Lithium LLabel instruction are no longer used as gap instructions.

src/x64/lithium-x64.h

 // Copyright 2011 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 390 matching lines @@
   int gap_instructions_size_;
 };
 
 
 class LDeoptimize: public LTemplateInstruction<0, 0, 0> {
  public:
   DECLARE_CONCRETE_INSTRUCTION(Deoptimize, "deoptimize")
 };
 
 
-class LLabel: public LGap {
+class LLabel: public LTemplateInstruction<0, 0, 0> {
  public:
   explicit LLabel(HBasicBlock* block)
-      : LGap(block), replacement_(NULL) { }
+      : block_(block), replacement_(NULL) { }
 
   DECLARE_CONCRETE_INSTRUCTION(Label, "label")
 
   virtual void PrintDataTo(StringStream* stream);
 
-  int block_id() const { return block()->block_id(); }
-  bool is_loop_header() const { return block()->IsLoopHeader(); }
+  int block_id() const { return block_->block_id(); }
+  bool is_loop_header() const { return block_->IsLoopHeader(); }
   Label* label() { return &label_; }
   LLabel* replacement() const { return replacement_; }
   void set_replacement(LLabel* label) { replacement_ = label; }
   bool HasReplacement() const { return replacement_ != NULL; }
 
  private:
   Label label_;
+  HBasicBlock* block_;
   LLabel* replacement_;
 };
 
 
 class LParameter: public LTemplateInstruction<1, 0, 0> {
  public:
   DECLARE_CONCRETE_INSTRUCTION(Parameter, "parameter")
 };
 
 
@@ skipping 1558 matching lines @@
   LGap* GetGapAt(int index) const;
   bool IsGapAt(int index) const;
   int NearestGapPos(int index) const;
   void MarkEmptyBlocks();
   const ZoneList<LPointerMap*>* pointer_maps() const { return &pointer_maps_; }
   LLabel* GetLabel(int block_id) const {
     HBasicBlock* block = graph_->blocks()->at(block_id);
     int first_instruction = block->first_instruction_index();
     return LLabel::cast(instructions_[first_instruction]);
   }
+  LGap* GetFirstGap(HBasicBlock* block) const {
+    int first_instruction = block->first_instruction_index();
+    return LGap::cast(instructions_[first_instruction + 1]);
+  }
   int LookupDestination(int block_id) const {
     LLabel* cur = GetLabel(block_id);
     while (cur->replacement() != NULL) {
       cur = cur->replacement();
     }
     return cur->block_id();
   }
   Label* GetAssemblyLabel(int block_id) const {
     LLabel* label = GetLabel(block_id);
     ASSERT(!label->HasReplacement());
@@ skipping 173 matching lines @@
   DISALLOW_COPY_AND_ASSIGN(LChunkBuilder);
 };
 
 #undef DECLARE_HYDROGEN_ACCESSOR
 #undef DECLARE_INSTRUCTION
 #undef DECLARE_CONCRETE_INSTRUCTION
 
 } }  // namespace v8::int
 
 #endif  // V8_X64_LITHIUM_X64_H_