diff --git a/ChangeLog b/ChangeLog
index 9c6e8916de..896e0b2814 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,8 +1,19 @@
+Thu Jan  9 15:12:30 2003  Yukihiro Matsumoto  <matz@ruby-lang.org>
+
+	* parse.y (stmt): NODE_NOT elimitation for if/unless/while/until node.
+
+	* parse.y (primary): ditto.
+
 Thu Jan  9 13:26:18 2003  Akinori MUSHA  <knu@iDaemons.org>
 
 	* st.h, st.c: Back out the introduction of st_*_func_t.  Some
 	  compilers complain about function type mismatch.
 
+Thu Jan  9 02:10:44 2003  Yukihiro Matsumoto  <matz@ruby-lang.org>
+
+	* eval.c (rb_eval): reduce recursive rb_eval() call by using sort
+	  of continuation passing style.
+
 Wed Jan 08 17:10:32 2003  NAKAMURA Usaku <usa@ruby-lang.org>
 
 	* ext/Win32API/lib/win32/registry.rb: added. [new]
diff --git a/eval.c b/eval.c
index 86671173d3..e954ac0d67 100644
--- a/eval.c
+++ b/eval.c
@@ -2209,6 +2209,7 @@ rb_eval(self, n)
     VALUE self;
     NODE *n;
 {
+    NODE * volatile contnode = 0;
     NODE * volatile node = n;
     int state;
     volatile VALUE result = Qnil;
@@ -2224,10 +2225,10 @@ rb_eval(self, n)
     ruby_current_node = node;
     switch (nd_type(node)) {
       case NODE_BLOCK:
-	while (node->nd_next) {
-	    rb_eval(self, node->nd_head);
-	    node = node->nd_next;
+	if (contnode) {
+	    rb_bug("nested NODE_BLOCK");
 	}
+	contnode = node->nd_next;
 	node = node->nd_head;
 	goto again;
 
@@ -3391,7 +3392,6 @@ rb_eval(self, n)
 	break;
 
       case NODE_NEWLINE:
-	ruby_sourceline = node->nd_nth;
 	if (trace_func) {
 	    call_trace_func("line", node, self,
 			    ruby_frame->last_func,
@@ -3405,6 +3405,11 @@ rb_eval(self, n)
     }
   finish:
     CHECK_INTS;
+    if (contnode) {
+	node = contnode;
+	contnode = 0;
+	goto again;
+    }
     return result;
 }
 
@@ -4304,7 +4309,7 @@ rb_with_disable_interrupt(proc, data)
     return result;
 }
 
-static void
+static inline void
 stack_check()
 {
     static int overflowing = 0;
diff --git a/parse.y b/parse.y
index 0309b41ff0..67da743135 100644
--- a/parse.y
+++ b/parse.y
@@ -407,11 +407,21 @@ stmt		: kALIAS fitem {lex_state = EXPR_FNAME;} fitem
 		    {
 			$$ = NEW_IF(cond($3), $1, 0);
 		        fixpos($$, $3);
+			if (nd_type($$->nd_cond) == NODE_NOT) {
+			    $$->nd_cond = $$->nd_cond->nd_body;
+		            $$->nd_else = $$->nd_body;
+		            $$->nd_body = 0;
+			}
 		    }
 		| stmt kUNLESS_MOD expr_value
 		    {
 			$$ = NEW_UNLESS(cond($3), $1, 0);
 		        fixpos($$, $3);
+			if (nd_type($$->nd_cond) == NODE_NOT) {
+			    $$->nd_cond = $$->nd_cond->nd_body;
+		            $$->nd_body = $$->nd_else;
+		            $$->nd_else = 0;
+			}
 		    }
 		| stmt kWHILE_MOD expr_value
 		    {
@@ -421,6 +431,10 @@ stmt		: kALIAS fitem {lex_state = EXPR_FNAME;} fitem
 			else {
 			    $$ = NEW_WHILE(cond($3), $1, 1);
 			}
+			if (nd_type($$->nd_cond) == NODE_NOT) {
+			    $$->nd_cond = $$->nd_cond->nd_body;
+			    nd_set_type($$, NODE_UNTIL);
+			}
 		    }
 		| stmt kUNTIL_MOD expr_value
 		    {
@@ -430,6 +444,10 @@ stmt		: kALIAS fitem {lex_state = EXPR_FNAME;} fitem
 			else {
 			    $$ = NEW_UNTIL(cond($3), $1, 1);
 			}
+			if (nd_type($$->nd_cond) == NODE_NOT) {
+			    $$->nd_cond = $$->nd_cond->nd_body;
+			    nd_set_type($$, NODE_WHILE);
+			}
 		    }
 		| klBEGIN
 		    {
@@ -1440,6 +1458,12 @@ primary		: literal
 		    {
 			$$ = NEW_IF(cond($2), $4, $5);
 		        fixpos($$, $2);
+			if (nd_type($$->nd_cond) == NODE_NOT) {
+		            NODE *tmp = $$->nd_body;
+			    $$->nd_cond = $$->nd_cond->nd_body;
+		            $$->nd_body = $$->nd_else;
+		            $$->nd_else = tmp;
+			}
 		    }
 		| kUNLESS expr_value then
 		  compstmt
@@ -1448,6 +1472,12 @@ primary		: literal
 		    {
 			$$ = NEW_UNLESS(cond($2), $4, $5);
 		        fixpos($$, $2);
+			if (nd_type($$->nd_cond) == NODE_NOT) {
+		            NODE *tmp = $$->nd_body;
+			    $$->nd_cond = $$->nd_cond->nd_body;
+		            $$->nd_body = $$->nd_else;
+		            $$->nd_else = tmp;
+			}
 		    }
 		| kWHILE {COND_PUSH(1);} expr_value do {COND_POP();}
 		  compstmt
@@ -1455,6 +1485,10 @@ primary		: literal
 		    {
 			$$ = NEW_WHILE(cond($3), $6, 1);
 		        fixpos($$, $3);
+			if (nd_type($$->nd_cond) == NODE_NOT) {
+			    $$->nd_cond = $$->nd_cond->nd_body;
+			    nd_set_type($$, NODE_UNTIL);
+			}
 		    }
 		| kUNTIL {COND_PUSH(1);} expr_value do {COND_POP();} 
 		  compstmt
@@ -1462,6 +1496,10 @@ primary		: literal
 		    {
 			$$ = NEW_UNTIL(cond($3), $6, 1);
 		        fixpos($$, $3);
+			if (nd_type($$->nd_cond) == NODE_NOT) {
+			    $$->nd_cond = $$->nd_cond->nd_body;
+			    nd_set_type($$, NODE_WHILE);
+			}
 		    }
 		| kCASE expr_value opt_terms
 		  case_body