Reduce use of Element in optimize.dart

pkg/compiler/lib/src/ssa/optimize.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 '../common/codegen.dart' show CodegenRegistry, CodegenWorkItem;
 import '../common/names.dart' show Selectors;
 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 CommonElements;
+import '../elements/elements.dart'
+    show ClassElement, Entity, FieldElement, MethodElement;
+import '../elements/entities.dart';
 import '../elements/resolution_types.dart';
-import '../elements/elements.dart';
-import '../elements/entities.dart';
 import '../js/js.dart' as js;
 import '../js_backend/backend_helpers.dart' show BackendHelpers;
 import '../js_backend/js_backend.dart';
 import '../native/native.dart' as native;
 import '../tree/dartstring.dart' as ast;
 import '../types/types.dart';
 import '../universe/selector.dart' show Selector;
 import '../universe/side_effects.dart' show SideEffects;
 import '../util/util.dart';
 import '../world.dart' show ClosedWorld;
@@ skipping 311 matching lines @@
     if (actualReceiver.isIndexablePrimitive(closedWorld)) {
       if (actualReceiver.isConstantString()) {
         HConstant constantInput = actualReceiver;
         StringConstantValue constant = constantInput.constant;
         return graph.addConstantInt(constant.length, closedWorld);
       } else if (actualReceiver.isConstantList()) {
         HConstant constantInput = actualReceiver;
         ListConstantValue constant = constantInput.constant;
         return graph.addConstantInt(constant.length, closedWorld);
       }
-      MemberElement element = helpers.jsIndexableLength;
+      MemberEntity element = helpers.jsIndexableLength;
       bool isFixed = isFixedLength(actualReceiver.instructionType, closedWorld);
       TypeMask actualType = node.instructionType;
       TypeMask resultType = closedWorld.commonMasks.positiveIntType;
       // If we already have computed a more specific type, keep that type.
       if (HInstruction.isInstanceOf(
           actualType, helpers.jsUInt31Class, closedWorld)) {
         resultType = closedWorld.commonMasks.uint31Type;
       } else if (HInstruction.isInstanceOf(
           actualType, helpers.jsUInt32Class, closedWorld)) {
         resultType = closedWorld.commonMasks.uint32Type;
@@ skipping 21 matching lines @@
 
     // Try converting the instruction to a builtin instruction.
     HInstruction instruction =
         node.specializer.tryConvertToBuiltin(node, compiler, closedWorld);
     if (instruction != null) return instruction;
 
     Selector selector = node.selector;
     TypeMask mask = node.mask;
     HInstruction input = node.inputs[1];
 
-    bool applies(Element element) {
+    bool applies(MemberEntity element) {
       return selector.applies(element) &&
           (mask == null || mask.canHit(element, selector, closedWorld));
     }
 
     if (selector.isCall || selector.isOperator) {
-      MethodElement target;
+      FunctionEntity target;
       if (input.isExtendableArray(closedWorld)) {
         if (applies(helpers.jsArrayRemoveLast)) {
           target = helpers.jsArrayRemoveLast;
         } else if (applies(helpers.jsArrayAdd)) {
           // The codegen special cases array calls, but does not
           // inline argument type checks.
           if (!compiler.options.enableTypeAssertions) {
             target = helpers.jsArrayAdd;
           }
         }
@@ skipping 40 matching lines @@
   }
 
   HInstruction visitInvokeDynamicMethod(HInvokeDynamicMethod node) {
     propagateConstantValueToUses(node);
     if (node.isInterceptedCall) {
       HInstruction folded = handleInterceptedCall(node);
       if (folded != node) return folded;
     }
 
     TypeMask receiverType = node.getDartReceiver(closedWorld).instructionType;
-    Element element =
+    MemberEntity element =
         closedWorld.locateSingleElement(node.selector, receiverType);
     // TODO(ngeoffray): Also fold if it's a getter or variable.
     if (element != null &&
         element.isFunction
         // If we found out that the only target is an implicitly called
         // [:noSuchMethod:] we just ignore it.
         &&
         node.selector.applies(element)) {
       MethodElement method = element;
 
       if (backend.isNative(method)) {
         HInstruction folded = tryInlineNativeMethod(node, method);
         if (folded != null) return folded;
       } else {
         // TODO(ngeoffray): If the method has optional parameters,
         // we should pass the default values.
-        FunctionSignature parameters = method.functionSignature;
-        if (parameters.optionalParameterCount == 0 ||
-            parameters.parameterCount == node.selector.argumentCount) {
+        FunctionType type = method.type;
+        int optionalParameterCount =
+            type.optionalParameterTypes.length + type.namedParameters.length;
+        if (optionalParameterCount == 0 ||
+                type.parameterTypes.length + optionalParameterCount ==
+                node.selector.argumentCount) {
           node.element = method;
         }
       }
       return node;
     }
 
