Auto merge of #109611 - Zoxc:query-engine-rem, r=cjgillot

Remove `QueryEngine` trait

This removes the `QueryEngine` trait and `Queries` from `rustc_query_impl` and replaced them with function pointers and fields in `QuerySystem`. As a side effect `OnDiskCache` is moved back into `rustc_middle` and the `OnDiskCache` trait is also removed.

This has a couple of benefits.
- `TyCtxt` is used in the query system instead of the removed `QueryCtxt` which is larger.
- Function pointers are more flexible to work with. A variant of https://github.com/rust-lang/rust/pull/107802 is included which avoids the double indirection. For https://github.com/rust-lang/rust/pull/108938 we can name entry point `__rust_end_short_backtrace` to avoid some overhead. For https://github.com/rust-lang/rust/pull/108062 it avoids the duplicate `QueryEngine` structs.
- `QueryContext` now implements `DepContext` which avoids many `dep_context()` calls in `rustc_query_system`.
- The `rustc_driver` size is reduced by 0.33%, hopefully that means some bootstrap improvements.
- This avoids the unsafe code around the `QueryEngine` trait.

r? `@cjgillot`

4 files changed, 144 insertions, 1269 deletions

diff --git a/compiler/rustc_query_impl/src/lib.rs b/compiler/rustc_query_impl/src/lib.rs
index 7001a1eed57..82b335f4b4b 100644
--- a/compiler/rustc_query_impl/src/lib.rs
+++ b/compiler/rustc_query_impl/src/lib.rs
@@ -12,11 +12,9 @@
 #![deny(rustc::diagnostic_outside_of_impl)]
 
 #[macro_use]
-extern crate rustc_macros;
-#[macro_use]
 extern crate rustc_middle;
 
-use rustc_data_structures::sync::AtomicU64;
+use crate::plumbing::{encode_all_query_results, try_mark_green};
 use rustc_middle::arena::Arena;
 use rustc_middle::dep_graph::{self, DepKind, DepKindStruct};
 use rustc_middle::query::erase::{erase, restore, Erase};
@@ -24,7 +22,7 @@ use rustc_middle::query::AsLocalKey;
 use rustc_middle::ty::query::{
     query_keys, query_provided, query_provided_to_value, query_storage, query_values,
 };
-use rustc_middle::ty::query::{ExternProviders, Providers, QueryEngine};
+use rustc_middle::ty::query::{ExternProviders, Providers, QueryEngine, QuerySystemFns};
 use rustc_middle::ty::TyCtxt;
 use rustc_query_system::dep_graph::SerializedDepNodeIndex;
 use rustc_query_system::Value;
@@ -32,15 +30,10 @@ use rustc_span::Span;
 
 #[macro_use]
 mod plumbing;
-pub use plumbing::QueryCtxt;
-use rustc_query_system::query::*;
-#[cfg(parallel_compiler)]
-pub use rustc_query_system::query::{deadlock, QueryContext};
+pub use crate::plumbing::QueryCtxt;
 
 pub use rustc_query_system::query::QueryConfig;
-
-mod on_disk_cache;
-pub use on_disk_cache::OnDiskCache;
+use rustc_query_system::query::*;
 
 mod profiling_support;
 pub use self::profiling_support::alloc_self_profile_query_strings;
@@ -54,9 +47,16 @@ trait QueryConfigRestored<'tcx>: QueryConfig<QueryCtxt<'tcx>> + Default {
 
