Remove class HSubgraph.

src/hydrogen.h

Index: src/hydrogen.h
diff --git a/src/hydrogen.h b/src/hydrogen.h
index 5be839b62fdb4e062a04b11f1e016c3565d1eb0a..b359db3f7dd3a4dffe5207e796e54b988d06fce8 100644
--- a/src/hydrogen.h
+++ b/src/hydrogen.h
@@ -192,40 +192,13 @@ class HLoopInformation: public ZoneObject {
 };
 
 
-class HSubgraph: public ZoneObject {
- public:
-  explicit HSubgraph(HGraph* graph)
-      : graph_(graph),
-        entry_block_(NULL),
-        exit_block_(NULL) {
-  }
-
-  HGraph* graph() const { return graph_; }
-  HBasicBlock* entry_block() const { return entry_block_; }
-  HBasicBlock* exit_block() const { return exit_block_; }
-  void set_exit_block(HBasicBlock* block) {
-    exit_block_ = block;
-  }
-
-  void Initialize(HBasicBlock* block) {
-    ASSERT(entry_block_ == NULL);
-    entry_block_ = block;
-    exit_block_ = block;
-  }
-
- protected:
-  HGraph* graph_;  // The graph this is a subgraph of.
-  HBasicBlock* entry_block_;
-  HBasicBlock* exit_block_;
-};
-
-
-class HGraph: public HSubgraph {
+class HGraph: public ZoneObject {
  public:
   explicit HGraph(CompilationInfo* info);
 
   const ZoneList<HBasicBlock*>* blocks() const { return &blocks_; }
   const ZoneList<HPhi*>* phi_list() const { return phi_list_; }
+  HBasicBlock* entry_block() const { return entry_block_; }
   HEnvironment* start_environment() const { return start_environment_; }
 
   void InitializeInferredTypes();
@@ -304,6 +277,7 @@ class HGraph: public HSubgraph {
   void CheckForBackEdge(HBasicBlock* block, HBasicBlock* successor);
 
   int next_block_id_;
+  HBasicBlock* entry_block_;
   HEnvironment* start_environment_;
   ZoneList<HBasicBlock*> blocks_;
   ZoneList<HValue*> values_;
@@ -315,8 +289,6 @@ class HGraph: public HSubgraph {
   SetOncePointer<HConstant> constant_false_;
   SetOncePointer<HArgumentsObject> arguments_object_;
 
-  friend class HSubgraph;
-
   DISALLOW_COPY_AND_ASSIGN(HGraph);
 };
 
@@ -643,7 +615,7 @@ class HGraphBuilder: public AstVisitor {
         ast_context_(NULL),
         break_scope_(NULL),
         graph_(NULL),
-        current_subgraph_(NULL),
+        current_block_(NULL),
         inlined_count_(0) {
     // This is not initialized in the initializer list because the
     // constructor for the initial state relies on function_state_ == NULL
@@ -655,14 +627,11 @@ class HGraphBuilder: public AstVisitor {
 
   // Simple accessors.
   HGraph* graph() const { return graph_; }
-  HSubgraph* subgraph() const { return current_subgraph_; }
   BreakAndContinueScope* break_scope() const { return break_scope_; }
   void set_break_scope(BreakAndContinueScope* head) { break_scope_ = head; }
 
-  HBasicBlock* current_block() const { return subgraph()->exit_block(); }
-  void set_current_block(HBasicBlock* block) {
-    subgraph()->set_exit_block(block);
-  }
+  HBasicBlock* current_block() const { return current_block_; }
+  void set_current_block(HBasicBlock* block) { current_block_ = block; }
   HEnvironment* environment() const {
     return current_block()->last_environment();
   }
@@ -753,10 +722,6 @@ class HGraphBuilder: public AstVisitor {
                             HBasicBlock* exit_block,
                             HBasicBlock* continue_block);
 
-  void AddToSubgraph(HSubgraph* graph, ZoneList<Statement*>* stmts);
-  void AddToSubgraph(HSubgraph* graph, Statement* stmt);
-  void AddToSubgraph(HSubgraph* graph, Expression* expr);
-
   HValue* Top() const { return environment()->Top(); }
   void Drop(int n) { environment()->Drop(n); }
   void Bind(Variable* var, HValue* value) { environment()->Bind(var, value); }
@@ -908,7 +873,7 @@ class HGraphBuilder: public AstVisitor {
   BreakAndContinueScope* break_scope_;
 
   HGraph* graph_;
-  HSubgraph* current_subgraph_;
+  HBasicBlock* current_block_;
 
   int inlined_count_;