To fully support hydrogen code stubs which accept a variable number of arguments,

src/ia32/deoptimizer-ia32.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 557 matching lines @@
   value = reinterpret_cast<intptr_t>(
       Smi::FromInt(StackFrame::STUB_FAILURE_TRAMPOLINE));
   output_frame->SetFrameSlot(output_frame_offset, value);
   if (trace_) {
     PrintF("    0x%08x: [top + %d] <- 0x%08x ; function (stub fail sentinel)\n",
            top_address + output_frame_offset, output_frame_offset, value);
   }
 
   int caller_arg_count = 0;
   if (descriptor->stack_parameter_count_ != NULL) {
+    // TODO(mvstanton): when a hydrogen stub with multiple arguments of any
+    // complexity comes along this code will fail because the register is likely
+    // consumed with another value. Retrieve the caller_arg_count from the
+    // environment instead via iterator.
     caller_arg_count =
         input_->GetRegister(descriptor->stack_parameter_count_->code());
   }
 
   // Build the Arguments object for the caller's parameters and a pointer to it.
   output_frame_offset -= kPointerSize;
   value = frame_ptr + StandardFrameConstants::kCallerSPOffset +
       (caller_arg_count - 1) * kPointerSize;
   output_frame->SetFrameSlot(output_frame_offset, value);
   if (trace_) {
@@ skipping 474 matching lines @@
   }
   __ bind(&done);
 }
 
 #undef __
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32