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rustc_metadata: Switch each_child_of_item from callback to iterator
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to avoid allocations.
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@petrochenkov
petrochenkov committed Feb 25, 2022
1 parent d981633 commit 7bd38c9
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Showing 4 changed files with 114 additions and 123 deletions.
212 changes: 103 additions & 109 deletions compiler/rustc_metadata/src/rmeta/decoder.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -41,10 +41,10 @@ use rustc_span::symbol::{sym, Ident, Symbol};
use rustc_span::{self, BytePos, ExpnId, Pos, Span, SyntaxContext, DUMMY_SP};

use proc_macro::bridge::client::ProcMacro;
use std::io;
use std::mem;
use smallvec::SmallVec;
use std::num::NonZeroUsize;
use std::path::Path;
use std::{io, iter, mem};
use tracing::debug;

pub(super) use cstore_impl::provide;
Expand Down Expand Up @@ -1000,7 +1000,7 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
.map(|index| self.get_variant(&self.kind(index), index, did))
.collect()
} else {
std::iter::once(self.get_variant(&kind, item_id, did)).collect()
iter::once(self.get_variant(&kind, item_id, did)).collect()
};

tcx.alloc_adt_def(did, adt_kind, variants, repr)
Expand Down Expand Up @@ -1055,118 +1055,122 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
/// including both proper items and reexports.
/// Module here is understood in name resolution sense - it can be a `mod` item,
/// or a crate root, or an enum, or a trait.
fn for_each_module_child(
fn get_module_children(
self,
id: DefIndex,
mut callback: impl FnMut(ModChild),
sess: &Session,
) {
if let Some(data) = &self.root.proc_macro_data {
// If we are loading as a proc macro, we want to return
// the view of this crate as a proc macro crate.
if id == CRATE_DEF_INDEX {
for def_index in data.macros.decode(self) {
let raw_macro = self.raw_proc_macro(def_index);
let res = Res::Def(
DefKind::Macro(macro_kind(raw_macro)),
self.local_def_id(def_index),
);
let ident = self.item_ident(def_index, sess);
callback(ModChild {
ident,
res,
vis: ty::Visibility::Public,
span: ident.span,
macro_rules: false,
});
}
sess: &'a Session,
) -> impl Iterator<Item = ModChild> + 'a {
// If we are loading as a proc macro, we want to return
// the view of this crate as a proc macro crate.
let is_proc_macro = self.root.proc_macro_data.is_some();
let proc_macros = match &self.root.proc_macro_data {
Some(data) if id == CRATE_DEF_INDEX => data.macros,
_ => Lazy::empty(),
};
let proc_macros = proc_macros.decode(self).map(move |def_index| {
let ident = self.item_ident(def_index, sess);
let macro_kind = match self.raw_proc_macro(def_index) {
ProcMacro::CustomDerive { .. } => MacroKind::Derive,
ProcMacro::Attr { .. } => MacroKind::Attr,
ProcMacro::Bang { .. } => MacroKind::Bang,
};
ModChild {
ident,
res: Res::Def(DefKind::Macro(macro_kind), self.local_def_id(def_index)),
vis: ty::Visibility::Public,
span: ident.span,
macro_rules: false,
}
return;
}
});

// 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,
};

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));
let proper_items = match self.root.tables.children.get(self, id) {
Some(children) if !is_proc_macro => children,
_ => Lazy::empty(),
};
let proper_items = proper_items.decode((self, sess)).map(move |child_index| {
let mut result = SmallVec::<[_; 2]>::new();

