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

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

Index: pkg/compiler/lib/src/ssa/builder.dart
diff --git a/pkg/compiler/lib/src/ssa/builder.dart b/pkg/compiler/lib/src/ssa/builder.dart
index 85fd58338a7e5e5b627034dbb009549182e4e9ba..2feabefdffd022ba84cc6a14217ad81191d3916c 100644
--- a/pkg/compiler/lib/src/ssa/builder.dart
+++ b/pkg/compiler/lib/src/ssa/builder.dart
@@ -2,7 +2,71 @@
 // 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 'dart:collection';
+
+import 'package:js_runtime/shared/embedded_names.dart';
+
+import '../closure.dart';
+import '../common.dart';
+import '../common/codegen.dart' show
+    CodegenRegistry,
+    CodegenWorkItem;
+import '../common/names.dart' show
+    Identifiers,
+    Selectors;
+import '../common/tasks.dart' show
+    CompilerTask;
+import '../compiler.dart' show
+    Compiler;
+import '../constants/constant_system.dart';
+import '../constants/expressions.dart';
+import '../constants/values.dart';
+import '../core_types.dart' show
+    CoreClasses;
+import '../dart_types.dart';
+import '../diagnostics/messages.dart' show
+    Message,
+    MessageTemplate;
+import '../elements/elements.dart';
+import '../elements/modelx.dart' show
+    ConstructorBodyElementX,
+    ElementX,
+    VariableElementX;
+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 '../resolution/operators.dart';
+import '../resolution/semantic_visitor.dart';
+import '../resolution/tree_elements.dart' show
+    TreeElements;
+import '../tree/tree.dart' as ast;
+import '../types/types.dart';
+import '../universe/call_structure.dart' show
+    CallStructure;
+import '../universe/selector.dart' show
+    Selector;
+import '../universe/side_effects.dart' show
+    SideEffects;
+import '../universe/use.dart' show
+    DynamicUse,
+    StaticUse,
+    TypeUse;
+import '../util/util.dart';
+import '../world.dart' show
+    ClassWorld,
+    World;
+import '../dump_info.dart' show InfoReporter;
+
+import 'nodes.dart';
+import 'codegen.dart';
+import 'optimize.dart';
+import 'types.dart';
 
 class SsaFunctionCompiler implements FunctionCompiler {
   final SsaCodeGeneratorTask generator;
@@ -2969,7 +3033,7 @@ class SsaBuilder extends ast.Visitor
       conditionBlock.postProcessLoopHeader();
       HLoopBlockInformation info =
           new HLoopBlockInformation(
-              HLoopBlockInformation.loopType(loop),
+              _loopKind(loop),
               wrapExpressionGraph(initializerGraph),
               wrapExpressionGraph(conditionExpression),
               wrapStatementGraph(bodyGraph),
@@ -4187,7 +4251,7 @@ class SsaBuilder extends ast.Visitor
     if (inputs.length != 2) {
       reporter.internalError(node.argumentsNode, 'Two arguments expected.');
     }
-    push(new HStringConcat(inputs[0], inputs[1], node, backend.stringType));
+    push(new HStringConcat(inputs[0], inputs[1], backend.stringType));
   }
 
   void handleForeignJsCurrentIsolateContext(ast.Send node) {
@@ -8711,14 +8775,14 @@ class StringBuilderVisitor extends ast.Visitor {
 
   HInstruction concat(HInstruction left, HInstruction right) {
     HInstruction instruction = new HStringConcat(
-        left, right, diagnosticNode, builder.backend.stringType);
+        left, right, builder.backend.stringType);
     builder.add(instruction);
     return instruction;
   }
 
   HInstruction stringify(ast.Node node, HInstruction expression) {
     HInstruction instruction =
-        new HStringify(expression, node, builder.backend.stringType);
+        new HStringify(expression, builder.backend.stringType);
     builder.add(instruction);
     return instruction;
   }
@@ -9246,3 +9310,19 @@ class TypeBuilder implements DartTypeVisitor<dynamic, SsaBuilder> {
     builder.push(new HDynamicType(type, new TypeMask.exact(cls, classWorld)));
   }
 }
+
+/// Determine what kind of loop [node] represents. The result is one of the
+/// kinds defined in [HLoopBlockInformation].
+int _loopKind(ast.Node node) => node.accept(const _LoopTypeVisitor());
+
+class _LoopTypeVisitor extends ast.Visitor {
+  const _LoopTypeVisitor();
+  int visitNode(ast.Node node) => HLoopBlockInformation.NOT_A_LOOP;
+  int visitWhile(ast.While node) => HLoopBlockInformation.WHILE_LOOP;
+  int visitFor(ast.For node) => HLoopBlockInformation.FOR_LOOP;
+  int visitDoWhile(ast.DoWhile node) => HLoopBlockInformation.DO_WHILE_LOOP;
+  int visitAsyncForIn(ast.AsyncForIn node) => HLoopBlockInformation.FOR_IN_LOOP;
+  int visitSyncForIn(ast.SyncForIn node) => HLoopBlockInformation.FOR_IN_LOOP;
+  int visitSwitchStatement(ast.SwitchStatement node) =>
+      HLoopBlockInformation.SWITCH_CONTINUE_LOOP;
+}