The IC exposes a register definition.

src/x64/deoptimizer-x64.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"
 
 #if V8_TARGET_ARCH_X64
 
 #include "src/codegen.h"
 #include "src/deoptimizer.h"
@@ skipping 90 matching lines @@
   // Fill the frame content from the actual data on the frame.
   for (unsigned i = 0; i < input_->GetFrameSize(); i += kPointerSize) {
     input_->SetFrameSlot(i, Memory::uintptr_at(tos + i));
   }
 }
 
 
 void Deoptimizer::SetPlatformCompiledStubRegisters(
     FrameDescription* output_frame, CodeStubInterfaceDescriptor* descriptor) {
   intptr_t handler =
-      reinterpret_cast<intptr_t>(descriptor->deoptimization_handler_);
+      reinterpret_cast<intptr_t>(descriptor->deoptimization_handler());
   int params = descriptor->GetHandlerParameterCount();
   output_frame->SetRegister(rax.code(), params);
   output_frame->SetRegister(rbx.code(), handler);
 }
 
 
 void Deoptimizer::CopyDoubleRegisters(FrameDescription* output_frame) {
   for (int i = 0; i < XMMRegister::NumAllocatableRegisters(); ++i) {
     double double_value = input_->GetDoubleRegister(i);
     output_frame->SetDoubleRegister(i, double_value);
@@ skipping 224 matching lines @@
   UNREACHABLE();
 }
 
 
 #undef __
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64