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 @@
   // LeaveInlined
   // 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; }
+  bool IsDeoptimizing() const {
+    return end() != NULL && end()->IsDeoptimize();
+  }
+
+  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 23 matching lines @@
   // 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_inline_return_target_ : 1;
-  bool is_deoptimizing_ : 1;
+  bool is_reachable_ : 1;
   bool dominates_loop_successors_ : 1;
   bool is_osr_entry_ : 1;
 };
 
 
 class HPredecessorIterator V8_FINAL BASE_EMBEDDED {
  public:
   explicit HPredecessorIterator(HBasicBlock* block)
       : predecessor_list_(block->predecessors()), current_(0) { }
 
@@ skipping 170 matching lines @@
   int maximum_environment_size() { return maximum_environment_size_; }
 
   bool use_optimistic_licm() {
     return use_optimistic_licm_;
   }
 
   void set_use_optimistic_licm(bool value) {
     use_optimistic_licm_ = value;
   }
 
-  bool has_soft_deoptimize() {
-    return has_soft_deoptimize_;
-  }
-
-  void set_has_soft_deoptimize(bool value) {
-    has_soft_deoptimize_ = value;
-  }
-
   void MarkRecursive() {
     is_recursive_ = true;
   }
 
   bool is_recursive() const {
     return is_recursive_;
   }
 
   void MarkDependsOnEmptyArrayProtoElements() {
     // Add map dependency if not already added.
@@ skipping 62 matching lines @@
   SetOncePointer<HConstant> constant_invalid_context_;
   SetOncePointer<HArgumentsObject> arguments_object_;
 
   HOsrBuilder* osr_;
 
   CompilationInfo* info_;
   Zone* zone_;
 
   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);
 };
 
 
 Zone* HBasicBlock::zone() const { return graph_->zone(); }
@@ skipping 1140 matching lines @@
 
 
 template<>
 inline HInstruction* HGraphBuilder::AddUncasted<HDeoptimize>(
     const char* reason, Deoptimizer::BailoutType type) {
   if (type == Deoptimizer::SOFT) {
     isolate()->counters()->soft_deopts_requested()->Increment();
     if (FLAG_always_opt) return NULL;
   }
   if (current_block()->IsDeoptimizing()) return NULL;
-  HDeoptimize* instr = New<HDeoptimize>(reason, type);
-  AddInstruction(instr);
+  HBasicBlock* after_deopt_block = CreateBasicBlock(
+      current_block()->last_environment());
+  HDeoptimize* instr = New<HDeoptimize>(reason, type, after_deopt_block);
   if (type == Deoptimizer::SOFT) {
     isolate()->counters()->soft_deopts_inserted()->Increment();
-    graph()->set_has_soft_deoptimize(true);
   }
-  current_block()->MarkAsDeoptimizing();
+  current_block()->Finish(instr);
+  set_current_block(after_deopt_block);
   return instr;
 }
 
 
 template<>
 inline HDeoptimize* HGraphBuilder::Add<HDeoptimize>(
     const char* reason, Deoptimizer::BailoutType type) {
   return static_cast<HDeoptimize*>(AddUncasted<HDeoptimize>(reason, type));
 }
 
@@ skipping 799 matching lines @@
   }
 
  private:
   HGraphBuilder* builder_;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_H_