StubCallInterfaceDescriptor takes a context register.

src/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_X64_LITHIUM_X64_H_
 #define V8_X64_LITHIUM_X64_H_
 
 #include "src/hydrogen.h"
 #include "src/lithium.h"
 #include "src/lithium-allocator.h"
@@ skipping 1832 matching lines @@
   DECLARE_HYDROGEN_ACCESSOR(CallJSFunction)
 
   virtual void PrintDataTo(StringStream* stream) V8_OVERRIDE;
 
   int arity() const { return hydrogen()->argument_count() - 1; }
 };
 
 
 class LCallWithDescriptor V8_FINAL : public LTemplateResultInstruction<1> {
  public:
-  LCallWithDescriptor(const CallInterfaceDescriptor* descriptor,
+  LCallWithDescriptor(const InterfaceDescriptor* descriptor,
                       const ZoneList<LOperand*>& operands,
                       Zone* zone)
-    : inputs_(descriptor->environment_length() + 1, zone) {
-    ASSERT(descriptor->environment_length() + 1 == operands.length());
+    : inputs_(descriptor->GetRegisterParameterCount() + 1, zone) {
+    ASSERT(descriptor->GetRegisterParameterCount() + 1 == operands.length());
     inputs_.AddAll(operands, zone);
   }
 
   LOperand* target() const { return inputs_[0]; }
 
  private:
   DECLARE_CONCRETE_INSTRUCTION(CallWithDescriptor, "call-with-descriptor")
   DECLARE_HYDROGEN_ACCESSOR(CallWithDescriptor)
 
   virtual void PrintDataTo(StringStream* stream) V8_OVERRIDE;
@@ skipping 991 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(LChunkBuilder);
 };
 
 #undef DECLARE_HYDROGEN_ACCESSOR
 #undef DECLARE_CONCRETE_INSTRUCTION
 
 } }  // namespace v8::int
 
 #endif  // V8_X64_LITHIUM_X64_H_