From 15ac6983930a0d49b921c0330dbbb5a4f8f1d34a Mon Sep 17 00:00:00 2001 From: lcnr Date: Mon, 30 Sep 2024 10:18:27 +0200 Subject: [PATCH 1/4] canonicalizer: rm region uniquification, add caching --- .../src/canonicalizer.rs | 247 ++++++++++-------- 1 file changed, 138 insertions(+), 109 deletions(-) diff --git a/compiler/rustc_next_trait_solver/src/canonicalizer.rs b/compiler/rustc_next_trait_solver/src/canonicalizer.rs index 196ddeb244302..5c3c35b7b3e46 100644 --- a/compiler/rustc_next_trait_solver/src/canonicalizer.rs +++ b/compiler/rustc_next_trait_solver/src/canonicalizer.rs @@ -1,5 +1,6 @@ use std::cmp::Ordering; +use rustc_type_ir::data_structures::HashMap; use rustc_type_ir::fold::{TypeFoldable, TypeFolder, TypeSuperFoldable}; use rustc_type_ir::inherent::*; use rustc_type_ir::visit::TypeVisitableExt; @@ -44,8 +45,15 @@ pub struct Canonicalizer<'a, D: SolverDelegate, I: Interner> { canonicalize_mode: CanonicalizeMode, variables: &'a mut Vec, + variable_lookup_table: HashMap, + primitive_var_infos: Vec>, binder_index: ty::DebruijnIndex, + + /// We only use the debruijn index during lookup as all other fields + /// should not be impacted by whether a type is folded once or multiple + /// times. + cache: HashMap<(ty::DebruijnIndex, I::Ty), I::Ty>, } impl<'a, D: SolverDelegate, I: Interner> Canonicalizer<'a, D, I> { @@ -60,12 +68,14 @@ impl<'a, D: SolverDelegate, I: Interner> Canonicalizer<'a, D, I> { canonicalize_mode, variables, + variable_lookup_table: Default::default(), primitive_var_infos: Vec::new(), binder_index: ty::INNERMOST, + + cache: Default::default(), }; let value = value.fold_with(&mut canonicalizer); - // FIXME: Restore these assertions. Should we uplift type flags? assert!(!value.has_infer(), "unexpected infer in {value:?}"); assert!(!value.has_placeholders(), "unexpected placeholders in {value:?}"); @@ -75,6 +85,37 @@ impl<'a, D: SolverDelegate, I: Interner> Canonicalizer<'a, D, I> { Canonical { defining_opaque_types, max_universe, variables, value } } + fn get_or_insert_bound_var( + &mut self, + arg: impl Into, + canonical_var_info: CanonicalVarInfo, + ) -> ty::BoundVar { + // FIXME: 16 is made up and arbitrary. We should look at some + // perf data here. + let arg = arg.into(); + let idx = if self.variables.len() > 16 { + if self.variable_lookup_table.is_empty() { + self.variable_lookup_table.extend(self.variables.iter().copied().zip(0..)); + } + + *self.variable_lookup_table.entry(arg).or_insert_with(|| { + let var = self.variables.len(); + self.variables.push(arg); + self.primitive_var_infos.push(canonical_var_info); + var + }) + } else { + self.variables.iter().position(|&v| v == arg).unwrap_or_else(|| { + let var = self.variables.len(); + self.variables.push(arg); + self.primitive_var_infos.push(canonical_var_info); + var + }) + }; + + ty::BoundVar::from(idx) + } + fn finalize(self) -> (ty::UniverseIndex, I::CanonicalVars) { let mut var_infos = self.primitive_var_infos; // See the rustc-dev-guide section about how we deal with universes @@ -124,8 +165,8 @@ impl<'a, D: SolverDelegate, I: Interner> Canonicalizer<'a, D, I> { // - var_infos: [E0, U1, E2, U1, E1, E6, U6], curr_compressed_uv: 2, next_orig_uv: 6 // - var_infos: [E0, U1, E1, U1, E1, E3, U3], curr_compressed_uv: 2, next_orig_uv: - // - // This algorithm runs in `O(n²)` where `n` is the number of different universe - // indices in the input. This should be fine as `n` is expected to be small. + // This algorithm runs in `O(mn)` where `n` is the number of different universes and + // `m` the number of variables. This should be fine as both are expected to be small. let mut curr_compressed_uv = ty::UniverseIndex::ROOT; let mut existential_in_new_uv = None; let mut next_orig_uv = Some(ty::UniverseIndex::ROOT); @@ -185,14 +226,16 @@ impl<'a, D: SolverDelegate, I: Interner> Canonicalizer<'a, D, I> { for var in var_infos.iter_mut() { // We simply put all regions from the input into the highest // compressed universe, so we only deal with them at the end. - if !var.is_region() && is_existential == var.is_existential() { - update_uv(var, orig_uv, is_existential) + if !var.is_region() { + if is_existential == var.is_existential() { + update_uv(var, orig_uv, is_existential) + } } } } } - // We uniquify regions and always put them into their own universe + // We put all regions into a separate universe. let mut first_region = true; for var in var_infos.iter_mut() { if var.is_region() { @@ -208,93 +251,8 @@ impl<'a, D: SolverDelegate, I: Interner> Canonicalizer<'a, D, I> { let