This patch performs following transformation.

%vector1 = shufflevector

%vector2 = shufflevector

%vector-res = vector-binaryop %vector1, %vector2

%scalar-res = extractelement <2 x fhalf> %vector-res, i32 0

ret half %scalar-res

## >

%scalar1 = extractelement <2 x fhalf> %vector1, i32 0

%scalar2 = extractelement <2 x fhalf> %vector2, i32 0

%scalar-res = scalar binaryop %scalar1, %scalar2

return half %scalar-res