bjoernager/rust
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Remove DropArena.

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Most arena-allocate types that impl `Drop` get their own `TypedArena`, but a
few infrequently used ones share a `DropArena`. This sharing adds complexity
but doesn't help performance or memory usage. Perhaps it was more effective in
the past prior to some other improvements to arenas.

This commit removes `DropArena` and the sharing of arenas via the `few`
attribute of the `arena_types` macro. This change removes over 100 lines of
code and nine uses of `unsafe` (one of which affects the parallel compiler) and
makes the remaining code easier to read.
This commit is contained in:
Nicholas Nethercote 2021-11-15 17:15:42 +11:00
parent ad44239975
commit fb80c73fb3
3 changed files with 17 additions and 154 deletions
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15
compiler/rustc_middle/src/arena.rs
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@ -1,10 +1,5 @@
/// This declares a list of types which can be allocated by `Arena`.
///
/// The `few` modifier will cause allocation to use the shared arena and recording the destructor.
/// This is faster and more memory efficient if there's only a few allocations of the type.
/// Leaving `few` out will cause the type to get its own dedicated `TypedArena` which is
/// faster and more memory efficient if there is lots of allocations.
///
/// Specifying the `decode` modifier will add decode impls for `&T` and `&[T]` where `T` is the type
/// listed. These impls will appear in the implement_ty_decoder! macro.
#[macro_export]
@ -37,7 +32,7 @@ macro_rules! arena_types {
[decode] code_region: rustc_middle::mir::coverage::CodeRegion,
[] const_allocs: rustc_middle::mir::interpret::Allocation,
// Required for the incremental on-disk cache
[few] mir_keys: rustc_hir::def_id::DefIdSet,
[] mir_keys: rustc_hir::def_id::DefIdSet,
[] region_scope_tree: rustc_middle::middle::region::ScopeTree,
[] dropck_outlives:
rustc_middle::infer::canonical::Canonical<'tcx,
@ -77,10 +72,10 @@ macro_rules! arena_types {
rustc_middle::infer::canonical::Canonical<'tcx,
rustc_middle::infer::canonical::QueryResponse<'tcx, rustc_middle::ty::Ty<'tcx>>
>,
[few] all_traits: Vec<rustc_hir::def_id::DefId>,
[few] privacy_access_levels: rustc_middle::middle::privacy::AccessLevels,
[few] foreign_module: rustc_session::cstore::ForeignModule,
[few] foreign_modules: Vec<rustc_session::cstore::ForeignModule>,
[] all_traits: Vec<rustc_hir::def_id::DefId>,
[] privacy_access_levels: rustc_middle::middle::privacy::AccessLevels,
[] foreign_module: rustc_session::cstore::ForeignModule,
[] foreign_modules: Vec<rustc_session::cstore::ForeignModule>,
[] upvars_mentioned: rustc_data_structures::fx::FxIndexMap<rustc_hir::HirId, rustc_hir::Upvar>,
[] object_safety_violations: rustc_middle::traits::ObjectSafetyViolation,
[] codegen_unit: rustc_middle::mir::mono::CodegenUnit<$tcx>,