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

src/ppc/macro-assembler-ppc.cc

Index: src/ppc/macro-assembler-ppc.cc
diff --git a/src/ppc/macro-assembler-ppc.cc b/src/ppc/macro-assembler-ppc.cc
index ba463896e580542bbf791696a72cde7eec5064e1..bda6541704db191b5ec8d7ff42951597bfcaaa40 100644
--- a/src/ppc/macro-assembler-ppc.cc
+++ b/src/ppc/macro-assembler-ppc.cc
@@ -716,8 +716,7 @@ MemOperand MacroAssembler::SafepointRegisterSlot(Register reg) {
 
 MemOperand MacroAssembler::SafepointRegistersAndDoublesSlot(Register reg) {
   // General purpose registers are pushed last on the stack.
-  const RegisterConfiguration* config =
-      RegisterConfiguration::ArchDefault(RegisterConfiguration::CRANKSHAFT);
+  const RegisterConfiguration* config = RegisterConfiguration::Crankshaft();
   int doubles_size = config->num_allocatable_double_registers() * kDoubleSize;
   int register_offset = SafepointRegisterStackIndex(reg.code()) * kPointerSize;
   return MemOperand(sp, doubles_size + register_offset);
@@ -4742,8 +4741,7 @@ Register GetRegisterThatIsNotOneOf(Register reg1, Register reg2, Register reg3,
   if (reg5.is_valid()) regs |= reg5.bit();
   if (reg6.is_valid()) regs |= reg6.bit();
 
-  const RegisterConfiguration* config =
-      RegisterConfiguration::ArchDefault(RegisterConfiguration::CRANKSHAFT);
+  const RegisterConfiguration* config = RegisterConfiguration::Crankshaft();
   for (int i = 0; i < config->num_allocatable_general_registers(); ++i) {
     int code = config->GetAllocatableGeneralCode(i);
     Register candidate = Register::from_code(code);