[ARM] Improve VFP register moves.

src/arm/constants-arm.h

Index: src/arm/constants-arm.h
diff --git a/src/arm/constants-arm.h b/src/arm/constants-arm.h
index 338ab40bae5fd5ee745d03184eada3c6c9df2fcf..21794a5a5c9d8b411f7043db2944c160b2eb4ef0 100644
--- a/src/arm/constants-arm.h
+++ b/src/arm/constants-arm.h
@@ -342,10 +342,15 @@ inline int NeonU(NeonDataType dt) { return static_cast<int>(dt) >> 2; }
 inline int NeonSz(NeonDataType dt) { return static_cast<int>(dt) & 0x3; }
 
 // Convert sizes to data types (U bit is clear).
-inline NeonDataType NeonSizeToDatatype(NeonSize size) {
+inline NeonDataType NeonSizeToDataType(NeonSize size) {
+  DCHECK_NE(Neon64, size);
   return static_cast<NeonDataType>(size);
 }
 
+inline NeonSize NeonDataTypeToSize(NeonDataType dt) {
+  return static_cast<NeonSize>(NeonSz(dt));
+}
+
 enum NeonListType {
   nlt_1 = 0x7,
   nlt_2 = 0xA,