Merging upstream version 1.74.1+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

10 files changed, 520 insertions, 184 deletions

diff --git a/compiler/rustc_metadata/messages.ftl b/compiler/rustc_metadata/messages.ftl
index cc58d51be..633004fdd 100644
--- a/compiler/rustc_metadata/messages.ftl
+++ b/compiler/rustc_metadata/messages.ftl
@@ -259,9 +259,6 @@ metadata_std_required =
 metadata_symbol_conflicts_current =
     the current crate is indistinguishable from one of its dependencies: it has the same crate-name `{$crate_name}` and was compiled with the same `-C metadata` arguments. This will result in symbol conflicts between the two.
 
-metadata_symbol_conflicts_others =
-    found two different crates with name `{$crate_name}` that are not distinguished by differing `-C metadata`. This will result in symbol conflicts between the two.
-
 metadata_target_no_std_support =
     the `{$locator_triple}` target may not support the standard library
 
diff --git a/compiler/rustc_metadata/src/creader.rs b/compiler/rustc_metadata/src/creader.rs
index fce80ab37..692214753 100644
--- a/compiler/rustc_metadata/src/creader.rs
+++ b/compiler/rustc_metadata/src/creader.rs
@@ -8,7 +8,7 @@ use rustc_ast::expand::allocator::{alloc_error_handler_name, global_fn_name, All
 use rustc_ast::{self as ast, *};
 use rustc_data_structures::fx::FxHashSet;
 use rustc_data_structures::svh::Svh;
-use rustc_data_structures::sync::{MappedReadGuard, MappedWriteGuard, ReadGuard, WriteGuard};
+use rustc_data_structures::sync::{FreezeReadGuard, FreezeWriteGuard};
 use rustc_expand::base::SyntaxExtension;
 use rustc_hir::def_id::{CrateNum, LocalDefId, StableCrateId, StableCrateIdMap, LOCAL_CRATE};
 use rustc_hir::definitions::Definitions;
@@ -134,14 +134,14 @@ impl<'a> std::fmt::Debug for CrateDump<'a> {
 }
 
 impl CStore {
-    pub fn from_tcx(tcx: TyCtxt<'_>) -> MappedReadGuard<'_, CStore> {
-        ReadGuard::map(tcx.untracked().cstore.read(), |cstore| {
+    pub fn from_tcx(tcx: TyCtxt<'_>) -> FreezeReadGuard<'_, CStore> {
+        FreezeReadGuard::map(tcx.untracked().cstore.read(), |cstore| {
             cstore.as_any().downcast_ref::<CStore>().expect("`tcx.cstore` is not a `CStore`")
         })
     }
 
-    pub fn from_tcx_mut(tcx: TyCtxt<'_>) -> MappedWriteGuard<'_, CStore> {
-        WriteGuard::map(tcx.untracked().cstore.write(), |cstore| {
+    pub fn from_tcx_mut(tcx: TyCtxt<'_>) -> FreezeWriteGuard<'_, CStore> {
+        FreezeWriteGuard::map(tcx.untracked().cstore.write(), |cstore| {
             cstore.untracked_as_any().downcast_mut().expect("`tcx.cstore` is not a `CStore`")
         })
     }
diff --git a/compiler/rustc_metadata/src/fs.rs b/compiler/rustc_metadata/src/fs.rs
index 2a9662b80..7eb2a347d 100644
--- a/compiler/rustc_metadata/src/fs.rs
+++ b/compiler/rustc_metadata/src/fs.rs
@@ -5,7 +5,6 @@ use crate::errors::{
 use crate::{encode_metadata, EncodedMetadata};
 
 use rustc_data_structures::temp_dir::MaybeTempDir;
-use rustc_hir::def_id::LOCAL_CRATE;
 use rustc_middle::ty::TyCtxt;
 use rustc_session::config::{OutFileName, OutputType};
 use rustc_session::output::filename_for_metadata;
@@ -40,8 +39,7 @@ pub fn emit_wrapper_file(
 }
 
 pub fn encode_and_write_metadata(tcx: TyCtxt<'_>) -> (EncodedMetadata, bool) {
-    let crate_name = tcx.crate_name(LOCAL_CRATE);
-    let out_filename = filename_for_metadata(tcx.sess, crate_name, tcx.output_filenames(()));
+    let out_filename = filename_for_metadata(tcx.sess, tcx.output_filenames(()));
     // To avoid races with another rustc process scanning the output directory,
     // we need to write the file somewhere else and atomically move it to its
     // final destination, with an `fs::rename` call. In order for the rename to
diff --git a/compiler/rustc_metadata/src/lib.rs b/compiler/rustc_metadata/src/lib.rs
index 87373d997..fa77b36c4 100644
--- a/compiler/rustc_metadata/src/lib.rs
+++ b/compiler/rustc_metadata/src/lib.rs
@@ -26,7 +26,7 @@ extern crate rustc_middle;
 #[macro_use]
 extern crate tracing;
 
-pub use rmeta::{provide, provide_extern};
+pub use rmeta::provide;
 use rustc_errors::{DiagnosticMessage, SubdiagnosticMessage};
 use rustc_fluent_macro::fluent_messages;
 
@@ -42,6 +42,6 @@ pub mod locator;
 
 pub use fs::{emit_wrapper_file, METADATA_FILENAME};
 pub use native_libs::find_native_static_library;
-pub use rmeta::{encode_metadata, EncodedMetadata, METADATA_HEADER};
+pub use rmeta::{encode_metadata, rendered_const, EncodedMetadata, METADATA_HEADER};
 
 fluent_messages! { "../messages.ftl" }
diff --git a/compiler/rustc_metadata/src/locator.rs b/compiler/rustc_metadata/src/locator.rs
index bf6004ba8..3062939d8 100644
--- a/compiler/rustc_metadata/src/locator.rs
+++ b/compiler/rustc_metadata/src/locator.rs
@@ -903,10 +903,11 @@ pub fn list_file_metadata(
     path: &Path,
     metadata_loader: &dyn MetadataLoader,
     out: &mut dyn Write,
+    ls_kinds: &[String],
 ) -> IoResult<()> {
     let flavor = get_flavor_from_path(path);
     match get_metadata_section(target, flavor, path, metadata_loader) {
-        Ok(metadata) => metadata.list_crate_metadata(out),
+        Ok(metadata) => metadata.list_crate_metadata(out, ls_kinds),
         Err(msg) => write!(out, "{msg}\n"),
     }
 }
diff --git a/compiler/rustc_metadata/src/rmeta/decoder.rs b/compiler/rustc_metadata/src/rmeta/decoder.rs
index e8f66c36a..b189e79df 100644
--- a/compiler/rustc_metadata/src/rmeta/decoder.rs
+++ b/compiler/rustc_metadata/src/rmeta/decoder.rs
@@ -9,7 +9,7 @@ use rustc_data_structures::captures::Captures;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::owned_slice::OwnedSlice;
 use rustc_data_structures::svh::Svh;
-use rustc_data_structures::sync::{AppendOnlyVec, AtomicBool, Lock, Lrc, OnceCell};
+use rustc_data_structures::sync::{AppendOnlyVec, AtomicBool, Lock, Lrc, OnceLock};
 use rustc_data_structures::unhash::UnhashMap;
 use rustc_expand::base::{SyntaxExtension, SyntaxExtensionKind};
 use rustc_expand::proc_macro::{AttrProcMacro, BangProcMacro, DeriveProcMacro};
@@ -24,7 +24,6 @@ use rustc_middle::middle::exported_symbols::{ExportedSymbol, SymbolExportInfo};
 use rustc_middle::mir::interpret::{AllocDecodingSession, AllocDecodingState};
 use rustc_middle::ty::codec::TyDecoder;
 use rustc_middle::ty::fast_reject::SimplifiedType;
-use rustc_middle::ty::GeneratorDiagnosticData;
 use rustc_middle::ty::{self, ParameterizedOverTcx, Ty, TyCtxt, Visibility};
 use rustc_serialize::opaque::MemDecoder;
 use rustc_serialize::{Decodable, Decoder};
@@ -44,7 +43,6 @@ use std::sync::atomic::Ordering;
 use std::{io, iter, mem};
 
