1 files changed, 460 insertions, 0 deletions
diff --git a/compiler/rustc_metadata/src/rmeta/mod.rs b/compiler/rustc_metadata/src/rmeta/mod.rs
new file mode 100644
index 000000000..66bdecc30
--- /dev/null
+++ b/compiler/rustc_metadata/src/rmeta/mod.rs
@@ -0,0 +1,460 @@
+use crate::creader::CrateMetadataRef;
+use decoder::Metadata;
+use def_path_hash_map::DefPathHashMapRef;
+use table::TableBuilder;
+
+use rustc_ast as ast;
+use rustc_attr as attr;
+use rustc_data_structures::svh::Svh;
+use rustc_data_structures::sync::MetadataRef;
+use rustc_hir as hir;
+use rustc_hir::def::{CtorKind, DefKind};
+use rustc_hir::def_id::{CrateNum, DefId, DefIndex, DefPathHash, StableCrateId};
+use rustc_hir::definitions::DefKey;
+use rustc_hir::lang_items;
+use rustc_index::{bit_set::FiniteBitSet, vec::IndexVec};
+use rustc_middle::metadata::ModChild;
+use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrs;
+use rustc_middle::middle::exported_symbols::{ExportedSymbol, SymbolExportInfo};
+use rustc_middle::mir;
+use rustc_middle::ty::fast_reject::SimplifiedType;
+use rustc_middle::ty::query::Providers;
+use rustc_middle::ty::{self, ReprOptions, Ty};
+use rustc_middle::ty::{GeneratorDiagnosticData, ParameterizedOverTcx, TyCtxt};
+use rustc_serialize::opaque::FileEncoder;
+use rustc_session::config::SymbolManglingVersion;
+use rustc_session::cstore::{CrateDepKind, ForeignModule, LinkagePreference, NativeLib};
+use rustc_span::edition::Edition;
+use rustc_span::hygiene::{ExpnIndex, MacroKind};
+use rustc_span::symbol::{Ident, Symbol};
+use rustc_span::{self, ExpnData, ExpnHash, ExpnId, Span};
+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};
+use rustc_span::hygiene::SyntaxContextData;
+
+mod decoder;
+mod def_path_hash_map;
+mod encoder;
+mod table;
+
+pub(crate) fn rustc_version() -> String {
+    format!("rustc {}", option_env!("CFG_VERSION").unwrap_or("unknown version"))
+}
+
+/// Metadata encoding version.
+/// N.B., increment this if you change the format of metadata such that
+/// the rustc version can't be found to compare with `rustc_version()`.
+const METADATA_VERSION: u8 = 6;
+
+/// Metadata header which includes `METADATA_VERSION`.
+///
+/// This header is followed by the position of the `CrateRoot`,
+/// which is encoded as a 32-bit big-endian unsigned integer,
+/// and further followed by the rustc version string.
+pub const METADATA_HEADER: &[u8] = &[b'r', b'u', b's', b't', 0, 0, 0, METADATA_VERSION];
+
+/// A value of type T referred to by its absolute position
+/// in the metadata, and which can be decoded lazily.
+///
+/// Metadata is effective a tree, encoded in post-order,
+/// and with the root's position written next to the header.
+/// That means every single `LazyValue` points to some previous
+/// location in the metadata and is part of a larger node.
+///
+/// The first `LazyValue` in a node is encoded as the backwards
+/// distance from the position where the containing node
+/// starts and where the `LazyValue` points to, while the rest
+/// use the forward distance from the previous `LazyValue`.
+/// Distances start at 1, as 0-byte nodes are invalid.
+/// Also invalid are nodes being referred in a different
+/// order than they were encoded in.
+#[must_use]
+struct LazyValue<T> {
+    position: NonZeroUsize,
+    _marker: PhantomData<fn() -> T>,
+}
+
+impl<T: ParameterizedOverTcx> ParameterizedOverTcx for LazyValue<T> {
+    type Value<'tcx> = LazyValue<T::Value<'tcx>>;
+}
+
+impl<T> LazyValue<T> {
+    fn from_position(position: NonZeroUsize) -> LazyValue<T> {
+        LazyValue { position, _marker: PhantomData }
+    }
+}
+
+/// A list of lazily-decoded values.
