Add CPS IR transformation to make the JavaScript backend specific semantics explicit in the tree.

pkg/compiler/lib/src/js_backend/codegen/task.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.
 
 /// Generate code using the cps-based IR pipeline.
 library code_generator_task;
 
 import 'glue.dart';
 import 'codegen.dart';
+import 'unsugar.dart';
 
 import '../js_backend.dart';
 import '../../dart2jslib.dart';
 import '../../source_file.dart';
 import '../../cps_ir/cps_ir_nodes.dart' as cps;
 import '../../cps_ir/cps_ir_builder.dart';
 import '../../tree_ir/tree_ir_nodes.dart' as tree_ir;
 import '../../tree/tree.dart' as ast;
 import '../../scanner/scannerlib.dart' as scanner;
 import '../../elements/elements.dart';
 import '../../closure.dart';
 import '../../js/js.dart' as js;
 import '../../source_map_builder.dart';
 import '../../tree_ir/tree_ir_builder.dart' as tree_builder;
 import '../../dart_backend/backend_ast_emitter.dart' as backend_ast_emitter;
 import '../../cps_ir/optimizers.dart';
 import '../../tracer.dart';
 import '../../js_backend/codegen/codegen.dart';
 import '../../ssa/ssa.dart' as ssa;
 import '../../tree_ir/optimization/optimization.dart';
-import '../../common.dart' show SelectorKind;
-import '../../constants/expressions.dart';
-import '../../constants/values.dart';
-
-class JsBackendTreeBuilder extends tree_builder.Builder {
-  final Glue glue;
-
-  JsBackendTreeBuilder(Compiler compiler, this.glue) : super(compiler);
-
-  Selector get identicalSelector {
-    return new Selector(SelectorKind.CALL, 'identical', null, 2);
-  }
-
-  /// TOOD(karlklose): cache this?
-  tree_ir.Constant get constantTrue {
-    ConstantExpression trueValue =
-        new PrimitiveConstantExpression(new TrueConstantValue());
-    return new tree_ir.Constant(trueValue);
-  }
-
-  /**
-   * Boolean conversion maps any object o into a boolean. Boolean conversion is
-   * defined by the function application
-   *   (bool v){
-   *     assert(v != null);
-   *     return identical(v, true);
-   *   }(o)
-   */
-  tree_ir.Expression visitIsTrue(cps.IsTrue node) {
-    tree_ir.Expression value = getVariableReference(node.value);
-    /// TODO(karlklose): implement the assert(v != null) check.
-    return new tree_ir.InvokeStatic(
-        glue.identicalFunction,
-        identicalSelector,
-        <tree_ir.Expression>[value, constantTrue]);
-  }
-
-}
 
 class CspFunctionCompiler implements FunctionCompiler {
   final IrBuilderTask irBuilderTask;
   final ConstantSystem constantSystem;
   final Compiler compiler;
   final Glue glue;
 
   // TODO(karlklose,sigurm): remove and update dart-doc of [compile].
   final FunctionCompiler fallbackCompiler;
 
@@ skipping 54 matching lines @@
     if (element.isGenerativeConstructorBody ||
         element.enclosingClass is ClosureClassElement ||
         element.isNative) {
       giveUp('unsupported element kind: ${element.name}:${element.kind}');
     }
 
     cps.FunctionDefinition cpsNode = irBuilderTask.buildNode(element);
     if (cpsNode == null) {
       giveUp('unable to build cps definition of $element');
     }
+    const UnsugarVisitor().rewrite(cpsNode);
     return cpsNode;
   }
 
   cps.FunctionDefinition optimizeCpsIR(cps.FunctionDefinition cpsNode) {
     // Transformations on the CPS IR.
     traceGraph("IR Builder", cpsNode);
     new ConstantPropagator(compiler, constantSystem)
         .rewrite(cpsNode);
     traceGraph("Sparse constant propagation", cpsNode);
     new RedundantPhiEliminator().rewrite(cpsNode);
     traceGraph("Redundant phi elimination", cpsNode);
     new ShrinkingReducer().rewrite(cpsNode);
     traceGraph("Shrinking reductions", cpsNode);
 
     // Do not rewrite the IR after variable allocation.  Allocation
     // makes decisions based on an approximation of IR variable live
     // ranges that can be invalidated by transforming the IR.
     new cps.RegisterAllocator().visit(cpsNode);
     return cpsNode;
   }
 
   tree_ir.FunctionDefinition compileToTreeIR(cps.FunctionDefinition cpsNode) {
-    tree_builder.Builder builder = new JsBackendTreeBuilder(compiler, glue);
+    tree_builder.Builder builder = new tree_builder.Builder(compiler);
     tree_ir.FunctionDefinition treeNode = builder.build(cpsNode);
     assert(treeNode != null);
     traceGraph('Tree builder', treeNode);
     return treeNode;
   }
 
   tree_ir.FunctionDefinition optimizeTreeIR(
       tree_ir.FunctionDefinition treeNode) {
     // Transformations on the Tree IR.
     new StatementRewriter().rewrite(treeNode);
@@ skipping 49 matching lines @@
           new TokenSourceFileLocation(sourceFile, endToken, name);
     }
     return node.withPosition(sourcePosition, endSourcePosition);
   }
 
   SourceFile sourceFileOfElement(Element element) {
     return element.implementation.compilationUnit.script.file;
   }
 
 }