Function param_index_of_origin 

fn param_index_of_origin(
    tcx: TyCtxt<'_>,
    caller: DefId,
    origin: &PlaceKey,
) -> Option<usize>

Return the 0-based argument index for origin when it is a direct, whole raw-pointer parameter (no field projections, no local-copy tracing).

Unlike resolve_param_origin, this returns a 0-based index into the call argument list (used by callsite_arg_origins) and does not trace through the alias tree.