     // Replace method calls through fields with a closure call on the value of
     // the field. This usually removes the demand for the call-through stub and
     // makes the field load available to further optimization, e.g. LICM.
 
     if (element != null &&
         element.isField &&
         element.name == node.selector.name) {
-      FieldElement field = element;
+      FieldEntity field = element;
       if (!backend.isNative(field) && !node.isCallOnInterceptor(closedWorld)) {
         HInstruction receiver = node.getDartReceiver(closedWorld);
         TypeMask type = TypeMaskFactory.inferredTypeForElement(
-            field, globalInferenceResults);
+            field as Entity, globalInferenceResults);

[sra1, 2017/01/04 17:20:48]

Why is 'as' needed? is a FieldEntity not an Entity?

[Johnni Winther, 2017/01/05 08:54:42]

It is. The Dart type system doesn't handle diamond properties in assignment: 

  Entity <: Element <: FieldElement
  Entity <: FieldEntity <: FieldElement

so I need to show it why FieldEntity and Element are related. Hopefully the VM
can realize that `as Entity` always succeeds.

[Siggi Cherem (dart-lang), 2017/01/05 18:14:08]

mmm... this feels like it might be hiding the issue, we could also just write
`as Object` :-). Maybe this should be `as Element` so that we know it can only
be removed when `inferredTypeForElement` changes to be based on entities?

[Johnni Winther, 2017/01/06 09:04:51]

I like _not_ being able to write `Element` in this file (part of my measure of
progress)...

I should be removed when [inferredTypeForElement] is using entities.

         HInstruction load = new HFieldGet(field, receiver, type);
         node.block.addBefore(node, load);
         Selector callSelector = new Selector.callClosureFrom(node.selector);
         List<HInstruction> inputs = <HInstruction>[load]
           ..addAll(node.inputs.skip(node.isInterceptedCall ? 2 : 1));
         HInstruction closureCall =
             new HInvokeClosure(callSelector, inputs, node.instructionType)
               ..sourceInformation = node.sourceInformation;
         node.block.addAfter(load, closureCall);
         return closureCall;
@@ skipping 14 matching lines @@
     // TODO(ngeoffray): There are some cases where we could still inline in
     // checked mode if we know the arguments have the right type. And we could
     // do the closure conversion as well as the return type annotation check.
 
     if (!node.isInterceptedCall) return null;
 
     // TODO(sra): Check for legacy methods with bodies in the native strings.
     //   foo() native 'return something';
     // They should not be used.
 
-    FunctionSignature signature = method.functionSignature;
-    if (signature.optionalParametersAreNamed) return null;
+    FunctionType type = method.type;
+    if (type.namedParameters.isNotEmpty) return null;
 
     // Return types on native methods don't need to be checked, since the
     // declaration has to be truthful.
 
     // The call site might omit optional arguments. The inlined code must
     // preserve the number of arguments, so check only the actual arguments.
 
     List<HInstruction> inputs = node.inputs.sublist(1);
-    int inputPosition = 1; // Skip receiver.
     bool canInline = true;
-    signature.forEachParameter((ParameterElement element) {
-      if (inputPosition++ < inputs.length && canInline) {
-        DartType type = element.type.unaliased;
-        if (type is FunctionType) {
-          canInline = false;
-        }
-        if (compiler.options.enableTypeAssertions) {
-          // TODO(sra): Check if [input] is guaranteed to pass the parameter
-          // type check.  Consider using a strengthened type check to avoid
-          // passing `null` to primitive types since the native methods usually
-          // have non-nullable primitive parameter types.
-          canInline = false;
+    if (compiler.options.enableTypeAssertions && inputs.length > 1) {
+      // TODO(sra): Check if [input] is guaranteed to pass the parameter
+      // type check.  Consider using a strengthened type check to avoid
+      // passing `null` to primitive types since the native methods usually
+      // have non-nullable primitive parameter types.
+      canInline = false;
+    } else {
+      int inputPosition = 1; // Skip receiver.
+      void checkParameterType(DartType type) {
+        if (inputPosition++ < inputs.length && canInline) {
+          if (type.unaliased.isFunctionType) {
+            canInline = false;
+          }
         }
       }
-    });
+
+      type.parameterTypes.forEach(checkParameterType);
+      type.optionalParameterTypes.forEach(checkParameterType);
+      type.namedParameterTypes.forEach(checkParameterType);
+    }
 
     if (!canInline) return null;
 