 rustc_query_append! { define_queries! }
 
-impl<'tcx> Queries<'tcx> {
-    // Force codegen in the dyn-trait transformation in this crate.
-    pub fn as_dyn(&'tcx self) -> &'tcx dyn QueryEngine<'tcx> {
-        self
+pub fn query_system_fns<'tcx>(
+    local_providers: Providers,
+    extern_providers: ExternProviders,
+) -> QuerySystemFns<'tcx> {
+    QuerySystemFns {
+        engine: engine(),
+        local_providers,
+        extern_providers,
+        query_structs: make_dep_kind_array!(query_structs).to_vec(),
+        encode_query_results: encode_all_query_results,
+        try_mark_green: try_mark_green,
     }
 }
diff --git a/compiler/rustc_query_impl/src/on_disk_cache.rs b/compiler/rustc_query_impl/src/on_disk_cache.rs
deleted file mode 100644
index c0f2d7803d4..00000000000
--- a/compiler/rustc_query_impl/src/on_disk_cache.rs
+++ /dev/null
@@ -1,1064 +0,0 @@
-use crate::QueryCtxt;
-use rustc_data_structures::fx::{FxHashMap, FxIndexSet};
-use rustc_data_structures::memmap::Mmap;
-use rustc_data_structures::stable_hasher::Hash64;
-use rustc_data_structures::sync::{HashMapExt, Lock, Lrc, RwLock};
-use rustc_data_structures::unhash::UnhashMap;
-use rustc_data_structures::unord::UnordSet;
-use rustc_hir::def_id::{CrateNum, DefId, DefIndex, LocalDefId, StableCrateId, LOCAL_CRATE};
-use rustc_hir::definitions::DefPathHash;
-use rustc_index::{Idx, IndexVec};
-use rustc_middle::dep_graph::{DepNodeIndex, SerializedDepNodeIndex};
-use rustc_middle::mir::interpret::{AllocDecodingSession, AllocDecodingState};
-use rustc_middle::mir::{self, interpret};
-use rustc_middle::ty::codec::{RefDecodable, TyDecoder, TyEncoder};
-use rustc_middle::ty::{self, Ty, TyCtxt};
-use rustc_query_system::dep_graph::DepContext;
-use rustc_query_system::query::{QueryCache, QuerySideEffects};
-use rustc_serialize::{
-    opaque::{FileEncodeResult, FileEncoder, IntEncodedWithFixedSize, MemDecoder},
-    Decodable, Decoder, Encodable, Encoder,
-};
-use rustc_session::Session;
-use rustc_span::hygiene::{
-    ExpnId, HygieneDecodeContext, HygieneEncodeContext, SyntaxContext, SyntaxContextData,
-};
-use rustc_span::source_map::{SourceMap, StableSourceFileId};
-use rustc_span::{BytePos, ExpnData, ExpnHash, Pos, SourceFile, Span};
-use rustc_span::{CachingSourceMapView, Symbol};
-use std::collections::hash_map::Entry;
-use std::io;
-use std::mem;
-
-const TAG_FILE_FOOTER: u128 = 0xC0FFEE_C0FFEE_C0FFEE_C0FFEE_C0FFEE;
-
-// A normal span encoded with both location information and a `SyntaxContext`
-const TAG_FULL_SPAN: u8 = 0;
-// A partial span with no location information, encoded only with a `SyntaxContext`
-const TAG_PARTIAL_SPAN: u8 = 1;
-const TAG_RELATIVE_SPAN: u8 = 2;
-
-const TAG_SYNTAX_CONTEXT: u8 = 0;
-const TAG_EXPN_DATA: u8 = 1;
-
-// Tags for encoding Symbol's
-const SYMBOL_STR: u8 = 0;
-const SYMBOL_OFFSET: u8 = 1;
-const SYMBOL_PREINTERNED: u8 = 2;
-
-/// Provides an interface to incremental compilation data cached from the
-/// previous compilation session. This data will eventually include the results
-/// of a few selected queries (like `typeck` and `mir_optimized`) and
-/// any side effects that have been emitted during a query.
-pub struct OnDiskCache<'sess> {
-    // The complete cache data in serialized form.
-    serialized_data: RwLock<Option<Mmap>>,
-
-    // Collects all `QuerySideEffects` created during the current compilation
-    // session.
-    current_side_effects: Lock<FxHashMap<DepNodeIndex, QuerySideEffects>>,
-
-    source_map: &'sess SourceMap,
-    file_index_to_stable_id: FxHashMap<SourceFileIndex, EncodedSourceFileId>,
-
-    // Caches that are populated lazily during decoding.
-    file_index_to_file: Lock<FxHashMap<SourceFileIndex, Lrc<SourceFile>>>,
-
-    // A map from dep-node to the position of the cached query result in
-    // `serialized_data`.
-    query_result_index: FxHashMap<SerializedDepNodeIndex, AbsoluteBytePos>,
-
-    // A map from dep-node to the position of any associated `QuerySideEffects` in
-    // `serialized_data`.
-    prev_side_effects_index: FxHashMap<SerializedDepNodeIndex, AbsoluteBytePos>,
-
-    alloc_decoding_state: AllocDecodingState,
-
-    // A map from syntax context ids to the position of their associated
-    // `SyntaxContextData`. We use a `u32` instead of a `SyntaxContext`
-    // to represent the fact that we are storing *encoded* ids. When we decode
-    // a `SyntaxContext`, a new id will be allocated from the global `HygieneData`,
-    // which will almost certainly be different than the serialized id.
-    syntax_contexts: FxHashMap<u32, AbsoluteBytePos>,
-    // A map from the `DefPathHash` of an `ExpnId` to the position
-    // of their associated `ExpnData`. Ideally, we would store a `DefId`,
-    // but we need to decode this before we've constructed a `TyCtxt` (which
-    // makes it difficult to decode a `DefId`).
-
-    // Note that these `DefPathHashes` correspond to both local and foreign
-    // `ExpnData` (e.g `ExpnData.krate` may not be `LOCAL_CRATE`). Alternatively,
-    // we could look up the `ExpnData` from the metadata of foreign crates,
-    // but it seemed easier to have `OnDiskCache` be independent of the `CStore`.
-    expn_data: UnhashMap<ExpnHash, AbsoluteBytePos>,
-    // Additional information used when decoding hygiene data.
-    hygiene_context: HygieneDecodeContext,
-    // Maps `ExpnHash`es to their raw value from the *previous*
-    // compilation session. This is used as an initial 'guess' when
-    // we try to map an `ExpnHash` to its value in the current
-    // compilation session.
-    foreign_expn_data: UnhashMap<ExpnHash, u32>,
-}
-
-// This type is used only for serialization and deserialization.
-#[derive(Encodable, Decodable)]
-struct Footer {
-    file_index_to_stable_id: FxHashMap<SourceFileIndex, EncodedSourceFileId>,
-    query_result_index: EncodedDepNodeIndex,
-    side_effects_index: EncodedDepNodeIndex,
-    // The location of all allocations.
-    interpret_alloc_index: Vec<u32>,
-    // See `OnDiskCache.syntax_contexts`
-    syntax_contexts: FxHashMap<u32, AbsoluteBytePos>,
-    // See `OnDiskCache.expn_data`
-    expn_data: UnhashMap<ExpnHash, AbsoluteBytePos>,
-    foreign_expn_data: UnhashMap<ExpnHash, u32>,
-}
-
-pub type EncodedDepNodeIndex = Vec<(SerializedDepNodeIndex, AbsoluteBytePos)>;
-
-#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug, Encodable, Decodable)]
-struct SourceFileIndex(u32);
-
-#[derive(Copy, Clone, Debug, Hash, Eq, PartialEq, Encodable, Decodable)]
-pub struct AbsoluteBytePos(u64);
-
-impl AbsoluteBytePos {
-    fn new(pos: usize) -> AbsoluteBytePos {
-        AbsoluteBytePos(pos.try_into().expect("Incremental cache file size overflowed u64."))
-    }
-
-    fn to_usize(self) -> usize {
-        self.0 as usize
-    }
-}
-
-/// An `EncodedSourceFileId` is the same as a `StableSourceFileId` except that
-/// the source crate is represented as a [StableCrateId] instead of as a
-/// `CrateNum`. This way `EncodedSourceFileId` can be encoded and decoded
-/// without any additional context, i.e. with a simple `opaque::Decoder` (which
-/// is the only thing available when decoding the cache's [Footer].
-#[derive(Encodable, Decodable, Clone, Debug)]
-struct EncodedSourceFileId {
-    file_name_hash: Hash64,
-    stable_crate_id: StableCrateId,
-}
-
-impl EncodedSourceFileId {
-    fn translate(&self, tcx: TyCtxt<'_>) -> StableSourceFileId {
-        let cnum = tcx.stable_crate_id_to_crate_num(self.stable_crate_id);
-        StableSourceFileId { file_name_hash: self.file_name_hash, cnum }
-    }
-
-    fn new(tcx: TyCtxt<'_>, file: &SourceFile) -> EncodedSourceFileId {
-        let source_file_id = StableSourceFileId::new(file);
-        EncodedSourceFileId {
-            file_name_hash: source_file_id.file_name_hash,
-            stable_crate_id: tcx.stable_crate_id(source_file_id.cnum),
-        }
-    }
-}
-
-impl<'sess> rustc_middle::ty::OnDiskCache<'sess> for OnDiskCache<'sess> {
-    /// Creates a new `OnDiskCache` instance from the serialized data in `data`.
-    fn new(sess: &'sess Session, data: Mmap, start_pos: usize) -> Self {
-        debug_assert!(sess.opts.incremental.is_some());
-
-        // Wrap in a scope so we can borrow `data`.
-        let footer: Footer = {
-            let mut decoder = MemDecoder::new(&data, start_pos);
-
-            // Decode the *position* of the footer, which can be found in the
-            // last 8 bytes of the file.
-            let footer_pos = decoder
-                .with_position(decoder.len() - IntEncodedWithFixedSize::ENCODED_SIZE, |decoder| {
-                    IntEncodedWithFixedSize::decode(decoder).0 as usize
-                });
-            // Decode the file footer, which contains all the lookup tables, etc.
-            decoder.with_position(footer_pos, |decoder| decode_tagged(decoder, TAG_FILE_FOOTER))
-        };
-
-        Self {
-            serialized_data: RwLock::new(Some(data)),
-            file_index_to_stable_id: footer.file_index_to_stable_id,
-            file_index_to_file: Default::default(),
-            source_map: sess.source_map(),
-            current_side_effects: Default::default(),
-            query_result_index: footer.query_result_index.into_iter().collect(),
-            prev_side_effects_index: footer.side_effects_index.into_iter().collect(),
-            alloc_decoding_state: AllocDecodingState::new(footer.interpret_alloc_index),
-            syntax_contexts: footer.syntax_contexts,
-            expn_data: footer.expn_data,
-            foreign_expn_data: footer.foreign_expn_data,
-            hygiene_context: Default::default(),
-        }
-    }
-
-    fn new_empty(source_map: &'sess SourceMap) -> Self {
-        Self {
-            serialized_data: RwLock::new(None),
-            file_index_to_stable_id: Default::default(),
-            file_index_to_file: Default::default(),
-            source_map,
-            current_side_effects: Default::default(),
-            query_result_index: Default::default(),
-            prev_side_effects_index: Default::default(),
-            alloc_decoding_state: AllocDecodingState::new(Vec::new()),
-            syntax_contexts: FxHashMap::default(),
-            expn_data: UnhashMap::default(),
-            foreign_expn_data: UnhashMap::default(),
-            hygiene_context: Default::default(),
-        }
-    }
-
-    /// Execute all cache promotions and release the serialized backing Mmap.
-    ///
-    /// Cache promotions require invoking queries, which needs to read the serialized data.
-    /// In order to serialize the new on-disk cache, the former on-disk cache file needs to be
-    /// deleted, hence we won't be able to refer to its memmapped data.
-    fn drop_serialized_data(&self, tcx: TyCtxt<'_>) {
-        // Load everything into memory so we can write it out to the on-disk
-        // cache. The vast majority of cacheable query results should already
-        // be in memory, so this should be a cheap operation.
-        // Do this *before* we clone 'latest_foreign_def_path_hashes', since
-        // loading existing queries may cause us to create new DepNodes, which
-        // may in turn end up invoking `store_foreign_def_id_hash`
-        tcx.dep_graph.exec_cache_promotions(tcx);
-
-        *self.serialized_data.write() = None;
-    }
-
-    fn serialize(&self, tcx: TyCtxt<'_>, encoder: FileEncoder) -> FileEncodeResult {
-        // Serializing the `DepGraph` should not modify it.
-        tcx.dep_graph.with_ignore(|| {
-            // Allocate `SourceFileIndex`es.
-            let (file_to_file_index, file_index_to_stable_id) = {
-                let files = tcx.sess.source_map().files();
-                let mut file_to_file_index =
-                    FxHashMap::with_capacity_and_hasher(files.len(), Default::default());
-                let mut file_index_to_stable_id =
-                    FxHashMap::with_capacity_and_hasher(files.len(), Default::default());
-
-                for (index, file) in files.iter().enumerate() {
-                    let index = SourceFileIndex(index as u32);
-                    let file_ptr: *const SourceFile = &**file as *const _;
-                    file_to_file_index.insert(file_ptr, index);
-                    let source_file_id = EncodedSourceFileId::new(tcx, &file);
-                    file_index_to_stable_id.insert(index, source_file_id);
-                }
-
-                (file_to_file_index, file_index_to_stable_id)
-            };
-
-            let hygiene_encode_context = HygieneEncodeContext::default();
-
-            let mut encoder = CacheEncoder {
-                tcx,
-                encoder,
-                type_shorthands: Default::default(),
-                predicate_shorthands: Default::default(),
-                interpret_allocs: Default::default(),
-                source_map: CachingSourceMapView::new(tcx.sess.source_map()),
-                file_to_file_index,
-                hygiene_context: &hygiene_encode_context,
-                symbol_table: Default::default(),
-            };
-
-            // Encode query results.
-            let mut query_result_index = EncodedDepNodeIndex::new();
-
-            tcx.sess.time("encode_query_results", || {
-                let enc = &mut encoder;
-                let qri = &mut query_result_index;
-                QueryCtxt::from_tcx(tcx).encode_query_results(enc, qri);
-            });
-
-            // Encode side effects.
-            let side_effects_index: EncodedDepNodeIndex = self
-                .current_side_effects
-                .borrow()
-                .iter()
-                .map(|(dep_node_index, side_effects)| {
-                    let pos = AbsoluteBytePos::new(encoder.position());
-                    let dep_node_index = SerializedDepNodeIndex::new(dep_node_index.index());
-                    encoder.encode_tagged(dep_node_index, side_effects);
-
-                    (dep_node_index, pos)
-                })
-                .collect();
-
-            let interpret_alloc_index = {
-                let mut interpret_alloc_index = Vec::new();
-                let mut n = 0;
-                loop {
-                    let new_n = encoder.interpret_allocs.len();
-                    // If we have found new IDs, serialize those too.
