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rustc_metadata: Support encoding/decoding LazyArray without an Option

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This commit is contained in:
Vadim Petrochenkov 2023-01-27 23:28:33 +04:00
parent 8cc5aa561c
commit eb5f2d3980
4 changed files with 66 additions and 30 deletions
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18
compiler/rustc_metadata/src/rmeta/decoder.rs
View File

@ -654,7 +654,7 @@ impl<'a, 'tcx, T> Decodable<DecodeContext<'a, 'tcx>> for LazyValue<T> {
impl<'a, 'tcx, T> Decodable<DecodeContext<'a, 'tcx>> for LazyArray<T> {
fn decode(decoder: &mut DecodeContext<'a, 'tcx>) -> Self {
let len = decoder.read_usize();
if len == 0 { LazyArray::empty() } else { decoder.read_lazy_array(len) }
if len == 0 { LazyArray::default() } else { decoder.read_lazy_array(len) }
}
}
@ -864,7 +864,7 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
.tables
.children
.get(self, index)
.unwrap_or_else(LazyArray::empty)
.unwrap_or_else(LazyArray::default)
.decode(self)
.map(|index| ty::FieldDef {
did: self.local_def_id(index),
@ -896,7 +896,7 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
.tables
.children
.get(self, item_id)
.unwrap_or_else(LazyArray::empty)
.unwrap_or_else(LazyArray::default)
.decode(self)
.filter_map(|index| {
let kind = self.def_kind(index);
@ -1045,7 +1045,7 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
.tables
.fn_arg_names
.get(self, id)
.unwrap_or_else(LazyArray::empty)
.unwrap_or_else(LazyArray::default)
.decode((self, sess))
.nth(0)
.map_or(false, |ident| ident.name == kw::SelfLower)
@ -1060,7 +1060,7 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
.tables
.children
.get(self, id)
.unwrap_or_else(LazyArray::empty)
.unwrap_or_else(LazyArray::default)
.decode((self, sess))
.map(move |child_index| self.local_def_id(child_index))
}
@ -1131,7 +1131,7 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
.tables
.children
.get(self, id)
.unwrap_or_else(LazyArray::empty)
.unwrap_or_else(LazyArray::default)
.decode(self)
.map(move |index| respan(self.get_span(index, sess), self.item_name(index)))
}
@ -1144,7 +1144,7 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
.tables
.children
.get(self, id)
.unwrap_or_else(LazyArray::empty)
.unwrap_or_else(LazyArray::default)
.decode(self)
.map(move |field_index| self.get_visibility(field_index))
}
@ -1159,7 +1159,7 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
.tables
.inherent_impls
.get(self, id)
.unwrap_or_else(LazyArray::empty)
.unwrap_or_else(LazyArray::default)
.decode(self)
.map(|index| self.local_def_id(index)),
)
@ -1174,7 +1174,7 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
.tables
.inherent_impls
.get(self, ty_index)
.unwrap_or_else(LazyArray::empty)
.unwrap_or_else(LazyArray::default)
.decode(self)
.map(move |impl_index| (ty_def_id, self.local_def_id(impl_index)))
})

6
compiler/rustc_metadata/src/rmeta/encoder.rs
View File

@ -76,13 +76,13 @@ pub(super) struct EncodeContext<'a, 'tcx> {
symbol_table: FxHashMap<Symbol, usize>,
}
/// If the current crate is a proc-macro, returns early with `LazyArray::empty()`.
/// If the current crate is a proc-macro, returns early with `LazyArray::default()`.
/// This is useful for skipping the encoding of things that aren't needed
/// for proc-macro crates.
macro_rules! empty_proc_macro {
($self:ident) => {
if $self.is_proc_macro {
return LazyArray::empty();
return LazyArray::default();
}
};
}
@ -1961,7 +1961,7 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
Linkage::Static => Some(LinkagePreference::RequireStatic),
}));
}
LazyArray::empty()
LazyArray::default()
}
fn encode_info_for_foreign_item(&mut self, def_id: DefId, nitem: &hir::ForeignItem<'_>) {

10
compiler/rustc_metadata/src/rmeta/mod.rs
View File

@ -115,14 +115,16 @@ impl<T: ParameterizedOverTcx> ParameterizedOverTcx for LazyArray<T> {
type Value<'tcx> = LazyArray<T::Value<'tcx>>;
}
impl<T> Default for LazyArray<T> {
fn default() -> LazyArray<T> {
LazyArray::from_position_and_num_elems(NonZeroUsize::new(1).unwrap(), 0)
}
}
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.

62
compiler/rustc_metadata/src/rmeta/table.rs
View File

@ -38,6 +38,12 @@ impl IsDefault for u32 {
}
}
impl<T> IsDefault for LazyArray<T> {
fn is_default(&self) -> bool {
self.num_elems == 0
}
}
/// Helper trait, for encoding to, and decoding from, a fixed number of bytes.
/// Used mainly for Lazy positions and lengths.
/// Unchecked invariant: `Self::default()` should encode as `[0; BYTE_LEN]`,
@ -286,32 +292,60 @@ 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 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;
Some(LazyArray::from_position_and_num_elems(position, len))
}
}
impl<T> FixedSizeEncoding for LazyArray<T> {
type ByteArray = [u8; 8];
#[inline]
fn from_bytes(b: &[u8; 8]) -> Self {
let ([position_bytes, meta_bytes],[])= b.as_chunks::<4>() else { panic!() };
if *meta_bytes == [0; 4] {
return Default::default();
}
LazyArray::from_bytes_impl(position_bytes, meta_bytes).unwrap()
}
#[inline]
fn write_to_bytes(self, b: &mut [u8; 8]) {
assert!(!self.is_default());
self.write_to_bytes_impl(b)
}
}
impl<T> FixedSizeEncoding for Option<LazyArray<T>> {
type ByteArray = [u8; 8];
#[inline]
fn from_bytes(b: &[u8; 8]) -> Self {
let ([position_bytes, meta_bytes],[])= b.as_chunks::<4>() else { panic!() };
let position = NonZeroUsize::new(u32::from_bytes(position_bytes) as usize)?;
let len = u32::from_bytes(meta_bytes) as usize;
Some(LazyArray::from_position_and_num_elems(position, len))
LazyArray::from_bytes_impl(position_bytes, meta_bytes)
}
#[inline]
fn write_to_bytes(self, b: &mut [u8; 8]) {
match self {
None => unreachable!(),
Some(lazy) => {
let ([position_bytes, meta_bytes],[])= b.as_chunks_mut::<4>() else { panic!() };
let position = lazy.position.get();
let position: u32 = position.try_into().unwrap();
position.write_to_bytes(position_bytes);
let len = lazy.num_elems;
let len: u32 = len.try_into().unwrap();
len.write_to_bytes(meta_bytes);
}
Some(lazy) => lazy.write_to_bytes_impl(b),
}
}
}