Skip expansion when f16 is enabled.

Author: brendandahl

llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp

@@ -143,9 +143,12 @@ WebAssemblyTargetLowering::WebAssemblyTargetLowering(
     // Support minimum and maximum, which otherwise default to expand.
     setOperationAction(ISD::FMINIMUM, T, Legal);
     setOperationAction(ISD::FMAXIMUM, T, Legal);
-    // WebAssembly currently has no builtin f16 support.
-    setOperationAction(ISD::FP16_TO_FP, T, Expand);
-    setOperationAction(ISD::FP_TO_FP16, T, Expand);
+    // When experimental vector f16 is enabled these instructions don't need to
+    // be expanded for v8f16.
+    if (T != MVT::v8f16) {
+      setOperationAction(ISD::FP16_TO_FP, T, Expand);
+      setOperationAction(ISD::FP_TO_FP16, T, Expand);
+    }
     setLoadExtAction(ISD::EXTLOAD, T, MVT::f16, Expand);
     setTruncStoreAction(T, MVT::f16, Expand);
   }