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,
};

result.push(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::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 {
Res::Def(DefKind::Ctor(CtorOf::Struct, ctor_kind), ctor_def_id);
let vis = self.get_visibility(ctor_def_id.index);
result.push(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));
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);
}
}
result.push(ModChild {
ident,
res: ctor_res,
vis,
span,
macro_rules: false,
});
}
_ => {}
}
}
}
};

match self.kind(id) {
EntryKind::Mod(exports) => {
for exp in exports.decode((self, sess)) {
callback(exp);
}
}
EntryKind::Enum(..) | EntryKind::Trait(..) => {}
_ => bug!("`for_each_module_child` is called on a non-module: {:?}", self.def_kind(id)),
}
result
});

let exports = match self.kind(id) {
EntryKind::Mod(exports) if !is_proc_macro => exports,
EntryKind::Mod(..) | EntryKind::Enum(..) | EntryKind::Trait(..) => Lazy::empty(),
_ => bug!("`get_module_children` is called on a non-module: {:?}", self.def_kind(id)),
};
let exports = exports.decode((self, sess));

proc_macros.chain(proper_items.flatten()).chain(exports)
}

fn is_ctfe_mir_available(self, id: DefIndex) -> bool {
Expand Down Expand Up @@ -1878,13 +1882,3 @@ impl CrateMetadata {
None
}
}

// Cannot be implemented on 'ProcMacro', as libproc_macro
// does not depend on librustc_ast
fn macro_kind(raw: &ProcMacro) -> MacroKind {
match raw {
ProcMacro::CustomDerive { .. } => MacroKind::Derive,
ProcMacro::Attr { .. } => MacroKind::Attr,
ProcMacro::Bang { .. } => MacroKind::Bang,
}
}
19 changes: 7 additions & 12 deletions compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -20,7 +20,6 @@ use rustc_span::source_map::{Span, Spanned};
use rustc_span::symbol::{kw, Symbol};

use rustc_data_structures::sync::Lrc;
use smallvec::SmallVec;
use std::any::Any;

macro_rules! provide_one {
Expand Down Expand Up @@ -205,9 +204,7 @@ provide! { <'tcx> tcx, def_id, other, cdata,
r
}
module_children => {
let mut result = SmallVec::<[_; 8]>::new();
cdata.for_each_module_child(def_id.index, |child| result.push(child), tcx.sess);
tcx.arena.alloc_slice(&result)
tcx.arena.alloc_from_iter(cdata.get_module_children(def_id.index, tcx.sess))
}
defined_lib_features => { cdata.get_lib_features(tcx) }
defined_lang_items => { tcx.arena.alloc_from_iter(cdata.get_lang_items()) }
Expand Down Expand Up @@ -400,14 +397,12 @@ impl CStore {
self.get_crate_data(def.krate).get_visibility(def.index)
}

pub fn module_children_untracked(&self, def_id: DefId, sess: &Session) -> Vec<ModChild> {
let mut result = vec![];
self.get_crate_data(def_id.krate).for_each_module_child(
def_id.index,
|child| result.push(child),
sess,
);
result
pub fn module_children_untracked<'a>(
&'a self,
def_id: DefId,
sess: &'a Session,
) -> impl Iterator<Item = ModChild> + 'a {
self.get_crate_data(def_id.krate).get_module_children(def_id.index, sess)
}

pub fn load_macro_untracked(&self, id: DefId, sess: &Session) -> LoadedMacro {
Expand Down
4 changes: 3 additions & 1 deletion compiler/rustc_resolve/src/build_reduced_graph.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -214,7 +214,9 @@ impl<'a> Resolver<'a> {
}

crate fn build_reduced_graph_external(&mut self, module: Module<'a>) {
for child in self.cstore().module_children_untracked(module.def_id(), self.session) {
for child in
Vec::from_iter(self.cstore().module_children_untracked(module.def_id(), self.session))
{
let parent_scope = ParentScope::module(module, self);
BuildReducedGraphVisitor { r: self, parent_scope }
.build_reduced_graph_for_external_crate_res(child);
Expand Down
2 changes: 1 addition & 1 deletion compiler/rustc_resolve/src/lib.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -3421,7 +3421,7 @@ impl<'a> Resolver<'a> {
if let Some(def_id) = def_id.as_local() {
self.reexport_map.get(&def_id).cloned().unwrap_or_default()
} else {
self.cstore().module_children_untracked(def_id, self.session)
self.cstore().module_children_untracked(def_id, self.session).collect()
}
}

Expand Down

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