+///
+/// Unlike `LazyValue<Vec<T>>`, the length is encoded next to the
+/// position, not at the position, which means that the length
+/// doesn't need to be known before encoding all the elements.
+///
+/// If the length is 0, no position is encoded, but otherwise,
+/// the encoding is that of `LazyArray`, with the distinction that
+/// the minimal distance the length of the sequence, i.e.
+/// it's assumed there's no 0-byte element in the sequence.
+struct LazyArray<T> {
+    position: NonZeroUsize,
+    num_elems: usize,
+    _marker: PhantomData<fn() -> T>,
+}
+
+impl<T: ParameterizedOverTcx> ParameterizedOverTcx for LazyArray<T> {
+    type Value<'tcx> = LazyArray<T::Value<'tcx>>;
+}
+
+impl<T> LazyArray<T> {
+    fn from_position_and_num_elems(position: NonZeroUsize, num_elems: usize) -> LazyArray<T> {
+        LazyArray { position, num_elems, _marker: PhantomData }
+    }
+
+    fn empty() -> LazyArray<T> {
+        LazyArray::from_position_and_num_elems(NonZeroUsize::new(1).unwrap(), 0)
+    }
+}
+
+/// A list of lazily-decoded values, with the added capability of random access.
+///
+/// Random-access table (i.e. offering constant-time `get`/`set`), similar to
+/// `LazyArray<T>`, but without requiring encoding or decoding all the values
+/// eagerly and in-order.
+struct LazyTable<I, T> {
+    position: NonZeroUsize,
+    encoded_size: usize,
+    _marker: PhantomData<fn(I) -> T>,
+}
+
+impl<I: 'static, T: ParameterizedOverTcx> ParameterizedOverTcx for LazyTable<I, T> {
+    type Value<'tcx> = LazyTable<I, T::Value<'tcx>>;
+}
+
+impl<I, T> LazyTable<I, T> {
+    fn from_position_and_encoded_size(
+        position: NonZeroUsize,
+        encoded_size: usize,
+    ) -> LazyTable<I, T> {
+        LazyTable { position, encoded_size, _marker: PhantomData }
+    }
+}
+
+impl<T> Copy for LazyValue<T> {}
+impl<T> Clone for LazyValue<T> {
+    fn clone(&self) -> Self {
+        *self
+    }
+}
+
+impl<T> Copy for LazyArray<T> {}
+impl<T> Clone for LazyArray<T> {
+    fn clone(&self) -> Self {
+        *self
+    }
+}
+
+impl<I, T> Copy for LazyTable<I, T> {}
+impl<I, T> Clone for LazyTable<I, T> {
+    fn clone(&self) -> Self {
+        *self
+    }
+}
+
+/// Encoding / decoding state for `Lazy`s (`LazyValue`, `LazyArray`, and `LazyTable`).
+#[derive(Copy, Clone, PartialEq, Eq, Debug)]
+enum LazyState {
+    /// Outside of a metadata node.
+    NoNode,
+
+    /// Inside a metadata node, and before any `Lazy`s.
+    /// The position is that of the node itself.
+    NodeStart(NonZeroUsize),
+
+    /// Inside a metadata node, with a previous `Lazy`s.
+    /// The position is where that previous `Lazy` would start.
+    Previous(NonZeroUsize),
+}
+
+type SyntaxContextTable = LazyTable<u32, LazyValue<SyntaxContextData>>;
+type ExpnDataTable = LazyTable<ExpnIndex, LazyValue<ExpnData>>;
+type ExpnHashTable = LazyTable<ExpnIndex, LazyValue<ExpnHash>>;
+
+#[derive(MetadataEncodable, MetadataDecodable)]
+pub(crate) struct ProcMacroData {
+    proc_macro_decls_static: DefIndex,
+    stability: Option<attr::Stability>,
+    macros: LazyArray<DefIndex>,
+}
+
+/// Serialized metadata for a crate.
