526 lines
16 KiB
Rust
526 lines
16 KiB
Rust
//! This module contains some shared code for encoding and decoding various
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//! things from the `ty` module, and in particular implements support for
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//! "shorthands" which allow to have pointers back into the already encoded
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//! stream instead of re-encoding the same thing twice.
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//!
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//! The functionality in here is shared between persisting to crate metadata and
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//! persisting to incr. comp. caches.
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use crate::arena::ArenaAllocatable;
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use crate::infer::canonical::{CanonicalVarInfo, CanonicalVarInfos};
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use crate::mir::{
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self,
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interpret::{AllocId, ConstAllocation},
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};
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use crate::traits;
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use crate::ty::subst::SubstsRef;
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use crate::ty::{self, AdtDef, Ty};
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use rustc_data_structures::fx::FxHashMap;
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use rustc_middle::ty::TyCtxt;
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use rustc_serialize::{Decodable, Encodable};
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use rustc_span::Span;
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pub use rustc_type_ir::{TyDecoder, TyEncoder};
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use std::hash::Hash;
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use std::intrinsics;
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use std::marker::DiscriminantKind;
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/// The shorthand encoding uses an enum's variant index `usize`
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/// and is offset by this value so it never matches a real variant.
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/// This offset is also chosen so that the first byte is never < 0x80.
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pub const SHORTHAND_OFFSET: usize = 0x80;
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pub trait EncodableWithShorthand<E: TyEncoder>: Copy + Eq + Hash {
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type Variant: Encodable<E>;
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fn variant(&self) -> &Self::Variant;
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}
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#[allow(rustc::usage_of_ty_tykind)]
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impl<'tcx, E: TyEncoder<I = TyCtxt<'tcx>>> EncodableWithShorthand<E> for Ty<'tcx> {
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type Variant = ty::TyKind<'tcx>;
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#[inline]
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fn variant(&self) -> &Self::Variant {
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self.kind()
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}
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}
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impl<'tcx, E: TyEncoder<I = TyCtxt<'tcx>>> EncodableWithShorthand<E> for ty::PredicateKind<'tcx> {
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type Variant = ty::PredicateKind<'tcx>;
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#[inline]
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fn variant(&self) -> &Self::Variant {
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self
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}
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}
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/// Trait for decoding to a reference.
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///
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/// This is a separate trait from `Decodable` so that we can implement it for
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/// upstream types, such as `FxHashSet`.
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///
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/// The `TyDecodable` derive macro will use this trait for fields that are
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/// references (and don't use a type alias to hide that).
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///
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/// `Decodable` can still be implemented in cases where `Decodable` is required
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/// by a trait bound.
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pub trait RefDecodable<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> {
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fn decode(d: &mut D) -> &'tcx Self;
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}
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/// Encode the given value or a previously cached shorthand.
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pub fn encode_with_shorthand<'tcx, E, T, M>(encoder: &mut E, value: &T, cache: M)
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where
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E: TyEncoder<I = TyCtxt<'tcx>>,
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M: for<'b> Fn(&'b mut E) -> &'b mut FxHashMap<T, usize>,
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T: EncodableWithShorthand<E>,
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// The discriminant and shorthand must have the same size.
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T::Variant: DiscriminantKind<Discriminant = isize>,
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{
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let existing_shorthand = cache(encoder).get(value).copied();
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if let Some(shorthand) = existing_shorthand {
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encoder.emit_usize(shorthand);
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return;
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}
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let variant = value.variant();
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let start = encoder.position();
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variant.encode(encoder);
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let len = encoder.position() - start;
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// The shorthand encoding uses the same usize as the
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// discriminant, with an offset so they can't conflict.
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let discriminant = intrinsics::discriminant_value(variant);
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assert!(SHORTHAND_OFFSET > discriminant as usize);
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let shorthand = start + SHORTHAND_OFFSET;
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// Get the number of bits that leb128 could fit
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// in the same space as the fully encoded type.
