Revert of Remove register index/code indirection

src/arm/assembler-arm-inl.h

Index: src/arm/assembler-arm-inl.h
diff --git a/src/arm/assembler-arm-inl.h b/src/arm/assembler-arm-inl.h
index 0037e30ddac1b1467ce5bbc0b0cb8d6c1b03afd2..8f8956c9e1c7eb25890726abb3cfd3addeceeb54 100644
--- a/src/arm/assembler-arm-inl.h
+++ b/src/arm/assembler-arm-inl.h
@@ -50,8 +50,50 @@
 bool CpuFeatures::SupportsCrankshaft() { return IsSupported(VFP3); }
 
 
-int DoubleRegister::NumRegisters() {
+int Register::NumAllocatableRegisters() {
+  return kMaxNumAllocatableRegisters;
+}
+
+
+int DwVfpRegister::NumRegisters() {
   return CpuFeatures::IsSupported(VFP32DREGS) ? 32 : 16;
+}
+
+
+int DwVfpRegister::NumReservedRegisters() {
+  return kNumReservedRegisters;
+}
+
+
+int DwVfpRegister::NumAllocatableRegisters() {
+  return NumRegisters() - kNumReservedRegisters;
+}
+
+
+// static
+int DwVfpRegister::NumAllocatableAliasedRegisters() {
+  return LowDwVfpRegister::kMaxNumLowRegisters - kNumReservedRegisters;
+}
+
+
+int DwVfpRegister::ToAllocationIndex(DwVfpRegister reg) {
+  DCHECK(!reg.is(kDoubleRegZero));
+  DCHECK(!reg.is(kScratchDoubleReg));
+  if (reg.code() > kDoubleRegZero.code()) {
+    return reg.code() - kNumReservedRegisters;
+  }
+  return reg.code();
+}
+
+
+DwVfpRegister DwVfpRegister::FromAllocationIndex(int index) {
+  DCHECK(index >= 0 && index < NumAllocatableRegisters());
+  DCHECK(kScratchDoubleReg.code() - kDoubleRegZero.code() ==
+         kNumReservedRegisters - 1);
+  if (index >= kDoubleRegZero.code()) {
+    return from_code(index + kNumReservedRegisters);
+  }
+  return from_code(index);
 }