diff --git a/compiler/rustc_infer/src/infer/context.rs b/compiler/rustc_infer/src/infer/context.rs index e6ddbd879f9b9..00a89b618bae1 100644 --- a/compiler/rustc_infer/src/infer/context.rs +++ b/compiler/rustc_infer/src/infer/context.rs @@ -198,7 +198,7 @@ impl<'tcx> rustc_type_ir::InferCtxtLike for InferCtxt<'tcx> { } fn equate_ty_vids_raw(&self, a: ty::TyVid, b: ty::TyVid) { - self.inner.borrow_mut().type_variables().equate(a, b); + self.inner.borrow_mut().equate_ty_vids(a, b); } fn sub_unify_ty_vids_raw(&self, a: ty::TyVid, b: ty::TyVid) { @@ -206,30 +206,27 @@ impl<'tcx> rustc_type_ir::InferCtxtLike for InferCtxt<'tcx> { } fn equate_int_vids_raw(&self, a: ty::IntVid, b: ty::IntVid) { - self.inner.borrow_mut().int_unification_table().union(a, b); + self.inner.borrow_mut().equate_int_vids(a, b); } fn equate_float_vids_raw(&self, a: ty::FloatVid, b: ty::FloatVid) { - self.inner.borrow_mut().float_unification_table().union(a, b); + self.inner.borrow_mut().equate_float_vids(a, b); } fn equate_const_vids_raw(&self, a: ty::ConstVid, b: ty::ConstVid) { - self.inner.borrow_mut().const_unification_table().union(a, b); + self.inner.borrow_mut().equate_const_vids(a, b); } fn instantiate_ty_var_raw(&self, vid: ty::TyVid, ty: Ty<'tcx>) { let ty = lower_universe(self, self.try_resolve_ty_var(vid).unwrap_err(), ty); - self.inner.borrow_mut().type_variables().instantiate(vid, ty); + self.inner.borrow_mut().instantiate_ty_var(vid, ty); } fn instantiate_const_var_raw(&self, vid: ty::ConstVid, ct: ty::Const<'tcx>) { let ct = lower_universe(self, self.try_resolve_const_var(vid).unwrap_err(), ct); - self.inner - .borrow_mut() - .const_unification_table() - .union_value(vid, ConstVariableValue::Known { value: ct }); + self.inner.borrow_mut().instantiate_const_var(vid, ct); } fn instantiate_ty_var>( @@ -250,11 +247,11 @@ impl<'tcx> rustc_type_ir::InferCtxtLike for InferCtxt<'tcx> { } fn instantiate_int_var_raw(&self, vid: ty::IntVid, value: ty::IntVarValue) { - self.inner.borrow_mut().int_unification_table().union_value(vid, value); + self.inner.borrow_mut().instantiate_int_var(vid, value); } fn instantiate_float_var_raw(&self, vid: ty::FloatVid, value: ty::FloatVarValue) { - self.inner.borrow_mut().float_unification_table().union_value(vid, value); + self.inner.borrow_mut().instantiate_float_var(vid, value); } fn instantiate_const_var>( @@ -464,7 +461,7 @@ impl<'a, 'tcx> ty::TypeFolder> for LowerUniverseFolder<'a, 'tcx> { let origin = inner.type_variables().var_origin(vid); let new_var_id = inner.type_variables().new_var(self.for_universe, origin); - inner.type_variables().equate(vid, new_var_id); + inner.equate_ty_vids(vid, new_var_id); Ty::new_var(self.cx(), new_var_id) } } @@ -504,7 +501,7 @@ impl<'a, 'tcx> ty::TypeFolder> for LowerUniverseFolder<'a, 'tcx> { }) .vid; - self.infcx.inner.borrow_mut().const_unification_table().union(vid, new_var_id); + self.infcx.inner.borrow_mut().equate_const_vids(vid, new_var_id); ty::Const::new_var(self.cx(), new_var_id) } diff --git a/compiler/rustc_infer/src/infer/mod.rs b/compiler/rustc_infer/src/infer/mod.rs index a49a4355b66b1..29c47b1aaa587 100644 --- a/compiler/rustc_infer/src/infer/mod.rs +++ b/compiler/rustc_infer/src/infer/mod.rs @@ -97,6 +97,11 @@ pub(crate) type UnificationTable<'a, 'tcx, T> = ut::UnificationTable< pub struct InferCtxtInner<'tcx> { undo_log: InferCtxtUndoLogs<'tcx>, + /// Bumped whenever an inference change may let a stalled fulfillment goal + /// make progress. Snapshots save and restore the value, but individual bumps + /// are not undo-log entries. + stalled_goal_generation: Option, + /// Cache for projections. /// /// This cache is snapshotted along with the infcx. @@ -168,9 +173,10 @@ pub struct InferCtxtInner<'tcx> { } impl<'tcx> InferCtxtInner<'tcx> { - fn new() -> InferCtxtInner<'tcx> { + fn new(next_trait_solver: bool) -> InferCtxtInner<'tcx> { InferCtxtInner { undo_log: InferCtxtUndoLogs::default(), + stalled_goal_generation: next_trait_solver.then_some(0), projection_cache: Default::default(), type_variable_storage: Default::default(), @@ -234,6 +240,79 @@ impl<'tcx> InferCtxtInner<'tcx> { self.const_unification_storage.with_log(&mut self.undo_log) } + #[inline] + pub(crate) fn start_snapshot(&mut self) -> snapshot::undo_log::Snapshot<'tcx> { + self.undo_log.start_snapshot(self.stalled_goal_generation) + } + + #[inline] + fn stalled_goal_generation(&self) -> Option { + self.stalled_goal_generation + } + + #[inline] + fn bump_stalled_goal_generation(&mut