From 72d17bfebbf5463dac1a7eb71c513b151b523e1f Mon Sep 17 00:00:00 2001 From: David Wood Date: Tue, 18 Mar 2025 03:06:17 +0000 Subject: re-use sized fast path There's an existing fast path for the `type_op_prove_predicate` predicate, checking for trivially `Sized` types, which can be re-used when evaluating obligations within queries. This should improve performance, particularly in anticipation of new sizedness traits being added which can take advantage of this. --- compiler/rustc_traits/src/codegen.rs | 11 +++++++++-- compiler/rustc_traits/src/evaluate_obligation.rs | 5 +++++ 2 files changed, 14 insertions(+), 2 deletions(-) (limited to 'compiler/rustc_traits/src') diff --git a/compiler/rustc_traits/src/codegen.rs b/compiler/rustc_traits/src/codegen.rs index 4a889abfc28..88f02d16c7d 100644 --- a/compiler/rustc_traits/src/codegen.rs +++ b/compiler/rustc_traits/src/codegen.rs @@ -6,11 +6,11 @@ use rustc_infer::infer::TyCtxtInferExt; use rustc_middle::bug; use rustc_middle::traits::CodegenObligationError; -use rustc_middle::ty::{self, PseudoCanonicalInput, TyCtxt, TypeVisitableExt}; +use rustc_middle::ty::{self, PseudoCanonicalInput, TyCtxt, TypeVisitableExt, Upcast}; use rustc_trait_selection::error_reporting::InferCtxtErrorExt; use rustc_trait_selection::traits::{ ImplSource, Obligation, ObligationCause, ObligationCtxt, ScrubbedTraitError, SelectionContext, - Unimplemented, + Unimplemented, sizedness_fast_path, }; use tracing::debug; @@ -34,6 +34,13 @@ pub(crate) fn codegen_select_candidate<'tcx>( let (infcx, param_env) = tcx.infer_ctxt().ignoring_regions().build_with_typing_env(typing_env); let mut selcx = SelectionContext::new(&infcx); + if sizedness_fast_path(tcx, trait_ref.upcast(tcx)) { + return Ok(&*tcx.arena.alloc(ImplSource::Builtin( + ty::solve::BuiltinImplSource::Trivial, + Default::default(), + ))); + } + let obligation_cause = ObligationCause::dummy(); let obligation = Obligation::new(tcx, obligation_cause, param_env, trait_ref); diff --git a/compiler/rustc_traits/src/evaluate_obligation.rs b/compiler/rustc_traits/src/evaluate_obligation.rs index c9ad096c6e9..7771db855d7 100644 --- a/compiler/rustc_traits/src/evaluate_obligation.rs +++ b/compiler/rustc_traits/src/evaluate_obligation.rs @@ -5,6 +5,7 @@ use rustc_span::DUMMY_SP; use rustc_trait_selection::traits::query::CanonicalPredicateGoal; use rustc_trait_selection::traits::{ EvaluationResult, Obligation, ObligationCause, OverflowError, SelectionContext, TraitQueryMode, + sizedness_fast_path, }; use tracing::debug; @@ -23,6 +24,10 @@ fn evaluate_obligation<'tcx>( debug!("evaluate_obligation: goal={:#?}", goal); let ParamEnvAnd { param_env, value: predicate } = goal; + if sizedness_fast_path(tcx, predicate) { + return Ok(EvaluationResult::EvaluatedToOk); + } + let mut selcx = SelectionContext::with_query_mode(infcx, TraitQueryMode::Canonical); let obligation = Obligation::new(tcx, ObligationCause::dummy(), param_env, predicate); -- cgit 1.4.1-3-g733a5