diff options
| -rw-r--r-- | compiler/rustc_middle/src/ty/instance.rs | 19 |
1 files changed, 16 insertions, 3 deletions
diff --git a/compiler/rustc_middle/src/ty/instance.rs b/compiler/rustc_middle/src/ty/instance.rs index ae54411d788..c50a98e88fd 100644 --- a/compiler/rustc_middle/src/ty/instance.rs +++ b/compiler/rustc_middle/src/ty/instance.rs @@ -5,6 +5,7 @@ use crate::ty::{ self, EarlyBinder, GenericArgs, GenericArgsRef, Ty, TyCtxt, TypeFoldable, TypeSuperFoldable, TypeSuperVisitable, TypeVisitable, TypeVisitableExt, TypeVisitor, }; +use rustc_data_structures::fx::FxHashMap; use rustc_errors::ErrorGuaranteed; use rustc_hir as hir; use rustc_hir::def::Namespace; @@ -388,13 +389,25 @@ impl<'tcx> InstanceKind<'tcx> { } fn type_length<'tcx>(item: impl TypeVisitable<TyCtxt<'tcx>>) -> usize { - struct Visitor { + struct Visitor<'tcx> { type_length: usize, + cache: FxHashMap<Ty<'tcx>, usize>, } - impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for Visitor { + impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for Visitor<'tcx> { fn visit_ty(&mut self, t: Ty<'tcx>) { + if let Some(&value) = self.cache.get(&t) { + self.type_length += value; + return; + } + + let prev = self.type_length; self.type_length += 1; t.super_visit_with(self); + + // We don't try to use the cache if the type is fairly small. + if self.type_length > 16 { + self.cache.insert(t, self.type_length - prev); + } } fn visit_const(&mut self, ct: ty::Const<'tcx>) { @@ -402,7 +415,7 @@ fn type_length<'tcx>(item: impl TypeVisitable<TyCtxt<'tcx>>) -> usize { ct.super_visit_with(self); } } - let mut visitor = Visitor { type_length: 0 }; + let mut visitor = Visitor { type_length: 0, cache: Default::default() }; item.visit_with(&mut visitor); visitor.type_length |