bjoernager/rust
bjoernager/rust
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Remove TinyList.

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It is optimized for lists with a single element, avoiding the need for
an allocation in that case. But `SmallVec<[T; 1]>` also avoids the
allocation, and is better in general: more standard, log2 number of
allocations if the list exceeds one item, and a much more capable API.

This commit removes `TinyList` and converts the two uses to
`SmallVec<[T; 1]>`. It also reorders the `use` items in the relevant
file so they are in just two sections (`pub` and non-`pub`), ordered
alphabetically, instead of many sections. (This is a relevant part of
the change because I had to decide where to add a `use` item for
`SmallVec`.)
This commit is contained in:
Nicholas Nethercote 2024-05-07 08:05:02 +10:00
parent d7814e72eb
commit f5d7d346a4
4 changed files with 8 additions and 245 deletions
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17
compiler/rustc_middle/src/mir/interpret/mod.rs
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@ -125,10 +125,11 @@ use std::io::{Read, Write};
use std::num::NonZero;
use std::sync::atomic::{AtomicU32, Ordering};
use smallvec::{smallvec, SmallVec};
use rustc_ast::LitKind;
use rustc_data_structures::fx::FxHashMap;
use rustc_data_structures::sync::{HashMapExt, Lock};
use rustc_data_structures::tiny_list::TinyList;
use rustc_errors::ErrorGuaranteed;
use rustc_hir::def_id::{DefId, LocalDefId};
use rustc_macros::{HashStable, TyDecodable, TyEncodable, TypeFoldable, TypeVisitable};
@ -266,8 +267,8 @@ type DecodingSessionId = NonZero<u32>;
#[derive(Clone)]
enum State {
Empty,
InProgressNonAlloc(TinyList<DecodingSessionId>),
InProgress(TinyList<DecodingSessionId>, AllocId),
InProgressNonAlloc(SmallVec<[DecodingSessionId; 1]>),
InProgress(SmallVec<[DecodingSessionId; 1]>, AllocId),
Done(AllocId),
}
@ -337,8 +338,7 @@ impl<'s> AllocDecodingSession<'s> {
// If this is an allocation, we need to reserve an
// `AllocId` so we can decode cyclic graphs.
let alloc_id = decoder.interner().reserve_alloc_id();
*entry =
State::InProgress(TinyList::new_single(self.session_id), alloc_id);
*entry = State::InProgress(smallvec![self.session_id], alloc_id);
Some(alloc_id)
}
AllocDiscriminant::Fn
@ -346,8 +346,7 @@ impl<'s> AllocDecodingSession<'s> {
| AllocDiscriminant::VTable => {
// Fns and statics cannot be cyclic, and their `AllocId`
// is determined later by interning.
*entry =
State::InProgressNonAlloc(TinyList::new_single(self.session_id));
*entry = State::InProgressNonAlloc(smallvec![self.session_id]);
None
}
}
@ -357,7 +356,7 @@ impl<'s> AllocDecodingSession<'s> {
bug!("this should be unreachable");
} else {
// Start decoding concurrently.
sessions.insert(self.session_id);
sessions.push(self.session_id);
None
}
}
@ -367,7 +366,7 @@ impl<'s> AllocDecodingSession<'s> {
return alloc_id;
} else {
// Start decoding concurrently.
sessions.insert(self.session_id);
sessions.push(self.session_id);
Some(alloc_id)
}
}