-                    if n == new_n {
-                        // Otherwise, abort.
-                        break;
-                    }
-                    interpret_alloc_index.reserve(new_n - n);
-                    for idx in n..new_n {
-                        let id = encoder.interpret_allocs[idx];
-                        let pos: u32 = encoder.position().try_into().unwrap();
-                        interpret_alloc_index.push(pos);
-                        interpret::specialized_encode_alloc_id(&mut encoder, tcx, id);
-                    }
-                    n = new_n;
-                }
-                interpret_alloc_index
-            };
-
-            let mut syntax_contexts = FxHashMap::default();
-            let mut expn_data = UnhashMap::default();
-            let mut foreign_expn_data = UnhashMap::default();
-
-            // Encode all hygiene data (`SyntaxContextData` and `ExpnData`) from the current
-            // session.
-
-            hygiene_encode_context.encode(
-                &mut encoder,
-                |encoder, index, ctxt_data| {
-                    let pos = AbsoluteBytePos::new(encoder.position());
-                    encoder.encode_tagged(TAG_SYNTAX_CONTEXT, ctxt_data);
-                    syntax_contexts.insert(index, pos);
-                },
-                |encoder, expn_id, data, hash| {
-                    if expn_id.krate == LOCAL_CRATE {
-                        let pos = AbsoluteBytePos::new(encoder.position());
-                        encoder.encode_tagged(TAG_EXPN_DATA, data);
-                        expn_data.insert(hash, pos);
-                    } else {
-                        foreign_expn_data.insert(hash, expn_id.local_id.as_u32());
-                    }
-                },
-            );
-
-            // Encode the file footer.
-            let footer_pos = encoder.position() as u64;
-            encoder.encode_tagged(
-                TAG_FILE_FOOTER,
-                &Footer {
-                    file_index_to_stable_id,
-                    query_result_index,
-                    side_effects_index,
-                    interpret_alloc_index,
-                    syntax_contexts,
-                    expn_data,
-                    foreign_expn_data,
-                },
-            );
-
-            // Encode the position of the footer as the last 8 bytes of the
-            // file so we know where to look for it.
-            IntEncodedWithFixedSize(footer_pos).encode(&mut encoder.encoder);
-
-            // DO NOT WRITE ANYTHING TO THE ENCODER AFTER THIS POINT! The address
-            // of the footer must be the last thing in the data stream.
-
-            encoder.finish()
-        })
-    }
-}
-
-impl<'sess> OnDiskCache<'sess> {
-    pub fn as_dyn(&self) -> &dyn rustc_middle::ty::OnDiskCache<'sess> {
-        self as _
-    }
-
-    /// Loads a `QuerySideEffects` created during the previous compilation session.
-    pub fn load_side_effects(
-        &self,
-        tcx: TyCtxt<'_>,
-        dep_node_index: SerializedDepNodeIndex,
-    ) -> QuerySideEffects {
-        let side_effects: Option<QuerySideEffects> =
-            self.load_indexed(tcx, dep_node_index, &self.prev_side_effects_index);
-
-        side_effects.unwrap_or_default()
-    }
-
-    /// Stores a `QuerySideEffects` emitted during the current compilation session.
-    /// Anything stored like this will be available via `load_side_effects` in
-    /// the next compilation session.
-    #[inline(never)]
-    #[cold]
-    pub fn store_side_effects(&self, dep_node_index: DepNodeIndex, side_effects: QuerySideEffects) {
-        let mut current_side_effects = self.current_side_effects.borrow_mut();
-        let prev = current_side_effects.insert(dep_node_index, side_effects);
-        debug_assert!(prev.is_none());
-    }
-
-    /// Return whether the cached query result can be decoded.
-    pub fn loadable_from_disk(&self, dep_node_index: SerializedDepNodeIndex) -> bool {
-        self.query_result_index.contains_key(&dep_node_index)
-        // with_decoder is infallible, so we can stop here
-    }
-
-    /// Returns the cached query result if there is something in the cache for
-    /// the given `SerializedDepNodeIndex`; otherwise returns `None`.
-    pub fn try_load_query_result<'tcx, T>(
-        &self,
-        tcx: TyCtxt<'tcx>,
-        dep_node_index: SerializedDepNodeIndex,
-    ) -> Option<T>
-    where
-        T: for<'a> Decodable<CacheDecoder<'a, 'tcx>>,
-    {
-        let opt_value = self.load_indexed(tcx, dep_node_index, &self.query_result_index);
-        debug_assert_eq!(opt_value.is_some(), self.loadable_from_disk(dep_node_index));
-        opt_value
-    }
-
-    /// Stores side effect emitted during computation of an anonymous query.
-    /// Since many anonymous queries can share the same `DepNode`, we aggregate
-    /// them -- as opposed to regular queries where we assume that there is a
-    /// 1:1 relationship between query-key and `DepNode`.
-    #[inline(never)]
-    #[cold]
-    pub fn store_side_effects_for_anon_node(
-        &self,
-        dep_node_index: DepNodeIndex,
-        side_effects: QuerySideEffects,
-    ) {
-        let mut current_side_effects = self.current_side_effects.borrow_mut();
-
-        let x = current_side_effects.entry(dep_node_index).or_default();
-        x.append(side_effects);
-    }
-
-    fn load_indexed<'tcx, T>(
-        &self,
-        tcx: TyCtxt<'tcx>,
-        dep_node_index: SerializedDepNodeIndex,
-        index: &FxHashMap<SerializedDepNodeIndex, AbsoluteBytePos>,
-    ) -> Option<T>
-    where
-        T: for<'a> Decodable<CacheDecoder<'a, 'tcx>>,
-    {
-        let pos = index.get(&dep_node_index).cloned()?;
-        let value = self.with_decoder(tcx, pos, |decoder| decode_tagged(decoder, dep_node_index));
-        Some(value)
-    }
-
-    fn with_decoder<'a, 'tcx, T, F: for<'s> FnOnce(&mut CacheDecoder<'s, 'tcx>) -> T>(
-        &'sess self,
-        tcx: TyCtxt<'tcx>,
-        pos: AbsoluteBytePos,
-        f: F,
-    ) -> T
-    where
-        T: Decodable<CacheDecoder<'a, 'tcx>>,
-    {
-        let serialized_data = self.serialized_data.read();
-        let mut decoder = CacheDecoder {
-            tcx,
-            opaque: MemDecoder::new(serialized_data.as_deref().unwrap_or(&[]), pos.to_usize()),
-            source_map: self.source_map,
-            file_index_to_file: &self.file_index_to_file,
-            file_index_to_stable_id: &self.file_index_to_stable_id,
-            alloc_decoding_session: self.alloc_decoding_state.new_decoding_session(),
-            syntax_contexts: &self.syntax_contexts,
-            expn_data: &self.expn_data,
-            foreign_expn_data: &self.foreign_expn_data,
-            hygiene_context: &self.hygiene_context,
-        };
-        f(&mut decoder)
-    }
-}
-
-//- DECODING -------------------------------------------------------------------
-
-/// A decoder that can read from the incremental compilation cache. It is similar to the one
-/// we use for crate metadata decoding in that it can rebase spans and eventually
-/// will also handle things that contain `Ty` instances.
-pub struct CacheDecoder<'a, 'tcx> {
-    tcx: TyCtxt<'tcx>,
-    opaque: MemDecoder<'a>,
-    source_map: &'a SourceMap,
-    file_index_to_file: &'a Lock<FxHashMap<SourceFileIndex, Lrc<SourceFile>>>,
-    file_index_to_stable_id: &'a FxHashMap<SourceFileIndex, EncodedSourceFileId>,
-    alloc_decoding_session: AllocDecodingSession<'a>,
-    syntax_contexts: &'a FxHashMap<u32, AbsoluteBytePos>,
-    expn_data: &'a UnhashMap<ExpnHash, AbsoluteBytePos>,
-    foreign_expn_data: &'a UnhashMap<ExpnHash, u32>,
-    hygiene_context: &'a HygieneDecodeContext,
-}
-
-impl<'a, 'tcx> CacheDecoder<'a, 'tcx> {
-    fn file_index_to_file(&self, index: SourceFileIndex) -> Lrc<SourceFile> {
-        let CacheDecoder {
-            tcx,
-            ref file_index_to_file,
-            ref file_index_to_stable_id,
-            ref source_map,
-            ..
-        } = *self;
-
-        file_index_to_file
-            .borrow_mut()
-            .entry(index)
-            .or_insert_with(|| {
-                let stable_id = file_index_to_stable_id[&index].translate(tcx);
-
-                // If this `SourceFile` is from a foreign crate, then make sure
-                // that we've imported all of the source files from that crate.
-                // This has usually already been done during macro invocation.
-                // However, when encoding query results like `TypeckResults`,
-                // we might encode an `AdtDef` for a foreign type (because it
-                // was referenced in the body of the function). There is no guarantee
-                // that we will load the source files from that crate during macro
-                // expansion, so we use `import_source_files` to ensure that the foreign
-                // source files are actually imported before we call `source_file_by_stable_id`.
-                if stable_id.cnum != LOCAL_CRATE {
-                    self.tcx.cstore_untracked().import_source_files(self.tcx.sess, stable_id.cnum);
-                }
-
-                source_map
-                    .source_file_by_stable_id(stable_id)
-                    .expect("failed to lookup `SourceFile` in new context")
-            })
-            .clone()
-    }
-}
-
-// Decodes something that was encoded with `encode_tagged()` and verify that the
-// tag matches and the correct amount of bytes was read.
-fn decode_tagged<D, T, V>(decoder: &mut D, expected_tag: T) -> V
-where
-    T: Decodable<D> + Eq + std::fmt::Debug,
-    V: Decodable<D>,
-    D: Decoder,
-{
-    let start_pos = decoder.position();
-
-    let actual_tag = T::decode(decoder);
-    assert_eq!(actual_tag, expected_tag);
-    let value = V::decode(decoder);
-    let end_pos = decoder.position();
-
-    let expected_len: u64 = Decodable::decode(decoder);
-    assert_eq!((end_pos - start_pos) as u64, expected_len);
-
-    value
-}
-
-impl<'a, 'tcx> TyDecoder for CacheDecoder<'a, 'tcx> {
-    type I = TyCtxt<'tcx>;
-    const CLEAR_CROSS_CRATE: bool = false;
-
-    #[inline]
-    fn interner(&self) -> TyCtxt<'tcx> {
-        self.tcx
-    }
-
-    fn cached_ty_for_shorthand<F>(&mut self, shorthand: usize, or_insert_with: F) -> Ty<'tcx>
-    where
-        F: FnOnce(&mut Self) -> Ty<'tcx>,
-    {
-        let tcx = self.tcx;
-
-        let cache_key = ty::CReaderCacheKey { cnum: None, pos: shorthand };
-
-        if let Some(&ty) = tcx.ty_rcache.borrow().get(&cache_key) {
-            return ty;
-        }
-
-        let ty = or_insert_with(self);
-        // This may overwrite the entry, but it should overwrite with the same value.
-        tcx.ty_rcache.borrow_mut().insert_same(cache_key, ty);
-        ty
-    }
-
-    fn with_position<F, R>(&mut self, pos: usize, f: F) -> R
-    where
-        F: FnOnce(&mut Self) -> R,
-    {
-        debug_assert!(pos < self.opaque.len());
-
-        let new_opaque = MemDecoder::new(self.opaque.data(), pos);
-        let old_opaque = mem::replace(&mut self.opaque, new_opaque);
-        let r = f(self);
-        self.opaque = old_opaque;
-        r
-    }
-
-    fn decode_alloc_id(&mut self) -> interpret::AllocId {
-        let alloc_decoding_session = self.alloc_decoding_session;
-        alloc_decoding_session.decode_alloc_id(self)
-    }
-}
-
-rustc_middle::implement_ty_decoder!(CacheDecoder<'a, 'tcx>);
-
-// This ensures that the `Decodable<opaque::Decoder>::decode` specialization for `Vec<u8>` is used
-// when a `CacheDecoder` is passed to `Decodable::decode`. Unfortunately, we have to manually opt
-// into specializations this way, given how `CacheDecoder` and the decoding traits currently work.
-impl<'a, 'tcx> Decodable<CacheDecoder<'a, 'tcx>> for Vec<u8> {
-    fn decode(d: &mut CacheDecoder<'a, 'tcx>) -> Self {
-        Decodable::decode(&mut d.opaque)
-    }
-}
-
-impl<'a, 'tcx> Decodable<CacheDecoder<'a, 'tcx>> for SyntaxContext {
-    fn decode(decoder: &mut CacheDecoder<'a, 'tcx>) -> Self {
-        let syntax_contexts = decoder.syntax_contexts;
-        rustc_span::hygiene::decode_syntax_context(decoder, decoder.hygiene_context, |this, id| {
-            // This closure is invoked if we haven't already decoded the data for the `SyntaxContext` we are deserializing.
-            // We look up the position of the associated `SyntaxData` and decode it.
-            let pos = syntax_contexts.get(&id).unwrap();
-            this.with_position(pos.to_usize(), |decoder| {
-                let data: SyntaxContextData = decode_tagged(decoder, TAG_SYNTAX_CONTEXT);
-                data
-            })
-        })
-    }
-}
-
-impl<'a, 'tcx> Decodable<CacheDecoder<'a, 'tcx>> for ExpnId {
-    fn decode(decoder: &mut CacheDecoder<'a, 'tcx>) -> Self {
-        let hash = ExpnHash::decode(decoder);
-        if hash.is_root() {
-            return ExpnId::root();
-        }
-
-        if let Some(expn_id) = ExpnId::from_hash(hash) {
-            return expn_id;
-        }
-
-        let krate = decoder.tcx.stable_crate_id_to_crate_num(hash.stable_crate_id());
-
-        let expn_id = if krate == LOCAL_CRATE {
-            // We look up the position of the associated `ExpnData` and decode it.
-            let pos = decoder
-                .expn_data
-                .get(&hash)
-                .unwrap_or_else(|| panic!("Bad hash {:?} (map {:?})", hash, decoder.expn_data));
-
-            let data: ExpnData = decoder
-                .with_position(pos.to_usize(), |decoder| decode_tagged(decoder, TAG_EXPN_DATA));
-            let expn_id = rustc_span::hygiene::register_local_expn_id(data, hash);
-
-            #[cfg(debug_assertions)]
-            {
-                use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
-                let local_hash = decoder.tcx.with_stable_hashing_context(|mut hcx| {
-                    let mut hasher = StableHasher::new();
-                    expn_id.expn_data().hash_stable(&mut hcx, &mut hasher);
-                    hasher.finish()
-                });
-                debug_assert_eq!(hash.local_hash(), local_hash);
-            }
-
-            expn_id
-        } else {
-            let index_guess = decoder.foreign_expn_data[&hash];