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let leb128_bits = len * 7;
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// Check that the shorthand is a not longer than the
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// full encoding itself, i.e., it's an obvious win.
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if leb128_bits >= 64 || (shorthand as u64) < (1 << leb128_bits) {
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cache(encoder).insert(*value, shorthand);
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}
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}
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impl<'tcx, E: TyEncoder<I = TyCtxt<'tcx>>> Encodable<E> for Ty<'tcx> {
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fn encode(&self, e: &mut E) {
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encode_with_shorthand(e, self, TyEncoder::type_shorthands);
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}
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}
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impl<'tcx, E: TyEncoder<I = TyCtxt<'tcx>>> Encodable<E>
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for ty::Binder<'tcx, ty::PredicateKind<'tcx>>
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{
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fn encode(&self, e: &mut E) {
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self.bound_vars().encode(e);
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encode_with_shorthand(e, &self.skip_binder(), TyEncoder::predicate_shorthands);
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}
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}
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impl<'tcx, E: TyEncoder<I = TyCtxt<'tcx>>> Encodable<E> for ty::Predicate<'tcx> {
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fn encode(&self, e: &mut E) {
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self.kind().encode(e);
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}
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}
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impl<'tcx, E: TyEncoder<I = TyCtxt<'tcx>>> Encodable<E> for ty::Region<'tcx> {
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fn encode(&self, e: &mut E) {
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self.kind().encode(e);
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}
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}
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impl<'tcx, E: TyEncoder<I = TyCtxt<'tcx>>> Encodable<E> for ty::Const<'tcx> {
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fn encode(&self, e: &mut E) {
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self.0.0.encode(e);
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}
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}
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impl<'tcx, E: TyEncoder<I = TyCtxt<'tcx>>> Encodable<E> for ConstAllocation<'tcx> {
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fn encode(&self, e: &mut E) {
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self.inner().encode(e)
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}
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}
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impl<'tcx, E: TyEncoder<I = TyCtxt<'tcx>>> Encodable<E> for AdtDef<'tcx> {
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fn encode(&self, e: &mut E) {
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self.0.0.encode(e)
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}
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}
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impl<'tcx, E: TyEncoder<I = TyCtxt<'tcx>>> Encodable<E> for AllocId {
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fn encode(&self, e: &mut E) {
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e.encode_alloc_id(self)
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}
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}
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#[inline]
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fn decode_arena_allocable<
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'tcx,
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D: TyDecoder<I = TyCtxt<'tcx>>,
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T: ArenaAllocatable<'tcx> + Decodable<D>,
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>(
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decoder: &mut D,
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) -> &'tcx T
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where
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D: TyDecoder,
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{
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decoder.interner().arena.alloc(Decodable::decode(decoder))
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}
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#[inline]
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fn decode_arena_allocable_slice<
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'tcx,
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D: TyDecoder<I = TyCtxt<'tcx>>,
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T: ArenaAllocatable<'tcx> + Decodable<D>,
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>(
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decoder: &mut D,
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) -> &'tcx [T]
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where
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D: TyDecoder,
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{
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decoder.interner().arena.alloc_from_iter(<Vec<T> as Decodable<D>>::decode(decoder))
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}
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impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> Decodable<D> for Ty<'tcx> {
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#[allow(rustc::usage_of_ty_tykind)]
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fn decode(decoder: &mut D) -> Ty<'tcx> {
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// Handle shorthands first, if we have a usize > 0x80.
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if decoder.positioned_at_shorthand() {
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let pos = decoder.read_usize();
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assert!(pos >= SHORTHAND_OFFSET);
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let shorthand = pos - SHORTHAND_OFFSET;
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decoder.cached_ty_for_shorthand(shorthand, |decoder| {
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decoder.with_position(shorthand, Ty::decode)
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})
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} else {
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let tcx = decoder.interner();
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tcx.mk_ty(rustc_type_ir::TyKind::decode(decoder))
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}
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}
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}
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impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> Decodable<D>
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for ty::Binder<'tcx, ty::PredicateKind<'tcx>>
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{
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fn decode(decoder: &mut D) -> ty::Binder<'tcx, ty::PredicateKind<'tcx>> {
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let bound_vars = Decodable::decode(decoder);
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// Handle shorthands first, if we have a usize > 0x80.