var_infos = self.delegate.cx().mk_canonical_var_infos(&var_infos); (curr_compressed_uv, var_infos) } -} - -impl, I: Interner> TypeFolder for Canonicalizer<'_, D, I> { - fn cx(&self) -> I { - self.delegate.cx() - } - - fn fold_binder(&mut self, t: ty::Binder) -> ty::Binder - where - T: TypeFoldable, - { - self.binder_index.shift_in(1); - let t = t.super_fold_with(self); - self.binder_index.shift_out(1); - t - } - - fn fold_region(&mut self, r: I::Region) -> I::Region { - let kind = match r.kind() { - ty::ReBound(..) => return r, - - // We may encounter `ReStatic` in item signatures or the hidden type - // of an opaque. `ReErased` should only be encountered in the hidden - // type of an opaque for regions that are ignored for the purposes of - // captures. - // - // FIXME: We should investigate the perf implications of not uniquifying - // `ReErased`. We may be able to short-circuit registering region - // obligations if we encounter a `ReErased` on one side, for example. - ty::ReStatic | ty::ReErased | ty::ReError(_) => match self.canonicalize_mode { - CanonicalizeMode::Input => CanonicalVarKind::Region(ty::UniverseIndex::ROOT), - CanonicalizeMode::Response { .. } => return r, - }, - - ty::ReEarlyParam(_) | ty::ReLateParam(_) => match self.canonicalize_mode { - CanonicalizeMode::Input => CanonicalVarKind::Region(ty::UniverseIndex::ROOT), - CanonicalizeMode::Response { .. } => { - panic!("unexpected region in response: {r:?}") - } - }, - - ty::RePlaceholder(placeholder) => match self.canonicalize_mode { - // We canonicalize placeholder regions as existentials in query inputs. - CanonicalizeMode::Input => CanonicalVarKind::Region(ty::UniverseIndex::ROOT), - CanonicalizeMode::Response { max_input_universe } => { - // If we have a placeholder region inside of a query, it must be from - // a new universe. - if max_input_universe.can_name(placeholder.universe()) { - panic!("new placeholder in universe {max_input_universe:?}: {r:?}"); - } - CanonicalVarKind::PlaceholderRegion(placeholder) - } - }, - - ty::ReVar(vid) => { - assert_eq!( - self.delegate.opportunistic_resolve_lt_var(vid), - r, - "region vid should have been resolved fully before canonicalization" - ); - match self.canonicalize_mode { - CanonicalizeMode::Input => CanonicalVarKind::Region(ty::UniverseIndex::ROOT), - CanonicalizeMode::Response { .. } => { - CanonicalVarKind::Region(self.delegate.universe_of_lt(vid).unwrap()) - } - } - } - }; - - let existing_bound_var = match self.canonicalize_mode { - CanonicalizeMode::Input => None, - CanonicalizeMode::Response { .. } => { - self.variables.iter().position(|&v| v == r.into()).map(ty::BoundVar::from) - } - }; - - let var = existing_bound_var.unwrap_or_else(|| { - let var = ty::BoundVar::from(self.variables.len()); - self.variables.push(r.into()); - self.primitive_var_infos.push(CanonicalVarInfo { kind }); - var - }); - Region::new_anon_bound(self.cx(), self.binder_index, var) - } - - fn fold_ty(&mut self, t: I::Ty) -> I::Ty { + fn cached_fold_ty(&mut self, t: I::Ty) -> I::Ty { let kind = match t.kind() { ty::Infer(i) => match i { ty::TyVar(vid) => { @@ -368,20 +326,98 @@ impl, I: Interner> TypeFolder for Canonicaliz | ty::Tuple(_) | ty::Alias(_, _) | ty::Bound(_, _) - | ty::Error(_) => return t.super_fold_with(self), + | ty::Error(_) => { + return t.super_fold_with(self); + } }; - let var = ty::BoundVar::from( - self.variables.iter().position(|&v| v == t.into()).unwrap_or_else(|| { - let var = self.variables.len(); - self.variables.push(t.into()); - self.primitive_var_infos.push(CanonicalVarInfo { kind }); - var - }), - ); + let var = self.get_or_insert_bound_var(t, CanonicalVarInfo { kind }); Ty::new_anon_bound(self.cx(), self.binder_index, var) } +} + +impl, I: Interner> TypeFolder for Canonicalizer<'_, D, I> { + fn cx(&self) -> I { + self.delegate.cx() + } + + fn fold_binder(&mut self, t: ty::Binder) -> ty::Binder + where + T: TypeFoldable, + { + self.binder_index.shift_in(1); + let t = t.super_fold_with(self); + self.binder_index.shift_out(1); + t + } + + fn fold_region(&mut self, r: I::Region) -> I::Region { + let kind = match r.kind() { + ty::ReBound(..) => return r, + + // We may encounter `ReStatic` in item signatures or the hidden type + // of an opaque. `ReErased` should only be encountered in the hidden + // type of an opaque for regions that are ignored for the purposes of + // captures. + // + // FIXME: We should investigate the perf implications of not uniquifying + // `ReErased`. We may be able to short-circuit registering region + // obligations if we encounter a `ReErased` on one side, for example. + ty::ReStatic | ty::ReErased | ty::ReError(_) => match self.canonicalize_mode { + CanonicalizeMode::Input => CanonicalVarKind::Region(ty::UniverseIndex::ROOT), + CanonicalizeMode::Response { .. } => return r, + }, + + ty::ReEarlyParam(_) | ty::ReLateParam(_) => match self.canonicalize_mode { + CanonicalizeMode::Input => CanonicalVarKind::Region(ty::UniverseIndex::ROOT), + CanonicalizeMode::Response { .. } => { + panic!