StubCallInterfaceDescriptor takes a context register.

src/code-stubs-hydrogen.cc

 // 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.
 
 #include "src/v8.h"
 
 #include "src/code-stubs.h"
 #include "src/field-index.h"
 #include "src/hydrogen.h"
 #include "src/lithium.h"
@@ skipping 108 matching lines @@
   int param_count = descriptor_->register_param_count();
   HEnvironment* start_environment = graph()->start_environment();
   HBasicBlock* next_block = CreateBasicBlock(start_environment);
   Goto(next_block);
   next_block->SetJoinId(BailoutId::StubEntry());
   set_current_block(next_block);
 
   bool runtime_stack_params = descriptor_->stack_parameter_count().is_valid();
   HInstruction* stack_parameter_count = NULL;
   for (int i = 0; i < param_count; ++i) {
-    Representation r = descriptor_->GetRegisterParameterRepresentation(i);
+    Representation r = descriptor_->GetParameterRepresentation(i);
     HParameter* param = Add<HParameter>(i, HParameter::REGISTER_PARAMETER, r);
     start_environment->Bind(i, param);
     parameters_[i] = param;
     if (descriptor_->IsParameterCountRegister(i)) {
       param->set_type(HType::Smi());
       stack_parameter_count = param;
       arguments_length_ = stack_parameter_count;
     }
   }
 
@@ skipping 1585 matching lines @@
   return Pop();
 }
 
 
 Handle<Code> KeyedLoadGenericElementStub::GenerateCode() {
   return DoGenerateCode(this);
 }
 
 
 } }  // namespace v8::internal