 pub(super) use cstore_impl::provide;
-pub use cstore_impl::provide_extern;
 use rustc_span::hygiene::HygieneDecodeContext;
 
 mod cstore_impl;
@@ -93,7 +91,7 @@ pub(crate) struct CrateMetadata {
     /// For every definition in this crate, maps its `DefPathHash` to its `DefIndex`.
     def_path_hash_map: DefPathHashMapRef<'static>,
     /// Likewise for ExpnHash.
-    expn_hash_map: OnceCell<UnhashMap<ExpnHash, ExpnIndex>>,
+    expn_hash_map: OnceLock<UnhashMap<ExpnHash, ExpnIndex>>,
     /// Used for decoding interpret::AllocIds in a cached & thread-safe manner.
     alloc_decoding_state: AllocDecodingState,
     /// Caches decoded `DefKey`s.
@@ -250,6 +248,7 @@ impl<'a, 'tcx> Metadata<'a, 'tcx> for (CrateMetadataRef<'a>, TyCtxt<'tcx>) {
 }
 
 impl<T: ParameterizedOverTcx> LazyValue<T> {
+    #[inline]
     fn decode<'a, 'tcx, M: Metadata<'a, 'tcx>>(self, metadata: M) -> T::Value<'tcx>
     where
         T::Value<'tcx>: Decodable<DecodeContext<'a, 'tcx>>,
@@ -294,6 +293,7 @@ unsafe impl<'a, 'tcx, T: Decodable<DecodeContext<'a, 'tcx>>> TrustedLen
 }
 
 impl<T: ParameterizedOverTcx> LazyArray<T> {
+    #[inline]
     fn decode<'a, 'tcx, M: Metadata<'a, 'tcx>>(
         self,
         metadata: M,
@@ -360,8 +360,8 @@ impl<'a, 'tcx> DecodeContext<'a, 'tcx> {
         self.read_lazy_offset_then(|pos| LazyArray::from_position_and_num_elems(pos, len))
     }
 
-    fn read_lazy_table<I, T>(&mut self, len: usize) -> LazyTable<I, T> {
-        self.read_lazy_offset_then(|pos| LazyTable::from_position_and_encoded_size(pos, len))
+    fn read_lazy_table<I, T>(&mut self, width: usize, len: usize) -> LazyTable<I, T> {
+        self.read_lazy_offset_then(|pos| LazyTable::from_position_and_encoded_size(pos, width, len))
     }
 
     #[inline]
@@ -420,6 +420,7 @@ impl<'a, 'tcx> TyDecoder for DecodeContext<'a, 'tcx> {
 }
 
 impl<'a, 'tcx> Decodable<DecodeContext<'a, 'tcx>> for CrateNum {
+    #[inline]
     fn decode(d: &mut DecodeContext<'a, 'tcx>) -> CrateNum {
         let cnum = CrateNum::from_u32(d.read_u32());
         d.map_encoded_cnum_to_current(cnum)
@@ -427,18 +428,21 @@ impl<'a, 'tcx> Decodable<DecodeContext<'a, 'tcx>> for CrateNum {
 }
 
 impl<'a, 'tcx> Decodable<DecodeContext<'a, 'tcx>> for DefIndex {
+    #[inline]
     fn decode(d: &mut DecodeContext<'a, 'tcx>) -> DefIndex {
         DefIndex::from_u32(d.read_u32())
     }
 }
 
 impl<'a, 'tcx> Decodable<DecodeContext<'a, 'tcx>> for ExpnIndex {
+    #[inline]
     fn decode(d: &mut DecodeContext<'a, 'tcx>) -> ExpnIndex {
         ExpnIndex::from_u32(d.read_u32())
     }
 }
 
 impl<'a, 'tcx> Decodable<DecodeContext<'a, 'tcx>> for ast::AttrId {
+    #[inline]
     fn decode(d: &mut DecodeContext<'a, 'tcx>) -> ast::AttrId {
         let sess = d.sess.expect("can't decode AttrId without Session");
         sess.parse_sess.attr_id_generator.mk_attr_id()
@@ -672,6 +676,7 @@ impl<'a, 'tcx, T> Decodable<DecodeContext<'a, 'tcx>> for LazyValue<T> {
 }
 
 impl<'a, 'tcx, T> Decodable<DecodeContext<'a, 'tcx>> for LazyArray<T> {
+    #[inline]
     fn decode(decoder: &mut DecodeContext<'a, 'tcx>) -> Self {
         let len = decoder.read_usize();
         if len == 0 { LazyArray::default() } else { decoder.read_lazy_array(len) }
@@ -680,8 +685,9 @@ impl<'a, 'tcx, T> Decodable<DecodeContext<'a, 'tcx>> for LazyArray<T> {
 
 impl<'a, 'tcx, I: Idx, T> Decodable<DecodeContext<'a, 'tcx>> for LazyTable<I, T> {
     fn decode(decoder: &mut DecodeContext<'a, 'tcx>) -> Self {
+        let width = decoder.read_usize();
         let len = decoder.read_usize();
-        decoder.read_lazy_table(len)
+        decoder.read_lazy_table(width, len)
     }
 }
 
@@ -717,25 +723,196 @@ impl MetadataBlob {
         LazyValue::<CrateRoot>::from_position(NonZeroUsize::new(pos).unwrap()).decode(self)
     }
 
