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

src/crankshaft/arm64/lithium-gap-resolver-arm64.h

 // Copyright 2013 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.
 
 #ifndef V8_CRANKSHAFT_ARM64_LITHIUM_GAP_RESOLVER_ARM64_H_
 #define V8_CRANKSHAFT_ARM64_LITHIUM_GAP_RESOLVER_ARM64_H_
 
 #include "src/crankshaft/arm64/delayed-masm-arm64.h"
 #include "src/crankshaft/lithium.h"
 
@@ skipping 48 matching lines @@
   // Emit a move from one stack slot to another.
   void EmitStackSlotMove(int index) {
     masm_.StackSlotMove(moves_[index].source(), moves_[index].destination());
   }
 
   // Verify the move list before performing moves.
   void Verify();
 
   // Registers used to solve cycles.
   const Register& SavedValueRegister() {
-    DCHECK(!masm_.ScratchRegister().IsAllocatable());
+    DCHECK(!RegisterConfiguration::Crankshaft()->IsAllocatableGeneralCode(
+        masm_.ScratchRegister().code()));
     return masm_.ScratchRegister();
   }
   // The scratch register is used to break cycles and to store constant.
   // These two methods switch from one mode to the other.
   void AcquireSavedValueRegister() { masm_.AcquireScratchRegister(); }
   void ReleaseSavedValueRegister() { masm_.ReleaseScratchRegister(); }
   const FPRegister& SavedFPValueRegister() {
     // We use the Crankshaft floating-point scratch register to break a cycle
     // involving double values as the MacroAssembler will not need it for the
     // operations performed by the gap resolver.
-    DCHECK(!crankshaft_fp_scratch.IsAllocatable());
+    DCHECK(!RegisterConfiguration::Crankshaft()->IsAllocatableGeneralCode(
+        crankshaft_fp_scratch.code()));
     return crankshaft_fp_scratch;
   }
 
   LCodeGen* cgen_;
   DelayedGapMasm masm_;
 
   // List of moves not yet resolved.
   ZoneList<LMoveOperands> moves_;
 
   int root_index_;
   bool in_cycle_;
   LOperand* saved_destination_;
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_CRANKSHAFT_ARM64_LITHIUM_GAP_RESOLVER_ARM64_H_