The IC exposes a register definition.

src/deoptimizer.cc

 // Copyright 2013 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/accessors.h"
 #include "src/codegen.h"
 #include "src/deoptimizer.h"
 #include "src/disasm.h"
@@ skipping 1540 matching lines @@
   CHECK(compiled_code_->is_crankshafted() &&
         compiled_code_->kind() != Code::OPTIMIZED_FUNCTION);
   int major_key = compiled_code_->major_key();
   CodeStubInterfaceDescriptor* descriptor =
       isolate_->code_stub_interface_descriptor(major_key);
 
   // The output frame must have room for all pushed register parameters
   // and the standard stack frame slots.  Include space for an argument
   // object to the callee and optionally the space to pass the argument
   // object to the stub failure handler.
-  CHECK_GE(descriptor->register_param_count_, 0);
-  int height_in_bytes = kPointerSize * descriptor->register_param_count_ +
+  CHECK_GE(descriptor->register_param_count(), 0);
+  int height_in_bytes = kPointerSize * descriptor->register_param_count() +
       sizeof(Arguments) + kPointerSize;
   int fixed_frame_size = StandardFrameConstants::kFixedFrameSize;
   int input_frame_size = input_->GetFrameSize();
   int output_frame_size = height_in_bytes + fixed_frame_size;
   if (trace_scope_ != NULL) {
     PrintF(trace_scope_->file(),
            "  translating %s => StubFailureTrampolineStub, height=%d\n",
            CodeStub::MajorName(static_cast<CodeStub::Major>(major_key), false),
            height_in_bytes);
   }
@@ skipping 74 matching lines @@
       Smi::FromInt(StackFrame::STUB_FAILURE_TRAMPOLINE));
   output_frame->SetFrameSlot(output_frame_offset, value);
   if (trace_scope_ != NULL) {
     PrintF(trace_scope_->file(),
            "    0x%08" V8PRIxPTR ": [top + %d] <- 0x%08"
            V8PRIxPTR " ; function (stub failure sentinel)\n",
            top_address + output_frame_offset, output_frame_offset, value);
   }
 
   intptr_t caller_arg_count = 0;
-  bool arg_count_known = !descriptor->stack_parameter_count_.is_valid();
+  bool arg_count_known = !descriptor->stack_parameter_count().is_valid();
 
   // Build the Arguments object for the caller's parameters and a pointer to it.
   output_frame_offset -= kPointerSize;
   int args_arguments_offset = output_frame_offset;
   intptr_t the_hole = reinterpret_cast<intptr_t>(
       isolate_->heap()->the_hole_value());
   if (arg_count_known) {
     value = frame_ptr + StandardFrameConstants::kCallerSPOffset +
         (caller_arg_count - 1) * kPointerSize;
   } else {
@@ skipping 27 matching lines @@
   output_frame->SetFrameSlot(output_frame_offset, value);
   if (trace_scope_ != NULL) {
     PrintF(trace_scope_->file(),
            "    0x%08" V8PRIxPTR ": [top + %d] <- 0x%08"
            V8PRIxPTR " ; args*\n",
            top_address + output_frame_offset, output_frame_offset, value);
   }
 
   // Copy the register parameters to the failure frame.
   int arguments_length_offset = -1;
-  for (int i = 0; i < descriptor->register_param_count_; ++i) {
+  for (int i = 0; i < descriptor->register_param_count(); ++i) {
     output_frame_offset -= kPointerSize;
     DoTranslateCommand(iterator, 0, output_frame_offset);
 
     if (!arg_count_known && descriptor->IsParameterCountRegister(i)) {
       arguments_length_offset = output_frame_offset;
     }
   }
 
   CHECK_EQ(output_frame_offset, 0);
 
@@ skipping 26 matching lines @@
   }
 
   // Copy the double registers from the input into the output frame.
   CopyDoubleRegisters(output_frame);
 
   // Fill registers containing handler and number of parameters.
   SetPlatformCompiledStubRegisters(output_frame, descriptor);
 
   // Compute this frame's PC, state, and continuation.
   Code* trampoline = NULL;
-  StubFunctionMode function_mode = descriptor->function_mode_;
+  StubFunctionMode function_mode = descriptor->function_mode();
   StubFailureTrampolineStub(isolate_,
                             function_mode).FindCodeInCache(&trampoline);
   ASSERT(trampoline != NULL);
   output_frame->SetPc(reinterpret_cast<intptr_t>(
       trampoline->instruction_start()));
   if (FLAG_enable_ool_constant_pool) {
     Register constant_pool_reg =
         StubFailureTrampolineFrame::constant_pool_pointer_register();
     intptr_t constant_pool_value =
         reinterpret_cast<intptr_t>(trampoline->constant_pool());
@@ skipping 1819 matching lines @@
 }
 
 
 void DeoptimizedFrameInfo::Iterate(ObjectVisitor* v) {
   v->VisitPointer(BitCast<Object**>(&function_));
   v->VisitPointers(parameters_, parameters_ + parameters_count_);
   v->VisitPointers(expression_stack_, expression_stack_ + expression_count_);
 }
 
 } }  // namespace v8::internal