-    pub(crate) fn list_crate_metadata(&self, out: &mut dyn io::Write) -> io::Result<()> {
+    pub(crate) fn list_crate_metadata(
+        &self,
+        out: &mut dyn io::Write,
+        ls_kinds: &[String],
+    ) -> io::Result<()> {
         let root = self.get_root();
-        writeln!(out, "Crate info:")?;
-        writeln!(out, "name {}{}", root.name(), root.extra_filename)?;
-        writeln!(out, "hash {} stable_crate_id {:?}", root.hash(), root.stable_crate_id)?;
-        writeln!(out, "proc_macro {:?}", root.proc_macro_data.is_some())?;
-        writeln!(out, "=External Dependencies=")?;
-
-        for (i, dep) in root.crate_deps.decode(self).enumerate() {
-            let CrateDep { name, extra_filename, hash, host_hash, kind, is_private } = dep;
-            let number = i + 1;
-
-            writeln!(
-                out,
-                "{number} {name}{extra_filename} hash {hash} host_hash {host_hash:?} kind {kind:?} {privacy}",
-                privacy = if is_private { "private" } else { "public" }
-            )?;
+
+        let all_ls_kinds = vec![
+            "root".to_owned(),
+            "lang_items".to_owned(),
+            "features".to_owned(),
+            "items".to_owned(),
+        ];
+        let ls_kinds = if ls_kinds.contains(&"all".to_owned()) { &all_ls_kinds } else { ls_kinds };
+
+        for kind in ls_kinds {
+            match &**kind {
+                "root" => {
+                    writeln!(out, "Crate info:")?;
+                    writeln!(out, "name {}{}", root.name(), root.extra_filename)?;
+                    writeln!(
+                        out,
+                        "hash {} stable_crate_id {:?}",
+                        root.hash(),
+                        root.stable_crate_id
+                    )?;
+                    writeln!(out, "proc_macro {:?}", root.proc_macro_data.is_some())?;
+                    writeln!(out, "triple {}", root.header.triple.triple())?;
+                    writeln!(out, "edition {}", root.edition)?;
+                    writeln!(out, "symbol_mangling_version {:?}", root.symbol_mangling_version)?;
+                    writeln!(
+                        out,
+                        "required_panic_strategy {:?} panic_in_drop_strategy {:?}",
+                        root.required_panic_strategy, root.panic_in_drop_strategy
+                    )?;
+                    writeln!(
+                        out,
+                        "has_global_allocator {} has_alloc_error_handler {} has_panic_handler {} has_default_lib_allocator {}",
+                        root.has_global_allocator,
+                        root.has_alloc_error_handler,
+                        root.has_panic_handler,
+                        root.has_default_lib_allocator
+                    )?;
+                    writeln!(
+                        out,
+                        "compiler_builtins {} needs_allocator {} needs_panic_runtime {} no_builtins {} panic_runtime {} profiler_runtime {}",
+                        root.compiler_builtins,
+                        root.needs_allocator,
+                        root.needs_panic_runtime,
+                        root.no_builtins,
+                        root.panic_runtime,
+                        root.profiler_runtime
+                    )?;
+
+                    writeln!(out, "=External Dependencies=")?;
+                    let dylib_dependency_formats =
+                        root.dylib_dependency_formats.decode(self).collect::<Vec<_>>();
+                    for (i, dep) in root.crate_deps.decode(self).enumerate() {
+                        let CrateDep { name, extra_filename, hash, host_hash, kind, is_private } =
+                            dep;
+                        let number = i + 1;
+
+                        writeln!(
+                            out,
+                            "{number} {name}{extra_filename} hash {hash} host_hash {host_hash:?} kind {kind:?} {privacy}{linkage}",
+                            privacy = if is_private { "private" } else { "public" },
+                            linkage = if dylib_dependency_formats.is_empty() {
+                                String::new()
+                            } else {
+                                format!(" linkage {:?}", dylib_dependency_formats[i])
+                            }
+                        )?;
+                    }
+                    write!(out, "\n")?;
+                }
+
+                "lang_items" => {
+                    writeln!(out, "=Lang items=")?;
+                    for (id, lang_item) in root.lang_items.decode(self) {
+                        writeln!(
+                            out,
+                            "{} = crate{}",
+                            lang_item.name(),
+                            DefPath::make(LOCAL_CRATE, id, |parent| root
+                                .tables
+                                .def_keys
+                                .get(self, parent)
+                                .unwrap()
+                                .decode(self))
+                            .to_string_no_crate_verbose()
+                        )?;
+                    }
+                    for lang_item in root.lang_items_missing.decode(self) {
+                        writeln!(out, "{} = <missing>", lang_item.name())?;
+                    }
+                    write!(out, "\n")?;
+                }
+
+                "features" => {
+                    writeln!(out, "=Lib features=")?;
+                    for (feature, since) in root.lib_features.decode(self) {
+                        writeln!(
+                            out,
+                            "{}{}",
+                            feature,
+                            if let Some(since) = since {
+                                format!(" since {since}")
+                            } else {
+                                String::new()
+                            }
+                        )?;
+                    }
+                    write!(out, "\n")?;
+                }
+
+                "items" => {
+                    writeln!(out, "=Items=")?;
+
+                    fn print_item(
+                        blob: &MetadataBlob,
+                        out: &mut dyn io::Write,
+                        item: DefIndex,
+                        indent: usize,
+                    ) -> io::Result<()> {
+                        let root = blob.get_root();
+
+                        let def_kind = root.tables.opt_def_kind.get(blob, item).unwrap();
+                        let def_key = root.tables.def_keys.get(blob, item).unwrap().decode(blob);
+                        let def_name = if item == CRATE_DEF_INDEX {
+                            rustc_span::symbol::kw::Crate
+                        } else {
+                            def_key
+                                .disambiguated_data
+                                .data
+                                .get_opt_name()
+                                .unwrap_or_else(|| Symbol::intern("???"))
+                        };
+                        let visibility =
+                            root.tables.visibility.get(blob, item).unwrap().decode(blob).map_id(
+                                |index| {
+                                    format!(
+                                        "crate{}",
+                                        DefPath::make(LOCAL_CRATE, index, |parent| root
+                                            .tables
+                                            .def_keys
+                                            .get(blob, parent)
+                                            .unwrap()
+                                            .decode(blob))
+                                        .to_string_no_crate_verbose()
+                                    )
+                                },
+                            );
+                        write!(
+                            out,
+                            "{nil: <indent$}{:?} {:?} {} {{",
+                            visibility,
+                            def_kind,
+                            def_name,
+                            nil = "",
+                        )?;
+
+                        if let Some(children) =
+                            root.tables.module_children_non_reexports.get(blob, item)
+                        {
+                            write!(out, "\n")?;
+                            for child in children.decode(blob) {
+                                print_item(blob, out, child, indent + 4)?;
+                            }
+                            writeln!(out, "{nil: <indent$}}}", nil = "")?;
+                        } else {
+                            writeln!(out, "}}")?;
+                        }
+
+                        Ok(())
+                    }
+
+                    print_item(self, out, CRATE_DEF_INDEX, 0)?;
+
+                    write!(out, "\n")?;
+                }
+
+                _ => {
+                    writeln!(
+                        out,
+                        "unknown -Zls kind. allowed values are: all, root, lang_items, features, items"
+                    )?;
+                }
+            }
         }
-        write!(out, "\n")?;
+
         Ok(())
     }
 }
@@ -1493,11 +1670,12 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
 
                 // We can't reuse an existing SourceFile, so allocate a new one
                 // containing the information we need.
+                let original_end_pos = source_file_to_import.end_position();
                 let rustc_span::SourceFile {
                     mut name,
                     src_hash,
-                    start_pos,
-                    end_pos,
+                    start_pos: original_start_pos,
+                    source_len,
                     lines,
                     multibyte_chars,
                     non_narrow_chars,
@@ -1539,59 +1717,38 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
                 // on `try_to_translate_virtual_to_real`).
                 try_to_translate_virtual_to_real(&mut name);
 
-                let source_length = (end_pos - start_pos).to_usize();
-
                 let local_version = sess.source_map().new_imported_source_file(
                     name,
                     src_hash,
                     name_hash,
-                    source_length,
+                    source_len.to_u32(),
                     self.cnum,
                     lines,
                     multibyte_chars,
                     non_narrow_chars,
                     normalized_pos,
-                    start_pos,
                     source_file_index,
                 );
                 debug!(
                     "CrateMetaData::imported_source_files alloc \
-                         source_file {:?} original (start_pos {:?} end_pos {:?}) \
-                         translated (start_pos {:?} end_pos {:?})",
+                         source_file {:?} original (start_pos {:?} source_len {:?}) \
+                         translated (start_pos {:?} source_len {:?})",
                     local_version.name,
-                    start_pos,
-                    end_pos,
+                    original_start_pos,
+                    source_len,
                     local_version.start_pos,
-                    local_version.end_pos
+                    local_version.source_len
                 );
 
                 ImportedSourceFile {
-                    original_start_pos: start_pos,
-                    original_end_pos: end_pos,
+                    original_start_pos,
+                    original_end_pos,
                     translated_source_file: local_version,
                 }
             })
             .clone()
     }
 
-    fn get_generator_diagnostic_data(
-        self,
-        tcx: TyCtxt<'tcx>,
-        id: DefIndex,
-    ) -> Option<GeneratorDiagnosticData<'tcx>> {
-        self.root
-            .tables
-            .generator_diagnostic_data
-            .get(self, id)
-            .map(|param| param.decode((self, tcx)))
-            .map(|generator_data| GeneratorDiagnosticData {
-                generator_interior_types: generator_data.generator_interior_types,
-                hir_owner: generator_data.hir_owner,
-                nodes_types: generator_data.nodes_types,
-                adjustments: generator_data.adjustments,
-            })
-    }
-
     fn get_attr_flags(self, index: DefIndex) -> AttrFlags {
         self.root.tables.attr_flags.get(self, index)
     }
diff --git a/compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs b/compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs
index aeda8af6d..f27eee0d7 100644
--- a/compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs
+++ b/compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs
@@ -14,10 +14,11 @@ use rustc_middle::arena::ArenaAllocatable;
 use rustc_middle::metadata::ModChild;
 use rustc_middle::middle::exported_symbols::ExportedSymbol;
 use rustc_middle::middle::stability::DeprecationEntry;
+use rustc_middle::query::ExternProviders;
 use rustc_middle::query::LocalCrate;
-use rustc_middle::query::{ExternProviders, Providers};
 use rustc_middle::ty::fast_reject::SimplifiedType;
 use rustc_middle::ty::{self, TyCtxt};
+use rustc_middle::util::Providers;
 use rustc_session::cstore::CrateStore;
 use rustc_session::{Session, StableCrateId};
 use rustc_span::hygiene::{ExpnHash, ExpnId};
@@ -126,12 +127,12 @@ macro_rules! provide_one {
             // External query providers call `crate_hash` in order to register a dependency
             // on the crate metadata. The exception is `crate_hash` itself, which obviously
             // doesn't need to do this (and can't, as it would cause a query cycle).
-            use rustc_middle::dep_graph::DepKind;
-            if DepKind::$name != DepKind::crate_hash && $tcx.dep_graph.is_fully_enabled() {
+            use rustc_middle::dep_graph::dep_kinds;
+            if dep_kinds::$name != dep_kinds::crate_hash && $tcx.dep_graph.is_fully_enabled() {
                 $tcx.ensure().crate_hash($def_id.krate);
             }
 
