Revert of Reland: Remove register index/code indirection

src/compiler/c-linkage.cc

 // Copyright 2015 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/assembler.h"
 #include "src/macro-assembler.h"
 
 #include "src/compiler/linkage.h"
 
 #include "src/zone.h"
 
 namespace v8 {
 namespace internal {
 namespace compiler {
 
 namespace {
 LinkageLocation regloc(Register reg) {
-  return LinkageLocation::ForRegister(reg.code());
+  return LinkageLocation::ForRegister(Register::ToAllocationIndex(reg));
 }
 
 
 // Platform-specific configuration for C calling convention.
 #if V8_TARGET_ARCH_IA32
 // ===========================================================================
 // == ia32 ===================================================================
 // ===========================================================================
 #define CALLEE_SAVE_REGISTERS esi.bit() | edi.bit() | ebx.bit()
 
@@ skipping 191 matching lines @@
       Operator::kNoProperties,       // properties
       kCalleeSaveRegisters,          // callee-saved registers
       kCalleeSaveFPRegisters,        // callee-saved fp regs
       CallDescriptor::kNoFlags,      // flags
       "c-call");
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8