-            decoder.tcx.cstore_untracked().expn_hash_to_expn_id(
-                decoder.tcx.sess,
-                krate,
-                index_guess,
-                hash,
-            )
-        };
-
-        debug_assert_eq!(expn_id.krate, krate);
-        expn_id
-    }
-}
-
-impl<'a, 'tcx> Decodable<CacheDecoder<'a, 'tcx>> for Span {
-    fn decode(decoder: &mut CacheDecoder<'a, 'tcx>) -> Self {
-        let ctxt = SyntaxContext::decode(decoder);
-        let parent = Option::<LocalDefId>::decode(decoder);
-        let tag: u8 = Decodable::decode(decoder);
-
-        if tag == TAG_PARTIAL_SPAN {
-            return Span::new(BytePos(0), BytePos(0), ctxt, parent);
-        } else if tag == TAG_RELATIVE_SPAN {
-            let dlo = u32::decode(decoder);
-            let dto = u32::decode(decoder);
-
-            let enclosing = decoder.tcx.source_span_untracked(parent.unwrap()).data_untracked();
-            let span = Span::new(
-                enclosing.lo + BytePos::from_u32(dlo),
-                enclosing.lo + BytePos::from_u32(dto),
-                ctxt,
-                parent,
-            );
-
-            return span;
-        } else {
-            debug_assert_eq!(tag, TAG_FULL_SPAN);
-        }
-
-        let file_lo_index = SourceFileIndex::decode(decoder);
-        let line_lo = usize::decode(decoder);
-        let col_lo = BytePos::decode(decoder);
-        let len = BytePos::decode(decoder);
-
-        let file_lo = decoder.file_index_to_file(file_lo_index);
-        let lo = file_lo.lines(|lines| lines[line_lo - 1] + col_lo);
-        let hi = lo + len;
-
-        Span::new(lo, hi, ctxt, parent)
-    }
-}
-
-// copy&paste impl from rustc_metadata
-impl<'a, 'tcx> Decodable<CacheDecoder<'a, 'tcx>> for Symbol {
-    fn decode(d: &mut CacheDecoder<'a, 'tcx>) -> Self {
-        let tag = d.read_u8();
-
-        match tag {
-            SYMBOL_STR => {
-                let s = d.read_str();
-                Symbol::intern(s)
-            }
-            SYMBOL_OFFSET => {
-                // read str offset
-                let pos = d.read_usize();
-
-                // move to str offset and read
-                d.opaque.with_position(pos, |d| {
-                    let s = d.read_str();
-                    Symbol::intern(s)
-                })
-            }
-            SYMBOL_PREINTERNED => {
-                let symbol_index = d.read_u32();
-                Symbol::new_from_decoded(symbol_index)
-            }
-            _ => unreachable!(),
-        }
-    }
-}
-
-impl<'a, 'tcx> Decodable<CacheDecoder<'a, 'tcx>> for CrateNum {
-    fn decode(d: &mut CacheDecoder<'a, 'tcx>) -> Self {
-        let stable_id = StableCrateId::decode(d);
-        let cnum = d.tcx.stable_crate_id_to_crate_num(stable_id);
-        cnum
-    }
-}
-
-// This impl makes sure that we get a runtime error when we try decode a
-// `DefIndex` that is not contained in a `DefId`. Such a case would be problematic
-// because we would not know how to transform the `DefIndex` to the current
-// context.
-impl<'a, 'tcx> Decodable<CacheDecoder<'a, 'tcx>> for DefIndex {
-    fn decode(_d: &mut CacheDecoder<'a, 'tcx>) -> DefIndex {
-        panic!("trying to decode `DefIndex` outside the context of a `DefId`")
-    }
-}
-
-// Both the `CrateNum` and the `DefIndex` of a `DefId` can change in between two
-// compilation sessions. We use the `DefPathHash`, which is stable across
-// sessions, to map the old `DefId` to the new one.
-impl<'a, 'tcx> Decodable<CacheDecoder<'a, 'tcx>> for DefId {
-    fn decode(d: &mut CacheDecoder<'a, 'tcx>) -> Self {
-        // Load the `DefPathHash` which is was we encoded the `DefId` as.
-        let def_path_hash = DefPathHash::decode(d);
-
-        // Using the `DefPathHash`, we can lookup the new `DefId`.
-        // Subtle: We only encode a `DefId` as part of a query result.
-        // If we get to this point, then all of the query inputs were green,
-        // which means that the definition with this hash is guaranteed to
-        // still exist in the current compilation session.
-        d.tcx.def_path_hash_to_def_id(def_path_hash, &mut || {
-            panic!("Failed to convert DefPathHash {def_path_hash:?}")
-        })
-    }
-}
-
-impl<'a, 'tcx> Decodable<CacheDecoder<'a, 'tcx>> for &'tcx UnordSet<LocalDefId> {
-    fn decode(d: &mut CacheDecoder<'a, 'tcx>) -> Self {
-        RefDecodable::decode(d)
-    }
-}
-
-impl<'a, 'tcx> Decodable<CacheDecoder<'a, 'tcx>>
-    for &'tcx FxHashMap<DefId, ty::EarlyBinder<Ty<'tcx>>>
-{
-    fn decode(d: &mut CacheDecoder<'a, 'tcx>) -> Self {
-        RefDecodable::decode(d)
-    }
-}
-
-impl<'a, 'tcx> Decodable<CacheDecoder<'a, 'tcx>>
-    for &'tcx IndexVec<mir::Promoted, mir::Body<'tcx>>
-{
-    fn decode(d: &mut CacheDecoder<'a, 'tcx>) -> Self {
-        RefDecodable::decode(d)
-    }
-}
-
-impl<'a, 'tcx> Decodable<CacheDecoder<'a, 'tcx>> for &'tcx [(ty::Predicate<'tcx>, Span)] {
-    fn decode(d: &mut CacheDecoder<'a, 'tcx>) -> Self {
-        RefDecodable::decode(d)
-    }
-}
-
-impl<'a, 'tcx> Decodable<CacheDecoder<'a, 'tcx>> for &'tcx [(ty::Clause<'tcx>, Span)] {
-    fn decode(d: &mut CacheDecoder<'a, 'tcx>) -> Self {
-        RefDecodable::decode(d)
-    }
-}
-
-impl<'a, 'tcx> Decodable<CacheDecoder<'a, 'tcx>> for &'tcx [rustc_ast::InlineAsmTemplatePiece] {
-    fn decode(d: &mut CacheDecoder<'a, 'tcx>) -> Self {
-        RefDecodable::decode(d)
-    }
-}
-
-macro_rules! impl_ref_decoder {
-    (<$tcx:tt> $($ty:ty,)*) => {
-        $(impl<'a, $tcx> Decodable<CacheDecoder<'a, $tcx>> for &$tcx [$ty] {
-            fn decode(d: &mut CacheDecoder<'a, $tcx>) -> Self {
-                RefDecodable::decode(d)
-            }
-        })*
-    };
-}
-
-impl_ref_decoder! {<'tcx>
-    Span,
-    rustc_ast::Attribute,
-    rustc_span::symbol::Ident,
-    ty::Variance,
-    rustc_span::def_id::DefId,
-    rustc_span::def_id::LocalDefId,
-    (rustc_middle::middle::exported_symbols::ExportedSymbol<'tcx>, rustc_middle::middle::exported_symbols::SymbolExportInfo),
-    ty::DeducedParamAttrs,
-}
-
-//- ENCODING -------------------------------------------------------------------
-
-/// An encoder that can write to the incremental compilation cache.
-pub struct CacheEncoder<'a, 'tcx> {
-    tcx: TyCtxt<'tcx>,
-    encoder: FileEncoder,
-    type_shorthands: FxHashMap<Ty<'tcx>, usize>,
-    predicate_shorthands: FxHashMap<ty::PredicateKind<'tcx>, usize>,
-    interpret_allocs: FxIndexSet<interpret::AllocId>,
-    source_map: CachingSourceMapView<'tcx>,
-    file_to_file_index: FxHashMap<*const SourceFile, SourceFileIndex>,
-    hygiene_context: &'a HygieneEncodeContext,
-    symbol_table: FxHashMap<Symbol, usize>,
-}
-
-impl<'a, 'tcx> CacheEncoder<'a, 'tcx> {
-    fn source_file_index(&mut self, source_file: Lrc<SourceFile>) -> SourceFileIndex {
-        self.file_to_file_index[&(&*source_file as *const SourceFile)]
-    }
-
-    /// Encode something with additional information that allows to do some
-    /// sanity checks when decoding the data again. This method will first
-    /// encode the specified tag, then the given value, then the number of
-    /// bytes taken up by tag and value. On decoding, we can then verify that
-    /// we get the expected tag and read the expected number of bytes.
-    fn encode_tagged<T: Encodable<Self>, V: Encodable<Self>>(&mut self, tag: T, value: &V) {
-        let start_pos = self.position();
-
-        tag.encode(self);
-        value.encode(self);
-
-        let end_pos = self.position();
-        ((end_pos - start_pos) as u64).encode(self);
-    }
-
-    fn finish(self) -> Result<usize, io::Error> {
-        self.encoder.finish()
-    }
-}
-
-impl<'a, 'tcx> Encodable<CacheEncoder<'a, 'tcx>> for SyntaxContext {
-    fn encode(&self, s: &mut CacheEncoder<'a, 'tcx>) {
-        rustc_span::hygiene::raw_encode_syntax_context(*self, s.hygiene_context, s);
-    }
-}
-
-impl<'a, 'tcx> Encodable<CacheEncoder<'a, 'tcx>> for ExpnId {
-    fn encode(&self, s: &mut CacheEncoder<'a, 'tcx>) {
-        s.hygiene_context.schedule_expn_data_for_encoding(*self);
-        self.expn_hash().encode(s);
-    }
-}
-
-impl<'a, 'tcx> Encodable<CacheEncoder<'a, 'tcx>> for Span {
-    fn encode(&self, s: &mut CacheEncoder<'a, 'tcx>) {
-        let span_data = self.data_untracked();
-        span_data.ctxt.encode(s);
-        span_data.parent.encode(s);
-
-        if span_data.is_dummy() {
-            return TAG_PARTIAL_SPAN.encode(s);
-        }
-
-        if let Some(parent) = span_data.parent {
-            let enclosing = s.tcx.source_span(parent).data_untracked();
-            if enclosing.contains(span_data) {
-                TAG_RELATIVE_SPAN.encode(s);
-                (span_data.lo - enclosing.lo).to_u32().encode(s);
-                (span_data.hi - enclosing.lo).to_u32().encode(s);
-                return;
-            }
-        }
-
-        let pos = s.source_map.byte_pos_to_line_and_col(span_data.lo);
-        let partial_span = match &pos {
-            Some((file_lo, _, _)) => !file_lo.contains(span_data.hi),
-            None => true,
-        };
-
-        if partial_span {
-            return TAG_PARTIAL_SPAN.encode(s);
-        }
-
-        let (file_lo, line_lo, col_lo) = pos.unwrap();
-
-        let len = span_data.hi - span_data.lo;
-
-        let source_file_index = s.source_file_index(file_lo);
-
-        TAG_FULL_SPAN.encode(s);
-        source_file_index.encode(s);
-        line_lo.encode(s);
-        col_lo.encode(s);
-        len.encode(s);
-    }
-}
-
-// copy&paste impl from rustc_metadata
-impl<'a, 'tcx> Encodable<CacheEncoder<'a, 'tcx>> for Symbol {
-    fn encode(&self, s: &mut CacheEncoder<'a, 'tcx>) {
-        // if symbol preinterned, emit tag and symbol index
-        if self.is_preinterned() {
-            s.encoder.emit_u8(SYMBOL_PREINTERNED);
-            s.encoder.emit_u32(self.as_u32());
-        } else {
-            // otherwise write it as string or as offset to it
-            match s.symbol_table.entry(*self) {
-                Entry::Vacant(o) => {
-                    s.encoder.emit_u8(SYMBOL_STR);
-                    let pos = s.encoder.position();
-                    o.insert(pos);
-                    s.emit_str(self.as_str());
-                }
-                Entry::Occupied(o) => {
-                    let x = *o.get();
-                    s.emit_u8(SYMBOL_OFFSET);
-                    s.emit_usize(x);
-                }
-            }
-        }
-    }
-}
-
-impl<'a, 'tcx> TyEncoder for CacheEncoder<'a, 'tcx> {
-    type I = TyCtxt<'tcx>;
-    const CLEAR_CROSS_CRATE: bool = false;
-
-    fn position(&self) -> usize {
-        self.encoder.position()
-    }
-    fn type_shorthands(&mut self) -> &mut FxHashMap<Ty<'tcx>, usize> {
-        &mut self.type_shorthands
-    }
-    fn predicate_shorthands(&mut self) -> &mut FxHashMap<ty::PredicateKind<'tcx>, usize> {
-        &mut self.predicate_shorthands
-    }
-    fn encode_alloc_id(&mut self, alloc_id: &interpret::AllocId) {
-        let (index, _) = self.interpret_allocs.insert_full(*alloc_id);
-
-        index.encode(self);
-    }
-}
-
-impl<'a, 'tcx> Encodable<CacheEncoder<'a, 'tcx>> for CrateNum {
-    fn encode(&self, s: &mut CacheEncoder<'a, 'tcx>) {
-        s.tcx.stable_crate_id(*self).encode(s);
-    }
-}
-
-impl<'a, 'tcx> Encodable<CacheEncoder<'a, 'tcx>> for DefId {
-    fn encode(&self, s: &mut CacheEncoder<'a, 'tcx>) {
-        s.tcx.def_path_hash(*self).encode(s);
-    }
-}
-
-impl<'a, 'tcx> Encodable<CacheEncoder<'a, 'tcx>> for DefIndex {
-    fn encode(&self, _: &mut CacheEncoder<'a, 'tcx>) {
-        bug!("encoding `DefIndex` without context");
-    }
-}
-
-macro_rules! encoder_methods {
-    ($($name:ident($ty:ty);)*) => {
-        #[inline]
-        $(fn $name(&mut self, value: $ty) {
-            self.encoder.$name(value)
-        })*
-    }
-}
-
-impl<'a, 'tcx> Encoder for CacheEncoder<'a, 'tcx> {
-    encoder_methods! {
-        emit_usize(usize);
-        emit_u128(u128);
-        emit_u64(u64);
-        emit_u32(u32);
-        emit_u16(u16);
-        emit_u8(u8);
-
-        emit_isize(isize);
-        emit_i128(i128);
-        emit_i64(i64);
-        emit_i32(i32);
-        emit_i16(i16);
-        emit_i8(i8);
-
-        emit_bool(bool);
-        emit_char(char);
-        emit_str(&str);
-        emit_raw_bytes(&[u8]);
-    }
-}
-
-// This ensures that the `Encodable<opaque::FileEncoder>::encode` specialization for byte slices
-// is used when a `CacheEncoder` having an `opaque::FileEncoder` is passed to `Encodable::encode`.
-// Unfortunately, we have to manually opt into specializations this way, given how `CacheEncoder`
-// and the encoding traits currently work.
-impl<'a, 'tcx> Encodable<CacheEncoder<'a, 'tcx>> for [u8] {
-    fn encode(&self, e: &mut CacheEncoder<'a, 'tcx>) {
-        self.encode(&mut e.encoder);
-    }
-}
-
-pub(crate) fn encode_query_results<'a, 'tcx, Q>(
-    query: Q,
-    qcx: QueryCtxt<'tcx>,
-    encoder: &mut CacheEncoder<'a, 'tcx>,
-    query_result_index: &mut EncodedDepNodeIndex,
-) where
-    Q: super::QueryConfigRestored<'tcx>,
-    Q::RestoredValue: Encodable<CacheEncoder<'a, 'tcx>>,
-{
-    let _timer = qcx
-        .tcx
-        .profiler()
-        .verbose_generic_activity_with_arg("encode_query_results_for", query.name());
-
-    assert!(query.query_state(qcx).all_inactive());
-    let cache = query.query_cache(qcx);
-    cache.iter(&mut |key, value, dep_node| {
-        if query.cache_on_disk(qcx.tcx, &key) {
-            let dep_node = SerializedDepNodeIndex::new(dep_node.index());
-
-            // Record position of the cache entry.
-            query_result_index.push((dep_node, AbsoluteBytePos::new(encoder.encoder.position())));
-
-            // Encode the type check tables with the `SerializedDepNodeIndex`
-            // as tag.
-            encoder.encode_tagged(dep_node, &Q::restore(*value));
-        }
-    });
-}
diff --git a/compiler/rustc_query_impl/src/plumbing.rs b/compiler/rustc_query_impl/src/plumbing.rs
index 32222df25d4..9f8ac7ccd0b 100644
--- a/compiler/rustc_query_impl/src/plumbing.rs
+++ b/compiler/rustc_query_impl/src/plumbing.rs
@@ -2,35 +2,44 @@
 //! generate the actual methods on tcx which find and execute the provider,
 //! manage the caches, and so forth.
 