("unexpected region in response: {r:?}") + } + }, + + ty::RePlaceholder(placeholder) => match self.canonicalize_mode { + // We canonicalize placeholder regions as existentials in query inputs. + CanonicalizeMode::Input => CanonicalVarKind::Region(ty::UniverseIndex::ROOT), + CanonicalizeMode::Response { max_input_universe } => { + // If we have a placeholder region inside of a query, it must be from + // a new universe. + if max_input_universe.can_name(placeholder.universe()) { + panic!("new placeholder in universe {max_input_universe:?}: {r:?}"); + } + CanonicalVarKind::PlaceholderRegion(placeholder) + } + }, + + ty::ReVar(vid) => { + assert_eq!( + self.delegate.opportunistic_resolve_lt_var(vid), + r, + "region vid should have been resolved fully before canonicalization" + ); + match self.canonicalize_mode { + CanonicalizeMode::Input => CanonicalVarKind::Region(ty::UniverseIndex::ROOT), + CanonicalizeMode::Response { .. } => { + CanonicalVarKind::Region(self.delegate.universe_of_lt(vid).unwrap()) + } + } + } + }; + + let var = self.get_or_insert_bound_var(r, CanonicalVarInfo { kind }); + + Region::new_anon_bound(self.cx(), self.binder_index, var) + } + + fn fold_ty(&mut self, t: I::Ty) -> I::Ty { + if let Some(&ty) = self.cache.get(&(self.binder_index, t)) { + ty + } else { + let res = self.cached_fold_ty(t); + assert!(self.cache.insert((self.binder_index, t), res).is_none()); + res + } + } fn fold_const(&mut self, c: I::Const) -> I::Const { let kind = match c.kind() { @@ -419,14 +455,7 @@ impl, I: Interner> TypeFolder for Canonicaliz | ty::ConstKind::Expr(_) => return c.super_fold_with(self), }; - let var = ty::BoundVar::from( - self.variables.iter().position(|&v| v == c.into()).unwrap_or_else(|| { - let var = self.variables.len(); - self.variables.push(c.into()); - self.primitive_var_infos.push(CanonicalVarInfo { kind }); - var - }), - ); + let var = self.get_or_insert_bound_var(c, CanonicalVarInfo { kind }); Const::new_anon_bound(self.cx(), self.binder_index, var) } From 13881f5404037e25a88d0b79a836e232dc73b1fc Mon Sep 17 00:00:00 2001 From: lcnr Date: Mon, 30 Sep 2024 10:18:55 +0200 Subject: [PATCH 2/4] add caches to multiple type folders --- .../rustc_infer/src/infer/relate/combine.rs | 7 +- .../src/infer/relate/type_relating.rs | 41 ++++++++- compiler/rustc_infer/src/infer/resolve.rs | 14 ++- compiler/rustc_middle/src/ty/fold.rs | 25 ++++- .../rustc_next_trait_solver/src/resolve.rs | 11 ++- .../src/solve/eval_ctxt/mod.rs | 51 +++++++--- .../src/data_structures/delayed_map.rs | 92 +++++++++++++++++++ .../mod.rs} | 3 + 8 files changed, 222 insertions(+), 22 deletions(-) create mode 100644 compiler/rustc_type_ir/src/data_structures/delayed_map.rs rename compiler/rustc_type_ir/src/{data_structures.rs => data_structures/mod.rs} (92%) diff --git a/compiler/rustc_infer/src/infer/relate/combine.rs b/compiler/rustc_infer/src/infer/relate/combine.rs index e75d7b7db1453..3b2ef3fe981e3 100644 --- a/compiler/rustc_infer/src/infer/relate/combine.rs +++ b/compiler/rustc_infer/src/infer/relate/combine.rs @@ -36,10 +36,15 @@ use crate::traits::{Obligation, PredicateObligation}; #[derive(Clone)] pub struct CombineFields<'infcx, 'tcx> { pub infcx: &'infcx InferCtxt<'tcx>, + // Immutable fields pub trace: TypeTrace<'tcx>, pub param_env: ty::ParamEnv<'tcx>, - pub goals: Vec>>, pub define_opaque_types: DefineOpaqueTypes, + // Mutable fields + // + // Adding any additional field likely requires + // changes to the cache of `TypeRelating`. + pub goals: Vec>>, } impl<'infcx, 'tcx> CombineFields<'infcx, 'tcx> { diff --git a/compiler/rustc_infer/src/infer/relate/type_relating.rs b/compiler/rustc_infer/src/infer/relate/type_relating.rs index a402a8009ff8d..c8ced4a2cda85 100644 --- a/compiler/rustc_infer/src/infer/relate/type_relating.rs +++ b/compiler/rustc_infer/src/infer/relate/type_relating.rs @@ -4,6 +4,7 @@ use rustc_middle::ty::relate::{ }; use rustc_middle::ty::{self, Ty, TyCtxt, TyVar}; use rustc_span::Span; +use rustc_type_ir::data_structures::DelayedSet; use