Make special RPO computation iterative during scheduling.

src/compiler/schedule.h

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_COMPILER_SCHEDULE_H_
 #define V8_COMPILER_SCHEDULE_H_
 
 #include <iosfwd>
 #include <vector>
 
@@ skipping 127 matching lines @@
   // Accessors.
   Control control() const { return control_; }
   void set_control(Control control);
 
   Node* control_input() const { return control_input_; }
   void set_control_input(Node* control_input);
 
   bool deferred() const { return deferred_; }
   void set_deferred(bool deferred) { deferred_ = deferred; }
 
+  int32_t dominator_depth() const { return dominator_depth_; }
+  void set_dominator_depth(int32_t dominator_depth);
+
   BasicBlock* dominator() const { return dominator_; }
   void set_dominator(BasicBlock* dominator);
 
   BasicBlock* loop_header() const { return loop_header_; }
   void set_loop_header(BasicBlock* loop_header);
 
+  BasicBlock* loop_end() const { return loop_end_; }
+  void set_loop_end(BasicBlock* loop_end);
+
   int32_t loop_depth() const { return loop_depth_; }
   void set_loop_depth(int32_t loop_depth);
 
-  int32_t loop_end() const { return loop_end_; }
-  void set_loop_end(int32_t loop_end);
-
   RpoNumber GetAoNumber() const { return RpoNumber::FromInt(ao_number_); }
   int32_t ao_number() const { return ao_number_; }
   void set_ao_number(int32_t ao_number) { ao_number_ = ao_number; }
 
   RpoNumber GetRpoNumber() const { return RpoNumber::FromInt(rpo_number_); }
   int32_t rpo_number() const { return rpo_number_; }
   void set_rpo_number(int32_t rpo_number);
 
   // Loop membership helpers.
-  inline bool IsLoopHeader() const { return loop_end_ >= 0; }
+  inline bool IsLoopHeader() const { return loop_end_ != NULL; }
   bool LoopContains(BasicBlock* block) const;
 
  private:
   int32_t ao_number_;        // assembly order number of the block.
   int32_t rpo_number_;       // special RPO number of the block.
   bool deferred_;            // true if the block contains deferred code.
+  int32_t dominator_depth_;  // Depth within the dominator tree.
   BasicBlock* dominator_;    // Immediate dominator of the block.
   BasicBlock* loop_header_;  // Pointer to dominating loop header basic block,
                              // NULL if none. For loop headers, this points to
                              // enclosing loop header.
+  BasicBlock* loop_end_;     // end of the loop, if this block is a loop header.
   int32_t loop_depth_;       // loop nesting, 0 is top-level
-  int32_t loop_end_;         // end of the loop, if this block is a loop header.
 
   Control control_;          // Control at the end of the block.
   Node* control_input_;      // Input value for control.
   NodeVector nodes_;         // nodes of this block in forward order.
 
   Successors successors_;
   Predecessors predecessors_;
   Id id_;
 
   DISALLOW_COPY_AND_ASSIGN(BasicBlock);
@@ skipping 89 matching lines @@
   DISALLOW_COPY_AND_ASSIGN(Schedule);
 };
 
 std::ostream& operator<<(std::ostream& os, const Schedule& s);
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_SCHEDULE_H_