Revert of Reland: Remove register index/code indirection

test/unittests/compiler/instruction-selector-unittest.cc

 // Copyright 2014 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 "test/unittests/compiler/instruction-selector-unittest.h"
 
 #include "src/compiler/graph.h"
 #include "src/compiler/schedule.h"
 #include "src/flags.h"
 #include "test/unittests/compiler/compiler-test-utils.h"
@@ skipping 109 matching lines @@
   CHECK(i != virtual_registers_.end());
   return i->second;
 }
 
 
 bool InstructionSelectorTest::Stream::IsFixed(const InstructionOperand* operand,
                                               Register reg) const {
   if (!operand->IsUnallocated()) return false;
   const UnallocatedOperand* unallocated = UnallocatedOperand::cast(operand);
   if (!unallocated->HasFixedRegisterPolicy()) return false;
-  return unallocated->fixed_register_index() == reg.code();
+  const int index = Register::ToAllocationIndex(reg);
+  return unallocated->fixed_register_index() == index;
 }
 
 
 bool InstructionSelectorTest::Stream::IsSameAsFirst(
     const InstructionOperand* operand) const {
   if (!operand->IsUnallocated()) return false;
   const UnallocatedOperand* unallocated = UnallocatedOperand::cast(operand);
   return unallocated->HasSameAsInputPolicy();
 }
 
@@ skipping 469 matching lines @@
   EXPECT_EQ(s.ToVreg(context2), s.ToVreg(call_instr->InputAt(14)));
   // Continuation.
 
   EXPECT_EQ(kArchRet, s[index++]->arch_opcode());
   EXPECT_EQ(index, s.size());
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8