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Auto merge of #119977 - Mark-Simulacrum:defid-cache, r=cjgillot

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Cache local DefId-keyed queries without hashing

This caches local DefId-keyed queries using just an IndexVec. This costs ~5% extra max-rss at most but brings significant runtime improvement, up to 13% cycle counts (mean: 4%) on primary benchmarks. It's possible that further tweaks could reduce the memory overhead further but this win seems worth landing despite the increased memory, particularly with regards to eliminating the present set in non-incr or storing it inline (skip list?) with the main data.

We tried applying this scheme to all keys in the [first perf run] but found that it carried a significant memory hit (50%). instructions/cycle counts were also much more mixed, though that may have been due to the lack of the present set optimization (needed for fast iter() calls in incremental scenarios).

Closes https://github.com/rust-lang/rust/issues/45275

[first perf run]: https://perf.rust-lang.org/compare.html?start=30dfb9e046aeb878db04332c74de76e52fb7db10&end=6235575300d8e6e2cc6f449cb9048722ef43f9c7&stat=instructions:u
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bors 2024-01-16 21:58:10 +00:00
commit 098d4fd74c
3 changed files with 82 additions and 3 deletions
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3
compiler/rustc_middle/src/query/keys.rs
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@ -9,6 +9,7 @@ use crate::ty::{self, Ty, TyCtxt};
use crate::ty::{GenericArg, GenericArgsRef};
use rustc_hir::def_id::{CrateNum, DefId, LocalDefId, LocalModDefId, ModDefId, LOCAL_CRATE};
use rustc_hir::hir_id::{HirId, OwnerId};
use rustc_query_system::query::DefIdCacheSelector;
use rustc_query_system::query::{DefaultCacheSelector, SingleCacheSelector, VecCacheSelector};
use rustc_span::symbol::{Ident, Symbol};
use rustc_span::{Span, DUMMY_SP};
@ -152,7 +153,7 @@ impl Key for LocalDefId {
}
impl Key for DefId {
type CacheSelector = DefaultCacheSelector<Self>;
type CacheSelector = DefIdCacheSelector;
fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
tcx.def_span(*self)