[RegisterConfiguration] Streamline access to arch defaults, simplify Registers.

test/unittests/compiler/move-optimizer-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 "src/compiler/move-optimizer.h"
 #include "src/compiler/pipeline.h"
 #include "test/unittests/compiler/instruction-sequence-unittest.h"
 
 namespace v8 {
 namespace internal {
@@ skipping 88 matching lines @@
 
   CHECK_EQ(0, NonRedundantSize(first_instr->parallel_moves()[0]));
   auto move = last_instr->parallel_moves()[0];
   CHECK_EQ(1, NonRedundantSize(move));
   CHECK(Contains(move, Reg(0), Reg(1)));
 }
 
 
 TEST_F(MoveOptimizerTest, RemovesRedundantExplicit) {
   int first_reg_index =
-      RegisterConfiguration::ArchDefault(RegisterConfiguration::TURBOFAN)
-          ->GetAllocatableGeneralCode(0);
+      RegisterConfiguration::Turbofan()->GetAllocatableGeneralCode(0);
   int second_reg_index =
-      RegisterConfiguration::ArchDefault(RegisterConfiguration::TURBOFAN)
-          ->GetAllocatableGeneralCode(1);
+      RegisterConfiguration::Turbofan()->GetAllocatableGeneralCode(1);
 
   StartBlock();
   auto first_instr = EmitNop();
   AddMove(first_instr, Reg(first_reg_index), ExplicitReg(second_reg_index));
   auto last_instr = EmitNop();
   AddMove(last_instr, Reg(second_reg_index), Reg(first_reg_index));
   EndBlock(Last());
 
   Optimize();
 
@@ skipping 211 matching lines @@
   ParallelMove* first_move = first_instr->parallel_moves()[0];
   CHECK_EQ(0, NonRedundantSize(first_move));
 
   ParallelMove* last_move = last_instr->parallel_moves()[0];
   CHECK_EQ(0, NonRedundantSize(last_move));
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8