Add a shrinking reduction for dead continuation parameters.

tests/compiler/dart2js/backend_dart/sexpr_unstringifier.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 // SExpressionUnstringifier implements the inverse operation to
 // [SExpressionStringifier].
 
 library sexpr_unstringifier;
 
 import 'package:compiler/src/constants/expressions.dart'
@@ skipping 101 matching lines @@
 /// Constructs a minimal in-memory representation of the IR represented
 /// by the given string. Many fields are currently simply set to null.
 class SExpressionUnstringifier {
 
   // Expressions
   static const String BRANCH = "Branch";
   static const String CONCATENATE_STRINGS = "ConcatenateStrings";
   static const String DECLARE_FUNCTION = "DeclareFunction";
   static const String INVOKE_CONSTRUCTOR = "InvokeConstructor";
   static const String INVOKE_CONTINUATION = "InvokeContinuation";
-  static const String INVOKE_CONTINUATION_RECURSIVE = "InvokeContinuation*";
   static const String INVOKE_STATIC = "InvokeStatic";
   static const String INVOKE_METHOD_DIRECTLY = "InvokeMethodDirectly";
   static const String INVOKE_METHOD = "InvokeMethod";
   static const String LET_PRIM = "LetPrim";
   static const String LET_CONT = "LetCont";
   static const String SET_CLOSURE_VARIABLE = "SetClosureVariable";
   static const String TYPE_OPERATOR = "TypeOperator";
 
   // Primitives
   static const String CONSTANT = "Constant";
@@ skipping 80 matching lines @@
     switch (tokens.next) {
       case BRANCH:
         return parseBranch();
       case CONCATENATE_STRINGS:
         return parseConcatenateStrings();
       case DECLARE_FUNCTION:
         return parseDeclareFunction();
       case INVOKE_CONSTRUCTOR:
         return parseInvokeConstructor();
       case INVOKE_CONTINUATION:
-        return parseInvokeContinuation(false);
-      case INVOKE_CONTINUATION_RECURSIVE:
-        return parseInvokeContinuation(true);
+        return parseInvokeContinuation();
       case INVOKE_METHOD:
         return parseInvokeMethod();
       case INVOKE_STATIC:
         return parseInvokeStatic();
       case INVOKE_METHOD_DIRECTLY:
         return parseInvokeMethodDirectly();
       case LET_PRIM:
         return parseLetPrim();
       case LET_CONT:
         return parseLetCont();
@@ skipping 144 matching lines @@
     List<Primitive> args = parsePrimitiveList();
 
     Continuation cont = name2variable[tokens.read()];
     assert(cont != null);
 
     tokens.consumeEnd();
     Selector selector = dummySelector(constructorName, args.length);
     return new InvokeConstructor(type, element, selector, cont, args);
   }
 
-  /// (InvokeContinuation name (args))
-  InvokeContinuation parseInvokeContinuation(bool recursive) {
-    tokens.consumeStart(recursive
-        ? INVOKE_CONTINUATION_RECURSIVE : INVOKE_CONTINUATION);
-
-    Continuation cont = name2variable[tokens.read()];
+  /// (InvokeContinuation rec? name (args))
+  InvokeContinuation parseInvokeContinuation() {
+    tokens.consumeStart(INVOKE_CONTINUATION);
+    String name = tokens.read();
+    bool isRecursive = name == "rec";
+    if (isRecursive) name = tokens.read();
+    
+    Continuation cont = name2variable[name];
     assert(cont != null);
 
     List<Primitive> args = parsePrimitiveList();
 
     tokens.consumeEnd();
-    return new InvokeContinuation(cont, args, recursive: recursive);
+    return new InvokeContinuation(cont, args, recursive: isRecursive);
   }
 
   /// (InvokeMethod receiver method (args) cont)
   InvokeMethod parseInvokeMethod() {
     tokens.consumeStart(INVOKE_METHOD);
 
     Definition receiver = name2variable[tokens.read()];
     assert(receiver != null);
 
     String methodName = tokens.read();
@@ skipping 282 matching lines @@
     return new ReifyTypeVar(type);
   }
 
   /// (This)
   This parseThis() {
     tokens.consumeStart(THIS);
     tokens.consumeEnd();
     return new This();
   }
 }