[crankshaft] Fixing ES6 tail call elimination.

src/crankshaft/x64/lithium-x64.h

 // Copyright 2012 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_CRANKSHAFT_X64_LITHIUM_X64_H_
 #define V8_CRANKSHAFT_X64_LITHIUM_X64_H_
 
 #include "src/crankshaft/hydrogen.h"
 #include "src/crankshaft/lithium.h"
 #include "src/crankshaft/lithium-allocator.h"
@@ skipping 203 matching lines @@
   void set_pointer_map(LPointerMap* p) { pointer_map_.set(p); }
   LPointerMap* pointer_map() const { return pointer_map_.get(); }
   bool HasPointerMap() const { return pointer_map_.is_set(); }
 
   void set_hydrogen_value(HValue* value) { hydrogen_value_ = value; }
   HValue* hydrogen_value() const { return hydrogen_value_; }
 
   void MarkAsCall() { bit_field_ = IsCallBits::update(bit_field_, true); }
   bool IsCall() const { return IsCallBits::decode(bit_field_); }
 
+  void MarkAsSyntacticTailCall() {
+    bit_field_ = IsSyntacticTailCallBits::update(bit_field_, true);
+  }
+  bool IsSyntacticTailCall() const {
+    return IsSyntacticTailCallBits::decode(bit_field_);
+  }
+
   // Interface to the register allocator and iterators.
   bool ClobbersTemps() const { return IsCall(); }
   bool ClobbersRegisters() const { return IsCall(); }
   virtual bool ClobbersDoubleRegisters(Isolate* isolate) const {
     return IsCall();
   }
 
   // Interface to the register allocator and iterators.
   bool IsMarkedAsCall() const { return IsCall(); }
 
@@ skipping 18 matching lines @@
 
  private:
   // Iterator support.
   friend class InputIterator;
 
   friend class TempIterator;
   virtual int TempCount() = 0;
   virtual LOperand* TempAt(int i) = 0;
 
   class IsCallBits: public BitField<bool, 0, 1> {};
+  class IsSyntacticTailCallBits : public BitField<bool, IsCallBits::kNext, 1> {
+  };
 
   LEnvironment* environment_;
   SetOncePointer<LPointerMap> pointer_map_;
   HValue* hydrogen_value_;
   int bit_field_;
 };
 
 
 // R = number of result operands (0 or 1).
 template<int R>
@@ skipping 2368 matching lines @@
   DISALLOW_COPY_AND_ASSIGN(LChunkBuilder);
 };
 
 #undef DECLARE_HYDROGEN_ACCESSOR
 #undef DECLARE_CONCRETE_INSTRUCTION
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_CRANKSHAFT_X64_LITHIUM_X64_H_