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Auto merge of #95899 - petrochenkov:modchild2, r=cjgillot 

rustc_metadata: Do not encode unnecessary module children

This should remove the syntax context shift and the special case for `ExternCrate` in decoder in https://github.com/rust-lang/rust/pull/95880.

This PR also shifts some work from decoding to encoding, which is typically useful for performance (but probably not much in this case).
r? `@cjgillot`
This commit is contained in:
bors 2022-04-16 22:04:10 +00:00
parent 878c7833f6 233fa659f4
commit 563ef23529
4 changed files with 94 additions and 69 deletions
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25
compiler/rustc_data_structures/src/lib.rs
View File

@ -14,6 +14,8 @@
#![feature(control_flow_enum)]
#![feature(core_intrinsics)]
#![feature(extend_one)]
#![feature(generator_trait)]
#![feature(generators)]
#![feature(let_else)]
#![feature(hash_raw_entry)]
#![feature(maybe_uninit_uninit_array)]
@ -112,6 +114,9 @@ pub mod unhash;
pub use ena::undo_log;
pub use ena::unify;
use std::ops::{Generator, GeneratorState};
use std::pin::Pin;
pub struct OnDrop<F: Fn()>(pub F);
impl<F: Fn()> OnDrop<F> {
@ -130,6 +135,26 @@ impl<F: Fn()> Drop for OnDrop<F> {
}
}
struct IterFromGenerator<G>(G);
impl<G: Generator<Return = ()> + Unpin> Iterator for IterFromGenerator<G> {
type Item = G::Yield;
fn next(&mut self) -> Option<Self::Item> {
match Pin::new(&mut self.0).resume(()) {
GeneratorState::Yielded(n) => Some(n),
GeneratorState::Complete(_) => None,
}
}
}
/// An adapter for turning a generator closure into an iterator, similar to `iter::from_fn`.
pub fn iter_from_generator<G: Generator<Return = ()> + Unpin>(
generator: G,
) -> impl Iterator<Item = G::Yield> {
IterFromGenerator(generator)
}
// See comments in src/librustc_middle/lib.rs
#[doc(hidden)]
pub fn __noop_fix_for_27438() {}

1
compiler/rustc_metadata/src/lib.rs
View File

@ -1,6 +1,7 @@
#![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
#![feature(crate_visibility_modifier)]
#![feature(drain_filter)]
#![feature(generators)]
#![feature(let_else)]
#![feature(nll)]
#![feature(once_cell)]

