Move on_disk_cache.rs

1 files changed, 0 insertions, 1064 deletions

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));
-        }
-    });
-}