[ARM] Refactor NEON binary ops in assembler.

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 e0c91fd4bf107e3e1adb8be63a82ddc7d6e49bca..0b86f3e149d0f1a56c66e6353777999d6b464812 100644
--- a/src/arm/constants-arm.h
+++ b/src/arm/constants-arm.h
@@ -327,16 +327,18 @@ enum LFlag {
 
 // NEON data type
 enum NeonDataType {
-  NeonS8 = 0x1,             // U = 0, imm3 = 0b001
-  NeonS16 = 0x2,            // U = 0, imm3 = 0b010
-  NeonS32 = 0x4,            // U = 0, imm3 = 0b100
-  NeonU8 = 1 << 24 | 0x1,   // U = 1, imm3 = 0b001
-  NeonU16 = 1 << 24 | 0x2,  // U = 1, imm3 = 0b010
-  NeonU32 = 1 << 24 | 0x4,  // U = 1, imm3 = 0b100
-  NeonDataTypeSizeMask = 0x7,
-  NeonDataTypeUMask = 1 << 24
+  NeonS8 = 0,
+  NeonS16 = 1,
+  NeonS32 = 2,
+  // Gap to make it easier to extract U and size.
+  NeonU8 = 4,
+  NeonU16 = 5,
+  NeonU32 = 6
 };
 
+inline int NeonU(NeonDataType dt) { return static_cast<int>(dt) >> 2; }
+inline int NeonSz(NeonDataType dt) { return static_cast<int>(dt) & 0x3; }
+
 enum NeonListType {
   nlt_1 = 0x7,
   nlt_2 = 0xA,