* parse.y: optimize 'for' statement when one variable given.

* benchmark/bm_loop_for.rb: added.
* benchmark/bm_loop_times.rb: modified.



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@19753 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,11 @@
+Sat Oct 11 03:54:05 2008  Koichi Sasada  <ko1@atdot.net>
+
+	* parse.y: optimize 'for' statement when one variable given.
+
+	* benchmark/bm_loop_for.rb: added.
+
+	* benchmark/bm_loop_times.rb: modified.
+
 Sat Oct 11 12:09:05 2008  James Edward Gray II  <jeg2@ruby-lang.org>
 
 	* lib/csv/csv.rb:  Added support for Encoding::default_internal.

benchmark/bm_loop_for.rb

@@ -0,0 +1,3 @@
+for i in 1..30_000_000
+  #
+end

benchmark/bm_loop_times.rb

@@ -1 +1 @@
-30000000.times{|e|}
+30_000_000.times{|e|}

parse.y

@@ -2772,16 +2772,27 @@ primary		: literal
 					     NEW_CALL(NEW_CALL(NEW_DVAR(id), rb_intern("[]"), zero),
 						      rb_intern("kind_of?"), NEW_LIST(NEW_LIT(rb_cArray))),
 					     0),
-					NEW_DASGN_CURR(id,
-						       NEW_CALL(NEW_DVAR(id), rb_intern("[]"), zero)),
-					0),
+				    NEW_DASGN_CURR(id,
+						   NEW_CALL(NEW_DVAR(id), rb_intern("[]"), zero)),
+				    0),
 				node_assign($2, NEW_DVAR(id)));
+
+			    args = new_args(m, 0, id, 0, 0);
 			}
 			else {
-			    m->nd_next = node_assign(NEW_MASGN(NEW_LIST($2), 0), NEW_DVAR(id));
+			    if (nd_type($2) == NODE_LASGN ||
+				nd_type($2) == NODE_DASGN ||
+				nd_type($2) == NODE_DASGN_CURR) {
+				$2->nd_value = NEW_DVAR(id);
+				m->nd_plen = 1;
+				m->nd_next = $2;
+				args = new_args(m, 0, 0, 0, 0);
+			    }
+			    else {
+				m->nd_next = node_assign(NEW_MASGN(NEW_LIST($2), 0), NEW_DVAR(id));
+				args = new_args(m, 0, id, 0, 0);
+			    }
 			}
-
-			args = new_args(m, 0, id, 0, 0);
 			scope = NEW_NODE(NODE_SCOPE, tbl, $8, args);
 			tbl[0] = 1; tbl[1] = id;
 			$$ = NEW_FOR(0, $5, scope);