     // Strengthen instruction type from annotations to help optimize
     // dependent instructions.
     native.NativeBehavior nativeBehavior =
         backend.getNativeMethodBehavior(method);
     TypeMask returnType =
         TypeMaskFactory.fromNativeBehavior(nativeBehavior, closedWorld);
     HInvokeDynamicMethod result =
@@ skipping 160 matching lines @@
         simplifyCondition(node.elseBlock, hoisted, true);
       });
     }
     simplifyCondition(node.thenBlock, condition, !isNegated);
     simplifyCondition(node.elseBlock, condition, isNegated);
     return node;
   }
 
   HInstruction visitIs(HIs node) {
     DartType type = node.typeExpression;
-    Element element = type.element;
 
     if (!node.isRawCheck) {
       return node;
     } else if (type.isTypedef) {
       return node;
-    } else if (element == commonElements.functionClass) {
+    } else if (type.isFunctionType) {
       return node;
     }
 
     if (type.isObject || type.treatAsDynamic) {
       return graph.addConstantBool(true, closedWorld);
     }
-
+    InterfaceType interfaceType = type;
+    ClassEntity element = interfaceType.element;
     HInstruction expression = node.expression;
     if (expression.isInteger(closedWorld)) {
       if (element == commonElements.intClass ||
           element == commonElements.numClass ||
           commonElements.isNumberOrStringSupertype(element)) {
         return graph.addConstantBool(true, closedWorld);
       } else if (element == commonElements.doubleClass) {
         // We let the JS semantics decide for that check. Currently
         // the code we emit will always return true.
         return node;
@@ skipping 82 matching lines @@
 
   HInstruction removeIfCheckAlwaysSucceeds(HCheck node, TypeMask checkedType) {
     if (checkedType.containsAll(closedWorld)) return node;
     HInstruction input = node.checkedInput;
     TypeMask inputType = input.instructionType;
     return inputType.isInMask(checkedType, closedWorld) ? input : node;
   }
 
   HInstruction removeCheck(HCheck node) => node.checkedInput;
 
-  FieldElement findConcreteFieldForDynamicAccess(
+  FieldEntity findConcreteFieldForDynamicAccess(
       HInstruction receiver, Selector selector) {
     TypeMask receiverType = receiver.instructionType;
     return closedWorld.locateSingleField(selector, receiverType);
   }
 
   HInstruction visitFieldGet(HFieldGet node) {
     if (node.isNullCheck) return node;
     var receiver = node.receiver;
     if (node.element == helpers.jsIndexableLength) {
       if (graph.allocatedFixedLists.contains(receiver)) {
@@ skipping 55 matching lines @@
     return node;
   }
 
   HInstruction visitInvokeDynamicGetter(HInvokeDynamicGetter node) {
     propagateConstantValueToUses(node);
     if (node.isInterceptedCall) {
       HInstruction folded = handleInterceptedCall(node);
       if (folded != node) return folded;
     }
     HInstruction receiver = node.getDartReceiver(closedWorld);
-    FieldElement field =
+    FieldEntity field =
         findConcreteFieldForDynamicAccess(receiver, node.selector);
     if (field != null) return directFieldGet(receiver, field);
 
     if (node.element == null) {
-      MemberElement element = closedWorld.locateSingleElement(
+      MemberEntity element = closedWorld.locateSingleElement(
           node.selector, receiver.instructionType);
       if (element != null && element.name == node.selector.name) {
         node.element = element;
         if (element.isFunction) {
           // A property extraction getter, aka a tear-off.
           node.sideEffects.clearAllDependencies();
           node.sideEffects.clearAllSideEffects();
           node.setUseGvn(); // We don't care about identity of tear-offs.
         }
       }
     }
     return node;
   }
 
-  HInstruction directFieldGet(HInstruction receiver, FieldElement field) {
-    bool isAssignable = !closedWorld.fieldNeverChanges(field);
+  HInstruction directFieldGet(HInstruction receiver, FieldEntity field) {
+    bool isAssignable = !closedWorld.fieldNeverChanges(field as MemberEntity);
 
