Change how query vtables are constructed.

Currently `define_dep_nodes` produces a macro `make_dep_kind_array` that
encodes the names of non-queries followed by queries. This macro is used
by `make_dep_kind_vtables` to make the full array of vtables, by
referring to vtable constructor functions that are put into `mod
_dep_kind_vtable_ctors`. Pretty weird!

This commit takes advantage of the previous commit's changes to
`rustc_with_all_queries`, which makes both query and non-query
information available. A new call to `rustc_with_all_queries` is used to
construct the vtable array. (This moves some dep_kind_vtable code from
`plumbing.rs` to `dep_kind_vtables.rs`, which is good.) It's
straightforward now with iterator chaining, and `mod
_dep_kind_vtable_ctors` is no longer needed.

Author: nnethercote

compiler/rustc_middle/src/dep_graph/dep_node.rs

@@ -284,15 +284,6 @@ macro_rules! define_dep_nodes {
             )*
         }
     ) => {
-        #[macro_export]
-        macro_rules! make_dep_kind_array {
-            ($mod:ident) => {[
-                $( $mod::$nq_name(), )*
-                $( $mod::$q_name(), )*
-            ]};
-        }
-
-        /// This enum serves as an index into arrays built by `make_dep_kind_array`.
         // This enum has more than u8::MAX variants so we need some kind of multi-byte
         // encoding. The derived Encodable/Decodable uses leb128 encoding which is
         // dense when only considering this enum. But DepKind is encoded in a larger

compiler/rustc_query_impl/src/dep_kind_vtables.rs

@@ -1,3 +1,4 @@
+use rustc_middle::arena::Arena;
 use rustc_middle::bug;
 use rustc_middle::dep_graph::{DepKindVTable, DepNodeKey, KeyFingerprintStyle};
 use rustc_middle::query::QueryCache;
@@ -133,24 +134,51 @@ where
     }
 }
 
-/// Helper module containing a [`DepKindVTable`] constructor for each dep kind,
-/// for use with [`rustc_middle::make_dep_kind_array`].
-///
-/// That macro will check that we gave it a constructor for every known dep kind.
-mod _dep_kind_vtable_ctors {
-    // Re-export all of the vtable constructors for non-query and query dep kinds.
-
-    // Non-query vtable constructors are defined in normal code.
-    pub(crate) use super::non_query::*;
-    // Query vtable constructors are defined via a macro.
-    pub(crate) use crate::_dep_kind_vtable_ctors_for_queries::*;
+macro_rules! define_dep_kind_vtables {
+    (
+        queries {
+            $(
+                $(#[$attr:meta])*
+                [$($modifiers:tt)*]
+                fn $name:ident($K:ty) -> $V:ty,
+            )*
+        }
+        non_queries {
+            $(
+                $(#[$nq_attr:meta])*
+                $nq_name:ident,
+            )*
+        }
+    ) => {{
+        // The small number of non-query vtables: `Null`, `Red`, etc.
+        let nq_vtables = [
+            $(
+                non_query::$nq_name(),
+            )*
+        ];
+
+        // The large number of query vtables.
+        let q_vtables: [DepKindVTable<'tcx>; _] = [
+            $(
+                $crate::dep_kind_vtables::make_dep_kind_vtable_for_query::<
+                    $crate::query_impl::$name::VTableGetter,
+                >(
+                    is_anon!([$($modifiers)*]),
+                    if_cache_on_disk!([$($modifiers)*] true false),
+                    is_eval_always!([$($modifiers)*]),
+                )
+            ),*
+        ];
+
+        (nq_vtables, q_vtables)
+    }}
 }
 
-pub fn make_dep_kind_vtables<'tcx>(
-    arena: &'tcx rustc_middle::arena::Arena<'tcx>,
-) -> &'tcx [DepKindVTable<'tcx>] {
-    // Create an array of vtables, one for each dep kind (non-query and query).
-    let dep_kind_vtables: [DepKindVTable<'tcx>; _] =
-        rustc_middle::make_dep_kind_array!(_dep_kind_vtable_ctors);
-    arena.alloc_from_iter(dep_kind_vtables)
+// Create an array of vtables, one for each dep kind (non-query and query).
+pub fn make_dep_kind_vtables<'tcx>(arena: &'tcx Arena<'tcx>) -> &'tcx [DepKindVTable<'tcx>] {
+    let (nq_vtables, q_vtables) =
+        rustc_middle::rustc_with_all_queries! { define_dep_kind_vtables! };
+
+    // Non-query vtables must come before query vtables, to match the order of `DepKind`.
+    arena.alloc_from_iter(nq_vtables.into_iter().chain(q_vtables.into_iter()))
 }

compiler/rustc_query_impl/src/plumbing.rs

@@ -693,23 +693,5 @@ macro_rules! define_queries {
                 })
             }
         }
-
-        /// Declares a dep-kind vtable constructor for each query.
-        mod _dep_kind_vtable_ctors_for_queries {
-            use ::rustc_middle::dep_graph::DepKindVTable;
-            use $crate::dep_kind_vtables::make_dep_kind_vtable_for_query;
-
-            $(
-                /// `DepKindVTable` constructor for this query.
-                pub(crate) fn $name<'tcx>() -> DepKindVTable<'tcx> {
-                    use $crate::query_impl::$name::VTableGetter;
-                    make_dep_kind_vtable_for_query::<VTableGetter>(
-                        is_anon!([$($modifiers)*]),
-                        if_cache_on_disk!([$($modifiers)*] true false),
-                        is_eval_always!([$($modifiers)*]),
-                    )
-                }
-            )*
-        }
     }
 }