-            let cdata = rustc_data_structures::sync::MappedReadGuard::map(CStore::from_tcx($tcx), |c| {
+            let cdata = rustc_data_structures::sync::FreezeReadGuard::map(CStore::from_tcx($tcx), |c| {
                 c.get_crate_data($def_id.krate).cdata
             });
             let $cdata = crate::creader::CrateMetadataRef {
@@ -147,7 +148,7 @@ macro_rules! provide_one {
 macro_rules! provide {
     ($tcx:ident, $def_id:ident, $other:ident, $cdata:ident,
       $($name:ident => { $($compute:tt)* })*) => {
-        pub fn provide_extern(providers: &mut ExternProviders) {
+        fn provide_extern(providers: &mut ExternProviders) {
             $(provide_one! {
                 $tcx, $def_id, $other, $cdata, $name => { $($compute)* }
             })*
@@ -209,6 +210,7 @@ provide! { tcx, def_id, other, cdata,
     inferred_outlives_of => { table_defaulted_array }
     super_predicates_of => { table }
     type_of => { table }
+    type_alias_is_lazy => { cdata.root.tables.type_alias_is_lazy.get(cdata, def_id.index) }
     variances_of => { table }
     fn_sig => { table }
     codegen_fn_attrs => { table }
@@ -373,7 +375,6 @@ provide! { tcx, def_id, other, cdata,
 
     crate_extern_paths => { cdata.source().paths().cloned().collect() }
     expn_that_defined => { cdata.get_expn_that_defined(def_id.index, tcx.sess) }
-    generator_diagnostic_data => { cdata.get_generator_diagnostic_data(tcx, def_id.index) }
     is_doc_hidden => { cdata.get_attr_flags(def_id.index).contains(AttrFlags::IS_DOC_HIDDEN) }
     doc_link_resolutions => { tcx.arena.alloc(cdata.get_doc_link_resolutions(def_id.index)) }
     doc_link_traits_in_scope => {
@@ -385,7 +386,7 @@ pub(in crate::rmeta) fn provide(providers: &mut Providers) {
     // FIXME(#44234) - almost all of these queries have no sub-queries and
     // therefore no actual inputs, they're just reading tables calculated in
     // resolve! Does this work? Unsure! That's what the issue is about
-    *providers = Providers {
+    providers.queries = rustc_middle::query::Providers {
         allocator_kind: |tcx, ()| CStore::from_tcx(tcx).allocator_kind(),
         alloc_error_handler_kind: |tcx, ()| CStore::from_tcx(tcx).alloc_error_handler_kind(),
         is_private_dep: |_tcx, LocalCrate| false,
@@ -510,11 +511,12 @@ pub(in crate::rmeta) fn provide(providers: &mut Providers) {
         crates: |tcx, ()| {
             // The list of loaded crates is now frozen in query cache,
             // so make sure cstore is not mutably accessed from here on.
-            tcx.untracked().cstore.leak();
+            tcx.untracked().cstore.freeze();
             tcx.arena.alloc_from_iter(CStore::from_tcx(tcx).iter_crate_data().map(|(cnum, _)| cnum))
         },
-        ..*providers
+        ..providers.queries
     };
+    provide_extern(&mut providers.extern_queries);
 }
 
 impl CStore {
diff --git a/compiler/rustc_metadata/src/rmeta/encoder.rs b/compiler/rustc_metadata/src/rmeta/encoder.rs
index be91ad408..a4ba94327 100644
--- a/compiler/rustc_metadata/src/rmeta/encoder.rs
+++ b/compiler/rustc_metadata/src/rmeta/encoder.rs
@@ -14,11 +14,12 @@ use rustc_data_structures::temp_dir::MaybeTempDir;
 use rustc_hir as hir;
 use rustc_hir::def::DefKind;
 use rustc_hir::def_id::{
-    CrateNum, DefId, DefIndex, LocalDefId, CRATE_DEF_ID, CRATE_DEF_INDEX, LOCAL_CRATE,
+    CrateNum, DefId, DefIndex, LocalDefId, LocalDefIdSet, CRATE_DEF_ID, CRATE_DEF_INDEX,
+    LOCAL_CRATE,
 };
 use rustc_hir::definitions::DefPathData;
-use rustc_hir::intravisit;
 use rustc_hir::lang_items::LangItem;
+use rustc_hir_pretty::id_to_string;
 use rustc_middle::middle::debugger_visualizer::DebuggerVisualizerFile;
 use rustc_middle::middle::dependency_format::Linkage;
 use rustc_middle::middle::exported_symbols::{
@@ -30,7 +31,6 @@ use rustc_middle::query::Providers;
 use rustc_middle::traits::specialization_graph;
 use rustc_middle::ty::codec::TyEncoder;
 use rustc_middle::ty::fast_reject::{self, SimplifiedType, TreatParams};
-use rustc_middle::ty::TypeVisitableExt;
 use rustc_middle::ty::{self, AssocItemContainer, SymbolName, Ty, TyCtxt};
 use rustc_middle::util::common::to_readable_str;
 use rustc_serialize::{opaque, Decodable, Decoder, Encodable, Encoder};
@@ -50,7 +50,6 @@ pub(super) struct EncodeContext<'a, 'tcx> {
     opaque: opaque::FileEncoder,
     tcx: TyCtxt<'tcx>,
     feat: &'tcx rustc_feature::Features,
-
     tables: TableBuilders,
 
     lazy_state: LazyState,
@@ -131,7 +130,8 @@ impl<'a, 'tcx, T> Encodable<EncodeContext<'a, 'tcx>> for LazyArray<T> {
 
 impl<'a, 'tcx, I, T> Encodable<EncodeContext<'a, 'tcx>> for LazyTable<I, T> {
     fn encode(&self, e: &mut EncodeContext<'a, 'tcx>) {
-        e.emit_usize(self.encoded_size);
+        e.emit_usize(self.width);
+        e.emit_usize(self.len);
         e.emit_lazy_distance(self.position);
     }
 }
@@ -279,8 +279,8 @@ impl<'a, 'tcx> Encodable<EncodeContext<'a, 'tcx>> for SpanData {
             // All of this logic ensures that the final result of deserialization is a 'normal'
             // Span that can be used without any additional trouble.
             let metadata_index = {
-                // Introduce a new scope so that we drop the 'lock()' temporary
-                match &*source_file.external_src.lock() {
+                // Introduce a new scope so that we drop the 'read()' temporary
+                match &*source_file.external_src.read() {
                     ExternalSource::Foreign { metadata_index, .. } => *metadata_index,
                     src => panic!("Unexpected external source {src:?}"),
                 }
@@ -347,6 +347,13 @@ impl<'a, 'tcx> Encodable<EncodeContext<'a, 'tcx>> for Symbol {
     }
 }
 
+impl<'a, 'tcx> Encodable<EncodeContext<'a, 'tcx>> for [u8] {
+    fn encode(&self, e: &mut EncodeContext<'a, 'tcx>) {
+        Encoder::emit_usize(e, self.len());
+        e.emit_raw_bytes(self);
+    }
+}
+
 impl<'a, 'tcx> TyEncoder for EncodeContext<'a, 'tcx> {
     const CLEAR_CROSS_CRATE: bool = true;
 
