load.c: use fstring for loaded features and expanded load path

Loaded features is an obvious candidate for fstring since
feature paths of Ruby sources are included in iseq locations,
and iseq locations are in the fstring table anyways.

Deduplicating expanded load path can reuse old objects, since since
repeated expansions may recycle before old expanded paths are GC-ed
away.

* load.c (rb_construct_expanded_load_path): fstring expanded path
  (get_loaded_features_index): fstring feature path
  (rb_provide_feature): ditto
  [ruby-core:69871] [Feature #11331]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@51261 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,10 @@
+Thu Jul 16 08:47:29 2015  Eric Wong  <e@80x24.org>
+
+	* load.c (rb_construct_expanded_load_path): fstring expanded path
+	  (get_loaded_features_index): fstring feature path
+	  (rb_provide_feature): ditto
+	  [ruby-core:69871] [Feature #11331]
+
 Thu Jul 16 02:56:14 2015  Eric Wong  <e@80x24.org>
 
 	* thread.c (thread_initialize): avoid RSTRING_PTR and NUMT2INT

load.c

@@ -87,7 +87,7 @@ rb_construct_expanded_load_path(int type, int *has_relative, int *has_non_cache)
 	as_str = rb_get_path_check_convert(path, as_str, level);
 	expanded_path = rb_file_expand_path_fast(as_str, Qnil);
 	rb_str_freeze(expanded_path);
-	rb_ary_push(ary, expanded_path);
+	rb_ary_push(ary, rb_fstring(expanded_path));
     }
     rb_obj_freeze(ary);
     vm->expanded_load_path = ary;
@@ -287,9 +287,9 @@ get_loaded_features_index(void)
 	    VALUE entry, as_str;
 	    as_str = entry = rb_ary_entry(features, i);
 	    StringValue(as_str);
+	    as_str = rb_fstring(rb_str_freeze(as_str));
 	    if (as_str != entry)
 		rb_ary_store(features, i, as_str);
-	    rb_str_freeze(as_str);
 	    features_index_add(as_str, INT2FIX(i));
 	}
 	reset_loaded_features_snapshot();
@@ -560,7 +560,7 @@ rb_provide_feature(VALUE feature)
     }
     rb_str_freeze(feature);
 
-    rb_ary_push(features, feature);
+    rb_ary_push(features, rb_fstring(feature));
     features_index_add(feature, INT2FIX(RARRAY_LEN(features)-1));
     reset_loaded_features_snapshot();
 }