tracing::{debug, instrument}; use super::combine::CombineFields; @@ -13,9 +14,36 @@ use crate::infer::{DefineOpaqueTypes, InferCtxt, SubregionOrigin}; /// Enforce that `a` is equal to or a subtype of `b`. pub struct TypeRelating<'combine, 'a, 'tcx> { + // Partially mutable. fields: &'combine mut CombineFields<'a, 'tcx>, + + // Immutable fields. structurally_relate_aliases: StructurallyRelateAliases, ambient_variance: ty::Variance, + + /// The cache has only tracks the `ambient_variance` as its the + /// only field which is mutable and which meaningfully changes + /// the result when relating types. + /// + /// The cache does not track whether the state of the + /// `InferCtxt` has been changed or whether we've added any + /// obligations to `self.fields.goals`. Whether a goal is added + /// once or multiple times is not really meaningful. + /// + /// Changes in the inference state may delay some type inference to + /// the next fulfillment loop. Given that this loop is already + /// necessary, this is also not a meaningful change. Consider + /// the following three relations: + /// ```text + /// Vec sub Vec + /// ?0 eq u32 + /// Vec sub Vec + /// ``` + /// Without a cache, the second `Vec sub Vec` would eagerly + /// constrain `?1` to `u32`. When using the cache entry from the + /// first time we've related these types, this only happens when + /// later proving the `Subtype(?0, ?1)` goal from the first relation. + cache: DelayedSet<(ty::Variance, Ty<'tcx>, Ty<'tcx>)>, } impl<'combine, 'infcx, 'tcx> TypeRelating<'combine, 'infcx, 'tcx> { @@ -24,7 +52,12 @@ impl<'combine, 'infcx, 'tcx> TypeRelating<'combine, 'infcx, 'tcx> { structurally_relate_aliases: StructurallyRelateAliases, ambient_variance: ty::Variance, ) -> TypeRelating<'combine, 'infcx, 'tcx> { - TypeRelating { fields: f, structurally_relate_aliases, ambient_variance } + TypeRelating { + fields: f, + structurally_relate_aliases, + ambient_variance, + cache: Default::default(), + } } } @@ -78,6 +111,10 @@ impl<'tcx> TypeRelation> for TypeRelating<'_, '_, 'tcx> { let a = infcx.shallow_resolve(a); let b = infcx.shallow_resolve(b); + if self.cache.contains(&(self.ambient_variance, a, b)) { + return Ok(a); + } + match (a.kind(), b.kind()) { (&ty::Infer(TyVar(a_id)), &ty::Infer(TyVar(b_id))) => { match self.ambient_variance { @@ -160,6 +197,8 @@ impl<'tcx> TypeRelation> for TypeRelating<'_, '_, 'tcx> { } } + assert!(self.cache.insert((self.ambient_variance, a, b))); + Ok(a) } diff --git a/compiler/rustc_infer/src/infer/resolve.rs b/compiler/rustc_infer/src/infer/resolve.rs index 34625ffb77879..671a66d504f9d 100644 --- a/compiler/rustc_infer/src/infer/resolve.rs +++ b/compiler/rustc_infer/src/infer/resolve.rs @@ -2,6 +2,7 @@ use rustc_middle::bug; use rustc_middle::ty::fold::{FallibleTypeFolder, TypeFolder, TypeSuperFoldable}; use rustc_middle::ty::visit::TypeVisitableExt; use rustc_middle::ty::{self, Const, InferConst, Ty, TyCtxt, TypeFoldable}; +use rustc_type_ir::data_structures::DelayedMap; use super::{FixupError, FixupResult, InferCtxt}; @@ -15,12 +16,15 @@ use super::{FixupError, FixupResult, InferCtxt}; /// points for correctness. pub struct OpportunisticVarResolver<'a, 'tcx> { infcx: &'a InferCtxt<'tcx>, + /// We're able to use a cache here as the folder does + /// not have any mutable state. + cache: DelayedMap, Ty<'tcx>>, } impl<'a, 'tcx> OpportunisticVarResolver<'a, 'tcx> { #[inline] pub fn new(infcx: &'a InferCtxt<'tcx>) -> Self { - OpportunisticVarResolver { infcx } + OpportunisticVarResolver { infcx, cache: Default::default() } } } @@ -33,9 +37,13 @@ impl<'a, 'tcx> TypeFolder> for OpportunisticVarResolver<'a, 'tcx> { fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> { if !t.has_non_region_infer() { t // micro-optimize -- if there is nothing in this type that this fold affects... + } else if let Some(&ty) = self.cache.get(&t) { + return ty; } else { - let t = self.infcx.shallow_resolve(t); - t.super_fold_with(self) + let shallow = self.infcx.shallow_resolve(t); + let res = shallow.super_fold_with(self); + assert!