Support allocation sinking for compound objects.

runtime/vm/flow_graph_optimizer.h

 // 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.
 
 #ifndef VM_FLOW_GRAPH_OPTIMIZER_H_
 #define VM_FLOW_GRAPH_OPTIMIZER_H_
 
 #include "vm/intermediate_language.h"
 #include "vm/flow_graph.h"
 
@@ skipping 411 matching lines @@
 class IfConverter : public AllStatic {
  public:
   static void Simplify(FlowGraph* flow_graph);
 };
 
 
 class AllocationSinking : public ZoneAllocated {
  public:
   explicit AllocationSinking(FlowGraph* flow_graph)
       : flow_graph_(flow_graph),
+        candidates_(5),
         materializations_(5) { }
 
+  const GrowableArray<AllocateObjectInstr*>& candidates() const {
+    return candidates_;
+  }
+
+  // Find the materialization insterted for the given allocation
+  // at the given exit.
+  MaterializeObjectInstr* MaterializationFor(Definition* alloc,
+                                             Instruction* exit);
+
   void Optimize();
 
   void DetachMaterializations();
 
  private:
+  void CollectCandidates();
+
+  void DiscoverFailedCandidates();
+
   void InsertMaterializations(AllocateObjectInstr* alloc);
 
   void CreateMaterializationAt(
       Instruction* exit,
       AllocateObjectInstr* alloc,
       const Class& cls,
       const ZoneGrowableArray<const Object*>& fields);
 
+  void EliminateAllocation(AllocateObjectInstr* alloc);
+
   Isolate* isolate() const { return flow_graph_->isolate(); }
 
   FlowGraph* flow_graph_;
 
+  GrowableArray<AllocateObjectInstr*> candidates_;
   GrowableArray<MaterializeObjectInstr*> materializations_;
 };
 
 
 // Optimize spill stores inside try-blocks by identifying values that always
 // contain a single known constant at catch block entry.
 class TryCatchAnalyzer : public AllStatic {
  public:
   static void Optimize(FlowGraph* flow_graph);
 };
 
 }  // namespace dart
 
 #endif  // VM_FLOW_GRAPH_OPTIMIZER_H_