Collect type feedback for fields.

runtime/vm/flow_graph_type_propagator.h

Index: runtime/vm/flow_graph_type_propagator.h
diff --git a/runtime/vm/flow_graph_type_propagator.h b/runtime/vm/flow_graph_type_propagator.h
index f01dc5f2dd6af2a3e3dcdb9cddf85792749c8602..a086186d519b4e1e9b35eba15c8ad839da9ac14e 100644
--- a/runtime/vm/flow_graph_type_propagator.h
+++ b/runtime/vm/flow_graph_type_propagator.h
@@ -18,6 +18,9 @@ class FlowGraphTypePropagator : public FlowGraphVisitor {
 
  private:
   void PropagateRecursive(BlockEntryInstr* block);
+  void HandleBranchOnNull(BlockEntryInstr* block);
+
+  void RollbackTo(intptr_t rollback_point);
 
   void VisitValue(Value* value);
 
@@ -25,6 +28,7 @@ class FlowGraphTypePropagator : public FlowGraphVisitor {
   virtual void VisitCheckSmi(CheckSmiInstr* instr);
   virtual void VisitCheckClass(CheckClassInstr* instr);
 
+

[Kevin Millikin (Google), 2013/03/12 12:14:56]

Huh?  I liked it better before.

[Vyacheslav Egorov (Google), 2013/03/12 16:54:40]

Done.

   // Current reaching type of the definition. Valid only during dominator tree
   // traversal.
   CompileType* TypeOf(Definition* def);
@@ -35,6 +39,8 @@ class FlowGraphTypePropagator : public FlowGraphVisitor {
   // Mark definition as having given class id in all dominated instructions.
   void SetCid(Definition* value, intptr_t cid);
 
+  void MarkNonNullable(Definition* value);
+
   void AddToWorklist(Definition* defn);
   Definition* RemoveLastFromWorklist();
 
@@ -44,6 +50,8 @@ class FlowGraphTypePropagator : public FlowGraphVisitor {
 
   FlowGraph* flow_graph_;
 
+  GrowableArray<bool> visited_;

[Kevin Millikin (Google), 2013/03/12 12:14:56]

BitVector?

[Vyacheslav Egorov (Google), 2013/03/12 16:54:40]

Yeah, that was stupid :-)

+
   // Mapping between SSA values and their current reaching types. Valid
   // only during dominator tree traversal.
   GrowableArray<CompileType*> types_;