-use crate::on_disk_cache::{CacheDecoder, CacheEncoder, EncodedDepNodeIndex};
-use crate::profiling_support::QueryKeyStringCache;
-use crate::{on_disk_cache, Queries};
+use crate::rustc_middle::dep_graph::DepContext;
+use crate::rustc_middle::ty::TyEncoder;
 use rustc_data_structures::stable_hasher::{Hash64, HashStable, StableHasher};
-use rustc_data_structures::sync::{AtomicU64, Lock};
-use rustc_errors::{Diagnostic, Handler};
+use rustc_data_structures::sync::Lock;
+use rustc_errors::Diagnostic;
+use rustc_index::Idx;
 use rustc_middle::dep_graph::{
     self, DepKind, DepKindStruct, DepNode, DepNodeIndex, SerializedDepNodeIndex,
 };
+use rustc_middle::query::on_disk_cache::AbsoluteBytePos;
+use rustc_middle::query::on_disk_cache::{CacheDecoder, CacheEncoder, EncodedDepNodeIndex};
 use rustc_middle::query::Key;
 use rustc_middle::ty::tls::{self, ImplicitCtxt};
 use rustc_middle::ty::{self, TyCtxt};
 use rustc_query_system::dep_graph::{DepNodeParams, HasDepContext};
 use rustc_query_system::ich::StableHashingContext;
 use rustc_query_system::query::{
-    force_query, QueryConfig, QueryContext, QueryJobId, QueryMap, QuerySideEffects, QueryStackFrame,
+    force_query, QueryCache, QueryConfig, QueryContext, QueryJobId, QueryMap, QuerySideEffects,
+    QueryStackFrame,
 };
 use rustc_query_system::{LayoutOfDepth, QueryOverflow};
 use rustc_serialize::Decodable;
+use rustc_serialize::Encodable;
 use rustc_session::Limit;
 use rustc_span::def_id::LOCAL_CRATE;
-use std::any::Any;
 use std::num::NonZeroU64;
 use thin_vec::ThinVec;
 
