provides a mechanism for optimizing compilers to select the different Register configuration.

src/compiler/pipeline.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/pipeline.h"
 
 #include <fstream>  // NOLINT(readability/streams)
 #include <sstream>
 
 #include "src/base/adapters.h"
@@ skipping 1281 matching lines @@
     // Output source position information before the graph is deleted.
     data_->source_positions()->Print(source_position_output);
   }
 
   data->DeleteGraphZone();
 
   BeginPhaseKind("register allocation");
 
   bool run_verifier = FLAG_turbo_verify_allocation;
   // Allocate registers.
-  AllocateRegisters(RegisterConfiguration::ArchDefault(), call_descriptor,
-                    run_verifier);
+  AllocateRegisters(RegisterConfiguration::ArchDefaultForTurbo(),
+                    call_descriptor, run_verifier);
   if (data->compilation_failed()) {
     info()->AbortOptimization(kNotEnoughVirtualRegistersRegalloc);
     return Handle<Code>();
   }
 
   BeginPhaseKind("code generation");
 
   // Optimimize jumps.
   if (FLAG_turbo_jt) {
     Run<JumpThreadingPhase>();
@@ skipping 130 matching lines @@
     tcf << AsC1VRegisterAllocationData("CodeGen",
                                        data->register_allocation_data());
   }
 
   data->DeleteRegisterAllocationZone();
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8