[x64] Make r12 allocatable.

src/x64/code-stubs-x64.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"
 
 #if V8_TARGET_ARCH_X64
 
 #include "src/bootstrapper.h"
 #include "src/code-stubs.h"
@@ skipping 2502 matching lines @@
     __ movdqu(Operand(rsp, EntryFrameConstants::kXMMRegisterSize * 4), xmm10);
     __ movdqu(Operand(rsp, EntryFrameConstants::kXMMRegisterSize * 5), xmm11);
     __ movdqu(Operand(rsp, EntryFrameConstants::kXMMRegisterSize * 6), xmm12);
     __ movdqu(Operand(rsp, EntryFrameConstants::kXMMRegisterSize * 7), xmm13);
     __ movdqu(Operand(rsp, EntryFrameConstants::kXMMRegisterSize * 8), xmm14);
     __ movdqu(Operand(rsp, EntryFrameConstants::kXMMRegisterSize * 9), xmm15);
 #endif
 
     // Set up the roots and smi constant registers.
     // Needs to be done before any further smi loads.
-    __ InitializeSmiConstantRegister();
     __ InitializeRootRegister();
   }
 
   // Save copies of the top frame descriptor on the stack.
   ExternalReference c_entry_fp(Isolate::kCEntryFPAddress, isolate());
   {
     Operand c_entry_fp_operand = masm->ExternalOperand(c_entry_fp);
     __ Push(c_entry_fp_operand);
   }
 
@@ skipping 2562 matching lines @@
   CallApiFunctionAndReturn(masm, api_function_address, thunk_ref, getter_arg,
                            kStackSpace, nullptr, return_value_operand, NULL);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64