Use an explicit 'this' parameter instead of 'This' nodes.

pkg/compiler/lib/src/tree_ir/tree_ir_builder.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.
 
 library tree_ir_builder;
 
 import '../dart2jslib.dart' as dart2js;
 import '../dart_types.dart';
 import '../elements/elements.dart';
 import '../cps_ir/cps_ir_nodes.dart' as cps_ir;
@@ skipping 49 matching lines @@
   /// A stack of singly-used labels that can be safely inlined at their use
   /// site.
   ///
   /// Code for continuations with exactly one use is inlined at the use site.
   /// This is not safe if the code is moved inside the scope of an exception
   /// handler (i.e., into a try block).  We keep a stack of singly-referenced
   /// continuations that are in scope without crossing a binding for a handler.
   List<cps_ir.Continuation> safeForInlining = <cps_ir.Continuation>[];
 
   ExecutableElement currentElement;
+  cps_ir.Parameter thisParameter;
   cps_ir.Continuation returnContinuation;
 
   Builder parent;
 
   Builder(this.internalError, [this.parent]);
 
   Builder createInnerBuilder() {
     return new Builder(internalError, this);
   }
 
@@ skipping 33 matching lines @@
     while (variables.length <= primitive.registerIndex) {
       variables.add(new Variable(currentElement, primitive.hint));
     }
     return variables[primitive.registerIndex];
   }
 
   /// Obtains a reference to the tree Variable corresponding to the IR primitive
   /// referred to by [reference].
   /// This increments the reference count for the given variable, so the
   /// returned expression must be used in the tree.
-  VariableUse getVariableUse(cps_ir.Reference<cps_ir.Primitive> reference) {
+  Expression getVariableUse(cps_ir.Reference<cps_ir.Primitive> reference) {
+    if (reference.definition == thisParameter) {
+      return new This();
+    }
     Variable variable = getVariable(reference.definition);
     if (variable == null) {
       // Note: this may fail because you forgot to implement a visit-function
       // in the RegisterAllocator.
       internalError(
           CURRENT_ELEMENT_SPANNABLE,
           "Reference to ${reference.definition} has no register");
     }
     return new VariableUse(variable);
   }
@@ skipping 29 matching lines @@
   Variable addFunctionParameter(cps_ir.Definition variable) {
     if (variable is cps_ir.Parameter) {
       return getVariable(variable);
     } else {
       return addMutableVariable(variable as cps_ir.MutableVariable);
     }
   }
 
   FunctionDefinition buildFunction(cps_ir.FunctionDefinition node) {
     currentElement = node.element;
+    thisParameter = node.thisParameter;
     List<Variable> parameters =
         node.parameters.map(addFunctionParameter).toList();
     Statement body;
     if (!node.isAbstract) {
       returnContinuation = node.body.returnContinuation;
       phiTempVar = new Variable(node.element, null);
       body = visit(node.body);
     }
 
     return new FunctionDefinition(node.element, parameters,
         body, node.localConstants, node.defaultParameterValues);
   }
 
   ConstructorDefinition buildConstructor(cps_ir.ConstructorDefinition node) {
     currentElement = node.element;
+    thisParameter = node.thisParameter;
     List<Variable> parameters =
         node.parameters.map(addFunctionParameter).toList();
     List<Initializer> initializers;
     Statement body;
     if (!node.isAbstract) {
       initializers = node.initializers.map(visit).toList();
       returnContinuation = node.body.returnContinuation;
 
       phiTempVar = new Variable(node.element, null);
       body = visit(node.body);
@@ skipping 370 matching lines @@
     assert(cont.parameters.isEmpty);
     elseStatement =
         cont.hasExactlyOneUse ? visit(cont.body) : new Break(labels[cont]);
     return new If(condition, thenStatement, elseStatement);
   }
 
   Expression visitConstant(cps_ir.Constant node) {
     return new Constant(node.expression);
   }
 
-  Expression visitThis(cps_ir.This node) {
-    return new This();
-  }
-
   Expression visitReifyTypeVar(cps_ir.ReifyTypeVar node) {
     return new ReifyTypeVar(node.typeVariable);
   }
 
   Expression visitLiteralList(cps_ir.LiteralList node) {
     return new LiteralList(
             node.type,
             translateArguments(node.values));
   }
 
@@ skipping 48 matching lines @@
   }
 
   Expression visitReifyRuntimeType(cps_ir.ReifyRuntimeType node) {
     return new ReifyRuntimeType(getVariableUse(node.value));
   }
 
   Expression visitReadTypeVariable(cps_ir.ReadTypeVariable node) {
     return new ReadTypeVariable(node.variable, getVariableUse(node.target));
   }
 }