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ty::Binder::bind_with_vars(
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if decoder.positioned_at_shorthand() {
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let pos = decoder.read_usize();
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assert!(pos >= SHORTHAND_OFFSET);
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let shorthand = pos - SHORTHAND_OFFSET;
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decoder.with_position(shorthand, ty::PredicateKind::decode)
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} else {
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ty::PredicateKind::decode(decoder)
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},
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bound_vars,
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)
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}
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}
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impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> Decodable<D> for ty::Predicate<'tcx> {
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fn decode(decoder: &mut D) -> ty::Predicate<'tcx> {
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let predicate_kind = Decodable::decode(decoder);
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decoder.interner().mk_predicate(predicate_kind)
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}
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}
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impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> Decodable<D> for SubstsRef<'tcx> {
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fn decode(decoder: &mut D) -> Self {
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let len = decoder.read_usize();
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let tcx = decoder.interner();
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tcx.mk_substs(
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(0..len).map::<ty::subst::GenericArg<'tcx>, _>(|_| Decodable::decode(decoder)),
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)
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}
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}
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impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> Decodable<D> for mir::Place<'tcx> {
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fn decode(decoder: &mut D) -> Self {
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let local: mir::Local = Decodable::decode(decoder);
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let len = decoder.read_usize();
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let projection = decoder.interner().mk_place_elems(
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(0..len).map::<mir::PlaceElem<'tcx>, _>(|_| Decodable::decode(decoder)),
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);
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mir::Place { local, projection }
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}
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}
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impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> Decodable<D> for ty::Region<'tcx> {
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fn decode(decoder: &mut D) -> Self {
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decoder.interner().mk_region(Decodable::decode(decoder))
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}
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}
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impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> Decodable<D> for CanonicalVarInfos<'tcx> {
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fn decode(decoder: &mut D) -> Self {
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let len = decoder.read_usize();
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let interned: Vec<CanonicalVarInfo<'tcx>> =
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(0..len).map(|_| Decodable::decode(decoder)).collect();
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decoder.interner().intern_canonical_var_infos(interned.as_slice())
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}
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}
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impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> Decodable<D> for AllocId {
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fn decode(decoder: &mut D) -> Self {
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decoder.decode_alloc_id()
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}
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}
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impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> Decodable<D> for ty::SymbolName<'tcx> {
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fn decode(decoder: &mut D) -> Self {
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ty::SymbolName::new(decoder.interner(), &decoder.read_str())
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}
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}
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macro_rules! impl_decodable_via_ref {
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($($t:ty),+) => {
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$(impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> Decodable<D> for $t {
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fn decode(decoder: &mut D) -> Self {
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RefDecodable::decode(decoder)
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}
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})*
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}
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}
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impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> RefDecodable<'tcx, D> for ty::List<Ty<'tcx>> {
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fn decode(decoder: &mut D) -> &'tcx Self {
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let len = decoder.read_usize();
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decoder.interner().mk_type_list((0..len).map::<Ty<'tcx>, _>(|_| Decodable::decode(decoder)))
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}
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}
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impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> RefDecodable<'tcx, D>