     TypeMask type;
     if (backend.isNative(field.enclosingClass)) {
       type = TypeMaskFactory.fromNativeBehavior(
           backend.getNativeFieldLoadBehavior(field), closedWorld);
     } else {
-      type =
-          TypeMaskFactory.inferredTypeForElement(field, globalInferenceResults);
+      type = TypeMaskFactory.inferredTypeForElement(
+          field as Entity, globalInferenceResults);
     }
 
     return new HFieldGet(field, receiver, type, isAssignable: isAssignable);
   }
 
   HInstruction visitInvokeDynamicSetter(HInvokeDynamicSetter node) {
     if (node.isInterceptedCall) {
       HInstruction folded = handleInterceptedCall(node);
       if (folded != node) return folded;
     }
@@ skipping 21 matching lines @@
       if (other != value) {
         node.block.addBefore(node, other);
         value = other;
       }
     }
     return new HFieldSet(field, receiver, value);
   }
 
   HInstruction visitInvokeStatic(HInvokeStatic node) {
     propagateConstantValueToUses(node);
-    MemberElement element = node.element;
+    MemberEntity element = node.element;
 
     if (element == backend.helpers.checkConcurrentModificationError) {
       if (node.inputs.length == 2) {
         HInstruction firstArgument = node.inputs[0];
         if (firstArgument is HConstant) {
           HConstant constant = firstArgument;
           if (constant.constant.isTrue) return constant;
         }
       }
     } else if (element == backend.helpers.checkInt) {
@@ skipping 110 matching lines @@
       return null;
     }
 
     return tryConstant() ?? tryToString() ?? node;
   }
 
   HInstruction visitOneShotInterceptor(HOneShotInterceptor node) {
     return handleInterceptedCall(node);
   }
 
-  bool needsSubstitutionForTypeVariableAccess(ClassElement cls) {
+  bool needsSubstitutionForTypeVariableAccess(ClassEntity cls) {
     if (closedWorld.isUsedAsMixin(cls)) return true;
 
-    return closedWorld.anyStrictSubclassOf(cls, (ClassElement subclass) {
+    return closedWorld.anyStrictSubclassOf(cls, (ClassEntity subclass) {
       return !backend.rti.isTrivialSubstitution(subclass, cls);
     });
   }
 
   HInstruction visitTypeInfoExpression(HTypeInfoExpression node) {
     // Identify the case where the type info expression would be of the form:
     //
     //  [getTypeArgumentByIndex(this, 0), .., getTypeArgumentByIndex(this, k)]
     //
     // and k is the number of type arguments of 'this'.  We can simply copy the
@@ skipping 217 matching lines @@
     index = insertBoundsCheck(node, node.receiver, index);
   }
 
   void visitIndexAssign(HIndexAssign node) {
     if (boundsChecked.contains(node)) return;
     HInstruction index = node.index;
     index = insertBoundsCheck(node, node.receiver, index);
   }
 
   void visitInvokeDynamicMethod(HInvokeDynamicMethod node) {
-    MemberElement element = node.element;
+    MemberEntity element = node.element;
     if (node.isInterceptedCall) return;
     if (element != helpers.jsArrayRemoveLast) return;
     if (boundsChecked.contains(node)) return;
     // `0` is the index we want to check, but we want to report `-1`, as if we
     // executed `a[a.length-1]`
     HBoundsCheck check = insertBoundsCheck(
         node, node.receiver, graph.addConstantInt(0, closedWorld));
     HInstruction minusOne = graph.addConstantInt(-1, closedWorld);
     check.inputs.add(minusOne);
     minusOne.usedBy.add(check);
@@ skipping 743 matching lines @@
 
     HTypeKnown newInput = new HTypeKnown.pinned(convertedType, input);
     dominator.addBefore(dominator.first, newInput);
     dominatedUsers.forEach((HInstruction user) {
       user.changeUse(input, newInput);
     });
   }
 
   void visitIs(HIs instruction) {
     DartType type = instruction.typeExpression;
-    Element element = type.element;
     if (!instruction.isRawCheck) {
       return;
-    } else if (element.isTypedef) {
+    } else if (type.isTypedef) {
       return;
     }
+    InterfaceType interfaceType = type;
+    ClassEntity cls = interfaceType.element;
 
