Reapply "Initial implementation of sparse conditional constant propagation."

runtime/vm/flow_graph.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_H_
 #define VM_FLOW_GRAPH_H_
 
 #include "vm/growable_array.h"
 #include "vm/parser.h"
 
@@ skipping 98 matching lines @@
   // TODO(zerny): Once the SSA is feature complete this should be removed.
   void Bailout(const char* reason) const;
 
 #ifdef DEBUG
   // Validation methods for debugging.
   bool ResetUseLists();
   bool ValidateUseLists();
 #endif  // DEBUG
 
  private:
+  friend class ConstantPropagator;
+
   void DiscoverBlocks();
 
   // SSA transformation methods and fields.
-  void ComputeDominators(
-      GrowableArray<BlockEntryInstr*>* preorder,
-      GrowableArray<intptr_t>* parent,
-      GrowableArray<BitVector*>* dominance_frontier);
+  void ComputeDominators(GrowableArray<BitVector*>* dominance_frontier);
 
   void CompressPath(
       intptr_t start_index,
       intptr_t current_index,
       GrowableArray<intptr_t>* parent,
       GrowableArray<intptr_t>* label);
 
   void Rename(GrowableArray<PhiInstr*>* live_phis);
   void RenameRecursive(
       BlockEntryInstr* block_entry,
@@ skipping 22 matching lines @@
   GraphEntryInstr* graph_entry_;
   GrowableArray<BlockEntryInstr*> preorder_;
   GrowableArray<BlockEntryInstr*> postorder_;
   GrowableArray<BlockEntryInstr*> reverse_postorder_;
   ZoneGrowableArray<ReturnInstr*>* exits_;
 };
 
 }  // namespace dart
 
 #endif  // VM_FLOW_GRAPH_H_