[WASM SIMD] Implement horizontal add for float and integer types.

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 0b86f3e149d0f1a56c66e6353777999d6b464812..338ab40bae5fd5ee745d03184eada3c6c9df2fcf 100644
--- a/src/arm/constants-arm.h
+++ b/src/arm/constants-arm.h
@@ -324,6 +324,8 @@ enum LFlag {
   Short = 0 << 22   // Short load/store coprocessor.
 };
 
+// Neon sizes.
+enum NeonSize { Neon8 = 0x0, Neon16 = 0x1, Neon32 = 0x2, Neon64 = 0x3 };
 
 // NEON data type
 enum NeonDataType {
@@ -339,6 +341,11 @@ enum NeonDataType {
 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) {
+  return static_cast<NeonDataType>(size);
+}
+
 enum NeonListType {
   nlt_1 = 0x7,
   nlt_2 = 0xA,
@@ -346,13 +353,6 @@ enum NeonListType {
   nlt_4 = 0x2
 };
 
-enum NeonSize {
-  Neon8 = 0x0,
-  Neon16 = 0x1,
-  Neon32 = 0x2,
-  Neon64 = 0x3
-};
-
 // -----------------------------------------------------------------------------
 // Supervisor Call (svc) specific support.