alias.h (ALIAS_SET_MEMORY_BARRIER): New.

[gcc.git] / gcc / alias.h

diff --git a/gcc/alias.h b/gcc/alias.h
index c9154b3e58f85845397f6ed8e5c8eb2cc4323579..83cc2d55094f4344f3202888f7a6e1bccf788a04 100644 (file)
--- a/gcc/alias.h
+++ b/gcc/alias.h
@@ -27,4 +27,10 @@ extern HOST_WIDE_INT get_frame_alias_set (void);
 extern void record_base_value (unsigned int, rtx, int);
 extern bool component_uses_parent_alias_set (tree);
 
+/* This alias set can be used to force a memory to conflict with all
+   other memories, creating a barrier across which no memory reference
+   can move.  Note that there are other legacy ways to create such
+   memory barriers, including an address of SCRATCH.  */
+#define ALIAS_SET_MEMORY_BARRIER       ((HOST_WIDE_INT) -1)
+
 #endif /* GCC_ALIAS_H */