dart2js cps: Refactor tracking of side effects.

pkg/compiler/lib/src/cps_ir/cps_ir_builder_task.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.
 
 library dart2js.ir_builder_task;
 
 import '../closure.dart' as closure;
 import '../common.dart';
 import '../common/names.dart' show
     Identifiers,
@@ skipping 860 matching lines @@
         callStructure.getOrderedNamedArguments());
   }
 
   /// Read the value of [field].
   ir.Primitive buildStaticFieldGet(FieldElement field, SourceInformation src) {
     ConstantValue constant = getConstantForVariable(field);
     if (constant != null && !field.isAssignable) {
       typeMaskSystem.associateConstantValueWithElement(constant, field);
       return irBuilder.buildConstant(constant, sourceInformation: src);
     } else if (backend.constants.lazyStatics.contains(field)) {
-      return irBuilder.addPrimitive(new ir.GetLazyStatic(field, src));
+      return irBuilder.addPrimitive(new ir.GetLazyStatic(field,
+          sourceInformation: src,
+          isFinal: compiler.world.fieldNeverChanges(field)));
     } else {
-      return irBuilder.addPrimitive(new ir.GetStatic(field, src));
+      return irBuilder.addPrimitive(new ir.GetStatic(field,
+          sourceInformation: src,
+          isFinal: compiler.world.fieldNeverChanges(field)));
     }
   }
 
   ir.FunctionDefinition _makeFunctionBody(
       IrBuilder builder,
       FunctionElement element,
       ast.FunctionExpression node) {
     FunctionSignature signature = element.functionSignature;
     List<Local> parameters = <Local>[];
     signature.orderedForEachParameter(
@@ skipping 1035 matching lines @@
       LocalElement element,
       _) {
     return irBuilder.buildLocalGet(element);
   }
 
   @override
   ir.Primitive handleStaticFunctionGet(
       ast.Send node,
       MethodElement function,
       _) {
-    return irBuilder.addPrimitive(new ir.GetStatic(function));
+    return irBuilder.addPrimitive(new ir.GetStatic(function, isFinal: true));
   }
 
   @override
   ir.Primitive handleStaticGetterGet(
       ast.Send node,
       FunctionElement getter,
       _) {
     return buildStaticGetterGet(getter, node);
   }
 
@@ skipping 945 matching lines @@
       CompoundRhs rhs,
       arg) {
     return translateCompounds(node, () {
       switch (getterKind) {
         case CompoundGetter.FIELD:
           SourceInformation src = sourceInformationBuilder.buildGet(node);
           return buildStaticFieldGet(getter, src);
         case CompoundGetter.GETTER:
           return buildStaticGetterGet(getter, node);
         case CompoundGetter.METHOD:
-          return irBuilder.addPrimitive(new ir.GetStatic(getter));
+          return irBuilder.addPrimitive(new ir.GetStatic(getter,
+              isFinal: true));
         case CompoundGetter.UNRESOLVED:
           return irBuilder.buildStaticNoSuchMethod(
               new Selector.getter(new Name(getter.name, getter.library)),
               <ir.Primitive>[]);
       }
     }, rhs, (ir.Primitive result) {
       switch (setterKind) {
         case CompoundSetter.FIELD:
           irBuilder.addPrimitive(new ir.SetStatic(setter, result));
           return;
@@ skipping 19 matching lines @@
       ast.Node rhs,
       _) {
     return translateSetIfNull(node, () {
       switch (getterKind) {
         case CompoundGetter.FIELD:
           SourceInformation src = sourceInformationBuilder.buildGet(node);
           return buildStaticFieldGet(getter, src);
         case CompoundGetter.GETTER:
           return buildStaticGetterGet(getter, node);
         case CompoundGetter.METHOD:
-          return irBuilder.addPrimitive(new ir.GetStatic(getter));
+          return irBuilder.addPrimitive(new ir.GetStatic(getter,
+              isFinal: true));
         case CompoundGetter.UNRESOLVED:
           return irBuilder.buildStaticNoSuchMethod(
               new Selector.getter(new Name(getter.name, getter.library)),
               <ir.Primitive>[]);
       }
     }, rhs, (ir.Primitive result) {
       switch (setterKind) {
         case CompoundSetter.FIELD:
           irBuilder.addPrimitive(new ir.SetStatic(setter, result));
           return;
@@ skipping 1051 matching lines @@
   }
 
   TypeMask getTypeMaskForNativeFunction(FunctionElement function) {
     return  _compiler.typesTask.getGuaranteedReturnTypeOfElement(function);
   }
 
   FieldElement locateSingleField(Selector selector, TypeMask type) {
     return _compiler.world.locateSingleField(selector, type);
   }
 
+  bool fieldNeverChanges(FieldElement field) {
+    return _compiler.world.fieldNeverChanges(field);
+  }
+
   Element get closureConverter {
     return _backend.helpers.closureConverter;
   }
 
   void addNativeMethod(FunctionElement function) {
     _backend.emitter.nativeEmitter.nativeMethods.add(function);
   }
 
   bool get trustJSInteropTypeAnnotations =>
       _compiler.trustJSInteropTypeAnnotations;
 
   bool isNative(ClassElement element) => _backend.isNative(element);
 
   bool isJsInterop(FunctionElement element) => _backend.isJsInterop(element);
 
   bool isJsInteropAnonymous(FunctionElement element) =>
     _backend.jsInteropAnalysis.hasAnonymousAnnotation(element.contextClass);
 
   String getJsInteropTargetPath(FunctionElement element) {
     return '${_backend.namer.fixedBackendPath(element)}.'
       '${_backend.getFixedBackendName(element)}';
   }
 
   DartType get jsJavascriptObjectType =>
     _backend.helpers.jsJavaScriptObjectClass.thisType;
 }