1 files changed, 114 insertions, 0 deletions
diff --git a/erts/include/internal/i386/ethr_membar.h b/erts/include/internal/i386/ethr_membar.h
new file mode 100644
index 0000000000..92d9de7f3f
--- /dev/null
+++ b/erts/include/internal/i386/ethr_membar.h
@@ -0,0 +1,114 @@
+/*
+ * %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__ */