     List<HBasicBlock> trueTargets = <HBasicBlock>[];
     List<HBasicBlock> falseTargets = <HBasicBlock>[];
 
     collectTargets(instruction, trueTargets, falseTargets);
 
     if (trueTargets.isEmpty && falseTargets.isEmpty) return;
 
-    TypeMask convertedType = new TypeMask.nonNullSubtype(element, closedWorld);
+    TypeMask convertedType = new TypeMask.nonNullSubtype(cls, closedWorld);
     HInstruction input = instruction.expression;
 
     for (HBasicBlock block in trueTargets) {
       insertTypePropagationForDominatedUsers(block, input, convertedType);
     }
     // TODO(sra): Also strengthen uses for when the condition is known
     // false. Avoid strengthening to `null`.
   }
 
   void visitIdentity(HIdentity instruction) {
@@ skipping 121 matching lines @@
     HInstruction instruction = block.first;
     while (instruction != null) {
       HInstruction next = instruction.next;
       instruction.accept(this);
       instruction = next;
     }
   }
 
   void visitFieldGet(HFieldGet instruction) {
     if (instruction.isNullCheck) return;
-    MemberElement element = instruction.element;
+    MemberEntity element = instruction.element;
     HInstruction receiver = instruction.getDartReceiver(closedWorld).nonCheck();
     HInstruction existing = memorySet.lookupFieldValue(element, receiver);
     if (existing != null) {
       instruction.block.rewriteWithBetterUser(instruction, existing);
       instruction.block.remove(instruction);
     } else {
       memorySet.registerFieldValue(element, receiver, instruction);
     }
   }
 
   void visitFieldSet(HFieldSet instruction) {
     HInstruction receiver = instruction.getDartReceiver(closedWorld).nonCheck();
     memorySet.registerFieldValueUpdate(
         instruction.element, receiver, instruction.inputs.last);
   }
 
   void visitCreate(HCreate instruction) {
     memorySet.registerAllocation(instruction);
     if (shouldTrackInitialValues(instruction)) {
       int argumentIndex = 0;
       compiler.codegenWorld.forEachInstanceField(instruction.element,
-          (_, FieldElement member) {
-        if (compiler.elementHasCompileTimeError(member)) return;
+          (_, FieldEntity member) {
+        if (compiler.elementHasCompileTimeError(member as Entity)) return;
         memorySet.registerFieldValue(
             member, instruction, instruction.inputs[argumentIndex++]);
       });
     }
     // In case this instruction has as input non-escaping objects, we
     // need to mark these objects as escaping.
     memorySet.killAffectedBy(instruction);
   }
 
   bool shouldTrackInitialValues(HCreate instruction) {
@@ skipping 35 matching lines @@
   }
 
   void visitInstruction(HInstruction instruction) {
     if (instruction.isAllocation) {
       memorySet.registerAllocation(instruction);
     }
     memorySet.killAffectedBy(instruction);
   }
 
   void visitLazyStatic(HLazyStatic instruction) {
-    FieldElement field = instruction.element;
+    FieldEntity field = instruction.element;
     handleStaticLoad(field, instruction);
   }
 
-  void handleStaticLoad(MemberElement element, HInstruction instruction) {
+  void handleStaticLoad(MemberEntity element, HInstruction instruction) {
     HInstruction existing = memorySet.lookupFieldValue(element, null);
     if (existing != null) {
       instruction.block.rewriteWithBetterUser(instruction, existing);
       instruction.block.remove(instruction);
     } else {
       memorySet.registerFieldValue(element, null, instruction);
     }
   }
 
   void visitStatic(HStatic instruction) {
@@ skipping 54 matching lines @@
  * other checks removed to ensure that checks and type refinements do not
  * confuse aliasing.  Values stored into a memory place keep the type
  * refinements to help further optimizations.
  */
 class MemorySet {
   final ClosedWorld closedWorld;
 
   /**
    * Maps a field to a map of receiver to value.
    */
-  final Map<Element, Map<HInstruction, HInstruction>> fieldValues =
-      <Element, Map<HInstruction, HInstruction>>{};
+  final Map<MemberEntity, Map<HInstruction, HInstruction>> fieldValues =
+      <MemberEntity, Map<HInstruction, HInstruction>>{};
 
   /**
    * Maps a receiver to a map of keys to value.
    */
   final Map<HInstruction, Map<HInstruction, HInstruction>> keyedValues =
       <HInstruction, Map<HInstruction, HInstruction>>{};
 
