Revert of Reland: Remove register index/code indirection

src/compiler/instruction.cc

Index: src/compiler/instruction.cc
diff --git a/src/compiler/instruction.cc b/src/compiler/instruction.cc
index a7ed0e5f236f7bae334f7810ee41efc80bcf624e..0fbb94979e41522d4df8d2472372559f4dab5160 100644
--- a/src/compiler/instruction.cc
+++ b/src/compiler/instruction.cc
@@ -74,15 +74,11 @@
         case UnallocatedOperand::NONE:
           return os;
         case UnallocatedOperand::FIXED_REGISTER:
-          return os << "(="
-                    << conf->GetGeneralRegisterName(
-                           unalloc->fixed_register_index())
-                    << ")";
+          return os << "(=" << conf->general_register_name(
+                                   unalloc->fixed_register_index()) << ")";
         case UnallocatedOperand::FIXED_DOUBLE_REGISTER:
-          return os << "(="
-                    << conf->GetDoubleRegisterName(
-                           unalloc->fixed_register_index())
-                    << ")";
+          return os << "(=" << conf->double_register_name(
+                                   unalloc->fixed_register_index()) << ")";
         case UnallocatedOperand::MUST_HAVE_REGISTER:
           return os << "(R)";
         case UnallocatedOperand::MUST_HAVE_SLOT:
@@ -115,12 +111,14 @@
           os << "[double_stack:" << DoubleStackSlotOperand::cast(op).index();
           break;
         case AllocatedOperand::REGISTER:
-          os << "[" << RegisterOperand::cast(op).GetRegister().ToString()
+          os << "["
+             << conf->general_register_name(RegisterOperand::cast(op).index())
              << "|R";
           break;
         case AllocatedOperand::DOUBLE_REGISTER:
-          os << "[" << DoubleRegisterOperand::cast(op).GetRegister().ToString()
-             << "|R";
+          os << "["
+             << conf->double_register_name(
+                    DoubleRegisterOperand::cast(op).index()) << "|R";
           break;
       }
       switch (allocated.machine_type()) {