(self.cache.insert(t, res)); + res } } diff --git a/compiler/rustc_middle/src/ty/fold.rs b/compiler/rustc_middle/src/ty/fold.rs index 2ee7497497aa9..e152d3f5fbe9f 100644 --- a/compiler/rustc_middle/src/ty/fold.rs +++ b/compiler/rustc_middle/src/ty/fold.rs @@ -1,5 +1,6 @@ use rustc_data_structures::fx::FxIndexMap; use rustc_hir::def_id::DefId; +use rustc_type_ir::data_structures::DelayedMap; pub use rustc_type_ir::fold::{ FallibleTypeFolder, TypeFoldable, TypeFolder, TypeSuperFoldable, shift_region, shift_vars, }; @@ -131,12 +132,20 @@ impl<'a, 'tcx> TypeFolder> for RegionFolder<'a, 'tcx> { /////////////////////////////////////////////////////////////////////////// // Bound vars replacer +/// A delegate used when instantiating bound vars. +/// +/// Any implementation must make sure that each bound variable always +/// gets mapped to the same result. `BoundVarReplacer` caches by using +/// a `DelayedMap` which does not cache the first few types it encounters. pub trait BoundVarReplacerDelegate<'tcx> { fn replace_region(&mut self, br: ty::BoundRegion) -> ty::Region<'tcx>; fn replace_ty(&mut self, bt: ty::BoundTy) -> Ty<'tcx>; fn replace_const(&mut self, bv: ty::BoundVar) -> ty::Const<'tcx>; } +/// A simple delegate taking 3 mutable functions. The used functions must +/// always return the same result for each bound variable, no matter how +/// frequently they are called. pub struct FnMutDelegate<'a, 'tcx> { pub regions: &'a mut (dyn FnMut(ty::BoundRegion) -> ty::Region<'tcx> + 'a), pub types: &'a mut (dyn FnMut(ty::BoundTy) -> Ty<'tcx> + 'a), @@ -164,11 +173,15 @@ struct BoundVarReplacer<'tcx, D> { current_index: ty::DebruijnIndex, delegate: D, + + /// This cache only tracks the `DebruijnIndex` and assumes that it does not matter + /// for the delegate how often its methods get used. + cache: DelayedMap<(ty::DebruijnIndex, Ty<'tcx>), Ty<'tcx>>, } impl<'tcx, D: BoundVarReplacerDelegate<'tcx>> BoundVarReplacer<'tcx, D> { fn new(tcx: TyCtxt<'tcx>, delegate: D) -> Self { - BoundVarReplacer { tcx, current_index: ty::INNERMOST, delegate } + BoundVarReplacer { tcx, current_index: ty::INNERMOST, delegate, cache: Default::default() } } } @@ -197,7 +210,15 @@ where debug_assert!(!ty.has_vars_bound_above(ty::INNERMOST)); ty::fold::shift_vars(self.tcx, ty, self.current_index.as_u32()) } - _ if t.has_vars_bound_at_or_above(self.current_index) => t.super_fold_with(self), + _ if t.has_vars_bound_at_or_above(self.current_index) => { + if let Some(&ty) = self.cache.get(&(self.current_index, t)) { + return ty; + } + + let res = t.super_fold_with(self); + assert!(self.cache.insert((self.current_index, t), res)); + res + } _ => t, } } diff --git a/compiler/rustc_next_trait_solver/src/resolve.rs b/compiler/rustc_next_trait_solver/src/resolve.rs index 132b7400300c5..a37066cec669f 100644 --- a/compiler/rustc_next_trait_solver/src/resolve.rs +++ b/compiler/rustc_next_trait_solver/src/resolve.rs @@ -1,3 +1,4 @@ +use rustc_type_ir::data_structures::DelayedMap; use rustc_type_ir::fold::{TypeFoldable, TypeFolder, TypeSuperFoldable}; use rustc_type_ir::inherent::*; use rustc_type_ir::visit::TypeVisitableExt; @@ -15,11 +16,12 @@ where I: Interner, { delegate: &'a D, + cache: DelayedMap, } impl<'a, D: SolverDelegate> EagerResolver<'a, D> { pub fn new(delegate: &'a D) -> Self { - EagerResolver { delegate } + EagerResolver { delegate, cache: Default::default() } } } @@ -42,7 +44,12 @@ impl, I: Interner> TypeFolder for EagerResolv ty::Infer(ty::FloatVar(vid)) => self.delegate.opportunistic_resolve_float_var(vid), _ => { if t.has_infer() { - t.super_fold_with(self) + if let Some(&ty) = self.cache.get(&t) { + return ty; + } + let res = t.super_fold_with(self); + assert!(self.cache.insert(t, res)); + res } else { t } diff --git a/compiler/rustc_next_trait_solver/src/solve/eval_ctxt/mod.rs b/compiler/rustc_next_trait_solver/src/solve/eval_ctxt/mod.rs index 12ad0724b5cb1..12b4b3cb3a9d8 100644 --- a/compiler/rustc_next_trait_solver/src/solve/eval_ctxt/mod.rs +++ b/compiler/rustc_next_trait_solver/src/solve/eval_ctxt/mod.rs @@ -3,7 +3,7 @@ use std::ops::ControlFlow; use derive_where::derive_where; #[cfg(feature = "nightly")] use rustc_macros::{HashStable_NoContext, TyDecodable, TyEncodable}; -use rustc_type_ir::data_structures::ensure_sufficient_stack; +use rustc_type_ir::data_structures::{HashMap, HashSet, ensure_sufficient_stack}; use rustc_type_ir::fold::{TypeFoldable, TypeFolder, TypeSuperFoldable}; use rustc_type_ir::inherent::*; use rustc_type_ir::relate::Relate; @@ -579,18 +579,16 @@ where #[instrument(level = "trace", skip(self))] pub(super) fn add_normalizes_to_goal(&mut self, mut goal: Goal>) { - goal.predicate = goal - .predicate - .fold_with(&mut ReplaceAliasWithInfer { ecx: self, param_env: goal.param_env }); + goal.predicate = + goal.predicate.fold_with(&mut ReplaceAliasWithInfer::new(self, goal.param_env)); self.inspect.add_normalizes_to_goal(self.delegate, self.max_input_universe, goal); self.nested_goals.normalizes_to_goals.push(goal); } #[instrument(level = "debug", skip(self))] pub(super) fn add_goal(&mut self, source: GoalSource, mut goal: Goal) { - goal.predicate = goal - .predicate - .fold_with(&mut ReplaceAliasWithInfer { ecx: self, param_env: goal.param_env }); + goal.predicate = + goal.predicate.fold_with(&mut ReplaceAliasWithInfer::new(self, goal.param_env)); self.inspect.add_goal(self.delegate, self.max_input_universe, source, goal); self.nested_goals.goals.push((source, goal)); } @@ -654,6 +652,7 @@ where term: I::Term, universe_of_term: ty::UniverseIndex, delegate: &'a D, + cache: HashSet, } impl, I: Interner> ContainsTermOrNotNameable<'_, D, I> { @@ -671,6 +670,10 @@ where { type Result = ControlFlow<()>; fn visit_ty(&mut self, t: I::Ty) -> Self::Result { + if self.cache.contains(&t) { + return ControlFlow::Continue(()); + } + match t.kind() { ty::Infer(ty::TyVar(vid)) => { if let ty::TermKind::Ty(term) = self.term.kind() { @@ -683,17 +686,18 @@ where } } - self.check_nameable(self.delegate.universe_of_ty(vid).unwrap()) + self.check_nameable(self.delegate.universe_of_ty(vid).unwrap())?; } - ty::Placeholder(p) => self.check_nameable(p.universe()), + ty::Placeholder(p) => self.check_nameable(p.universe())?, _ => { if t.has_non_region_infer() || t.has_placeholders() { - t.super_visit_with(self) - } else { - ControlFlow::Continue(()) + t.super_visit_with(self)? } } } + + assert!(self.cache.insert(t)); + ControlFlow::Continue(()) } fn visit_const(&mut self, c: I::Const) -> Self::Result { @@ -728,6 +732,7 @@ where delegate: self.delegate, universe_of_term, term: goal.predicate.term, + cache: Default::default(), }; goal.predicate.alias.visit_with(&mut visitor).is_continue() && goal.param_env.visit_with(&mut visitor).is_continue() @@ -1015,6 +1020,17 @@ where { ecx: &'me mut EvalCtxt<'a, D>, param_env: I::ParamEnv, + cache: HashMap, +} + +impl<'me, 'a, D, I> ReplaceAliasWithInfer<'me, 'a, D, I> +where + D: SolverDelegate, + I: Interner, +{ + fn new(ecx: &'me mut EvalCtxt<'a, D>, param_env: I::ParamEnv) -> Self { + ReplaceAliasWithInfer { ecx, param_env, cache: Default::default() } + } } impl TypeFolder for ReplaceAliasWithInfer<'_, '_, D, I> @@ -1041,7 +1057,16 @@ where ); infer_ty } - _ => ty.super_fold_with(self), + _ if ty.has_aliases() => { + if let Some(&entry) = self.cache.get(&ty) { + return entry; + } + + let res = ty.super_fold_with(self); + assert!(self.cache.insert(ty, res).is_none()); + res + } + _ => ty, } } diff --git a/compiler/rustc_type_ir/src/data_structures/delayed_map.rs b/compiler/rustc_type_ir/src/data_structures/delayed_map.rs new file mode 100644 index 0000000000000..7e7406e37066e --- /dev/null +++ b/compiler/rustc_type_ir/src/data_structures/delayed_map.rs @@ -0,0 +1,92 @@ +use std::hash::Hash; + +use crate::data_structures::{HashMap, HashSet}; + +const CACHE_CUTOFF: u32 = 32; + +/// A hashmap which only starts hashing after ignoring the first few inputs. +/// +/// This is used in type folders as in nearly all cases caching is not worth it +/// as nearly all folded types are tiny. However, there are very rare incredibly +/// large types for which caching is necessary to avoid hangs. +#[derive(Debug)] +pub struct DelayedMap { + cache: HashMap, + count: u32, +} + +impl Default for DelayedMap { + fn default() -> Self { + DelayedMap { cache: Default::default(), count: 0 } + } +} + +impl DelayedMap { + #[inline(always)] + pub fn insert(&mut self, key: K, value: V) -> bool { + if self.count >= CACHE_CUTOFF { + self.cold_insert(key, value) + } else { + self.count += 1; + true + } + } + + #[cold] + #[inline(never)] + fn cold_insert(&mut self, key: K, value: V) -> bool { + self.cache.insert(key, value).is_none() + } + + #[inline(always)] + pub fn get(&self, key: &K) -> Option<&V> { + if self.cache.is_empty() { None } else { self.cold_get(key) } + } + + #[cold] + #[inline(never)] + fn cold_get(&self, key: &K) -> Option<&V> { + self.cache.get(key) + } +} + +#[derive(Debug)] +pub struct DelayedSet { + cache: HashSet, + count: u32, +} + +impl Default for DelayedSet { + fn default() -> Self { + DelayedSet { cache: Default::default(), count: 0 } + } +} + +impl DelayedSet { + #[inline(always)] + pub fn insert(&mut self, value: T) -> bool { + if self.count >= CACHE_CUTOFF { + self.cold_insert(value) + } else { + self.count += 1; + true + } + } + + #[cold] + #[inline(never)] + fn cold_insert(&mut self, value: T) -> bool { + self.cache.insert(value) + } + + #[inline(always)] + pub fn contains(&self, value: &T) -> bool { + !self.cache.is_empty() && self.cold_contains(value) + } + + #[cold] + #[inline(never)] + fn