Detect dead code, and handle breaks and continues in inferrer.

tests/compiler/dart2js/simple_inferrer_test.dart

 // Copyright (c) 2013, 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 'package:expect/expect.dart';
 import
     '../../../sdk/lib/_internal/compiler/implementation/types/types.dart'
     show TypeMask;
 
 import 'compiler_helper.dart';
@@ skipping 218 matching lines @@
 returnIntAsNum() {
   return 0 as num;
 }
 
 typedef int Foo();
 
 returnAsTypedef() {
   return topLevelGetter() as Foo;
 }
 
+testDeadCode() {
+  return 42;
+  return 'foo';
+}
+
+testLabeledIf(a) {
+  var c;
+  L1: if (a > 1) {
+    if (a == 2) {
+      break L1;
+    }
+    c = 42;
+  } else {
+    c = 38;
+  }
+  return c;
+}
+
 testSwitch1() {
   var a = null;
   switch (topLevelGetter) {
     case 100: a = 42.5; break;
     case 200: a = 42; break;
   }
   return a;
 }
 
 testSwitch2() {
@@ skipping 10 matching lines @@
 testSwitch3() {
   var a = 42;
   var b;
   switch (topLevelGetter) {
     L1: case 1: b = a + 42; break;
     case 2: a = 'foo'; continue L1;
   }
   return b;
 }
 
+testContinue1() {
+  var a = 42;
+  var b;
+  while (true) {
+    b = a + 54;
+    if (b == 42) continue;
+    a = 'foo';
+  }
+  return b;
+}
+
+testBreak1() {
+  var a = 42;
+  var b;
+  while (true) {
+    b = a + 54;
+    if (b == 42) break;
+    b = 'foo';
+  }
+  return b;
+}
+
+testContinue2() {
+  var a = 42;
+  var b;
+  while (true) {
+    b = a + 54;
+    if (b == 42) {
+      b = 'foo';
+      continue;
+    }
+  }
+  return b;
+}
+
+testBreak2() {
+  var a = 42;
+  var b;
+  while (true) {
+    b = a + 54;
+    if (b == 42) {
+      a = 'foo';
+      break;
+    }
+  }
+  return b;
+}
+
 get topLevelGetter => 42;
 returnDynamic() => topLevelGetter(42);
 
 class A {
   factory A() = A.generative;
   A.generative();
   operator==(other) => 42;
 
   get myField => 42;
   set myField(a) {}
@@ skipping 51 matching lines @@
   testIsCheck13(topLevelGetter());
   testIsCheck14(topLevelGetter());
   testIsCheck15(topLevelGetter());
   testIsCheck16(topLevelGetter());
   testIsCheck17(topLevelGetter());
   testIsCheck18(topLevelGetter());
   testIsCheck19(topLevelGetter());
   returnAsString();
   returnIntAsNum();
   returnAsTypedef();
+  testDeadCode();
+  testLabeledIf();
   testSwitch1();
   testSwitch2();
   testSwitch3();
+  testContinue1();
+  testBreak1();
+  testContinue2();
+  testBreak2();
   new A() == null;
   new A()..returnInt1()
          ..returnInt2()
          ..returnInt3()
          ..returnInt4()
          ..returnInt5()
          ..returnInt6();
 
   new B()..returnInt1()
          ..returnInt2()
@@ skipping 52 matching lines @@
   checkReturn('testIsCheck14', typesInferrer.dynamicType);
   checkReturn('testIsCheck15', intType);
   checkReturn('testIsCheck16', typesInferrer.dynamicType);
   checkReturn('testIsCheck17', intType);
   checkReturn('testIsCheck18', typesInferrer.dynamicType);
   checkReturn('testIsCheck19', typesInferrer.dynamicType);
   checkReturn('returnAsString',
       new TypeMask.subtype(compiler.stringClass.computeType(compiler)));
   checkReturn('returnIntAsNum', typesInferrer.intType);
   checkReturn('returnAsTypedef', typesInferrer.functionType.nullable());
+  checkReturn('testDeadCode', typesInferrer.intType);
+  checkReturn('testLabeledIf', typesInferrer.intType.nullable());
   checkReturn('testSwitch1',
     typesInferrer.intType.union(typesInferrer.doubleType, compiler).nullable());
   checkReturn('testSwitch2', typesInferrer.intType);
   checkReturn('testSwitch3', interceptorType.nullable());
+  checkReturn('testContinue1', interceptorType.nullable());
+  checkReturn('testBreak1', interceptorType.nullable());
+  checkReturn('testContinue2', interceptorType.nullable());
+  checkReturn('testBreak2', typesInferrer.intType.nullable());
 
   checkReturnInClass(String className, String methodName, type) {
     var cls = findElement(compiler, className);
     var element = cls.lookupLocalMember(buildSourceString(methodName));
     Expect.equals(type, typesInferrer.internal.returnTypeOf[element]);
   }
 
   checkReturnInClass('A', 'returnInt1', typesInferrer.intType);
   checkReturnInClass('A', 'returnInt2', typesInferrer.intType);
   checkReturnInClass('A', 'returnInt3', typesInferrer.intType);
@@ skipping 12 matching lines @@
   checkReturnInClass('B', 'returnInt8', typesInferrer.intType);
 
   checkFactoryConstructor(String className) {
     var cls = findElement(compiler, className);
     var element = cls.localLookup(buildSourceString(className));
     Expect.equals(new TypeMask.nonNullExact(cls.rawType),
                   typesInferrer.internal.returnTypeOf[element]);
   }
   checkFactoryConstructor('A');
 }