@@ -819,7 +826,7 @@ fn should_encode_span(def_kind: DefKind) -> bool {
         | DefKind::Enum
         | DefKind::Variant
         | DefKind::Trait
-        | DefKind::TyAlias { .. }
+        | DefKind::TyAlias
         | DefKind::ForeignTy
         | DefKind::TraitAlias
         | DefKind::AssocTy
@@ -854,7 +861,7 @@ fn should_encode_attrs(def_kind: DefKind) -> bool {
         | DefKind::Enum
         | DefKind::Variant
         | DefKind::Trait
-        | DefKind::TyAlias { .. }
+        | DefKind::TyAlias
         | DefKind::ForeignTy
         | DefKind::TraitAlias
         | DefKind::AssocTy
@@ -895,7 +902,7 @@ fn should_encode_expn_that_defined(def_kind: DefKind) -> bool {
         | DefKind::Variant
         | DefKind::Trait
         | DefKind::Impl { .. } => true,
-        DefKind::TyAlias { .. }
+        DefKind::TyAlias
         | DefKind::ForeignTy
         | DefKind::TraitAlias
         | DefKind::AssocTy
@@ -930,7 +937,7 @@ fn should_encode_visibility(def_kind: DefKind) -> bool {
         | DefKind::Enum
         | DefKind::Variant
         | DefKind::Trait
-        | DefKind::TyAlias { .. }
+        | DefKind::TyAlias
         | DefKind::ForeignTy
         | DefKind::TraitAlias
         | DefKind::AssocTy
@@ -974,7 +981,7 @@ fn should_encode_stability(def_kind: DefKind) -> bool {
         | DefKind::Const
         | DefKind::Fn
         | DefKind::ForeignMod
-        | DefKind::TyAlias { .. }
+        | DefKind::TyAlias
         | DefKind::OpaqueTy
         | DefKind::Enum
         | DefKind::Union
@@ -994,15 +1001,31 @@ fn should_encode_stability(def_kind: DefKind) -> bool {
     }
 }
 
-/// Whether we should encode MIR.
+/// Whether we should encode MIR. Return a pair, resp. for CTFE and for LLVM.
 ///
 /// Computing, optimizing and encoding the MIR is a relatively expensive operation.
 /// We want to avoid this work when not required. Therefore:
 /// - we only compute `mir_for_ctfe` on items with const-eval semantics;
 /// - we skip `optimized_mir` for check runs.
+/// - we only encode `optimized_mir` that could be generated in other crates, that is, a code that
+///   is either generic or has inline hint, and is reachable from the other crates (contained
+///   in reachable set).
 ///
-/// Return a pair, resp. for CTFE and for LLVM.
-fn should_encode_mir(tcx: TyCtxt<'_>, def_id: LocalDefId) -> (bool, bool) {
+/// Note: Reachable set describes definitions that might be generated or referenced from other
+/// crates and it can be used to limit optimized MIR that needs to be encoded. On the other hand,
+/// the reachable set doesn't have much to say about which definitions might be evaluated at compile
+/// time in other crates, so it cannot be used to omit CTFE MIR. For example, `f` below is
+/// unreachable and yet it can be evaluated in other crates:
+///
+/// ```
+/// const fn f() -> usize { 0 }
+/// pub struct S { pub a: [usize; f()] }
+/// ```
+fn should_encode_mir(
+    tcx: TyCtxt<'_>,
+    reachable_set: &LocalDefIdSet,
+    def_id: LocalDefId,
+) -> (bool, bool) {
     match tcx.def_kind(def_id) {
         // Constructors
         DefKind::Ctor(_, _) => {
@@ -1019,14 +1042,15 @@ fn should_encode_mir(tcx: TyCtxt<'_>, def_id: LocalDefId) -> (bool, bool) {
         // Full-fledged functions + closures
         DefKind::AssocFn | DefKind::Fn | DefKind::Closure => {
             let generics = tcx.generics_of(def_id);
-            let needs_inline = (generics.requires_monomorphization(tcx)
-                || tcx.codegen_fn_attrs(def_id).requests_inline())
-                && tcx.sess.opts.output_types.should_codegen();
+            let opt = tcx.sess.opts.unstable_opts.always_encode_mir
+                || (tcx.sess.opts.output_types.should_codegen()
+                    && reachable_set.contains(&def_id)
+                    && (generics.requires_monomorphization(tcx)
+                        || tcx.codegen_fn_attrs(def_id).requests_inline()));
             // The function has a `const` modifier or is in a `#[const_trait]`.
             let is_const_fn = tcx.is_const_fn_raw(def_id.to_def_id())
                 || tcx.is_const_default_method(def_id.to_def_id());
-            let always_encode_mir = tcx.sess.opts.unstable_opts.always_encode_mir;
-            (is_const_fn, needs_inline || always_encode_mir)
+            (is_const_fn, opt)
         }
         // Generators require optimized MIR to compute layout.
         DefKind::Generator => (false, true),
@@ -1067,9 +1091,7 @@ fn should_encode_variances<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId, def_kind: Def
         | DefKind::Closure
         | DefKind::Generator
         | DefKind::ExternCrate => false,
-        DefKind::TyAlias { lazy } => {
-            lazy || tcx.type_of(def_id).instantiate_identity().has_opaque_types()
-        }
+        DefKind::TyAlias => tcx.type_alias_is_lazy(def_id),
     }
 }
 
@@ -1080,7 +1102,7 @@ fn should_encode_generics(def_kind: DefKind) -> bool {
         | DefKind::Enum
         | DefKind::Variant
         | DefKind::Trait
-        | DefKind::TyAlias { .. }
+        | DefKind::TyAlias
         | DefKind::ForeignTy
         | DefKind::TraitAlias
         | DefKind::AssocTy
@@ -1120,7 +1142,7 @@ fn should_encode_type(tcx: TyCtxt<'_>, def_id: LocalDefId, def_kind: DefKind) ->
         | DefKind::Fn
         | DefKind::Const
         | DefKind::Static(..)
-        | DefKind::TyAlias { .. }
+        | DefKind::TyAlias
         | DefKind::ForeignTy
         | DefKind::Impl { .. }
         | DefKind::AssocFn
@@ -1180,7 +1202,7 @@ fn should_encode_fn_sig(def_kind: DefKind) -> bool {
         | DefKind::Const
         | DefKind::Static(..)
         | DefKind::Ctor(..)
-        | DefKind::TyAlias { .. }
+        | DefKind::TyAlias
         | DefKind::OpaqueTy
         | DefKind::ForeignTy
         | DefKind::Impl { .. }
@@ -1221,7 +1243,7 @@ fn should_encode_constness(def_kind: DefKind) -> bool {
         | DefKind::AssocConst
         | DefKind::AnonConst
         | DefKind::Static(..)
-        | DefKind::TyAlias { .. }
+        | DefKind::TyAlias
         | DefKind::OpaqueTy
         | DefKind::Impl { of_trait: false }
         | DefKind::ForeignTy
@@ -1254,7 +1276,7 @@ fn should_encode_const(def_kind: DefKind) -> bool {
         | DefKind::Field
         | DefKind::Fn
         | DefKind::Static(..)
-        | DefKind::TyAlias { .. }
+        | DefKind::TyAlias
         | DefKind::OpaqueTy
         | DefKind::ForeignTy
         | DefKind::Impl { .. }
@@ -1414,7 +1436,8 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
                 }
             }
             if let DefKind::Generator = def_kind {
-                self.encode_info_for_generator(local_id);
+                let data = self.tcx.generator_kind(def_id).unwrap();
+                record!(self.tables.generator_kind[def_id] <- data);
             }
             if let DefKind::Enum | DefKind::Struct | DefKind::Union = def_kind {
                 self.encode_info_for_adt(local_id);
@@ -1425,6 +1448,11 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
             if let DefKind::Macro(_) = def_kind {
                 self.encode_info_for_macro(local_id);
             }
+            if let DefKind::TyAlias = def_kind {
+                self.tables
+                    .type_alias_is_lazy
+                    .set(def_id.index, self.tcx.type_alias_is_lazy(def_id));
+            }
             if let DefKind::OpaqueTy = def_kind {
                 self.encode_explicit_item_bounds(def_id);
                 self.tables
@@ -1572,9 +1600,10 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
         }
 
         let tcx = self.tcx;
+        let reachable_set = tcx.reachable_set(());
 
         let keys_and_jobs = tcx.mir_keys(()).iter().filter_map(|&def_id| {
-            let (encode_const, encode_opt) = should_encode_mir(tcx, def_id);
+            let (encode_const, encode_opt) = should_encode_mir(tcx, reachable_set, def_id);
             if encode_const || encode_opt { Some((def_id, encode_const, encode_opt)) } else { None }
         });
         for (def_id, encode_const, encode_opt) in keys_and_jobs {
@@ -1586,8 +1615,7 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
                 record!(self.tables.closure_saved_names_of_captured_variables[def_id.to_def_id()]
                     <- tcx.closure_saved_names_of_captured_variables(def_id));
 