 #[derive(Copy, Clone)]
 pub struct QueryCtxt<'tcx> {
     pub tcx: TyCtxt<'tcx>,
-    pub queries: &'tcx Queries<'tcx>,
+}
+
+impl<'tcx> QueryCtxt<'tcx> {
+    #[inline]
+    pub fn new(tcx: TyCtxt<'tcx>) -> Self {
+        QueryCtxt { tcx }
+    }
 }
 
 impl<'tcx> std::ops::Deref for QueryCtxt<'tcx> {
@@ -53,44 +62,56 @@ impl<'tcx> HasDepContext for QueryCtxt<'tcx> {
 }
 
 impl QueryContext for QueryCtxt<'_> {
+    #[inline]
     fn next_job_id(self) -> QueryJobId {
         QueryJobId(
             NonZeroU64::new(
-                self.queries.jobs.fetch_add(1, rustc_data_structures::sync::Ordering::Relaxed),
+                self.query_system.jobs.fetch_add(1, rustc_data_structures::sync::Ordering::Relaxed),
             )
             .unwrap(),
         )
     }
 
+    #[inline]
     fn current_query_job(self) -> Option<QueryJobId> {
-        tls::with_related_context(*self, |icx| icx.query)
+        tls::with_related_context(self.tcx, |icx| icx.query)
     }
 
     fn try_collect_active_jobs(self) -> Option<QueryMap<DepKind>> {
-        self.queries.try_collect_active_jobs(*self)
+        let mut jobs = QueryMap::default();
+
+        for query in &self.query_system.fns.query_structs {
+            (query.try_collect_active_jobs)(self.tcx, &mut jobs);
+        }
+
+        Some(jobs)
     }
 
     // Interactions with on_disk_cache
     fn load_side_effects(self, prev_dep_node_index: SerializedDepNodeIndex) -> QuerySideEffects {
-        self.queries
+        self.query_system
             .on_disk_cache
             .as_ref()
-            .map(|c| c.load_side_effects(*self, prev_dep_node_index))
+            .map(|c| c.load_side_effects(self.tcx, prev_dep_node_index))
             .unwrap_or_default()
     }
 
+    #[inline(never)]
+    #[cold]
     fn store_side_effects(self, dep_node_index: DepNodeIndex, side_effects: QuerySideEffects) {
-        if let Some(c) = self.queries.on_disk_cache.as_ref() {
+        if let Some(c) = self.query_system.on_disk_cache.as_ref() {
             c.store_side_effects(dep_node_index, side_effects)
         }
     }
 
+    #[inline(never)]
+    #[cold]
     fn store_side_effects_for_anon_node(
         self,
         dep_node_index: DepNodeIndex,
         side_effects: QuerySideEffects,
     ) {
-        if let Some(c) = self.queries.on_disk_cache.as_ref() {
+        if let Some(c) = self.query_system.on_disk_cache.as_ref() {
             c.store_side_effects_for_anon_node(dep_node_index, side_effects)
         }
     }
@@ -109,14 +130,14 @@ impl QueryContext for QueryCtxt<'_> {
         // The `TyCtxt` stored in TLS has the same global interner lifetime
         // as `self`, so we use `with_related_context` to relate the 'tcx lifetimes
         // when accessing the `ImplicitCtxt`.
-        tls::with_related_context(*self, move |current_icx| {
+        tls::with_related_context(self.tcx, move |current_icx| {
             if depth_limit && !self.recursion_limit().value_within_limit(current_icx.query_depth) {
                 self.depth_limit_error(token);
             }
 