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for ty::List<ty::Binder<'tcx, ty::ExistentialPredicate<'tcx>>>
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{
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fn decode(decoder: &mut D) -> &'tcx Self {
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let len = decoder.read_usize();
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decoder.interner().mk_poly_existential_predicates(
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(0..len).map::<ty::Binder<'tcx, _>, _>(|_| Decodable::decode(decoder)),
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)
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}
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}
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impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> Decodable<D> for ty::Const<'tcx> {
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fn decode(decoder: &mut D) -> Self {
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decoder.interner().mk_const(Decodable::decode(decoder))
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}
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}
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impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> RefDecodable<'tcx, D> for [ty::ValTree<'tcx>] {
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fn decode(decoder: &mut D) -> &'tcx Self {
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decoder.interner().arena.alloc_from_iter(
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(0..decoder.read_usize()).map(|_| Decodable::decode(decoder)).collect::<Vec<_>>(),
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)
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}
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}
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impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> Decodable<D> for ConstAllocation<'tcx> {
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fn decode(decoder: &mut D) -> Self {
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decoder.interner().intern_const_alloc(Decodable::decode(decoder))
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}
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}
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impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> Decodable<D> for AdtDef<'tcx> {
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fn decode(decoder: &mut D) -> Self {
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decoder.interner().intern_adt_def(Decodable::decode(decoder))
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}
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}
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impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> RefDecodable<'tcx, D>
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for [(ty::Predicate<'tcx>, Span)]
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{
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fn decode(decoder: &mut D) -> &'tcx Self {
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decoder.interner().arena.alloc_from_iter(
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(0..decoder.read_usize()).map(|_| Decodable::decode(decoder)).collect::<Vec<_>>(),
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)
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}
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}
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impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> RefDecodable<'tcx, D>
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for [ty::abstract_const::Node<'tcx>]
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{
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fn decode(decoder: &mut D) -> &'tcx Self {
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decoder.interner().arena.alloc_from_iter(
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(0..decoder.read_usize()).map(|_| Decodable::decode(decoder)).collect::<Vec<_>>(),
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)
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}
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}
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impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> RefDecodable<'tcx, D>
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for [ty::abstract_const::NodeId]
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{
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fn decode(decoder: &mut D) -> &'tcx Self {
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decoder.interner().arena.alloc_from_iter(
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(0..decoder.read_usize()).map(|_| Decodable::decode(decoder)).collect::<Vec<_>>(),
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)
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}
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}
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impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> RefDecodable<'tcx, D>
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for ty::List<ty::BoundVariableKind>
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{
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fn decode(decoder: &mut D) -> &'tcx Self {
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let len = decoder.read_usize();
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decoder.interner().mk_bound_variable_kinds(
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(0..len).map::<ty::BoundVariableKind, _>(|_| Decodable::decode(decoder)),
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)
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}
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}
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impl_decodable_via_ref! {
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&'tcx ty::TypeckResults<'tcx>,
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&'tcx ty::List<Ty<'tcx>>,
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&'tcx ty::List<ty::Binder<'tcx, ty::ExistentialPredicate<'tcx>>>,
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&'tcx traits::ImplSource<'tcx, ()>,
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&'tcx mir::Body<'tcx>,
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&'tcx mir::UnsafetyCheckResult,
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&'tcx mir::BorrowCheckResult<'tcx>,
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&'tcx mir::coverage::CodeRegion,
