bjoernager/rust
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effective visibility: Remove questionable optimizations

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First, they require eagerly calculating private visibility (current normal module), which is somewhat expensive.
Private visibilities are also lost once calculated, instead of being cached in the table.

Second, I cannot prove that the optimizations are correct.
Maybe they can be partially reinstated in the future in cases when it's cheap and provably correct to do them.
They will also probably be merged into `fn update` in that case.

Partially fixes https://github.com/rust-lang/rust/issues/104249
Fixes https://github.com/rust-lang/rust/issues/104539
This commit is contained in:
Vadim Petrochenkov 2022-11-23 19:19:06 +03:00
parent 3f20f4ac42
commit f0843b89d1
6 changed files with 70 additions and 43 deletions
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50
compiler/rustc_resolve/src/effective_visibilities.rs
View file

@ -42,6 +42,24 @@ impl Resolver<'_> {
fn nearest_normal_mod(&mut self, def_id: LocalDefId) -> LocalDefId {
self.get_nearest_non_block_module(def_id.to_def_id()).nearest_parent_mod().expect_local()
}
fn private_vis_import(&mut self, binding: ImportId<'_>) -> Visibility {
let NameBindingKind::Import { import, .. } = binding.kind else { unreachable!() };
Visibility::Restricted(
import
.id()
.map(|id| self.nearest_normal_mod(self.local_def_id(id)))
.unwrap_or(CRATE_DEF_ID),
)
}
fn private_vis_def(&mut self, def_id: LocalDefId) -> Visibility {
if def_id == CRATE_DEF_ID {
Visibility::Public
} else {
Visibility::Restricted(self.nearest_normal_mod(def_id))
}
}
}
impl<'a, 'b> IntoDefIdTree for &'b mut Resolver<'a> {
@ -143,36 +161,12 @@ impl<'r, 'a> EffectiveVisibilitiesVisitor<'r, 'a> {
.copied()
}
/// The update is guaranteed to not change the table and we can skip it.
fn is_noop_update(
&self,
parent_id: ParentId<'a>,
nominal_vis: Visibility,
default_vis: Visibility,
) -> bool {
nominal_vis == default_vis
|| match parent_id {
ParentId::Def(def_id) => self.r.visibilities[&def_id],
ParentId::Import(binding) => binding.vis.expect_local(),
} == default_vis
}
fn update_import(&mut self, binding: ImportId<'a>, parent_id: ParentId<'a>) {
let NameBindingKind::Import { import, .. } = binding.kind else { unreachable!() };
let nominal_vis = binding.vis.expect_local();
let default_vis = Visibility::Restricted(
import
.id()
.map(|id| self.r.nearest_normal_mod(self.r.local_def_id(id)))
.unwrap_or(CRATE_DEF_ID),
);
if self.is_noop_update(parent_id, nominal_vis, default_vis) {
return;
}
self.changed |= self.import_effective_visibilities.update(
binding,
nominal_vis,
|r| (default_vis, r),
|r| (r.private_vis_import(binding), r),
self.effective_vis(parent_id),
parent_id.level(),
&mut *self.r,
@ -180,14 +174,10 @@ impl<'r, 'a> EffectiveVisibilitiesVisitor<'r, 'a> {
}
fn update_def(&mut self, def_id: LocalDefId, nominal_vis: Visibility, parent_id: ParentId<'a>) {
let default_vis = Visibility::Restricted(self.r.nearest_normal_mod(def_id));
if self.is_noop_update(parent_id, nominal_vis, default_vis) {
return;
}
self.changed |= self.def_effective_visibilities.update(
def_id,
nominal_vis,
|r| (if def_id == CRATE_DEF_ID { Visibility::Public } else { default_vis }, r),
|r| (r.private_vis_def(def_id), r),
self.effective_vis(parent_id),
parent_id.level(),
&mut *self.r,