+/// When compiling a proc-macro crate, we encode many of
+/// the `LazyArray<T>` fields as `Lazy::empty()`. This serves two purposes:
+///
+/// 1. We avoid performing unnecessary work. Proc-macro crates can only
+/// export proc-macros functions, which are compiled into a shared library.
+/// As a result, a large amount of the information we normally store
+/// (e.g. optimized MIR) is unneeded by downstream crates.
+/// 2. We avoid serializing invalid `CrateNum`s. When we deserialize
+/// a proc-macro crate, we don't load any of its dependencies (since we
+/// just need to invoke a native function from the shared library).
+/// This means that any foreign `CrateNum`s that we serialize cannot be
+/// deserialized, since we will not know how to map them into the current
+/// compilation session. If we were to serialize a proc-macro crate like
+/// a normal crate, much of what we serialized would be unusable in addition
+/// to being unused.
+#[derive(MetadataEncodable, MetadataDecodable)]
+pub(crate) struct CrateRoot {
+    name: Symbol,
+    triple: TargetTriple,
+    extra_filename: String,
+    hash: Svh,
+    stable_crate_id: StableCrateId,
+    required_panic_strategy: Option<PanicStrategy>,
+    panic_in_drop_strategy: PanicStrategy,
+    edition: Edition,
+    has_global_allocator: bool,
+    has_panic_handler: bool,
+    has_default_lib_allocator: bool,
+
+    crate_deps: LazyArray<CrateDep>,
+    dylib_dependency_formats: LazyArray<Option<LinkagePreference>>,
+    lib_features: LazyArray<(Symbol, Option<Symbol>)>,
+    stability_implications: LazyArray<(Symbol, Symbol)>,
+    lang_items: LazyArray<(DefIndex, usize)>,
+    lang_items_missing: LazyArray<lang_items::LangItem>,
+    diagnostic_items: LazyArray<(Symbol, DefIndex)>,
+    native_libraries: LazyArray<NativeLib>,
+    foreign_modules: LazyArray<ForeignModule>,
+    traits: LazyArray<DefIndex>,
+    impls: LazyArray<TraitImpls>,
+    incoherent_impls: LazyArray<IncoherentImpls>,
+    interpret_alloc_index: LazyArray<u32>,
+    proc_macro_data: Option<ProcMacroData>,
+
+    tables: LazyTables,
+    debugger_visualizers: LazyArray<rustc_span::DebuggerVisualizerFile>,
+
+    exported_symbols: LazyArray<(ExportedSymbol<'static>, SymbolExportInfo)>,
+
+    syntax_contexts: SyntaxContextTable,
+    expn_data: ExpnDataTable,
+    expn_hashes: ExpnHashTable,
+
+    def_path_hash_map: LazyValue<DefPathHashMapRef<'static>>,
+
+    source_map: LazyArray<rustc_span::SourceFile>,
+
+    compiler_builtins: bool,
+    needs_allocator: bool,
+    needs_panic_runtime: bool,
+    no_builtins: bool,
+    panic_runtime: bool,
+    profiler_runtime: bool,
+    symbol_mangling_version: SymbolManglingVersion,
+}
+
+/// On-disk representation of `DefId`.
+/// This creates a type-safe way to enforce that we remap the CrateNum between the on-disk
+/// representation and the compilation session.
