMORY_BARRIER__ \
do { \
volatile ethr_sint32_t x__ = 0; \
__asm__ __volatile__ ("lock; orl $0x0, %0\n\t" \
: "=m"(x__) \
: "m"(x__) \
: "memory"); \
} while (0)
static __inline__ void
ethr_cfence__(void)
{
__asm__ __volatile__ ("" : : : "memory");
}
static __inline__ void
ethr_mfence__(void)
{
#if ETHR_SIZEOF_PTR == 4
if (ETHR_X86_RUNTIME_CONF_HAVE_NO_SSE2__)
ETHR_NO_SSE2_MEMORY_BARRIER__;
else
#endif
__asm__ __volatile__ ("mfence\n\t" : : : "memory");
}
static __inline__ void
ethr_sfence__(void)
{
#if ETHR_SIZEOF_PTR == 4
if (ETHR_X86_RUNTIME_CONF_HAVE_NO_SSE2__)
ETHR_NO_SSE2_MEMORY_BARRIER__;
else
#endif
__asm__ __volatile__ ("sfence\n\t" : : : "memory");
}
static __inline__ void
ethr_lfence__(void)
{
#if ETHR_SIZEOF_PTR == 4
if (ETHR_X86_RUNTIME_CONF_HAVE_NO_SSE2__)
ETHR_NO_SSE2_MEMORY_BARRIER__;
else
#endif
__asm__ __volatile__ ("lfence\n\t" : : : "memory");
}
#define ETHR_X86_OUT_OF_ORDER_MEMBAR(B) \
ETHR_CHOOSE_EXPR((B) == ETHR_StoreStore, \
ethr_sfence__(), \
ETHR_CHOOSE_EXPR((B) == ETHR_LoadLoad, \
ethr_lfence__(), \
ethr_mfence__()))
#ifdef ETHR_X86_OUT_OF_ORDER
#define ETHR_MEMBAR(B) \
ETHR_X86_OUT_OF_ORDER_MEMBAR((B))
#else /* !ETHR_X86_OUT_OF_ORDER (the default) */
/*
* We assume that only stores before loads may be reordered. That is,
* we assume that *no* instructions like these are used:
* - CLFLUSH,
* - streaming stores executed with non-temporal move,
* - string operations, or
* - other instructions which aren't LoadLoad, LoadStore, and StoreStore
* ordered by themselves
* If such instructions are used, either insert memory barriers
* using ETHR_X86_OUT_OF_ORDER_MEMBAR() at appropriate places, or
* define ETHR_X86_OUT_OF_ORDER. For more info see Intel 64 and IA-32
* Architectures Software Developer's Manual; Vol 3A; Chapter 8.2.2.
*/
#define ETHR_MEMBAR(B) \
ETHR_CHOOSE_EXPR((B) & ETHR_StoreLoad, ethr_mfence__(), ethr_cfence__())
#endif /* !ETHR_X86_OUT_OF_ORDER */
#endif /* ETHR_X86_MEMBAR_H__ */
