Cleanup 1: split parts into their own libraries, remove unused imports

pkg/compiler/lib/src/ssa/codegen.dart

 // Copyright (c) 2012, 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.
 
-part of ssa;
+import '../common.dart';
+import '../common/codegen.dart' show
+    CodegenRegistry,
+    CodegenWorkItem;
+import '../common/tasks.dart' show
+    CompilerTask;
+import '../compiler.dart' show
+    Compiler;
+import '../constants/constant_system.dart';
+import '../constants/values.dart';
+import '../core_types.dart' show
+    CoreClasses;
+import '../dart_types.dart';
+import '../elements/elements.dart';
+import '../io/source_information.dart';
+import '../js/js.dart' as js;
+import '../js_backend/backend_helpers.dart' show
+    BackendHelpers;
+import '../js_backend/js_backend.dart';
+import '../js_emitter/js_emitter.dart' show
+    CodeEmitterTask,
+    NativeEmitter;
+import '../native/native.dart' as native;
+import '../types/types.dart';
+import '../universe/call_structure.dart' show
+    CallStructure;
+import '../universe/selector.dart' show
+    Selector;
+import '../universe/use.dart' show
+    DynamicUse,
+    StaticUse,
+    TypeUse;
+import '../util/util.dart';
+import '../world.dart' show
+    ClassWorld,
+    World;
+
+import 'nodes.dart';
+import 'codegen_helpers.dart';
+import 'variable_allocator.dart';
 
 class SsaCodeGeneratorTask extends CompilerTask {
 
   final JavaScriptBackend backend;
   final SourceInformationStrategy sourceInformationFactory;
 
   SsaCodeGeneratorTask(JavaScriptBackend backend,
                        this.sourceInformationFactory)
       : this.backend = backend,
         super(backend.compiler);
@@ skipping 390 matching lines @@
    * If the [block] only contains one statement returns that statement. If the
    * that statement itself is a block, recursively calls this method.
    *
    * If the block is empty, returns a new instance of [js.NOP].
    */
   js.Statement unwrapStatement(js.Block block) {
     int len = block.statements.length;
     if (len == 0) return new js.EmptyStatement();
     if (len == 1) {
       js.Statement result = block.statements[0];
-      if (result is ast.Block) return unwrapStatement(result);
+      if (result is js.Block) return unwrapStatement(result);
       return result;
     }
     return block;
   }
 
   /**
    * Generate expressions from block information.
    */
   js.Expression generateExpression(HExpressionInformation expression) {
     // Currently we only handle sub-expression graphs.
@@ skipping 983 matching lines @@
       LabelDefinition label = node.label;
       if (!tryCallAction(continueAction, label)) {
         // TODO(floitsch): should this really be the breakLabelName?
         pushStatement(
             new js.Continue(backend.namer.breakLabelName(label))
                 .withSourceInformation(node.sourceInformation));
       }
     } else {
       JumpTarget target = node.target;
       if (!tryCallAction(continueAction, target)) {
-        if (target.statement is ast.SwitchStatement) {
+        if (target.isSwitch) {
           pushStatement(
               new js.Continue(backend.namer.implicitContinueLabelName(target))
                   .withSourceInformation(node.sourceInformation));
         } else {
           pushStatement(new js.Continue(null)
               .withSourceInformation(node.sourceInformation));
         }
       }
     }
   }
@@ skipping 1482 matching lines @@
         new StaticUse.staticInvoke(helper,
             new CallStructure.unnamed(argumentCount)));
     return backend.emitter.staticFunctionAccess(helper);
   }
 
   @override
   void visitRef(HRef node) {
     visit(node.value);
   }
 }