}
func decomposeUserPhi(v *Value) {
	switch {
	case v.Type.IsStruct():
		decomposeStructPhi(v)
	case v.Type.IsArray():
		decomposeArrayPhi(v)
	}
}

// decomposeStructPhi replaces phi-of-struct with structmake(phi-for-each-field),
// and then recursively decomposes the phis for each field.
func decomposeStructPhi(v *Value) {
	t := v.Type
	n := t.NumFields()
	var fields [MaxStruct]*Value