diff options
| -rw-r--r-- | compiler/rustc_middle/src/traits/solve.rs | 14 | ||||
| -rw-r--r-- | compiler/rustc_type_ir/src/solve/mod.rs | 8 |
2 files changed, 22 insertions, 0 deletions
diff --git a/compiler/rustc_middle/src/traits/solve.rs b/compiler/rustc_middle/src/traits/solve.rs index 145561b76c4..ef5223de0e8 100644 --- a/compiler/rustc_middle/src/traits/solve.rs +++ b/compiler/rustc_middle/src/traits/solve.rs @@ -49,6 +49,13 @@ impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for ExternalConstraints<'tcx> { self, folder: &mut F, ) -> Result<Self, F::Error> { + // Perf testing has found that this check is slightly faster than + // folding and re-interning an empty `ExternalConstraintsData`. + // See: <https://github.com/rust-lang/rust/pull/142430>. + if self.is_empty() { + return Ok(self); + } + Ok(FallibleTypeFolder::cx(folder).mk_external_constraints(ExternalConstraintsData { region_constraints: self.region_constraints.clone().try_fold_with(folder)?, opaque_types: self @@ -64,6 +71,13 @@ impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for ExternalConstraints<'tcx> { } fn fold_with<F: TypeFolder<TyCtxt<'tcx>>>(self, folder: &mut F) -> Self { + // Perf testing has found that this check is slightly faster than + // folding and re-interning an empty `ExternalConstraintsData`. + // See: <https://github.com/rust-lang/rust/pull/142430>. + if self.is_empty() { + return self; + } + TypeFolder::cx(folder).mk_external_constraints(ExternalConstraintsData { region_constraints: self.region_constraints.clone().fold_with(folder), opaque_types: self.opaque_types.iter().map(|opaque| opaque.fold_with(folder)).collect(), diff --git a/compiler/rustc_type_ir/src/solve/mod.rs b/compiler/rustc_type_ir/src/solve/mod.rs index 2e05c23a645..ba777c7c59a 100644 --- a/compiler/rustc_type_ir/src/solve/mod.rs +++ b/compiler/rustc_type_ir/src/solve/mod.rs @@ -236,6 +236,14 @@ pub struct ExternalConstraintsData<I: Interner> { pub normalization_nested_goals: NestedNormalizationGoals<I>, } +impl<I: Interner> ExternalConstraintsData<I> { + pub fn is_empty(&self) -> bool { + self.region_constraints.is_empty() + && self.opaque_types.is_empty() + && self.normalization_nested_goals.is_empty() + } +} + #[derive_where(Clone, Hash, PartialEq, Eq, Debug, Default; I: Interner)] #[derive(TypeVisitable_Generic, TypeFoldable_Generic)] #[cfg_attr(feature = "nightly", derive(HashStable_NoContext))] |