e3175c34b4
create a "provisional cache" to restore performance in the case of cycles Introduce a "provisional cache" that caches the results of auto trait resolutions but keeps them from entering the *main* cache until everything is ready. This turned out a bit more complex than I hoped, but I don't see another short term fix -- happy to take suggestions! In the meantime, it's very clear we need to rework the trait solver. This resolves the extreme performance slowdown experienced in #60846 -- I plan to add a perf.rust-lang.org regression test to track this. Caveat: I've not run `x.py test` in full yet. r? @pnkfelix cc @arielb1 Fixes #60846
36 lines
1.0 KiB
Rust
36 lines
1.0 KiB
Rust
use rustc::traits::query::CanonicalPredicateGoal;
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use rustc::traits::{
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EvaluationResult, Obligation, ObligationCause, OverflowError, SelectionContext, TraitQueryMode,
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};
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use rustc::ty::query::Providers;
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use rustc::ty::{ParamEnvAnd, TyCtxt};
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use syntax::source_map::DUMMY_SP;
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crate fn provide(p: &mut Providers<'_>) {
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*p = Providers {
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evaluate_obligation,
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..*p
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};
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}
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fn evaluate_obligation<'tcx>(
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tcx: TyCtxt<'tcx>,
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canonical_goal: CanonicalPredicateGoal<'tcx>,
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) -> Result<EvaluationResult, OverflowError> {
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tcx.infer_ctxt().enter_with_canonical(
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DUMMY_SP,
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&canonical_goal,
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|ref infcx, goal, _canonical_inference_vars| {
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let ParamEnvAnd {
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param_env,
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value: predicate,
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} = goal;
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let mut selcx = SelectionContext::with_query_mode(&infcx, TraitQueryMode::Canonical);
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let obligation = Obligation::new(ObligationCause::dummy(), param_env, predicate);
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selcx.evaluate_root_obligation(&obligation)
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},
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)
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}
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