-                if tcx.sess.opts.unstable_opts.drop_tracking_mir
-                    && let DefKind::Generator = self.tcx.def_kind(def_id)
+                if let DefKind::Generator = self.tcx.def_kind(def_id)
                     && let Some(witnesses) = tcx.mir_generator_witnesses(def_id)
                 {
                     record!(self.tables.mir_generator_witnesses[def_id.to_def_id()] <- witnesses);
@@ -1607,13 +1635,19 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
                     record!(self.tables.mir_const_qualif[def_id.to_def_id()] <- qualifs);
                     let body_id = tcx.hir().maybe_body_owned_by(def_id);
                     if let Some(body_id) = body_id {
-                        let const_data = self.encode_rendered_const_for_body(body_id);
+                        let const_data = rendered_const(self.tcx, body_id);
                         record!(self.tables.rendered_const[def_id.to_def_id()] <- const_data);
                     }
                 }
             }
             record!(self.tables.promoted_mir[def_id.to_def_id()] <- tcx.promoted_mir(def_id));
 
+            if let DefKind::Generator = self.tcx.def_kind(def_id)
+                && let Some(witnesses) = tcx.mir_generator_witnesses(def_id)
+            {
+                record!(self.tables.mir_generator_witnesses[def_id.to_def_id()] <- witnesses);
+            }
+
             let instance = ty::InstanceDef::Item(def_id.to_def_id());
             let unused = tcx.unused_generic_params(instance);
             self.tables.unused_generic_params.set(def_id.local_def_index, unused);
@@ -1675,14 +1709,6 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
         }
     }
 
-    fn encode_rendered_const_for_body(&mut self, body_id: hir::BodyId) -> String {
-        let hir = self.tcx.hir();
-        let body = hir.body(body_id);
-        rustc_hir_pretty::to_string(&(&hir as &dyn intravisit::Map<'_>), |s| {
-            s.print_expr(&body.value)
-        })
-    }
-
     #[instrument(level = "debug", skip(self))]
     fn encode_info_for_macro(&mut self, def_id: LocalDefId) {
         let tcx = self.tcx;
@@ -1694,15 +1720,6 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
         record!(self.tables.macro_definition[def_id.to_def_id()] <- &*macro_def.body);
     }
 
-    #[instrument(level = "debug", skip(self))]
-    fn encode_info_for_generator(&mut self, def_id: LocalDefId) {
-        let typeck_result: &'tcx ty::TypeckResults<'tcx> = self.tcx.typeck(def_id);
-        let data = self.tcx.generator_kind(def_id).unwrap();
-        let generator_diagnostic_data = typeck_result.get_generator_diagnostic_data();
-        record!(self.tables.generator_kind[def_id.to_def_id()] <- data);
-        record!(self.tables.generator_diagnostic_data[def_id.to_def_id()]  <- generator_diagnostic_data);
-    }
-
     fn encode_native_libraries(&mut self) -> LazyArray<NativeLib> {
         empty_proc_macro!(self);
         let used_libraries = self.tcx.native_libraries(LOCAL_CRATE);
@@ -2067,8 +2084,9 @@ fn prefetch_mir(tcx: TyCtxt<'_>) {
         return;
     }
 
+    let reachable_set = tcx.reachable_set(());
     par_for_each_in(tcx.mir_keys(()), |&def_id| {
-        let (encode_const, encode_opt) = should_encode_mir(tcx, def_id);
+        let (encode_const, encode_opt) = should_encode_mir(tcx, reachable_set, def_id);
 
         if encode_const {
             tcx.ensure_with_value().mir_for_ctfe(def_id);
@@ -2284,3 +2302,97 @@ pub fn provide(providers: &mut Providers) {
         ..*providers
     }
 }
+
+/// Build a textual representation of an unevaluated constant expression.
+///
+/// If the const expression is too complex, an underscore `_` is returned.
+/// For const arguments, it's `{ _ }` to be precise.
+/// This means that the output is not necessarily valid Rust code.
+///
+/// Currently, only
+///
+/// * literals (optionally with a leading `-`)
+/// * unit `()`
+/// * blocks (`{ … }`) around simple expressions and
+/// * paths without arguments
+///
+/// are considered simple enough. Simple blocks are included since they are
+/// necessary to disambiguate unit from the unit type.
+/// This list might get extended in the future.
+///
+/// Without this censoring, in a lot of cases the output would get too large
+/// and verbose. Consider `match` expressions, blocks and deeply nested ADTs.
+/// Further, private and `doc(hidden)` fields of structs would get leaked
+/// since HIR datatypes like the `body` parameter do not contain enough
+/// semantic information for this function to be able to hide them –
+/// at least not without significant performance overhead.
+///
+/// Whenever possible, prefer to evaluate the constant first and try to
+/// use a different method for pretty-printing. Ideally this function
+/// should only ever be used as a fallback.
+pub fn rendered_const<'tcx>(tcx: TyCtxt<'tcx>, body: hir::BodyId) -> String {
+    let hir = tcx.hir();
+    let value = &hir.body(body).value;
+
+    #[derive(PartialEq, Eq)]
+    enum Classification {
+        Literal,
+        Simple,
+        Complex,
+    }
+
+    use Classification::*;
+
+    fn classify(expr: &hir::Expr<'_>) -> Classification {
+        match &expr.kind {
+            hir::ExprKind::Unary(hir::UnOp::Neg, expr) => {
+                if matches!(expr.kind, hir::ExprKind::Lit(_)) { Literal } else { Complex }
+            }
+            hir::ExprKind::Lit(_) => Literal,
+            hir::ExprKind::Tup([]) => Simple,
+            hir::ExprKind::Block(hir::Block { stmts: [], expr: Some(expr), .. }, _) => {
+                if classify(expr) == Complex { Complex } else { Simple }
+            }
+            // Paths with a self-type or arguments are too “complex” following our measure since
+            // they may leak private fields of structs (with feature `adt_const_params`).
+            // Consider: `<Self as Trait<{ Struct { private: () } }>>::CONSTANT`.
+            // Paths without arguments are definitely harmless though.
+            hir::ExprKind::Path(hir::QPath::Resolved(_, hir::Path { segments, .. })) => {
+                if segments.iter().all(|segment| segment.args.is_none()) { Simple } else { Complex }
+            }
+            // FIXME: Claiming that those kinds of QPaths are simple is probably not true if the Ty
+            //        contains const arguments. Is there a *concise* way to check for this?
+            hir::ExprKind::Path(hir::QPath::TypeRelative(..)) => Simple,
+            // FIXME: Can they contain const arguments and thus leak private struct fields?
+            hir::ExprKind::Path(hir::QPath::LangItem(..)) => Simple,
+            _ => Complex,
+        }
+    }
+
+    let classification = classify(value);
+
+    if classification == Literal
+    && !value.span.from_expansion()
+    && let Ok(snippet) = tcx.sess.source_map().span_to_snippet(value.span) {
+        // For literals, we avoid invoking the pretty-printer and use the source snippet instead to
+        // preserve certain stylistic choices the user likely made for the sake legibility like
+        //
+        // * hexadecimal notation
+        // * underscores
+        // * character escapes
+        //
+        // FIXME: This passes through `-/*spacer*/0` verbatim.
+        snippet
+    } else if classification == Simple {
+        // Otherwise we prefer pretty-printing to get rid of extraneous whitespace, comments and
+        // other formatting artifacts.
+        id_to_string(&hir, body.hir_id)
+    } else if tcx.def_kind(hir.body_owner_def_id(body).to_def_id()) == DefKind::AnonConst {
+        // FIXME: Omit the curly braces if the enclosing expression is an array literal
+        //        with a repeated element (an `ExprKind::Repeat`) as in such case it
+        //        would not actually need any disambiguation.
+        "{ _ }".to_owned()
+    } else {
+        "_".to_owned()
+    }
+}
diff --git a/compiler/rustc_metadata/src/rmeta/mod.rs b/compiler/rustc_metadata/src/rmeta/mod.rs
index a89e235ff..42764af52 100644
--- a/compiler/rustc_metadata/src/rmeta/mod.rs
+++ b/compiler/rustc_metadata/src/rmeta/mod.rs
@@ -21,10 +21,10 @@ use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrs;
 use rustc_middle::middle::exported_symbols::{ExportedSymbol, SymbolExportInfo};
 use rustc_middle::middle::resolve_bound_vars::ObjectLifetimeDefault;
 use rustc_middle::mir;
-use rustc_middle::query::Providers;
 use rustc_middle::ty::fast_reject::SimplifiedType;
 use rustc_middle::ty::{self, ReprOptions, Ty, UnusedGenericParams};
-use rustc_middle::ty::{DeducedParamAttrs, GeneratorDiagnosticData, ParameterizedOverTcx, TyCtxt};
+use rustc_middle::ty::{DeducedParamAttrs, ParameterizedOverTcx, TyCtxt};
+use rustc_middle::util::Providers;
 use rustc_serialize::opaque::FileEncoder;
 use rustc_session::config::SymbolManglingVersion;
 use rustc_session::cstore::{CrateDepKind, ForeignModule, LinkagePreference, NativeLib};
@@ -38,11 +38,10 @@ use rustc_target::spec::{PanicStrategy, TargetTriple};
 use std::marker::PhantomData;
 use std::num::NonZeroUsize;
 
