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Rollup merge of #66399 - eddyb:rmeta-table-cleanup, r=Mark-Simulacrum

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rustc_metadata: simplify the interactions between Lazy and Table.

These are small post-#59953 cleanups (including undoing some contrivances from that PR).

r? @michaelwoerister
This commit is contained in:
Tyler Mandry 2019-11-27 15:28:34 -06:00 • committed by GitHub
commit 5139b53836
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4 changed files with 99 additions and 161 deletions
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18
src/librustc_metadata/rmeta/decoder.rs
View file

@ -1,9 +1,9 @@
// Decoding metadata from a single crate's metadata
use crate::rmeta::*;
use crate::rmeta::table::{FixedSizeEncoding, PerDefTable};
use crate::rmeta::table::{FixedSizeEncoding, Table};
use rustc_index::vec::IndexVec;
use rustc_index::vec::{Idx, IndexVec};
use rustc_data_structures::sync::{Lrc, Lock, Once, AtomicCell};
use rustc::hir::map::{DefKey, DefPath, DefPathData, DefPathHash};
use rustc::hir::map::definitions::DefPathTable;
@ -32,7 +32,7 @@ use std::mem;
use std::num::NonZeroUsize;
use std::u32;
use rustc_serialize::{Decodable, Decoder, Encodable, SpecializedDecoder, opaque};
use rustc_serialize::{Decodable, Decoder, SpecializedDecoder, opaque};
use syntax::attr;
use syntax::ast::{self, Ident};
use syntax::source_map::{self, respan, Spanned};
@ -217,7 +217,7 @@ impl<'a, 'tcx> Metadata<'a, 'tcx> for (&'a CrateMetadata, TyCtxt<'tcx>) {
}
}
impl<'a, 'tcx, T: Encodable + Decodable> Lazy<T> {
impl<'a, 'tcx, T: Decodable> Lazy<T> {
fn decode<M: Metadata<'a, 'tcx>>(self, metadata: M) -> T {
let mut dcx = metadata.decoder(self.position.get());
dcx.lazy_state = LazyState::NodeStart(self.position);
@ -225,7 +225,7 @@ impl<'a, 'tcx, T: Encodable + Decodable> Lazy<T> {
}
}
impl<'a: 'x, 'tcx: 'x, 'x, T: Encodable + Decodable> Lazy<[T]> {
impl<'a: 'x, 'tcx: 'x, 'x, T: Decodable> Lazy<[T]> {
fn decode<M: Metadata<'a, 'tcx>>(
self,
metadata: M,
@ -324,13 +324,13 @@ impl<'a, 'tcx> TyDecoder<'tcx> for DecodeContext<'a, 'tcx> {
}
}
impl<'a, 'tcx, T: Encodable> SpecializedDecoder<Lazy<T>> for DecodeContext<'a, 'tcx> {
impl<'a, 'tcx, T> SpecializedDecoder<Lazy<T>> for DecodeContext<'a, 'tcx> {
fn specialized_decode(&mut self) -> Result<Lazy<T>, Self::Error> {
self.read_lazy_with_meta(())
}
}
impl<'a, 'tcx, T: Encodable> SpecializedDecoder<Lazy<[T]>> for DecodeContext<'a, 'tcx> {
impl<'a, 'tcx, T> SpecializedDecoder<Lazy<[T]>> for DecodeContext<'a, 'tcx> {
fn specialized_decode(&mut self) -> Result<Lazy<[T]>, Self::Error> {
let len = self.read_usize()?;
if len == 0 {
@ -341,10 +341,10 @@ impl<'a, 'tcx, T: Encodable> SpecializedDecoder<Lazy<[T]>> for DecodeContext<'a,
}
}
impl<'a, 'tcx, T> SpecializedDecoder<Lazy<PerDefTable<T>>> for DecodeContext<'a, 'tcx>
impl<'a, 'tcx, I: Idx, T> SpecializedDecoder<Lazy<Table<I, T>>> for DecodeContext<'a, 'tcx>
where Option<T>: FixedSizeEncoding,
{
fn specialized_decode(&mut self) -> Result<Lazy<PerDefTable<T>>, Self::Error> {
fn specialized_decode(&mut self) -> Result<Lazy<Table<I, T>>, Self::Error> {
let len = self.read_usize()?;
self.read_lazy_with_meta(len)
}

67
src/librustc_metadata/rmeta/encoder.rs
View file

@ -1,5 +1,5 @@
use crate::rmeta::*;
use crate::rmeta::table::{FixedSizeEncoding, PerDefTable};
use crate::rmeta::table::FixedSizeEncoding;