+#[derive(Copy, Clone)]
+pub(crate) struct RawDefId {
+    krate: u32,
+    index: u32,
+}
+
+impl Into<RawDefId> for DefId {
+    fn into(self) -> RawDefId {
+        RawDefId { krate: self.krate.as_u32(), index: self.index.as_u32() }
+    }
+}
+
+impl RawDefId {
+    /// This exists so that `provide_one!` is happy
+    fn decode(self, meta: (CrateMetadataRef<'_>, TyCtxt<'_>)) -> DefId {
+        self.decode_from_cdata(meta.0)
+    }
+
+    fn decode_from_cdata(self, cdata: CrateMetadataRef<'_>) -> DefId {
+        let krate = CrateNum::from_u32(self.krate);
+        let krate = cdata.map_encoded_cnum_to_current(krate);
+        DefId { krate, index: DefIndex::from_u32(self.index) }
+    }
+}
+
+#[derive(Encodable, Decodable)]
+pub(crate) struct CrateDep {
+    pub name: Symbol,
+    pub hash: Svh,
+    pub host_hash: Option<Svh>,
+    pub kind: CrateDepKind,
+    pub extra_filename: String,
+}
+
+#[derive(MetadataEncodable, MetadataDecodable)]
+pub(crate) struct TraitImpls {
+    trait_id: (u32, DefIndex),
+    impls: LazyArray<(DefIndex, Option<SimplifiedType>)>,
+}
+
+#[derive(MetadataEncodable, MetadataDecodable)]
+pub(crate) struct IncoherentImpls {
+    self_ty: SimplifiedType,
+    impls: LazyArray<DefIndex>,
+}
+
+/// Define `LazyTables` and `TableBuilders` at the same time.
+macro_rules! define_tables {
+    ($($name:ident: Table<$IDX:ty, $T:ty>),+ $(,)?) => {
+        #[derive(MetadataEncodable, MetadataDecodable)]
+        pub(crate) struct LazyTables {
+            $($name: LazyTable<$IDX, $T>),+
+        }
+
+        #[derive(Default)]
+        struct TableBuilders {
+            $($name: TableBuilder<$IDX, $T>),+
+        }
+
+        impl TableBuilders {
+            fn encode(&self, buf: &mut FileEncoder) -> LazyTables {
+                LazyTables {
+                    $($name: self.$name.encode(buf)),+
+                }
+            }
+        }
+    }
+}
+
+define_tables! {
+    kind: Table<DefIndex, LazyValue<EntryKind>>,
+    attributes: Table<DefIndex, LazyArray<ast::Attribute>>,
+    children: Table<DefIndex, LazyArray<DefIndex>>,
+
+    opt_def_kind: Table<DefIndex, DefKind>,
+    visibility: Table<DefIndex, LazyValue<ty::Visibility>>,
+    def_span: Table<DefIndex, LazyValue<Span>>,
+    def_ident_span: Table<DefIndex, LazyValue<Span>>,
+    lookup_stability: Table<DefIndex, LazyValue<attr::Stability>>,
+    lookup_const_stability: Table<DefIndex, LazyValue<attr::ConstStability>>,
+    lookup_deprecation_entry: Table<DefIndex, LazyValue<attr::Deprecation>>,
+    // As an optimization, a missing entry indicates an empty `&[]`.
+    explicit_item_bounds: Table<DefIndex, LazyArray<(ty::Predicate<'static>, Span)>>,
+    explicit_predicates_of: Table<DefIndex, LazyValue<ty::GenericPredicates<'static>>>,
+    generics_of: Table<DefIndex, LazyValue<ty::Generics>>,
+    // As an optimization, a missing entry indicates an empty `&[]`.
+    inferred_outlives_of: Table<DefIndex, LazyArray<(ty::Predicate<'static>, Span)>>,
+    super_predicates_of: Table<DefIndex, LazyValue<ty::GenericPredicates<'static>>>,
+    type_of: Table<DefIndex, LazyValue<Ty<'static>>>,
+    variances_of: Table<DefIndex, LazyArray<ty::Variance>>,
+    fn_sig: Table<DefIndex, LazyValue<ty::PolyFnSig<'static>>>,
+    codegen_fn_attrs: Table<DefIndex, LazyValue<CodegenFnAttrs>>,
+    impl_trait_ref: Table<DefIndex, LazyValue<ty::TraitRef<'static>>>,
+    const_param_default: Table<DefIndex, LazyValue<rustc_middle::ty::Const<'static>>>,
+    optimized_mir: Table<DefIndex, LazyValue<mir::Body<'static>>>,
+    mir_for_ctfe: Table<DefIndex, LazyValue<mir::Body<'static>>>,
+    promoted_mir: Table<DefIndex, LazyValue<IndexVec<mir::Promoted, mir::Body<'static>>>>,
+    // FIXME(compiler-errors): Why isn't this a LazyArray?
