diff options
| -rw-r--r-- | compiler/rustc_trait_selection/src/traits/select/mod.rs | 24 |
1 files changed, 9 insertions, 15 deletions
diff --git a/compiler/rustc_trait_selection/src/traits/select/mod.rs b/compiler/rustc_trait_selection/src/traits/select/mod.rs index d2d75d2aa4c..6bb53418bea 100644 --- a/compiler/rustc_trait_selection/src/traits/select/mod.rs +++ b/compiler/rustc_trait_selection/src/traits/select/mod.rs @@ -2,12 +2,6 @@ //! //! [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/traits/resolution.html#selection -// FIXME: The `map` field in ProvisionalEvaluationCache should be changed to -// a `FxIndexMap` to avoid query instability, but right now it causes a perf regression. This would be -// fixed or at least lightened by the addition of the `drain_filter` method to `FxIndexMap` -// Relevant: https://github.com/rust-lang/rust/pull/103723 and https://github.com/bluss/indexmap/issues/242 -#![allow(rustc::potential_query_instability)] - use self::EvaluationResult::*; use self::SelectionCandidate::*; @@ -32,8 +26,7 @@ use crate::traits::project::ProjectAndUnifyResult; use crate::traits::project::ProjectionCacheKeyExt; use crate::traits::ProjectionCacheKey; use crate::traits::Unimplemented; -use rustc_data_structures::fx::FxHashMap; -use rustc_data_structures::fx::{FxHashSet, FxIndexSet}; +use rustc_data_structures::fx::{FxHashSet, FxIndexMap, FxIndexSet}; use rustc_data_structures::stack::ensure_sufficient_stack; use rustc_errors::Diagnostic; use rustc_hir as hir; @@ -2782,7 +2775,7 @@ struct ProvisionalEvaluationCache<'tcx> { /// - then we determine that `E` is in error -- we will then clear /// all cache values whose DFN is >= 4 -- in this case, that /// means the cached value for `F`. - map: RefCell<FxHashMap<ty::PolyTraitPredicate<'tcx>, ProvisionalEvaluation>>, + map: RefCell<FxIndexMap<ty::PolyTraitPredicate<'tcx>, ProvisionalEvaluation>>, /// The stack of args that we assume to be true because a `WF(arg)` predicate /// is on the stack above (and because of wellformedness is coinductive). @@ -2930,12 +2923,13 @@ impl<'tcx> ProvisionalEvaluationCache<'tcx> { /// have a performance impact in practice. fn on_completion(&self, dfn: usize) { debug!(?dfn, "on_completion"); - - for (fresh_trait_pred, eval) in - self.map.borrow_mut().drain_filter(|_k, eval| eval.from_dfn >= dfn) - { - debug!(?fresh_trait_pred, ?eval, "on_completion"); - } + self.map.borrow_mut().retain(|fresh_trait_pred, eval| { + if eval.from_dfn >= dfn { + debug!(?fresh_trait_pred, ?eval, "on_completion"); + return false; + } + true + }); } } |