use rustc::middle::cstore::{LinkagePreference, NativeLibrary,
EncodedMetadata, ForeignModule};
@ -8,7 +8,7 @@ use rustc::hir::def_id::{CrateNum, CRATE_DEF_INDEX, DefIndex, DefId, LocalDefId,
use rustc::hir::{GenericParamKind, AnonConst};
use rustc::hir::map::definitions::DefPathTable;
use rustc_data_structures::fingerprint::Fingerprint;
use rustc_index::vec::IndexVec;
use rustc_index::vec::Idx;
use rustc::middle::dependency_format::Linkage;
use rustc::middle::exported_symbols::{ExportedSymbol, SymbolExportLevel,
metadata_symbol_name};
@ -47,7 +47,7 @@ struct EncodeContext<'tcx> {
opaque: opaque::Encoder,
tcx: TyCtxt<'tcx>,
per_def: PerDefTables<'tcx>,
per_def: PerDefTableBuilders<'tcx>,
lazy_state: LazyState,
type_shorthands: FxHashMap<Ty<'tcx>, usize>,
@ -60,30 +60,6 @@ struct EncodeContext<'tcx> {
source_file_cache: Lrc<SourceFile>,
}
#[derive(Default)]
struct PerDefTables<'tcx> {
kind: PerDefTable<Lazy<EntryKind<'tcx>>>,
visibility: PerDefTable<Lazy<ty::Visibility>>,
span: PerDefTable<Lazy<Span>>,
attributes: PerDefTable<Lazy<[ast::Attribute]>>,
children: PerDefTable<Lazy<[DefIndex]>>,
stability: PerDefTable<Lazy<attr::Stability>>,
deprecation: PerDefTable<Lazy<attr::Deprecation>>,
ty: PerDefTable<Lazy<Ty<'tcx>>>,
fn_sig: PerDefTable<Lazy<ty::PolyFnSig<'tcx>>>,
impl_trait_ref: PerDefTable<Lazy<ty::TraitRef<'tcx>>>,
inherent_impls: PerDefTable<Lazy<[DefIndex]>>,
variances: PerDefTable<Lazy<[ty::Variance]>>,
generics: PerDefTable<Lazy<ty::Generics>>,
explicit_predicates: PerDefTable<Lazy<ty::GenericPredicates<'tcx>>>,
inferred_outlives: PerDefTable<Lazy<&'tcx [(ty::Predicate<'tcx>, Span)]>>,
super_predicates: PerDefTable<Lazy<ty::GenericPredicates<'tcx>>>,
mir: PerDefTable<Lazy<mir::Body<'tcx>>>,
promoted_mir: PerDefTable<Lazy<IndexVec<mir::Promoted, mir::Body<'tcx>>>>,
}
macro_rules! encoder_methods {
($($name:ident($ty:ty);)*) => {
$(fn $name(&mut self, value: $ty) -> Result<(), Self::Error> {
@ -122,13 +98,13 @@ impl<'tcx> Encoder for EncodeContext<'tcx> {
}
}
impl<'tcx, T: Encodable> SpecializedEncoder<Lazy<T>> for EncodeContext<'tcx> {
impl<'tcx, T> SpecializedEncoder<Lazy<T>> for EncodeContext<'tcx> {
fn specialized_encode(&mut self, lazy: &Lazy<T>) -> Result<(), Self::Error> {
self.emit_lazy_distance(*lazy)
}
}
impl<'tcx, T: Encodable> SpecializedEncoder<Lazy<[T]>> for EncodeContext<'tcx> {
impl<'tcx, T> SpecializedEncoder<Lazy<[T]>> for EncodeContext<'tcx> {
fn specialized_encode(&mut self, lazy: &Lazy<[T]>) -> Result<(), Self::Error> {
self.emit_usize(lazy.meta)?;
if lazy.meta == 0 {
@ -138,10 +114,10 @@ impl<'tcx, T: Encodable> SpecializedEncoder<Lazy<[T]>> for EncodeContext<'tcx> {
}
}
impl<'tcx, T> SpecializedEncoder<Lazy<PerDefTable<T>>> for EncodeContext<'tcx>
impl<'tcx, I: Idx, T> SpecializedEncoder<Lazy<Table<I, T>>> for EncodeContext<'tcx>
where Option<T>: FixedSizeEncoding,
{
fn specialized_encode(&mut self, lazy: &Lazy<PerDefTable<T>>) -> Result<(), Self::Error> {
fn specialized_encode(&mut self, lazy: &Lazy<Table<I, T>>) -> Result<(), Self::Error> {
self.emit_usize(lazy.meta)?;
self.emit_lazy_distance(*lazy)
}
@ -307,14 +283,14 @@ impl<I, T: Encodable> EncodeContentsForLazy<[T]> for I
}
}
// Shorthand for `$self.$tables.$table.set($key, $self.lazy($value))`, which would
// Shorthand for `$self.$tables.$table.set($def_id.index, $self.lazy($value))`, which would
// normally need extra variables to avoid errors about multiple mutable borrows.