             // Update the `ImplicitCtxt` to point to our new query job.
             let new_icx = ImplicitCtxt {
-                tcx: *self,
+                tcx: self.tcx,
                 query: Some(token),
                 diagnostics,
                 query_depth: current_icx.query_depth + depth_limit as usize,
@@ -152,51 +173,20 @@ impl QueryContext for QueryCtxt<'_> {
     }
 }
 
-impl<'tcx> QueryCtxt<'tcx> {
-    #[inline]
-    pub fn from_tcx(tcx: TyCtxt<'tcx>) -> Self {
-        let queries = tcx.queries.as_any();
-        let queries = unsafe {
-            let queries = std::mem::transmute::<&dyn Any, &dyn Any>(queries);
-            let queries = queries.downcast_ref().unwrap();
-            let queries = std::mem::transmute::<&Queries<'_>, &Queries<'_>>(queries);
-            queries
-        };
-        QueryCtxt { tcx, queries }
-    }
-
-    pub(crate) fn on_disk_cache(self) -> Option<&'tcx on_disk_cache::OnDiskCache<'tcx>> {
-        self.queries.on_disk_cache.as_ref()
-    }
+pub(super) fn try_mark_green<'tcx>(tcx: TyCtxt<'tcx>, dep_node: &dep_graph::DepNode) -> bool {
+    tcx.dep_graph.try_mark_green(QueryCtxt::new(tcx), dep_node).is_some()
+}
 
-    pub(super) fn encode_query_results(
-        self,
-        encoder: &mut CacheEncoder<'_, 'tcx>,
-        query_result_index: &mut EncodedDepNodeIndex,
-    ) {
-        for query in &self.queries.query_structs {
-            if let Some(encode) = query.encode_query_results {
-                encode(self, encoder, query_result_index);
-            }
+pub(super) fn encode_all_query_results<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    encoder: &mut CacheEncoder<'_, 'tcx>,
+    query_result_index: &mut EncodedDepNodeIndex,
+) {
+    for query in &tcx.query_system.fns.query_structs {
+        if let Some(encode) = query.encode_query_results {
+            encode(tcx, encoder, query_result_index);
         }
     }
-
-    pub fn try_print_query_stack(
-        self,
-        query: Option<QueryJobId>,
-        handler: &Handler,
-        num_frames: Option<usize>,
-    ) -> usize {
-        rustc_query_system::query::print_query_stack(self, query, handler, num_frames)
-    }
-}
-
-#[derive(Clone, Copy)]
-pub(crate) struct QueryStruct<'tcx> {
-    pub try_collect_active_jobs: fn(QueryCtxt<'tcx>, &mut QueryMap<DepKind>) -> Option<()>,
-    pub alloc_self_profile_query_strings: fn(TyCtxt<'tcx>, &mut QueryKeyStringCache),
-    pub encode_query_results:
-        Option<fn(QueryCtxt<'tcx>, &mut CacheEncoder<'_, 'tcx>, &mut EncodedDepNodeIndex)>,
 }
 
 macro_rules! handle_cycle_error {
@@ -276,13 +266,13 @@ macro_rules! hash_result {
 
 macro_rules! call_provider {
     ([][$qcx:expr, $name:ident, $key:expr]) => {{
-        ($qcx.queries.local_providers.$name)($qcx.tcx, $key)
+        ($qcx.query_system.fns.local_providers.$name)($qcx, $key)
     }};
     ([(separate_provide_extern) $($rest:tt)*][$qcx:expr, $name:ident, $key:expr]) => {{
         if let Some(key) = $key.as_local_key() {
-            ($qcx.queries.local_providers.$name)($qcx.tcx, key)
+            ($qcx.query_system.fns.local_providers.$name)($qcx, key)
         } else {
-            ($qcx.queries.extern_providers.$name)($qcx.tcx, $key)
+            ($qcx.query_system.fns.extern_providers.$name)($qcx, $key)
         }
     }};
     ([$other:tt $($modifiers:tt)*][$($args:tt)*]) => {
@@ -306,7 +296,7 @@ pub(crate) fn create_query_frame<
     'tcx,
     K: Copy + Key + for<'a> HashStable<StableHashingContext<'a>>,
 >(
-    tcx: QueryCtxt<'tcx>,
+    tcx: TyCtxt<'tcx>,
     do_describe: fn(TyCtxt<'tcx>, K) -> String,
     key: K,
     kind: DepKind,
@@ -318,7 +308,7 @@ pub(crate) fn create_query_frame<
         // Showing visible path instead of any path is not that important in production.
         ty::print::with_no_visible_paths!(
             // Force filename-line mode to avoid invoking `type_of` query.
-            ty::print::with_forced_impl_filename_line!(do_describe(tcx.tcx, key))
+            ty::print::with_forced_impl_filename_line!(do_describe(tcx, key))
         )
     );
     let description =
@@ -328,7 +318,7 @@ pub(crate) fn create_query_frame<
         // so exit to avoid infinite recursion.
         None
     } else {
-        Some(key.default_span(*tcx))
+        Some(key.default_span(tcx))
     };
     let def_id = key.key_as_def_id();
     let def_kind = if kind == dep_graph::DepKind::opt_def_kind {
@@ -350,6 +340,34 @@ pub(crate) fn create_query_frame<
     QueryStackFrame::new(description, span, def_id, def_kind, kind, ty_adt_id, hash)
 }
 
+pub(crate) fn encode_query_results<'a, 'tcx, Q>(
+    query: Q,
+    qcx: QueryCtxt<'tcx>,
+    encoder: &mut CacheEncoder<'a, 'tcx>,
+    query_result_index: &mut EncodedDepNodeIndex,
+) where
+    Q: super::QueryConfigRestored<'tcx>,
+    Q::RestoredValue: Encodable<CacheEncoder<'a, 'tcx>>,
+{
+    let _timer =
+        qcx.profiler().verbose_generic_activity_with_arg("encode_query_results_for", query.name());
+
+    assert!(query.query_state(qcx).all_inactive());
+    let cache = query.query_cache(qcx);
+    cache.iter(&mut |key, value, dep_node| {
+        if query.cache_on_disk(qcx.tcx, &key) {
+            let dep_node = SerializedDepNodeIndex::new(dep_node.index());
+
+            // Record position of the cache entry.
+            query_result_index.push((dep_node, AbsoluteBytePos::new(encoder.position())));
+
+            // Encode the type check tables with the `SerializedDepNodeIndex`
+            // as tag.
+            encoder.encode_tagged(dep_node, &Q::restore(*value));
+        }
+    });
+}
+
 fn try_load_from_on_disk_cache<'tcx, Q>(query: Q, tcx: TyCtxt<'tcx>, dep_node: DepNode)
 where
     Q: QueryConfig<QueryCtxt<'tcx>>,
@@ -364,8 +382,8 @@ where
     }
 }
 
-pub(crate) fn loadable_from_disk<'tcx>(tcx: QueryCtxt<'tcx>, id: SerializedDepNodeIndex) -> bool {
-    if let Some(cache) = tcx.on_disk_cache().as_ref() {
+pub(crate) fn loadable_from_disk<'tcx>(tcx: TyCtxt<'tcx>, id: SerializedDepNodeIndex) -> bool {
+    if let Some(cache) = tcx.query_system.on_disk_cache.as_ref() {
         cache.loadable_from_disk(id)
     } else {
         false
@@ -373,13 +391,13 @@ pub(crate) fn loadable_from_disk<'tcx>(tcx: QueryCtxt<'tcx>, id: SerializedDepNo
 }
 
 pub(crate) fn try_load_from_disk<'tcx, V>(
-    tcx: QueryCtxt<'tcx>,
+    tcx: TyCtxt<'tcx>,
     id: SerializedDepNodeIndex,
 ) -> Option<V>
 where
     V: for<'a> Decodable<CacheDecoder<'a, 'tcx>>,
 {
-    tcx.on_disk_cache().as_ref()?.try_load_query_result(*tcx, id)
+    tcx.query_system.on_disk_cache.as_ref()?.try_load_query_result(tcx, id)
 }
 
 fn force_from_dep_node<'tcx, Q>(query: Q, tcx: TyCtxt<'tcx>, dep_node: DepNode) -> bool
@@ -407,8 +425,7 @@ where
     if let Some(key) = Q::Key::recover(tcx, &dep_node) {
         #[cfg(debug_assertions)]
         let _guard = tracing::span!(tracing::Level::TRACE, stringify!($name), ?key).entered();
-        let tcx = QueryCtxt::from_tcx(tcx);
-        force_query(query, tcx, key, dep_node);
+        force_query(query, QueryCtxt::new(tcx), key, dep_node);
         true
     } else {
         false
@@ -461,8 +478,33 @@ macro_rules! define_queries {
     (
      $($(#[$attr:meta])*
         [$($modifiers:tt)*] fn $name:ident($($K:tt)*) -> $V:ty,)*) => {
-        define_queries_struct! {
-            input: ($(([$($modifiers)*] [$($attr)*] [$name]))*)
+        mod get_query {
+            use super::*;
+
+            $(
+                #[inline(always)]
+                #[tracing::instrument(level = "trace", skip(tcx))]
+                pub(super) fn $name<'tcx>(
+                    tcx: TyCtxt<'tcx>,
+                    span: Span,
+                    key: query_keys::$name<'tcx>,
+                    mode: QueryMode,
+                ) -> Option<Erase<query_values::$name<'tcx>>> {
+                    get_query(
+                        queries::$name::default(),
+                        QueryCtxt::new(tcx),
+                        span,
+                        key,
+                        mode
+                    )
+                }
+            )*
+        }
+
+        pub(crate) fn engine() -> QueryEngine {
+            QueryEngine {
+                $($name: get_query::$name,)*
+            }
         }
 