cold_contains(&self, value: &T) -> bool { + self.cache.contains(value) + } +} diff --git a/compiler/rustc_type_ir/src/data_structures.rs b/compiler/rustc_type_ir/src/data_structures/mod.rs similarity index 92% rename from compiler/rustc_type_ir/src/data_structures.rs rename to compiler/rustc_type_ir/src/data_structures/mod.rs index 96036e53b0abb..d9766d91845cb 100644 --- a/compiler/rustc_type_ir/src/data_structures.rs +++ b/compiler/rustc_type_ir/src/data_structures/mod.rs @@ -6,6 +6,8 @@ pub use rustc_hash::{FxHashMap as HashMap, FxHashSet as HashSet}; pub type IndexMap = indexmap::IndexMap>; pub type IndexSet = indexmap::IndexSet>; +mod delayed_map; + #[cfg(feature = "nightly")] mod impl_ { pub use rustc_data_structures::sso::{SsoHashMap, SsoHashSet}; @@ -24,4 +26,5 @@ mod impl_ { } } +pub use delayed_map::{DelayedMap, DelayedSet}; pub use impl_::*; From a7b114420c70a1c0bc082d078d5284af6ff4af23 Mon Sep 17 00:00:00 2001 From: lcnr Date: Mon, 30 Sep 2024 10:19:00 +0200 Subject: [PATCH 3/4] add tests --- .../coherence-alias-hang-with-region.rs | 30 ++++++++++++++++ .../overflow}/coherence-alias-hang.rs | 11 ++++-- .../next-solver/overflow/nalgebra-hang.rs | 35 +++++++++++++++++++ 3 files changed, 74 insertions(+), 2 deletions(-) create mode 100644 tests/ui/traits/next-solver/overflow/coherence-alias-hang-with-region.rs rename tests/ui/traits/{ => next-solver/overflow}/coherence-alias-hang.rs (57%) create mode 100644 tests/ui/traits/next-solver/overflow/nalgebra-hang.rs diff --git a/tests/ui/traits/next-solver/overflow/coherence-alias-hang-with-region.rs b/tests/ui/traits/next-solver/overflow/coherence-alias-hang-with-region.rs new file mode 100644 index 0000000000000..4ade8a13ca914 --- /dev/null +++ b/tests/ui/traits/next-solver/overflow/coherence-alias-hang-with-region.rs @@ -0,0 +1,30 @@ +//@ check-pass +//@ revisions: ai ia ii +//@ compile-flags: -Znext-solver=coherence + +// Regression test for nalgebra hang . + +#![feature(lazy_type_alias)] +#![allow(incomplete_features)] + +type Id = T; +trait NotImplemented {} + +struct W<'a, T: ?Sized, U: ?Sized>(&'a (), *const T, *const U); +trait Trait { + type Assoc: ?Sized; +} +impl<'a, T: ?Sized + Trait> Trait for W<'a, T, T> { + #[cfg(ai)] + type Assoc = W<'a, T::Assoc, Id>; + #[cfg(ia)] + type Assoc = W<'a, Id, T::Assoc>; + #[cfg(ii)] + type Assoc = W<'a, Id, Id>; +} + +trait Overlap {} +impl<'a, T: ?Sized> Overlap for W<'a, T, T> {} +impl Overlap for T {} + +fn main() {} diff --git a/tests/ui/traits/coherence-alias-hang.rs b/tests/ui/traits/next-solver/overflow/coherence-alias-hang.rs similarity index 57% rename from tests/ui/traits/coherence-alias-hang.rs rename to tests/ui/traits/next-solver/overflow/coherence-alias-hang.rs index c2b4d2e42d214..0d5f42231e4ad 100644 --- a/tests/ui/traits/coherence-alias-hang.rs +++ b/tests/ui/traits/next-solver/overflow/coherence-alias-hang.rs @@ -1,6 +1,8 @@ //@ check-pass -//@ revisions: current next -//[next]@ compile-flags: -Znext-solver +//@ revisions: ai_current ai_next ia_current ia_next ii_current ii_next +//@[ai_next] compile-flags: -Znext-solver +//@[ia_next] compile-flags: -Znext-solver +//@[ii_next] compile-flags: -Znext-solver // Regression test for nalgebra hang . @@ -15,7 +17,12 @@ trait Trait { type Assoc: ?Sized; } impl Trait for W { + #[cfg(any(ai_current, ai_next))] type Assoc = W>; + #[cfg(any(ia_current, ia_next))] + type Assoc = W, T::Assoc>; + #[cfg(any(ii_current, ii_next))] + type Assoc = W, Id>; } trait Overlap {} diff --git a/tests/ui/traits/next-solver/overflow/nalgebra-hang.rs b/tests/ui/traits/next-solver/overflow/nalgebra-hang.rs new file mode 100644 index 0000000000000..4bc6039c57dfd --- /dev/null +++ b/tests/ui/traits/next-solver/overflow/nalgebra-hang.rs @@ -0,0 +1,35 @@ +//@ check-pass +//@ revisions: current next +//@[next] compile-flags: -Znext-solver + +// Regression test for nalgebra hang from +// https://github.com/rust-lang/rust/pull/130654#issuecomment-2365465354 +trait HasAlias {} + +struct Dummy; +trait DummyTrait { + type DummyType; +} +impl DummyTrait for Dummy { + type DummyType = T; +} +type AliasOf = ::DummyType; + +struct Matrix(T, S); +type OMatrix = Matrix>; + +impl HasAlias for OMatrix {} + +trait SimdValue { + type Element; +} +impl> SimdValue for OMatrix { + type Element = OMatrix; +} + +trait Unimplemented {} +pub trait MyFrom {} +impl MyFrom for T {} +impl> MyFrom for OMatrix {} + +fn main() {} From 1a04a317c447210306396e5ad4a100f423b1dfa6 Mon Sep 17 00:00:00 2001 From: lcnr