More functionality in kernel_impact.

pkg/compiler/lib/src/ssa/builder.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.
 
 import 'dart:collection';
 
 import 'package:js_runtime/shared/embedded_names.dart';
 
 import '../closure.dart';
 import '../common.dart';
@@ skipping 6179 matching lines @@
     if (switchCases.isEmpty) {
       return;
     }
 
     HSwitch switchInstruction = new HSwitch(<HInstruction>[expression]);
     HBasicBlock expressionEnd = close(switchInstruction);
     LocalsHandler savedLocals = localsHandler;
 
     List<HStatementInformation> statements = <HStatementInformation>[];
     bool hasDefault = false;
-    Element getFallThroughErrorElement = helpers.fallThroughError;
     HasNextIterator<ast.Node> caseIterator =
         new HasNextIterator<ast.Node>(switchCases.iterator);
     while (caseIterator.hasNext) {
       ast.SwitchCase switchCase = caseIterator.next();
       HBasicBlock block = graph.addNewBlock();
       for (ConstantValue constant in getConstants(switchCase)) {
         HConstant hConstant = graph.addConstant(constant, compiler);
         switchInstruction.inputs.add(hConstant);
         hConstant.usedBy.add(switchInstruction);
         expressionEnd.addSuccessor(block);
       }
 
       if (isDefaultCase(switchCase)) {
         // An HSwitch has n inputs and n+1 successors, the last being the
         // default case.
         expressionEnd.addSuccessor(block);
         hasDefault = true;
       }
       open(block);
       localsHandler = new LocalsHandler.from(savedLocals);
       buildSwitchCase(switchCase);
       if (!isAborted()) {
-        if (caseIterator.hasNext) {
-          pushInvokeStatic(switchCase, getFallThroughErrorElement, []);
+        if (caseIterator.hasNext && isReachable) {
+          pushInvokeStatic(switchCase, helpers.fallThroughError, []);
           HInstruction error = pop();
           closeAndGotoExit(new HThrow(error, error.sourceInformation));
         } else if (!isDefaultCase(switchCase)) {
           // If there is no default, we will add one later to avoid
           // the critical edge. So we generate a break statement to make
           // sure the last case does not fall through to the default case.
           jumpHandler.generateBreak();
         }
       }
       statements.add(
@@ skipping 811 matching lines @@
     if (unaliased is TypedefType) throw 'unable to unalias $type';
     unaliased.accept(this, builder);
   }
 
   void visitDynamicType(DynamicType type, SsaBuilder builder) {
     JavaScriptBackend backend = builder.compiler.backend;
     ClassElement cls = backend.helpers.DynamicRuntimeType;
     builder.push(new HDynamicType(type, new TypeMask.exact(cls, closedWorld)));
   }
 }