Q::Key: DepNodeParams<TyCtxt<'tcx>>,
Q::Value: Value<TyCtxt<'tcx>>,
{
+ // We must avoid ever having to call `force_from_dep_node()` for a
+ // `DepNode::codegen_unit`:
+ // Since we cannot reconstruct the query key of a `DepNode::codegen_unit`, we
+ // would always end up having to evaluate the first caller of the
+ // `codegen_unit` query that *is* reconstructible. This might very well be
+ // the `compile_codegen_unit` query, thus re-codegenning the whole CGU just
+ // to re-trigger calling the `codegen_unit` query with the right key. At
+ // that point we would already have re-done all the work we are trying to
+ // avoid doing in the first place.
+ // The solution is simple: Just explicitly call the `codegen_unit` query for
+ // each CGU, right after partitioning. This way `try_mark_green` will always
+ // hit the cache instead of having to go through `force_from_dep_node`.
+ // This assertion makes sure, we actually keep applying the solution above.
+ debug_assert!(
+ dep_node.kind != DepKind::codegen_unit,
+ "calling force_from_dep_node() on DepKind::codegen_unit"
+ );
+
if let Some(key) = Q::Key::recover(tcx, &dep_node) {
#[cfg(debug_assertions)]
let _guard = tracing::span!(tracing::Level::TRACE, stringify!($name), ?key).entered();