Date: Wed, 2 Oct 2024 14:39:43 +0200 Subject: [PATCH 4/4] review --- .../src/infer/relate/type_relating.rs | 8 +++++--- compiler/rustc_middle/src/ty/fold.rs | 17 +++++++++-------- .../src/canonicalizer.rs | 12 +++++++----- compiler/rustc_next_trait_solver/src/resolve.rs | 2 ++ .../src/solve/eval_ctxt/mod.rs | 15 ++++++++------- 5 files changed, 31 insertions(+), 23 deletions(-) diff --git a/compiler/rustc_infer/src/infer/relate/type_relating.rs b/compiler/rustc_infer/src/infer/relate/type_relating.rs index c8ced4a2cda85..7acfea643dd1e 100644 --- a/compiler/rustc_infer/src/infer/relate/type_relating.rs +++ b/compiler/rustc_infer/src/infer/relate/type_relating.rs @@ -14,14 +14,16 @@ use crate::infer::{DefineOpaqueTypes, InferCtxt, SubregionOrigin}; /// Enforce that `a` is equal to or a subtype of `b`. pub struct TypeRelating<'combine, 'a, 'tcx> { - // Partially mutable. + // Immutable except for the `InferCtxt` and the + // resulting nested `goals`. fields: &'combine mut CombineFields<'a, 'tcx>, - // Immutable fields. + // Immutable field. structurally_relate_aliases: StructurallyRelateAliases, + // Mutable field. ambient_variance: ty::Variance, - /// The cache has only tracks the `ambient_variance` as its the + /// The cache only tracks the `ambient_variance` as it's the /// only field which is mutable and which meaningfully changes /// the result when relating types. /// diff --git a/compiler/rustc_middle/src/ty/fold.rs b/compiler/rustc_middle/src/ty/fold.rs index e152d3f5fbe9f..b5a77b3c9423e 100644 --- a/compiler/rustc_middle/src/ty/fold.rs +++ b/compiler/rustc_middle/src/ty/fold.rs @@ -210,16 +210,17 @@ where debug_assert!(!ty.has_vars_bound_above(ty::INNERMOST)); ty::fold::shift_vars(self.tcx, ty, self.current_index.as_u32()) } - _ if t.has_vars_bound_at_or_above(self.current_index) => { - if let Some(&ty) = self.cache.get(&(self.current_index, t)) { - return ty; + _ => { + if !t.has_vars_bound_at_or_above(self.current_index) { + t + } else if let Some(&t) = self.cache.get(&(self.current_index, t)) { + t + } else { + let res = t.super_fold_with(self); + assert!(self.cache.insert((self.current_index, t), res)); + res } - - let res = t.super_fold_with(self); - assert!(self.cache.insert((self.current_index, t), res)); - res } - _ => t, } } diff --git a/compiler/rustc_next_trait_solver/src/canonicalizer.rs b/compiler/rustc_next_trait_solver/src/canonicalizer.rs index 5c3c35b7b3e46..0bf9d7b924952 100644 --- a/compiler/rustc_next_trait_solver/src/canonicalizer.rs +++ b/compiler/rustc_next_trait_solver/src/canonicalizer.rs @@ -42,17 +42,19 @@ pub enum CanonicalizeMode { pub struct Canonicalizer<'a, D: SolverDelegate, I: Interner> { delegate: &'a D, + + // Immutable field. canonicalize_mode: CanonicalizeMode, + // Mutable fields. variables: &'a mut Vec, - variable_lookup_table: HashMap, - primitive_var_infos: Vec>, + variable_lookup_table: HashMap, binder_index: ty::DebruijnIndex, - /// We only use the debruijn index during lookup as all other fields - /// should not be impacted by whether a type is folded once or multiple - /// times. + /// We only use the debruijn index during lookup. We don't need to + /// track the `variables` as each generic arg only results in a single + /// bound variable regardless of how many times it is encountered. cache: HashMap<(ty::DebruijnIndex, I::Ty), I::Ty>, } diff --git a/compiler/rustc_next_trait_solver/src/resolve.rs b/compiler/rustc_next_trait_solver/src/resolve.rs index a37066cec669f..f2654f7534e1d 100644 --- a/compiler/rustc_next_trait_solver/src/resolve.rs +++ b/compiler/rustc_next_trait_solver/src/resolve.rs @@ -16,6 +16,8 @@ where I: Interner, { delegate: &'a D, + /// We're able to use a cache here as the folder does not have any + /// mutable state. cache: DelayedMap, } diff --git a/compiler/rustc_next_trait_solver/src/solve/eval_ctxt/mod.rs b/compiler/rustc_next_trait_solver/src/solve/eval_ctxt/mod.rs index 12b4b3cb3a9d8..baa00465c0cce 100644 --- a/compiler/rustc_next_trait_solver/src/solve/eval_ctxt/mod.rs +++ b/compiler/rustc_next_trait_solver/src/solve/eval_ctxt/mod.rs @@ -1057,16 +1057,17 @@ where ); infer_ty } - _ if ty.has_aliases() => { - if let Some(&entry) = self.cache.get(&ty) { + _ => { + if !ty.has_aliases() { + ty + } else if let Some(&entry) = self.cache.get(&ty) { return entry; + } else { + let res = ty.super_fold_with(self); + assert!(self.cache.insert(ty, res).is_none()); + res } - - let res = ty.super_fold_with(self); - assert!(self.cache.insert(ty, res).is_none()); - res } - _ => ty, } }