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&'tcx ty::List<ty::BoundVariableKind>
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}
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|
#[macro_export]
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macro_rules! __impl_decoder_methods {
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($($name:ident -> $ty:ty;)*) => {
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$(
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#[inline]
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fn $name(&mut self) -> $ty {
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self.opaque.$name()
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}
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)*
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}
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|
}
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|
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|
macro_rules! impl_arena_allocatable_decoder {
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|
([]$args:tt) => {};
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|
([decode $(, $attrs:ident)*]
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[$name:ident: $ty:ty]) => {
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impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> RefDecodable<'tcx, D> for $ty {
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#[inline]
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fn decode(decoder: &mut D) -> &'tcx Self {
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decode_arena_allocable(decoder)
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}
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}
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|
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|
impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> RefDecodable<'tcx, D> for [$ty] {
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#[inline]
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fn decode(decoder: &mut D) -> &'tcx Self {
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decode_arena_allocable_slice(decoder)
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}
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}
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};
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}
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macro_rules! impl_arena_allocatable_decoders {
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([$($a:tt $name:ident: $ty:ty,)*]) => {
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$(
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impl_arena_allocatable_decoder!($a [$name: $ty]);
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)*
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}
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}
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rustc_hir::arena_types!(impl_arena_allocatable_decoders);
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arena_types!(impl_arena_allocatable_decoders);
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|
macro_rules! impl_arena_copy_decoder {
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|
(<$tcx:tt> $($ty:ty,)*) => {
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$(impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> RefDecodable<'tcx, D> for $ty {
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|
#[inline]
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|
fn decode(decoder: &mut D) -> &'tcx Self {
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decoder.interner().arena.alloc(Decodable::decode(decoder))
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}
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}
|
|
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impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> RefDecodable<'tcx, D> for [$ty] {
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|
#[inline]
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|
fn decode(decoder: &mut D) -> &'tcx Self {
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decoder.interner().arena.alloc_from_iter(<Vec<_> as Decodable<D>>::decode(decoder))
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}
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})*
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};
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}
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|
impl_arena_copy_decoder! {<'tcx>
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|
Span,
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|
rustc_span::symbol::Ident,
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|
ty::Variance,
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|
rustc_span::def_id::DefId,
|
|
rustc_span::def_id::LocalDefId,
|
|
(rustc_middle::middle::exported_symbols::ExportedSymbol<'tcx>, rustc_middle::middle::exported_symbols::SymbolExportInfo),
|
|
}
|
|
|
|
#[macro_export]
|
|
macro_rules! implement_ty_decoder {
|
|
($DecoderName:ident <$($typaram:tt),*>) => {
|
|
mod __ty_decoder_impl {
|
|
use std::borrow::Cow;
|
|
use rustc_serialize::Decoder;
|
|
|
|
use super::$DecoderName;
|
|
|
|
impl<$($typaram ),*> Decoder for $DecoderName<$($typaram),*> {
|
|
$crate::__impl_decoder_methods! {
|
|
read_u128 -> u128;
|
|
read_u64 -> u64;
|
|
read_u32 -> u32;
|
|
read_u16 -> u16;
|
|
read_u8 -> u8;
|
|
read_usize -> usize;
|
|
|
|
read_i128 -> i128;
|
|
read_i64 -> i64;
|
|
read_i32 -> i32;
|
|
read_i16 -> i16;
|
|
read_i8 -> i8;
|
|
read_isize -> isize;
|
|
|
|
read_bool -> bool;
|
|
read_f64 -> f64;
|
|
read_f32 -> f32;
|
|
read_char -> char;
|
|
read_str -> &str;
|
|
}
|
|
|
|
#[inline]
|
|
fn read_raw_bytes(&mut self, len: usize) -> &[u8] {
|
|
self.opaque.read_raw_bytes(len)
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
macro_rules! impl_binder_encode_decode {
|
|
($($t:ty),+ $(,)?) => {
|
|
$(
|
|
impl<'tcx, E: TyEncoder<I = TyCtxt<'tcx>>> Encodable<E> for ty::Binder<'tcx, $t> {
|
|
fn encode(&self, e: &mut E) {
|
|
self.bound_vars().encode(e);
|
|
self.as_ref().skip_binder().encode(e);
|
|
}
|
|
}
|
|
impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> Decodable<D> for ty::Binder<'tcx, $t> {
|
|
fn decode(decoder: &mut D) -> Self {
|
|
let bound_vars = Decodable::decode(decoder);
|
|
ty::Binder::bind_with_vars(Decodable::decode(decoder), bound_vars)
|
|
}
|
|
}
|
|
)*
|
|
}
|
|
}
|
|
|
|
impl_binder_encode_decode! {
|
|
&'tcx ty::List<Ty<'tcx>>,
|
|
ty::FnSig<'tcx>,
|
|
ty::ExistentialPredicate<'tcx>,
|
|
ty::TraitRef<'tcx>,
|
|
Vec<ty::GeneratorInteriorTypeCause<'tcx>>,
|
|
}
|