+    thir_abstract_const: Table<DefIndex, LazyValue<&'static [ty::abstract_const::Node<'static>]>>,
+    impl_parent: Table<DefIndex, RawDefId>,
+    impl_polarity: Table<DefIndex, ty::ImplPolarity>,
+    constness: Table<DefIndex, hir::Constness>,
+    is_intrinsic: Table<DefIndex, ()>,
+    impl_defaultness: Table<DefIndex, hir::Defaultness>,
+    // FIXME(eddyb) perhaps compute this on the fly if cheap enough?
+    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>,
+    fn_arg_names: Table<DefIndex, LazyArray<Ident>>,
+    generator_kind: Table<DefIndex, LazyValue<hir::GeneratorKind>>,
+    trait_def: Table<DefIndex, LazyValue<ty::TraitDef>>,
+
+    trait_item_def_id: Table<DefIndex, RawDefId>,
+    inherent_impls: Table<DefIndex, LazyArray<DefIndex>>,
+    expn_that_defined: Table<DefIndex, LazyValue<ExpnId>>,
+    unused_generic_params: Table<DefIndex, LazyValue<FiniteBitSet<u32>>>,
+    repr_options: Table<DefIndex, LazyValue<ReprOptions>>,
+    // `def_keys` and `def_path_hashes` represent a lazy version of a
+    // `DefPathTable`. This allows us to avoid deserializing an entire
+    // `DefPathTable` up front, since we may only ever use a few
+    // definitions from any given crate.
+    def_keys: Table<DefIndex, LazyValue<DefKey>>,
+    def_path_hashes: Table<DefIndex, DefPathHash>,
+    proc_macro_quoted_spans: Table<usize, LazyValue<Span>>,
+    generator_diagnostic_data: Table<DefIndex, LazyValue<GeneratorDiagnosticData<'static>>>,
+    may_have_doc_links: Table<DefIndex, ()>,
+}
+
+#[derive(Copy, Clone, MetadataEncodable, MetadataDecodable)]
+enum EntryKind {
+    AnonConst,
+    Const,
+    Static,
+    ForeignStatic,
+    ForeignMod,
+    ForeignType,
+    GlobalAsm,
+    Type,
+    TypeParam,
+    ConstParam,
+    OpaqueTy,
+    Enum,
+    Field,
+    Variant(LazyValue<VariantData>),
+    Struct(LazyValue<VariantData>),
+    Union(LazyValue<VariantData>),
+    Fn,
+    ForeignFn,
+    Mod(LazyArray<ModChild>),
+    MacroDef(LazyValue<ast::MacArgs>, /*macro_rules*/ bool),
+    ProcMacro(MacroKind),
+    Closure,
+    Generator,
+    Trait,
+    Impl,
+    AssocFn { container: ty::AssocItemContainer, has_self: bool },
+    AssocType(ty::AssocItemContainer),
+    AssocConst(ty::AssocItemContainer),
+    TraitAlias,
+}
+
+#[derive(TyEncodable, TyDecodable)]
+struct VariantData {
+    ctor_kind: CtorKind,
+    discr: ty::VariantDiscr,
+    /// If this is unit or tuple-variant/struct, then this is the index of the ctor id.
+    ctor: Option<DefIndex>,
+    is_non_exhaustive: bool,
+}
+
+#[derive(TyEncodable, TyDecodable)]
+struct GeneratorData<'tcx> {
+    layout: mir::GeneratorLayout<'tcx>,
+}
+
+// Tags used for encoding Spans:
+const TAG_VALID_SPAN_LOCAL: u8 = 0;
+const TAG_VALID_SPAN_FOREIGN: u8 = 1;
+const TAG_PARTIAL_SPAN: u8 = 2;
+
+pub fn provide(providers: &mut Providers) {
+    encoder::provide(providers);
+    decoder::provide(providers);
+}
+
+trivially_parameterized_over_tcx! {
+    VariantData,
+    EntryKind,
+    RawDefId,
+    TraitImpls,
+    IncoherentImpls,
+    CrateRoot,
+    CrateDep,
+}