macro_rules! record {
($self:ident.$tables:ident.$table:ident[$key:expr] <- $value:expr) => {{
($self:ident.$tables:ident.$table:ident[$def_id:expr] <- $value:expr) => {{
{
let value = $value;
let lazy = $self.lazy(value);
$self.$tables.$table.set($key, lazy);
$self.$tables.$table.set($def_id.index, lazy);
}
}}
}
@ -509,28 +485,7 @@ impl<'tcx> EncodeContext<'tcx> {
i = self.position();
let per_def = LazyPerDefTables {
kind: self.per_def.kind.encode(&mut self.opaque),
visibility: self.per_def.visibility.encode(&mut self.opaque),
span: self.per_def.span.encode(&mut self.opaque),
attributes: self.per_def.attributes.encode(&mut self.opaque),
children: self.per_def.children.encode(&mut self.opaque),
stability: self.per_def.stability.encode(&mut self.opaque),
deprecation: self.per_def.deprecation.encode(&mut self.opaque),
ty: self.per_def.ty.encode(&mut self.opaque),
fn_sig: self.per_def.fn_sig.encode(&mut self.opaque),
impl_trait_ref: self.per_def.impl_trait_ref.encode(&mut self.opaque),
inherent_impls: self.per_def.inherent_impls.encode(&mut self.opaque),
variances: self.per_def.variances.encode(&mut self.opaque),
generics: self.per_def.generics.encode(&mut self.opaque),
explicit_predicates: self.per_def.explicit_predicates.encode(&mut self.opaque),
inferred_outlives: self.per_def.inferred_outlives.encode(&mut self.opaque),
super_predicates: self.per_def.super_predicates.encode(&mut self.opaque),
mir: self.per_def.mir.encode(&mut self.opaque),
promoted_mir: self.per_def.promoted_mir.encode(&mut self.opaque),
};
let per_def = self.per_def.encode(&mut self.opaque);
let per_def_bytes = self.position() - i;
// Encode the proc macro data

77
src/librustc_metadata/rmeta/mod.rs
View file

@ -1,5 +1,5 @@
use decoder::Metadata;
use table::PerDefTable;
use table::{Table, TableBuilder};
use rustc::hir;
use rustc::hir::def::{self, CtorKind};
@ -15,7 +15,7 @@ use rustc_target::spec::{PanicStrategy, TargetTriple};
use rustc_index::vec::IndexVec;
use rustc_data_structures::svh::Svh;
use rustc_data_structures::sync::MetadataRef;
use rustc_serialize::Encodable;
use rustc_serialize::opaque::Encoder;
use syntax::{ast, attr};
use syntax::edition::Edition;
use syntax::symbol::Symbol;
@ -59,7 +59,7 @@ trait LazyMeta {
fn min_size(meta: Self::Meta) -> usize;
}
impl<T: Encodable> LazyMeta for T {
impl<T> LazyMeta for T {
type Meta = ();
fn min_size(_: ()) -> usize {
@ -68,7 +68,7 @@ impl<T: Encodable> LazyMeta for T {
}
}
impl<T: Encodable> LazyMeta for [T] {
impl<T> LazyMeta for [T] {
type Meta = usize;
fn min_size(len: usize) -> usize {
@ -124,13 +124,13 @@ impl<T: ?Sized + LazyMeta> Lazy<T> {
}
}
impl<T: Encodable> Lazy<T> {
impl<T> Lazy<T> {
fn from_position(position: NonZeroUsize) -> Lazy<T> {
Lazy::from_position_and_meta(position, ())
}
}
impl<T: Encodable> Lazy<[T]> {
impl<T> Lazy<[T]> {
fn empty() -> Lazy<[T]> {
Lazy::from_position_and_meta(NonZeroUsize::new(1).unwrap(), 0)
}
@ -166,8 +166,7 @@ enum LazyState {
// manually, instead of relying on the default, to get the correct variance.
