Strengthen alias_ptr_types_compatible_p in LTO mode.

2019-08-09  Martin Liska  <mliska@suse.cz>

	* alias.c (alias_ptr_types_compatible_p): Strengten
	type comparison in LTO mode.

From-SVN: r274235

gcc/ChangeLog

+2019-08-09  Martin Liska  <mliska@suse.cz>
+
+	* alias.c (alias_ptr_types_compatible_p): Strengten
+	type comparison in LTO mode.
+
 2019-08-09  Richard Sandiford  <richard.sandiford@arm.com>
 
 	PR middle-end/90313

gcc/alias.c

@@ -793,8 +793,16 @@ alias_ptr_types_compatible_p (tree t1, tree t2)
       || ref_all_alias_ptr_type_p (t2))
     return false;
 
-  return (TYPE_MAIN_VARIANT (TREE_TYPE (t1))
-	  == TYPE_MAIN_VARIANT (TREE_TYPE (t2)));
+    /* This function originally abstracts from simply comparing
+       get_deref_alias_set so that we are sure this still computes
+       the same result after LTO type merging is applied.
+       When in LTO type merging is done we can actually do this compare.
+    */
+  if (in_lto_p)
+    return get_deref_alias_set (t1) == get_deref_alias_set (t2);
+  else
+    return (TYPE_MAIN_VARIANT (TREE_TYPE (t1))
+	    == TYPE_MAIN_VARIANT (TREE_TYPE (t2)));
 }
 
 /* Create emptry alias set entry.  */