103
compiler/rustc_metadata/src/rmeta/decoder.rs
View File

@ -1089,63 +1089,32 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
// Iterate over all children.
if let Some(children) = self.root.tables.children.get(self, id) {
for child_index in children.decode((self, sess)) {
if let Some(ident) = self.opt_item_ident(child_index, sess) {
let kind = self.def_kind(child_index);
let def_id = self.local_def_id(child_index);
let res = Res::Def(kind, def_id);
let vis = self.get_visibility(child_index);
let span = self.get_span(child_index, sess);
let macro_rules = match kind {
DefKind::Macro(..) => match self.kind(child_index) {
EntryKind::MacroDef(_, macro_rules) => macro_rules,
_ => unreachable!(),
},
_ => false,
};
let ident = self.item_ident(child_index, sess);
let kind = self.def_kind(child_index);
let def_id = self.local_def_id(child_index);
let res = Res::Def(kind, def_id);
let vis = self.get_visibility(child_index);
let span = self.get_span(child_index, sess);
let macro_rules = match kind {
DefKind::Macro(..) => match self.kind(child_index) {
EntryKind::MacroDef(_, macro_rules) => macro_rules,
_ => unreachable!(),
},
_ => false,
};
callback(ModChild { ident, res, vis, span, macro_rules });
callback(ModChild { ident, res, vis, span, macro_rules });
// For non-re-export structs and variants add their constructors to children.
// Re-export lists automatically contain constructors when necessary.
match kind {
DefKind::Struct => {
if let Some((ctor_def_id, ctor_kind)) =
self.get_ctor_def_id_and_kind(child_index)
{
let ctor_res =
Res::Def(DefKind::Ctor(CtorOf::Struct, ctor_kind), ctor_def_id);
let vis = self.get_visibility(ctor_def_id.index);
callback(ModChild {
ident,
res: ctor_res,
vis,
span,
macro_rules: false,
});
}
}
DefKind::Variant => {
// Braced variants, unlike structs, generate unusable names in
// value namespace, they are reserved for possible future use.
// It's ok to use the variant's id as a ctor id since an
// error will be reported on any use of such resolution anyway.
let (ctor_def_id, ctor_kind) = self
.get_ctor_def_id_and_kind(child_index)
.unwrap_or((def_id, CtorKind::Fictive));
// For non-re-export structs and variants add their constructors to children.
// Re-export lists automatically contain constructors when necessary.
match kind {
DefKind::Struct => {
if let Some((ctor_def_id, ctor_kind)) =
self.get_ctor_def_id_and_kind(child_index)
{
let ctor_res =
Res::Def(DefKind::Ctor(CtorOf::Variant, ctor_kind), ctor_def_id);
let mut vis = self.get_visibility(ctor_def_id.index);
if ctor_def_id == def_id && vis.is_public() {
// For non-exhaustive variants lower the constructor visibility to
// within the crate. We only need this for fictive constructors,
// for other constructors correct visibilities
// were already encoded in metadata.
let mut attrs = self.get_item_attrs(def_id.index, sess);
if attrs.any(|item| item.has_name(sym::non_exhaustive)) {
let crate_def_id = self.local_def_id(CRATE_DEF_INDEX);
vis = ty::Visibility::Restricted(crate_def_id);
}
}
Res::Def(DefKind::Ctor(CtorOf::Struct, ctor_kind), ctor_def_id);
let vis = self.get_visibility(ctor_def_id.index);
callback(ModChild {
ident,
res: ctor_res,
@ -1154,8 +1123,32 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
macro_rules: false,
});
}
_ => {}
}
DefKind::Variant => {
// Braced variants, unlike structs, generate unusable names in
// value namespace, they are reserved for possible future use.
// It's ok to use the variant's id as a ctor id since an
// error will be reported on any use of such resolution anyway.
let (ctor_def_id, ctor_kind) = self
.get_ctor_def_id_and_kind(child_index)
.unwrap_or((def_id, CtorKind::Fictive));
let ctor_res =
Res::Def(DefKind::Ctor(CtorOf::Variant, ctor_kind), ctor_def_id);
let mut vis = self.get_visibility(ctor_def_id.index);
if ctor_def_id == def_id && vis.is_public() {
// For non-exhaustive variants lower the constructor visibility to
// within the crate. We only need this for fictive constructors,
// for other constructors correct visibilities
// were already encoded in metadata.
let mut attrs = self.get_item_attrs(def_id.index, sess);
if attrs.any(|item| item.has_name(sym::non_exhaustive)) {
let crate_def_id = self.local_def_id(CRATE_DEF_INDEX);
vis = ty::Visibility::Restricted(crate_def_id);
}
}
callback(ModChild { ident, res: ctor_res, vis, span, macro_rules: false });
}
_ => {}
}
}
}

34
compiler/rustc_metadata/src/rmeta/encoder.rs
View File

@ -4,6 +4,7 @@ use crate::rmeta::*;
use rustc_data_structures::fingerprint::Fingerprint;
use rustc_data_structures::fx::{FxHashMap, FxIndexSet};
use rustc_data_structures::iter_from_generator;
use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
use rustc_data_structures::sync::{join, par_iter, Lrc, ParallelIterator};
use rustc_hir as hir;
@ -1107,21 +1108,26 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
// Encode this here because we don't do it in encode_def_ids.
record!(self.tables.expn_that_defined[def_id] <- tcx.expn_that_defined(local_def_id));
} else {
let direct_children = md.item_ids.iter().map(|item_id| item_id.def_id.local_def_index);
// Foreign items are planted into their parent modules from name resolution point of view.
let tcx = self.tcx;
let foreign_item_children = md
.item_ids
.iter()
.filter_map(|item_id| match tcx.hir().item(*item_id).kind {
hir::ItemKind::ForeignMod { items, .. } => {
Some(items.iter().map(|fi_ref| fi_ref.id.def_id.local_def_index))
record!(self.tables.children[def_id] <- iter_from_generator(|| {
for item_id in md.item_ids {
match tcx.hir().item(*item_id).kind {
// Foreign items are planted into their parent modules
// from name resolution point of view.
hir::ItemKind::ForeignMod { items, .. } => {
for foreign_item in items {
yield foreign_item.id.def_id.local_def_index;
}
}
// Only encode named non-reexport children, reexports are encoded
// separately and unnamed items are not used by name resolution.
hir::ItemKind::ExternCrate(..) => continue,
_ if tcx.def_key(item_id.def_id.to_def_id()).get_opt_name().is_some() => {
yield item_id.def_id.local_def_index;
}
_ => continue,
}
_ => None,
})
.flatten();
record!(self.tables.children[def_id] <- direct_children.chain(foreign_item_children));
}
}));
}
}