Function insert_null_check

fn insert_null_check<'tcx>(
    tcx: TyCtxt<'tcx>,
    pointer: Place<'tcx>,
    pointee_ty: Ty<'tcx>,
    context: PlaceContext,
    local_decls: &mut IndexVec<Local, LocalDecl<'tcx>>,
    stmts: &mut Vec<Statement<'tcx>>,
    source_info: SourceInfo,
) -> PointerCheck<'tcx>