-pub use decoder::provide_extern;
 use decoder::DecodeContext;
 pub(crate) use decoder::{CrateMetadata, CrateNumMap, MetadataBlob};
 use encoder::EncodeContext;
-pub use encoder::{encode_metadata, EncodedMetadata};
+pub use encoder::{encode_metadata, rendered_const, EncodedMetadata};
 use rustc_span::hygiene::SyntaxContextData;
 
 mod decoder;
@@ -142,7 +141,11 @@ impl<T> LazyArray<T> {
 /// eagerly and in-order.
 struct LazyTable<I, T> {
     position: NonZeroUsize,
-    encoded_size: usize,
+    /// The encoded size of the elements of a table is selected at runtime to drop
+    /// trailing zeroes. This is the number of bytes used for each table element.
+    width: usize,
+    /// How many elements are in the table.
+    len: usize,
     _marker: PhantomData<fn(I) -> T>,
 }
 
@@ -153,9 +156,10 @@ impl<I: 'static, T: ParameterizedOverTcx> ParameterizedOverTcx for LazyTable<I,
 impl<I, T> LazyTable<I, T> {
     fn from_position_and_encoded_size(
         position: NonZeroUsize,
-        encoded_size: usize,
+        width: usize,
+        len: usize,
     ) -> LazyTable<I, T> {
-        LazyTable { position, encoded_size, _marker: PhantomData }
+        LazyTable { position, width, len, _marker: PhantomData }
     }
 }
 
@@ -379,6 +383,7 @@ define_tables! {
     is_intrinsic: Table<DefIndex, bool>,
     is_macro_rules: Table<DefIndex, bool>,
     is_type_alias_impl_trait: Table<DefIndex, bool>,
+    type_alias_is_lazy: Table<DefIndex, bool>,
     attr_flags: Table<DefIndex, AttrFlags>,
     def_path_hashes: Table<DefIndex, DefPathHash>,
     explicit_item_bounds: Table<DefIndex, LazyArray<(ty::Clause<'static>, Span)>>,
@@ -434,7 +439,7 @@ define_tables! {
     coerce_unsized_info: Table<DefIndex, LazyValue<ty::adjustment::CoerceUnsizedInfo>>,
     mir_const_qualif: Table<DefIndex, LazyValue<mir::ConstQualifs>>,
     rendered_const: Table<DefIndex, LazyValue<String>>,
-    asyncness: Table<DefIndex, hir::IsAsync>,
+    asyncness: Table<DefIndex, ty::Asyncness>,
     fn_arg_names: Table<DefIndex, LazyArray<Ident>>,
     generator_kind: Table<DefIndex, LazyValue<hir::GeneratorKind>>,
     trait_def: Table<DefIndex, LazyValue<ty::TraitDef>>,
@@ -448,7 +453,6 @@ define_tables! {
     // definitions from any given crate.
     def_keys: Table<DefIndex, LazyValue<DefKey>>,
     proc_macro_quoted_spans: Table<usize, LazyValue<Span>>,
-    generator_diagnostic_data: Table<DefIndex, LazyValue<GeneratorDiagnosticData<'static>>>,
     variant_data: Table<DefIndex, LazyValue<VariantData>>,
     assoc_container: Table<DefIndex, ty::AssocItemContainer>,
     macro_definition: Table<DefIndex, LazyValue<ast::DelimArgs>>,
diff --git a/compiler/rustc_metadata/src/rmeta/table.rs b/compiler/rustc_metadata/src/rmeta/table.rs
index ea66c770b..bb1320942 100644
--- a/compiler/rustc_metadata/src/rmeta/table.rs
+++ b/compiler/rustc_metadata/src/rmeta/table.rs
@@ -5,7 +5,6 @@ use rustc_hir::def::{CtorKind, CtorOf};
 use rustc_index::Idx;
 use rustc_middle::ty::{ParameterizedOverTcx, UnusedGenericParams};
 use rustc_serialize::opaque::FileEncoder;
-use rustc_serialize::Encoder as _;
 use rustc_span::hygiene::MacroKind;
 use std::marker::PhantomData;
 use std::num::NonZeroUsize;
@@ -38,6 +37,12 @@ impl IsDefault for u32 {
     }
 }
 
+impl IsDefault for u64 {
+    fn is_default(&self) -> bool {
+        *self == 0
+    }
+}
+
 impl<T> IsDefault for LazyArray<T> {
     fn is_default(&self) -> bool {
         self.num_elems == 0
@@ -89,6 +94,20 @@ impl FixedSizeEncoding for u32 {
     }
 }
 
+impl FixedSizeEncoding for u64 {
+    type ByteArray = [u8; 8];
+
+    #[inline]
+    fn from_bytes(b: &[u8; 8]) -> Self {
+        Self::from_le_bytes(*b)
+    }
+
+    #[inline]
+    fn write_to_bytes(self, b: &mut [u8; 8]) {
+        *b = self.to_le_bytes();
+    }
+}
+
 macro_rules! fixed_size_enum {
     ($ty:ty { $(($($pat:tt)*))* }) => {
         impl FixedSizeEncoding for Option<$ty> {
@@ -126,8 +145,7 @@ fixed_size_enum! {
         ( Enum                                     )
         ( Variant                                  )
         ( Trait                                    )
-        ( TyAlias { lazy: false }                  )
-        ( TyAlias { lazy: true }                   )
+        ( TyAlias                                  )
         ( ForeignTy                                )
         ( TraitAlias                               )
         ( AssocTy                                  )
@@ -186,9 +204,9 @@ fixed_size_enum! {
 }
 
 fixed_size_enum! {
-    hir::IsAsync {
-        ( NotAsync )
-        ( Async    )
+    ty::Asyncness {
+        ( Yes )
+        ( No  )
     }
 }
 
@@ -300,21 +318,21 @@ impl FixedSizeEncoding for UnusedGenericParams {
 // generic `LazyValue<T>` impl, but in the general case we might not need / want
 // to fit every `usize` in `u32`.
 impl<T> FixedSizeEncoding for Option<LazyValue<T>> {
-    type ByteArray = [u8; 4];
+    type ByteArray = [u8; 8];
 
     #[inline]
-    fn from_bytes(b: &[u8; 4]) -> Self {
-        let position = NonZeroUsize::new(u32::from_bytes(b) as usize)?;
+    fn from_bytes(b: &[u8; 8]) -> Self {
+        let position = NonZeroUsize::new(u64::from_bytes(b) as usize)?;
         Some(LazyValue::from_position(position))
     }
 