   /**
    * Set of objects that we know don't escape the current function.
    */
@@ skipping 15 matching lines @@
     if (mustAlias(first, second)) return true;
     if (isConcrete(first) && isConcrete(second)) return false;
     if (nonEscapingReceivers.contains(first)) return false;
     if (nonEscapingReceivers.contains(second)) return false;
     // Typed arrays of different types might have a shared buffer.
     if (couldBeTypedArray(first) && couldBeTypedArray(second)) return true;
     return !first.instructionType
         .isDisjoint(second.instructionType, closedWorld);
   }
 
-  bool isFinal(Element element) {
+  bool isFinal(MemberEntity element) {
     return closedWorld.fieldNeverChanges(element);
   }
 
   bool isConcrete(HInstruction instruction) {
     return instruction is HCreate ||
         instruction is HConstant ||
         instruction is HLiteralList;
   }
 
   bool couldBeTypedArray(HInstruction receiver) {
@@ skipping 11 matching lines @@
   void registerAllocation(HInstruction instruction) {
     assert(instruction == instruction.nonCheck());
     nonEscapingReceivers.add(instruction);
   }
 
   /**
    * Sets `receiver.element` to contain [value]. Kills all potential places that
    * may be affected by this update.
    */
   void registerFieldValueUpdate(
-      MemberElement element, HInstruction receiver, HInstruction value) {
+      MemberEntity element, HInstruction receiver, HInstruction value) {
     assert(receiver == null || receiver == receiver.nonCheck());
-    if (closedWorld.backendClasses.isNative(element)) {
+    if (closedWorld.backendClasses.isNativeMember(element)) {
       return; // TODO(14955): Remove this restriction?
     }
     // [value] is being set in some place in memory, we remove it from
     // the non-escaping set.
     nonEscapingReceivers.remove(value.nonCheck());
     Map<HInstruction, HInstruction> map =
         fieldValues.putIfAbsent(element, () => <HInstruction, HInstruction>{});
     map.forEach((key, value) {
       if (mayAlias(receiver, key)) map[key] = null;
     });
     map[receiver] = value;
   }
 
   /**
    * Registers that `receiver.element` is now [value].
    */
   void registerFieldValue(
-      MemberElement element, HInstruction receiver, HInstruction value) {
+      MemberEntity element, HInstruction receiver, HInstruction value) {
     assert(receiver == null || receiver == receiver.nonCheck());
-    if (closedWorld.backendClasses.isNative(element)) {
+    if (closedWorld.backendClasses.isNativeMember(element)) {
       return; // TODO(14955): Remove this restriction?
     }
     Map<HInstruction, HInstruction> map =
         fieldValues.putIfAbsent(element, () => <HInstruction, HInstruction>{});
     map[receiver] = value;
   }
 
   /**
    * Returns the value stored in `receiver.element`. Returns `null` if we don't
    * know.
    */
-  HInstruction lookupFieldValue(Element element, HInstruction receiver) {
+  HInstruction lookupFieldValue(MemberEntity element, HInstruction receiver) {
     assert(receiver == null || receiver == receiver.nonCheck());
     Map<HInstruction, HInstruction> map = fieldValues[element];
     return (map == null) ? null : map[receiver];
   }
 
   /**
    * Kill all places that may be affected by this [instruction]. Also update the
    * set of non-escaping objects in case [instruction] has non-escaping objects
    * in its inputs.
    */
   void killAffectedBy(HInstruction instruction) {
     // Even if [instruction] does not have side effects, it may use non-escaping
     // objects and store them in a new object, which make these objects
     // escaping.
     instruction.inputs.forEach((input) {
       nonEscapingReceivers.remove(input.nonCheck());
     });
 
     if (instruction.sideEffects.changesInstanceProperty() ||
         instruction.sideEffects.changesStaticProperty()) {
-      fieldValues.forEach((element, map) {
+      fieldValues.forEach((MemberEntity element, map) {
         if (isFinal(element)) return;
         map.forEach((receiver, value) {
           if (escapes(receiver)) {
             map[receiver] = null;
           }
         });
       });
     }
 
     if (instruction.sideEffects.changesIndex()) {
@@ skipping 162 matching lines @@
 
     keyedValues.forEach((receiver, values) {
       result.keyedValues[receiver] =
           new Map<HInstruction, HInstruction>.from(values);
     });
 
     result.nonEscapingReceivers.addAll(nonEscapingReceivers);
     return result;
   }
 }