The IC exposes a register definition.

src/x87/ic-x87.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_X87
 
 #include "src/codegen.h"
 #include "src/ic-inl.h"
@@ skipping 1007 matching lines @@
   __ push(ecx);  // name
   __ push(ebx);  // return address
 
   // Perform tail call to the entry.
   ExternalReference ref =
       ExternalReference(IC_Utility(kKeyedLoadIC_Miss), masm->isolate());
   __ TailCallExternalReference(ref, 2, 1);
 }
 
 
+// IC register specifications
+const Register LoadIC::ReceiverRegister() { return edx; }
+const Register LoadIC::NameRegister() { return ecx; }
+
+
+const Register KeyedLoadIC::ReceiverRegister() {
+  return LoadIC::ReceiverRegister();
+}
+
+
+const Register KeyedLoadIC::NameRegister() { return LoadIC::NameRegister(); }
+
+
+const Register* KeyedLoadIC::AllocateRegisterArray() {
+  Register* registers = new Register[kRegisterArgumentCount];
+  registers[0] = ReceiverRegister();
+  registers[1] = NameRegister();
+  return registers;
+}
+
+
 void KeyedLoadIC::GenerateRuntimeGetProperty(MacroAssembler* masm) {
   // ----------- S t a t e -------------
   //  -- ecx    : key
   //  -- edx    : receiver
   //  -- esp[0] : return address
   // -----------------------------------
 
   __ pop(ebx);
   __ push(edx);  // receiver
   __ push(ecx);  // name
@@ skipping 243 matching lines @@
   Condition cc = (check == ENABLE_INLINED_SMI_CHECK)
       ? (*jmp_address == Assembler::kJncShortOpcode ? not_zero : zero)
       : (*jmp_address == Assembler::kJnzShortOpcode ? not_carry : carry);
   *jmp_address = static_cast<byte>(Assembler::kJccShortPrefix | cc);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X87