Improve and simplify removal of unreachable code

src/hydrogen.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 152 matching lines @@
   // Simulate (caller's environment)
   // Goto (target block)
   bool IsInlineReturnTarget() const { return is_inline_return_target_; }
   void MarkAsInlineReturnTarget(HBasicBlock* inlined_entry_block) {
     is_inline_return_target_ = true;
     inlined_entry_block_ = inlined_entry_block;
   }
   HBasicBlock* inlined_entry_block() { return inlined_entry_block_; }
 
   bool IsDeoptimizing() const { return is_deoptimizing_; }
-  void MarkAsDeoptimizing() { is_deoptimizing_ = true; }
+  void MarkAsDeoptimizing();
+
+  void MarkUnreachable();
+  bool IsUnreachable() const { return !is_reachable_; }
+  bool IsReachable() const { return is_reachable_; }
 
   bool IsLoopSuccessorDominator() const {
     return dominates_loop_successors_;
   }
   void MarkAsLoopSuccessorDominator() {
     dominates_loop_successors_ = true;
   }
 
   inline Zone* zone() const;
 
@@ skipping 22 matching lines @@
   HEnvironment* last_environment_;
   // Outgoing parameter count at block exit, set during lithium translation.
   int argument_count_;
   // Instruction indices into the lithium code stream.
   int first_instruction_index_;
   int last_instruction_index_;
   ZoneList<int> deleted_phis_;
   HBasicBlock* parent_loop_header_;
   // For blocks marked as inline return target: the block with HEnterInlined.
   HBasicBlock* inlined_entry_block_;
+  bool is_reachable_ : 1;
   bool is_inline_return_target_ : 1;
   bool is_deoptimizing_ : 1;
   bool dominates_loop_successors_ : 1;
   bool is_osr_entry_ : 1;
 };
 
 
 class HPredecessorIterator BASE_EMBEDDED {
  public:
   explicit HPredecessorIterator(HBasicBlock* block)
@@ skipping 221 matching lines @@
   }
 
   void RecordUint32Instruction(HInstruction* instr) {
     ASSERT(uint32_instructions_ == NULL || !uint32_instructions_->is_empty());
     if (uint32_instructions_ == NULL) {
       uint32_instructions_ = new(zone()) ZoneList<HInstruction*>(4, zone());
     }
     uint32_instructions_->Add(instr, zone());
   }
 
+  void MarkHasUnreachableCode() { has_unreachable_code_ = true; }
+  bool HasUnreachableCode() const { return has_unreachable_code_; }
+
   void IncrementInNoSideEffectsScope() { no_side_effects_scope_count_++; }
   void DecrementInNoSideEffectsScope() { no_side_effects_scope_count_--; }
   bool IsInsideNoSideEffectsScope() { return no_side_effects_scope_count_ > 0; }
 
  private:
   HConstant* GetConstant(SetOncePointer<HConstant>* pointer,
                          int32_t integer_value);
 
   template<class Phase>
   void Run() {
@@ skipping 23 matching lines @@
   SetOncePointer<HConstant> constant_the_hole_;
   SetOncePointer<HConstant> constant_null_;
   SetOncePointer<HConstant> constant_invalid_context_;
   SetOncePointer<HArgumentsObject> arguments_object_;
 
   HOsrBuilder* osr_;
 
   CompilationInfo* info_;
   Zone* zone_;
 
+  bool has_unreachable_code_;
   bool is_recursive_;
   bool use_optimistic_licm_;
   bool has_soft_deoptimize_;
   bool depends_on_empty_array_proto_elements_;
   int type_change_checksum_;
   int maximum_environment_size_;
   int no_side_effects_scope_count_;
 
   DISALLOW_COPY_AND_ASSIGN(HGraph);
 };
@@ skipping 1812 matching lines @@
   }
 
  private:
   HGraphBuilder* builder_;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_H_