     #[inline]
-    fn write_to_bytes(self, b: &mut [u8; 4]) {
+    fn write_to_bytes(self, b: &mut [u8; 8]) {
         match self {
             None => unreachable!(),
             Some(lazy) => {
                 let position = lazy.position.get();
-                let position: u32 = position.try_into().unwrap();
+                let position: u64 = position.try_into().unwrap();
                 position.write_to_bytes(b)
             }
         }
@@ -323,55 +341,75 @@ impl<T> FixedSizeEncoding for Option<LazyValue<T>> {
 
 impl<T> LazyArray<T> {
     #[inline]
-    fn write_to_bytes_impl(self, b: &mut [u8; 8]) {
-        let ([position_bytes, meta_bytes], []) = b.as_chunks_mut::<4>() else { panic!() };
-
-        let position = self.position.get();
-        let position: u32 = position.try_into().unwrap();
-        position.write_to_bytes(position_bytes);
-
-        let len = self.num_elems;
-        let len: u32 = len.try_into().unwrap();
-        len.write_to_bytes(meta_bytes);
+    fn write_to_bytes_impl(self, b: &mut [u8; 16]) {
+        let position = (self.position.get() as u64).to_le_bytes();
+        let len = (self.num_elems as u64).to_le_bytes();
+
+        // Element width is selected at runtime on a per-table basis by omitting trailing
+        // zero bytes in table elements. This works very naturally when table elements are
+        // simple numbers but `LazyArray` is a pair of integers. If naively encoded, the second
+        // element would shield the trailing zeroes in the first. Interleaving the bytes
+        // of the position and length exposes trailing zeroes in both to the optimization.
+        // We encode length second because we generally expect it to be smaller.
+        for i in 0..8 {
+            b[2 * i] = position[i];
+            b[2 * i + 1] = len[i];
+        }
     }
 
-    fn from_bytes_impl(position_bytes: &[u8; 4], meta_bytes: &[u8; 4]) -> Option<LazyArray<T>> {
-        let position = NonZeroUsize::new(u32::from_bytes(position_bytes) as usize)?;
-        let len = u32::from_bytes(meta_bytes) as usize;
+    fn from_bytes_impl(position: &[u8; 8], meta: &[u8; 8]) -> Option<LazyArray<T>> {
+        let position = NonZeroUsize::new(u64::from_bytes(&position) as usize)?;
+        let len = u64::from_bytes(&meta) as usize;
         Some(LazyArray::from_position_and_num_elems(position, len))
     }
 }
 
+// Decoding helper for the encoding scheme used by `LazyArray`.
+// Interleaving the bytes of the two integers exposes trailing bytes in the first integer
+// to the varint scheme that we use for tables.
+#[inline]
+fn decode_interleaved(encoded: &[u8; 16]) -> ([u8; 8], [u8; 8]) {
+    let mut first = [0u8; 8];
+    let mut second = [0u8; 8];
+    for i in 0..8 {
+        first[i] = encoded[2 * i];
+        second[i] = encoded[2 * i + 1];
+    }
+    (first, second)
+}
+
 impl<T> FixedSizeEncoding for LazyArray<T> {
-    type ByteArray = [u8; 8];
+    type ByteArray = [u8; 16];
 
     #[inline]
-    fn from_bytes(b: &[u8; 8]) -> Self {
-        let ([position_bytes, meta_bytes], []) = b.as_chunks::<4>() else { panic!() };
-        if *meta_bytes == [0; 4] {
+    fn from_bytes(b: &[u8; 16]) -> Self {
+        let (position, meta) = decode_interleaved(b);
+
+        if meta == [0; 8] {
             return Default::default();
         }
-        LazyArray::from_bytes_impl(position_bytes, meta_bytes).unwrap()
+        LazyArray::from_bytes_impl(&position, &meta).unwrap()
     }
 
     #[inline]
-    fn write_to_bytes(self, b: &mut [u8; 8]) {
+    fn write_to_bytes(self, b: &mut [u8; 16]) {
         assert!(!self.is_default());
         self.write_to_bytes_impl(b)
     }
 }
 
 impl<T> FixedSizeEncoding for Option<LazyArray<T>> {
-    type ByteArray = [u8; 8];
+    type ByteArray = [u8; 16];
 
     #[inline]
-    fn from_bytes(b: &[u8; 8]) -> Self {
-        let ([position_bytes, meta_bytes], []) = b.as_chunks::<4>() else { panic!() };
-        LazyArray::from_bytes_impl(position_bytes, meta_bytes)
+    fn from_bytes(b: &[u8; 16]) -> Self {
+        let (position, meta) = decode_interleaved(b);
+
+        LazyArray::from_bytes_impl(&position, &meta)
     }
 
     #[inline]
-    fn write_to_bytes(self, b: &mut [u8; 8]) {
+    fn write_to_bytes(self, b: &mut [u8; 16]) {
         match self {
             None => unreachable!(),
             Some(lazy) => lazy.write_to_bytes_impl(b),
@@ -381,13 +419,14 @@ impl<T> FixedSizeEncoding for Option<LazyArray<T>> {
 
 /// Helper for constructing a table's serialization (also see `Table`).
 pub(super) struct TableBuilder<I: Idx, T: FixedSizeEncoding> {
+    width: usize,
     blocks: IndexVec<I, T::ByteArray>,
     _marker: PhantomData<T>,
 }
 
 impl<I: Idx, T: FixedSizeEncoding> Default for TableBuilder<I, T> {
     fn default() -> Self {
-        TableBuilder { blocks: Default::default(), _marker: PhantomData }
+        TableBuilder { width: 0, blocks: Default::default(), _marker: PhantomData }
     }
 }
 
@@ -415,40 +454,66 @@ impl<I: Idx, const N: usize, T: FixedSizeEncoding<ByteArray = [u8; N]>> TableBui
             // > store bit-masks of which item in each bucket is actually serialized).
             let block = self.blocks.ensure_contains_elem(i, || [0; N]);
             value.write_to_bytes(block);
+            if self.width != N {
+                let width = N - trailing_zeros(block);
+                self.width = self.width.max(width);
+            }
         }
     }
 
     pub(crate) fn encode(&self, buf: &mut FileEncoder) -> LazyTable<I, T> {
         let pos = buf.position();
+
+        let width = self.width;
         for block in &self.blocks {
-            buf.emit_raw_bytes(block);
+            buf.write_with(|dest| {
+                *dest = *block;
+                width
+            });
         }
-        let num_bytes = self.blocks.len() * N;
+
         LazyTable::from_position_and_encoded_size(
             NonZeroUsize::new(pos as usize).unwrap(),
-            num_bytes,
+            width,
+            self.blocks.len(),
         )
     }
 }
 
+fn trailing_zeros(x: &[u8]) -> usize {
+    x.iter().rev().take_while(|b| **b == 0).count()
+}
+
 impl<I: Idx, const N: usize, T: FixedSizeEncoding<ByteArray = [u8; N]> + ParameterizedOverTcx>
     LazyTable<I, T>
 where
     for<'tcx> T::Value<'tcx>: FixedSizeEncoding<ByteArray = [u8; N]>,
 {
     /// Given the metadata, extract out the value at a particular index (if any).
-    #[inline(never)]
     pub(super) fn get<'a, 'tcx, M: Metadata<'a, 'tcx>>(&self, metadata: M, i: I) -> T::Value<'tcx> {
-        trace!("LazyTable::lookup: index={:?} len={:?}", i, self.encoded_size);
+        trace!("LazyTable::lookup: index={:?} len={:?}", i, self.len);
+
+        // Access past the end of the table returns a Default
+        if i.index() >= self.len {
+            return Default::default();
+        }
 
-        let start = self.position.get();
-        let bytes = &metadata.blob()[start..start + self.encoded_size];
-        let (bytes, []) = bytes.as_chunks::<N>() else { panic!() };
-        bytes.get(i.index()).map_or_else(Default::default, FixedSizeEncoding::from_bytes)
+        let width = self.width;
+        let start = self.position.get() + (width * i.index());
+        let end = start + width;
+        let bytes = &metadata.blob()[start..end];
+
+        if let Ok(fixed) = bytes.try_into() {
+            FixedSizeEncoding::from_bytes(fixed)
+        } else {
+            let mut fixed = [0u8; N];
+            fixed[..width].copy_from_slice(bytes);
+            FixedSizeEncoding::from_bytes(&fixed)
+        }
     }
 
     /// Size of the table in entries, including possible gaps.
     pub(super) fn size(&self) -> usize {
-        self.encoded_size / N
+        self.len
     }
 }