Function global 

pub fn global<'c>(
    context: &'c Context,
    name: &str,
    visibility: Option<&str>,
    type: MemRefType<'c>,
    value: Option<Attribute<'c>>,
    constant: bool,
    alignment: Option<IntegerAttribute<'c>>,
    location: Location<'c>,
) -> Operation<'c>

Create a memref.global operation.