+/* Print a warning about casts that might indicate violation
+ of strict aliasing rules if -Wstrict-aliasing is used and
+ strict aliasing mode is in effect. otype is the original
+ TREE_TYPE of expr, and type the type we're casting to. */
+
+void
+strict_aliasing_warning(tree otype, tree type, tree expr)
+{
+ if (flag_strict_aliasing && warn_strict_aliasing
+ && POINTER_TYPE_P (type) && POINTER_TYPE_P (otype)
+ && TREE_CODE (expr) == ADDR_EXPR
+ && (DECL_P (TREE_OPERAND (expr, 0))
+ || TREE_CODE (TREE_OPERAND (expr, 0)) == COMPONENT_REF)
+ && !VOID_TYPE_P (TREE_TYPE (type)))
+ {
+ /* Casting the address of an object to non void pointer. Warn
+ if the cast breaks type based aliasing. */
+ if (!COMPLETE_TYPE_P (TREE_TYPE (type)))
+ warning (OPT_Wstrict_aliasing, "type-punning to incomplete type "
+ "might break strict-aliasing rules");
+ else
+ {
+ HOST_WIDE_INT set1 = get_alias_set (TREE_TYPE (TREE_OPERAND (expr, 0)));
+ HOST_WIDE_INT set2 = get_alias_set (TREE_TYPE (type));
+
+ if (!alias_sets_conflict_p (set1, set2))
+ warning (OPT_Wstrict_aliasing, "dereferencing type-punned "
+ "pointer will break strict-aliasing rules");
+ else if (warn_strict_aliasing > 1
+ && !alias_sets_might_conflict_p (set1, set2))
+ warning (OPT_Wstrict_aliasing, "dereferencing type-punned "
+ "pointer might break strict-aliasing rules");
+ }
+ }
+}
+