// Only needed when `T` itself contains a parameter (e.g. `'tcx`).
macro_rules! Lazy {
(Table<$T:ty>) => {Lazy<Table<$T>, usize>};
(PerDefTable<$T:ty>) => {Lazy<PerDefTable<$T>, usize>};
(Table<$I:ty, $T:ty>) => {Lazy<Table<$I, $T>, usize>};
([$T:ty]) => {Lazy<[$T], usize>};
($T:ty) => {Lazy<$T, ()>};
}
@ -232,31 +231,53 @@ crate struct TraitImpls {
impls: Lazy<[DefIndex]>,
}
#[derive(RustcEncodable, RustcDecodable)]
crate struct LazyPerDefTables<'tcx> {
kind: Lazy!(PerDefTable<Lazy!(EntryKind<'tcx>)>),
visibility: Lazy!(PerDefTable<Lazy<ty::Visibility>>),
span: Lazy!(PerDefTable<Lazy<Span>>),
attributes: Lazy!(PerDefTable<Lazy<[ast::Attribute]>>),
children: Lazy!(PerDefTable<Lazy<[DefIndex]>>),
stability: Lazy!(PerDefTable<Lazy<attr::Stability>>),
deprecation: Lazy!(PerDefTable<Lazy<attr::Deprecation>>),
ty: Lazy!(PerDefTable<Lazy!(Ty<'tcx>)>),
fn_sig: Lazy!(PerDefTable<Lazy!(ty::PolyFnSig<'tcx>)>),
impl_trait_ref: Lazy!(PerDefTable<Lazy!(ty::TraitRef<'tcx>)>),
inherent_impls: Lazy!(PerDefTable<Lazy<[DefIndex]>>),
variances: Lazy!(PerDefTable<Lazy<[ty::Variance]>>),
generics: Lazy!(PerDefTable<Lazy<ty::Generics>>),
explicit_predicates: Lazy!(PerDefTable<Lazy!(ty::GenericPredicates<'tcx>)>),
/// Define `LazyPerDefTables` and `PerDefTableBuilders` at the same time.
macro_rules! define_per_def_tables {
($($name:ident: Table<DefIndex, $T:ty>),+ $(,)?) => {
#[derive(RustcEncodable, RustcDecodable)]
crate struct LazyPerDefTables<'tcx> {
$($name: Lazy!(Table<DefIndex, $T>)),+
}
#[derive(Default)]
struct PerDefTableBuilders<'tcx> {
$($name: TableBuilder<DefIndex, $T>),+
}
impl PerDefTableBuilders<'tcx> {
fn encode(&self, buf: &mut Encoder) -> LazyPerDefTables<'tcx> {
LazyPerDefTables {
$($name: self.$name.encode(buf)),+
}
}
}
}
}
define_per_def_tables! {
kind: Table<DefIndex, Lazy!(EntryKind<'tcx>)>,
visibility: Table<DefIndex, Lazy<ty::Visibility>>,
span: Table<DefIndex, Lazy<Span>>,
attributes: Table<DefIndex, Lazy<[ast::Attribute]>>,
children: Table<DefIndex, Lazy<[DefIndex]>>,
stability: Table<DefIndex, Lazy<attr::Stability>>,
deprecation: Table<DefIndex, Lazy<attr::Deprecation>>,
ty: Table<DefIndex, Lazy!(Ty<'tcx>)>,
fn_sig: Table<DefIndex, Lazy!(ty::PolyFnSig<'tcx>)>,
impl_trait_ref: Table<DefIndex, Lazy!(ty::TraitRef<'tcx>)>,
inherent_impls: Table<DefIndex, Lazy<[DefIndex]>>,
variances: Table<DefIndex, Lazy<[ty::Variance]>>,
generics: Table<DefIndex, Lazy<ty::Generics>>,
explicit_predicates: Table<DefIndex, Lazy!(ty::GenericPredicates<'tcx>)>,
// FIXME(eddyb) this would ideally be `Lazy<[...]>` but `ty::Predicate`
// doesn't handle shorthands in its own (de)serialization impls,
// as it's an `enum` for which we want to derive (de)serialization,
// so the `ty::codec` APIs handle the whole `&'tcx [...]` at once.
