Merge branch 'rickard/atomics-api/OTP-9014' and OTP_R14B04

Conflicts:
	erts/aclocal.m4
	erts/emulator/beam/erl_db.c
	erts/emulator/sys/win32/sys.c
	erts/include/internal/ethread_header_config.h.in

1 files changed, 73 insertions, 0 deletions

diff --git a/erts/include/internal/gcc/ethr_membar.h b/erts/include/internal/gcc/ethr_membar.h
new file mode 100644
index 0000000000..7d428fc68e
--- /dev/null
+++ b/erts/include/internal/gcc/ethr_membar.h
@@ -0,0 +1,73 @@
+/*
+ * %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 when using gcc's builtins
+ * Author: Rickard Green
+ */
+
+#ifndef ETHR_GCC_MEMBAR_H__
+#define ETHR_GCC_MEMBAR_H__
+
+#define ETHR_LoadLoad	(1 << 0)
+#define ETHR_LoadStore	(1 << 1)
+#define ETHR_StoreLoad	(1 << 2)
+#define ETHR_StoreStore	(1 << 3)
+
+/*
+ * According to the documentation __sync_synchronize() will
+ * issue a full memory barrier. However, __sync_synchronize()
+ * is known to erroneously be a noop on at least some
+ * platforms with some gcc versions. This has suposedly been
+ * fixed in some gcc version, but we don't know from which
+ * version. Therefore, we only use it when it has been
+ * verified to work. Otherwise we use the workaround
+ * below.
+ */
+
+#if defined(ETHR_HAVE___SYNC_VAL_COMPARE_AND_SWAP32)
+#  define ETHR_MB_T__ ethr_sint32_t
+#elif defined(ETHR_HAVE___SYNC_VAL_COMPARE_AND_SWAP64)
+#  define ETHR_MB_T__ ethr_sint64_t
+#else
+#  error "No __sync_val_compare_and_swap"
+#endif
+#define ETHR_SYNC_SYNCHRONIZE_WORKAROUND__ \
+do { \
+    volatile ETHR_MB_T__ x___ = 0; \
+    (void) __sync_val_compare_and_swap(&x___, (ETHR_MB_T__) 0, (ETHR_MB_T__) 1); \
+} while (0)
+
+#define ETHR_COMPILER_BARRIER __asm__ __volatile__("" : : : "memory")
+
+#if defined(__mips__) && ETHR_AT_LEAST_GCC_VSN__(4, 2, 0)
+#  define ETHR_MEMBAR(B) __sync_synchronize()
+#  define ETHR_READ_DEPEND_MEMORY_BARRIER __sync_synchronize()
+#elif ((defined(__powerpc__) || defined(__ppc__)) \
+       && ETHR_AT_LEAST_GCC_VSN__(4, 1, 2))
+#  define ETHR_MEMBAR(B) __sync_synchronize()
+#else /* Use workaround */
+#  define ETHR_MEMBAR(B) \
+     ETHR_SYNC_SYNCHRONIZE_WORKAROUND__
+#  define ETHR_READ_DEPEND_MEMORY_BARRIER \
+     ETHR_SYNC_SYNCHRONIZE_WORKAROUND__
+#endif
+
+
+#endif /* ETHR_GCC_MEMBAR_H__ */