-extern HOST_WIDE_INT new_alias_set (void);
-extern HOST_WIDE_INT get_varargs_alias_set (void);
-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);
+#include "coretypes.h"
+
+/* The type of an alias set. Code currently assumes that variables of
+ this type can take the values 0 (the alias set which aliases
+ everything) and -1 (sometimes indicating that the alias set is
+ unknown, sometimes indicating a memory barrier) and -2 (indicating
+ that the alias set should be set to a unique value but has not been
+ set yet). */
+typedef int alias_set_type;
+
+extern alias_set_type new_alias_set (void);
+extern alias_set_type get_alias_set (tree);
+extern alias_set_type get_deref_alias_set (tree);
+extern alias_set_type get_varargs_alias_set (void);
+extern alias_set_type get_frame_alias_set (void);
+extern bool component_uses_parent_alias_set (const_tree);
+extern bool alias_set_subset_of (alias_set_type, alias_set_type);
+extern void record_alias_subset (alias_set_type, alias_set_type);
+extern void record_component_aliases (tree);
+extern int alias_sets_conflict_p (alias_set_type, alias_set_type);
+extern int alias_sets_must_conflict_p (alias_set_type, alias_set_type);
+extern int objects_must_conflict_p (tree, tree);
+extern int nonoverlapping_memrefs_p (const_rtx, const_rtx, bool);
+
+/* 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 ((alias_set_type) -1)