         #[allow(nonstandard_style)]
@@ -502,7 +544,7 @@ macro_rules! define_queries {
             fn query_state<'a>(self, tcx: QueryCtxt<'tcx>) -> &'a QueryState<Self::Key, crate::dep_graph::DepKind>
                 where QueryCtxt<'tcx>: 'a
             {
-                &tcx.queries.$name
+                &tcx.query_system.states.$name
             }
 
             #[inline(always)]
@@ -521,7 +563,7 @@ macro_rules! define_queries {
             fn compute(self, qcx: QueryCtxt<'tcx>, key: Self::Key) -> Self::Value {
                 query_provided_to_value::$name(
                     qcx.tcx,
-                    call_provider!([$($modifiers)*][qcx, $name, key])
+                    call_provider!([$($modifiers)*][qcx.tcx, $name, key])
                 )
             }
 
@@ -535,7 +577,7 @@ macro_rules! define_queries {
                     if ::rustc_middle::query::cached::$name(_qcx.tcx, _key) {
                         Some(|qcx: QueryCtxt<'tcx>, dep_node| {
                             let value = $crate::plumbing::try_load_from_disk::<query_provided::$name<'tcx>>(
-                                qcx,
+                                qcx.tcx,
                                 dep_node
                             );
                             value.map(|value| query_provided_to_value::$name(qcx.tcx, value))
@@ -557,7 +599,7 @@ macro_rules! define_queries {
             ) -> bool {
                 should_ever_cache_on_disk!([$($modifiers)*] {
                     self.cache_on_disk(_qcx.tcx, _key) &&
-                        $crate::plumbing::loadable_from_disk(_qcx, _index)
+                        $crate::plumbing::loadable_from_disk(_qcx.tcx, _index)
                 } {
                     false
                 })
@@ -684,14 +726,13 @@ macro_rules! define_queries {
         }
 
         mod query_structs {
-            use rustc_middle::ty::TyCtxt;
-            use $crate::plumbing::{QueryStruct, QueryCtxt};
-            use $crate::profiling_support::QueryKeyStringCache;
-            use rustc_query_system::query::QueryMap;
+            use super::*;
+            use rustc_middle::ty::query::QueryStruct;
+            use rustc_middle::ty::query::QueryKeyStringCache;
             use rustc_middle::dep_graph::DepKind;
 
             pub(super) const fn dummy_query_struct<'tcx>() -> QueryStruct<'tcx> {
-                fn noop_try_collect_active_jobs(_: QueryCtxt<'_>, _: &mut QueryMap<DepKind>) -> Option<()> {
+                fn noop_try_collect_active_jobs(_: TyCtxt<'_>, _: &mut QueryMap<DepKind>) -> Option<()> {
                     None
                 }
                 fn noop_alloc_self_profile_query_strings(_: TyCtxt<'_>, _: &mut QueryKeyStringCache) {}
@@ -717,7 +758,7 @@ macro_rules! define_queries {
                         let name = stringify!($name);
                         $crate::plumbing::create_query_frame(tcx, rustc_middle::query::descs::$name, key, kind, name)
                     };
-                    tcx.queries.$name.try_collect_active_jobs(
+                    tcx.query_system.states.$name.try_collect_active_jobs(
                         tcx,
                         make_query,
                         qmap,
@@ -731,10 +772,10 @@ macro_rules! define_queries {
                         string_cache,
                     )
                 },
-                encode_query_results: expand_if_cached!([$($modifiers)*], |qcx, encoder, query_result_index|
-                    $crate::on_disk_cache::encode_query_results::<super::queries::$name<'tcx>>(
+                encode_query_results: expand_if_cached!([$($modifiers)*], |tcx, encoder, query_result_index|
+                    $crate::plumbing::encode_query_results::<super::queries::$name<'tcx>>(
                         super::queries::$name::default(),
-                        qcx,
+                        QueryCtxt::new(tcx),
                         encoder,
                         query_result_index,
                     )
@@ -747,93 +788,3 @@ macro_rules! define_queries {
         }
     }
 }
-
-use crate::{ExternProviders, OnDiskCache, Providers};
-
-impl<'tcx> Queries<'tcx> {
-    pub fn new(
-        local_providers: Providers,
-        extern_providers: ExternProviders,
-        on_disk_cache: Option<OnDiskCache<'tcx>>,
-    ) -> Self {
-        use crate::query_structs;
-        Queries {
-            local_providers: Box::new(local_providers),
-            extern_providers: Box::new(extern_providers),
-            query_structs: make_dep_kind_array!(query_structs).to_vec(),
-            on_disk_cache,
-            jobs: AtomicU64::new(1),
-            ..Queries::default()
-        }
-    }
-}
-
-macro_rules! define_queries_struct {
-    (
-     input: ($(([$($modifiers:tt)*] [$($attr:tt)*] [$name:ident]))*)) => {
-        #[derive(Default)]
-        pub struct Queries<'tcx> {
-            local_providers: Box<Providers>,
-            extern_providers: Box<ExternProviders>,
-            query_structs: Vec<$crate::plumbing::QueryStruct<'tcx>>,
-            pub on_disk_cache: Option<OnDiskCache<'tcx>>,
-            jobs: AtomicU64,
-
-            $(
-                $(#[$attr])*
-                $name: QueryState<
-                    <queries::$name<'tcx> as QueryConfig<QueryCtxt<'tcx>>>::Key,
-                    rustc_middle::dep_graph::DepKind,
-                >,
-            )*
-        }
-
-        impl<'tcx> Queries<'tcx> {
-            pub(crate) fn try_collect_active_jobs(
-                &'tcx self,
-                tcx: TyCtxt<'tcx>,
-            ) -> Option<QueryMap<rustc_middle::dep_graph::DepKind>> {
-                let tcx = QueryCtxt { tcx, queries: self };
-                let mut jobs = QueryMap::default();
-
-                for query in &self.query_structs {
-                    (query.try_collect_active_jobs)(tcx, &mut jobs);
-                }
-
-                Some(jobs)
-            }
-        }
-
-        impl<'tcx> QueryEngine<'tcx> for Queries<'tcx> {
-            fn as_any(&'tcx self) -> &'tcx dyn std::any::Any {
-                let this = unsafe { std::mem::transmute::<&Queries<'_>, &Queries<'_>>(self) };
-                this as _
-            }
-
-            fn try_mark_green(&'tcx self, tcx: TyCtxt<'tcx>, dep_node: &dep_graph::DepNode) -> bool {
-                let qcx = QueryCtxt { tcx, queries: self };
-                tcx.dep_graph.try_mark_green(qcx, dep_node).is_some()
-            }
-
-            $($(#[$attr])*
-            #[inline(always)]
-            #[tracing::instrument(level = "trace", skip(self, tcx))]
-            fn $name(
-                &'tcx self,
-                tcx: TyCtxt<'tcx>,
-                span: Span,
-                key: query_keys::$name<'tcx>,
-                mode: QueryMode,
-            ) -> Option<Erase<query_values::$name<'tcx>>> {
-                let qcx = QueryCtxt { tcx, queries: self };
-                get_query(
-                    queries::$name::default(),
-                    qcx,
-                    span,
-                    key,
-                    mode
-                )
-            })*
-        }
-    };
-}
diff --git a/compiler/rustc_query_impl/src/profiling_support.rs b/compiler/rustc_query_impl/src/profiling_support.rs
index 08b588a8c94..7d9306f8087 100644
--- a/compiler/rustc_query_impl/src/profiling_support.rs
+++ b/compiler/rustc_query_impl/src/profiling_support.rs
@@ -1,24 +1,13 @@
-use crate::QueryCtxt;
 use measureme::{StringComponent, StringId};
-use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::profiling::SelfProfiler;
 use rustc_hir::def_id::{CrateNum, DefId, DefIndex, LocalDefId, LOCAL_CRATE};
 use rustc_hir::definitions::DefPathData;
+use rustc_middle::ty::query::QueryKeyStringCache;
 use rustc_middle::ty::TyCtxt;
 use rustc_query_system::query::QueryCache;
 use std::fmt::Debug;
 use std::io::Write;
 
-pub(crate) struct QueryKeyStringCache {
-    def_id_cache: FxHashMap<DefId, StringId>,
-}
-
-impl QueryKeyStringCache {
-    fn new() -> QueryKeyStringCache {
-        QueryKeyStringCache { def_id_cache: Default::default() }
-    }
-}
-
 struct QueryKeyStringBuilder<'p, 'tcx> {
     profiler: &'p SelfProfiler,
     tcx: TyCtxt<'tcx>,
@@ -253,9 +242,8 @@ pub fn alloc_self_profile_query_strings(tcx: TyCtxt<'_>) {
     }
 
     let mut string_cache = QueryKeyStringCache::new();
-    let queries = QueryCtxt::from_tcx(tcx);
 
-    for query in &queries.queries.query_structs {
+    for query in &tcx.query_system.fns.query_structs {
         (query.alloc_self_profile_query_strings)(tcx, &mut string_cache);
     }
 }