// Also, as an optimization, a missing entry indicates an empty `&[]`.
inferred_outlives: Lazy!(PerDefTable<Lazy!(&'tcx [(ty::Predicate<'tcx>, Span)])>),
super_predicates: Lazy!(PerDefTable<Lazy!(ty::GenericPredicates<'tcx>)>),
mir: Lazy!(PerDefTable<Lazy!(mir::Body<'tcx>)>),
promoted_mir: Lazy!(PerDefTable<Lazy!(IndexVec<mir::Promoted, mir::Body<'tcx>>)>),
inferred_outlives: Table<DefIndex, Lazy!(&'tcx [(ty::Predicate<'tcx>, Span)])>,
super_predicates: Table<DefIndex, Lazy!(ty::GenericPredicates<'tcx>)>,
mir: Table<DefIndex, Lazy!(mir::Body<'tcx>)>,
promoted_mir: Table<DefIndex, Lazy!(IndexVec<mir::Promoted, mir::Body<'tcx>>)>,
}
#[derive(Copy, Clone, RustcEncodable, RustcDecodable)]

98
src/librustc_metadata/rmeta/table.rs
View file

@ -1,6 +1,6 @@
use crate::rmeta::*;
use rustc::hir::def_id::{DefId, DefIndex};
use rustc_index::vec::Idx;
use rustc_serialize::{Encodable, opaque::Encoder};
use std::convert::TryInto;
use std::marker::PhantomData;
@ -117,37 +117,46 @@ impl<T: Encodable> FixedSizeEncoding for Option<Lazy<[T]>> {
}
}
/// Random-access table (i.e. offeringconstant-time `get`/`set`), similar to
/// Random-access table (i.e. offering constant-time `get`/`set`), similar to
/// `Vec<Option<T>>`, but without requiring encoding or decoding all the values
/// eagerly and in-order.
/// A total of `(max_idx + 1) * <Option<T> as FixedSizeEncoding>::BYTE_LEN` bytes
/// are used for a table, where `max_idx` is the largest index passed to `set`.
// FIXME(eddyb) replace `Vec` with `[_]` here, such that `Box<Table<T>>` would be used
// when building it, and `Lazy<Table<T>>` or `&Table<T>` when reading it.
// (not sure if that is possible given that the `Vec` is being resized now)
pub(super) struct Table<T> where Option<T>: FixedSizeEncoding {
// FIXME(eddyb) store `[u8; <Option<T>>::BYTE_LEN]` instead of `u8` in `Vec`,
// once that starts being allowed by the compiler (i.e. lazy normalization).
bytes: Vec<u8>,
_marker: PhantomData<T>,
/// are used for a table, where `max_idx` is the largest index passed to
/// `TableBuilder::set`.
pub(super) struct Table<I: Idx, T> where Option<T>: FixedSizeEncoding {
_marker: PhantomData<(fn(&I), T)>,
// NOTE(eddyb) this makes `Table` not implement `Sized`, but no
// value of `Table` is ever created (it's always behind `Lazy`).
_bytes: [u8],
}
impl<T> Default for Table<T> where Option<T>: FixedSizeEncoding {
/// Helper for constructing a table's serialization (also see `Table`).
pub(super) struct TableBuilder<I: Idx, T> where Option<T>: FixedSizeEncoding {
// FIXME(eddyb) use `IndexVec<I, [u8; <Option<T>>::BYTE_LEN]>` instead of
// `Vec<u8>`, once that starts working (i.e. lazy normalization).
// Then again, that has the downside of not allowing `TableBuilder::encode` to
// obtain a `&[u8]` entirely in safe code, for writing the bytes out.
bytes: Vec<u8>,
_marker: PhantomData<(fn(&I), T)>,
}
impl<I: Idx, T> Default for TableBuilder<I, T> where Option<T>: FixedSizeEncoding {
fn default() -> Self {
Table {
TableBuilder {
bytes: vec![],
_marker: PhantomData,
}
}
}
impl<T> Table<T> where Option<T>: FixedSizeEncoding {
fn set(&mut self, i: usize, value: T) {
impl<I: Idx, T> TableBuilder<I, T> where Option<T>: FixedSizeEncoding {
pub(super) fn set(&mut self, i: I, value: T) {
// FIXME(eddyb) investigate more compact encodings for sparse tables.
