dart2js ssa: Avoid tracking too much in load elimination

pkg/compiler/lib/src/ssa/nodes.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.
 
 part of ssa;
 
 abstract class HVisitor<R> {
   R visitAdd(HAdd node);
   R visitAwait(HAwait node);
   R visitBitAnd(HBitAnd node);
@@ skipping 112 matching lines @@
         assert(instruction != list.first);
       }
     }
 
     currentBlock = node;
     visitInstructionList(node);
   }
 }
 
 class HGraph {
+  Element element;  // Used for debug printing.
   HBasicBlock entry;
   HBasicBlock exit;
   HThis thisInstruction;
   /// Receiver parameter, set for methods using interceptor calling convention.
   HParameterValue explicitReceiverParameter;
   bool isRecursiveMethod = false;
   bool calledInLoop = false;
-  final List<HBasicBlock> blocks;
+  final List<HBasicBlock> blocks = <HBasicBlock>[];
 
   // We canonicalize all constants used within a graph so we do not
   // have to worry about them for global value numbering.
-  Map<ConstantValue, HConstant> constants;
+  Map<ConstantValue, HConstant> constants = new Map<ConstantValue, HConstant>();
 
-  HGraph()
-      : blocks = new List<HBasicBlock>(),
-        constants = new Map<ConstantValue, HConstant>() {
+  HGraph() {
     entry = addNewBlock();
     // The exit block will be added later, so it has an id that is
     // after all others in the system.
     exit = new HBasicBlock();
   }
 
   void addBlock(HBasicBlock block) {
     int id = blocks.length;
     block.id = id;
     blocks.add(block);
@@ skipping 96 matching lines @@
         }
       }
     }
   }
 
   bool isValid() {
     HValidator validator = new HValidator();
     validator.visitGraph(this);
     return validator.isValid;
   }
+
+  toString() => 'HGraph($element)';
 }
 
 class HBaseVisitor extends HGraphVisitor implements HVisitor {
   HBasicBlock currentBlock;
 
   visitBasicBlock(HBasicBlock node) {
     currentBlock = node;
 
     HInstruction instruction = node.first;
     while (instruction != null) {
@@ skipping 1601 matching lines @@
   /// type arguments. See also [SsaFromAstMixin.currentInlinedInstantiations].
   List<DartType> instantiatedTypes;
 
   HForeignNew(this.element, TypeMask type, List<HInstruction> inputs,
               [this.instantiatedTypes])
       : super(type, inputs);
 
   accept(HVisitor visitor) => visitor.visitForeignNew(this);
 
   bool get isAllocation => true;
+
+  String toString() => 'HForeignNew($element)';
 }
 
 abstract class HInvokeBinary extends HInstruction {
   final Selector selector;
   HInvokeBinary(
       HInstruction left, HInstruction right, this.selector, TypeMask type)
       : super(<HInstruction>[left, right], type) {
     sideEffects.clearAllSideEffects();
     sideEffects.clearAllDependencies();
     setUseGvn();
@@ skipping 1426 matching lines @@
 class HDynamicType extends HRuntimeType {
   HDynamicType(DynamicType dartType, TypeMask instructionType)
       : super(const <HInstruction>[], dartType, instructionType);
 
   accept(HVisitor visitor) => visitor.visitDynamicType(this);
 
   int typeCode() => HInstruction.DYNAMIC_TYPE_TYPECODE;
 
   bool typeEquals(HInstruction other) => other is HDynamicType;
 }