Function try_execute_query 

fn try_execute_query<'tcx, C: QueryCache, const INCR: bool>(
    query: &'tcx QueryVTable<'tcx, C>,
    tcx: TyCtxt<'tcx>,
    span: Span,
    key: C::Key,
    dep_node: Option<DepNode>,
) -> (C::Value, Option<DepNodeIndex>)

Shared main part of both execute_query_incr_inner and execute_query_non_incr_inner.