// On the PR @michaelwoerister mentioned:
// > Space requirements could perhaps be optimized by using the HAMT `popcnt`
// > trick (i.e. divide things into buckets of 32 or 64 items and then
// > store bit-masks of which item in each bucket is actually serialized).
let i = i.index();
let needed = (i + 1) * <Option<T>>::BYTE_LEN;
if self.bytes.len() < needed {
self.bytes.resize(needed, 0);
@ -156,7 +165,7 @@ impl<T> Table<T> where Option<T>: FixedSizeEncoding {
Some(value).write_to_bytes_at(&mut self.bytes, i);
}
fn encode(&self, buf: &mut Encoder) -> Lazy<Self> {
pub(super) fn encode(&self, buf: &mut Encoder) -> Lazy<Table<I, T>> {
let pos = buf.position();
buf.emit_raw_bytes(&self.bytes);
Lazy::from_position_and_meta(
@ -166,7 +175,7 @@ impl<T> Table<T> where Option<T>: FixedSizeEncoding {
}
}
impl<T> LazyMeta for Table<T> where Option<T>: FixedSizeEncoding {
impl<I: Idx, T> LazyMeta for Table<I, T> where Option<T>: FixedSizeEncoding {
type Meta = usize;
fn min_size(len: usize) -> usize {
@ -174,65 +183,18 @@ impl<T> LazyMeta for Table<T> where Option<T>: FixedSizeEncoding {
}
}
impl<T> Lazy<Table<T>> where Option<T>: FixedSizeEncoding {
impl<I: Idx, T> Lazy<Table<I, T>> where Option<T>: FixedSizeEncoding {
/// Given the metadata, extract out the value at a particular index (if any).
#[inline(never)]
fn get<'a, 'tcx, M: Metadata<'a, 'tcx>>(
pub(super) fn get<'a, 'tcx, M: Metadata<'a, 'tcx>>(
&self,
metadata: M,
i: usize,
i: I,
) -> Option<T> {
debug!("Table::lookup: index={:?} len={:?}", i, self.meta);
let start = self.position.get();
let bytes = &metadata.raw_bytes()[start..start + self.meta];
<Option<T>>::maybe_read_from_bytes_at(bytes, i)?
}
}
/// Like a `Table` but using `DefIndex` instead of `usize` as keys.
// FIXME(eddyb) replace by making `Table` behave like `IndexVec`,
// and by using `newtype_index!` to define `DefIndex`.
pub(super) struct PerDefTable<T>(Table<T>) where Option<T>: FixedSizeEncoding;
impl<T> Default for PerDefTable<T> where Option<T>: FixedSizeEncoding {
fn default() -> Self {
PerDefTable(Table::default())
}
}
impl<T> PerDefTable<T> where Option<T>: FixedSizeEncoding {
pub(super) fn set(&mut self, def_id: DefId, value: T) {
assert!(def_id.is_local());
self.0.set(def_id.index.index(), value);
}
pub(super) fn encode(&self, buf: &mut Encoder) -> Lazy<Self> {
let lazy = self.0.encode(buf);
Lazy::from_position_and_meta(lazy.position, lazy.meta)
}
}
impl<T> LazyMeta for PerDefTable<T> where Option<T>: FixedSizeEncoding {
type Meta = <Table<T> as LazyMeta>::Meta;
fn min_size(meta: Self::Meta) -> usize {
Table::<T>::min_size(meta)
}
}
impl<T> Lazy<PerDefTable<T>> where Option<T>: FixedSizeEncoding {
fn as_table(&self) -> Lazy<Table<T>> {
Lazy::from_position_and_meta(self.position, self.meta)
}
/// Given the metadata, extract out the value at a particular DefIndex (if any).
#[inline(never)]
pub(super) fn get<'a, 'tcx, M: Metadata<'a, 'tcx>>(
&self,
metadata: M,
def_index: DefIndex,
) -> Option<T> {
self.as_table().get(metadata, def_index.index())
<Option<T>>::maybe_read_from_bytes_at(bytes, i.index())?
}
}