self) { + if let Some(generation) = &mut self.stalled_goal_generation { + *generation = generation.wrapping_add(1); + } + } + + #[inline] + fn equate_ty_vids(&mut self, a: ty::TyVid, b: ty::TyVid) { + self.bump_stalled_goal_generation(); + self.type_variables().equate(a, b); + } + + #[inline] + fn sub_unify_ty_vids(&mut self, a: ty::TyVid, b: ty::TyVid) { + self.bump_stalled_goal_generation(); + self.type_variables().sub_unify(a, b); + } + + #[inline] + fn instantiate_ty_var(&mut self, vid: ty::TyVid, ty: Ty<'tcx>) { + self.bump_stalled_goal_generation(); + self.type_variables().instantiate(vid, ty); + } + + // These mutations can unblock stalled goals too, so route them through the + // same generation bump. + #[inline] + fn equate_int_vids(&mut self, a: ty::IntVid, b: ty::IntVid) { + self.bump_stalled_goal_generation(); + self.int_unification_table().union(a, b); + } + + #[inline] + fn equate_float_vids(&mut self, a: ty::FloatVid, b: ty::FloatVid) { + self.bump_stalled_goal_generation(); + self.float_unification_table().union(a, b); + } + + #[inline] + fn equate_const_vids(&mut self, a: ty::ConstVid, b: ty::ConstVid) { + self.bump_stalled_goal_generation(); + self.const_unification_table().union(a, b); + } + + #[inline] + fn instantiate_int_var(&mut self, vid: ty::IntVid, value: ty::IntVarValue) { + self.bump_stalled_goal_generation(); + self.int_unification_table().union_value(vid, value); + } + + #[inline] + fn instantiate_float_var(&mut self, vid: ty::FloatVid, value: ty::FloatVarValue) { + self.bump_stalled_goal_generation(); + self.float_unification_table().union_value(vid, value); + } + + #[inline] + fn instantiate_const_var(&mut self, vid: ty::ConstVid, value: ty::Const<'tcx>) { + self.bump_stalled_goal_generation(); + self.const_unification_table().union_value(vid, ConstVariableValue::Known { value }); + } + #[inline] pub fn unwrap_region_constraints(&mut self) -> RegionConstraintCollector<'_, 'tcx> { self.region_constraint_storage @@ -681,7 +760,7 @@ impl<'tcx> InferCtxtBuilder<'tcx> { considering_regions, in_hir_typeck, skip_leak_check, - inner: RefCell::new(InferCtxtInner::new()), + inner: RefCell::new(InferCtxtInner::new(next_trait_solver)), lexical_region_resolutions: RefCell::new(None), selection_cache: Default::default(), evaluation_cache: Default::default(), @@ -1352,7 +1431,7 @@ impl<'tcx> InferCtxt<'tcx> { } pub fn sub_unify_ty_vids_raw(&self, a: ty::TyVid, b: ty::TyVid) { - self.inner.borrow_mut().type_variables().sub_unify(a, b); + self.inner.borrow_mut().sub_unify_ty_vids(a, b); } pub fn sub_unification_table_root_var(&self, var: ty::TyVid) -> ty::TyVid { @@ -1651,6 +1730,14 @@ impl<'tcx> InferCtxt<'tcx> { self.typing_env(param_env).as_query_input(value) } + #[inline] + pub fn stalled_goal_generation(&self) -> u64 { + self.inner + .borrow() + .stalled_goal_generation() + .expect("stalled-goal generation requires the next trait solver") + } + /// The returned function is used in a fast path. If it returns `true` the variable is /// unchanged, `false` indicates that the status is unknown. #[inline] diff --git a/compiler/rustc_infer/src/infer/relate/generalize.rs b/compiler/rustc_infer/src/infer/relate/generalize.rs index afdabb38c3b20..7e49b2cbc2716 100644 --- a/compiler/rustc_infer/src/infer/relate/generalize.rs +++ b/compiler/rustc_infer/src/infer/relate/generalize.rs @@ -245,7 +245,7 @@ impl<'tcx> InferCtxt<'tcx> { match (l, r.kind()) { (TermVid::Ty(l), ty::TermKind::Ty(r)) => { if let Some(r) = r.ty_vid() { - self.inner.borrow_mut().type_variables().equate(l, r) + self.inner.borrow_mut().equate_ty_vids(l, r) } else { // Ideally, we put this assert into `type_variables().instantiate()`. // But we can't pass the infcx into it as the infcx is already @@ -253,22 +253,19 @@ impl<'tcx> InferCtxt<'tcx> { debug_assert!( self.try_resolve_ty_var(l).unwrap_err().can_name(ty::max_universe(self, r)) ); - self.inner.borrow_mut().type_variables().instantiate(l, r) + self.inner.borrow_mut().instantiate_ty_var(l, r) } } (TermVid::Const(l), ty::TermKind::Const(r)) => { if let Some(r) = r.ct_vid() { - self.inner.borrow_mut().const_unification_table().union(l, r) + self.inner.borrow_mut().equate_const_vids(l, r) } else { debug_assert!( self.try_resolve_const_var(l) .unwrap_err() .can_name(ty::max_universe(self, r)) ); - self.inner - .borrow_mut() - .const_unification_table() - .union_value(l, ConstVariableValue::Known { value: r }) + self.inner.borrow_mut().instantiate_const_var(l, r) } } _ => bug!("mismatched term kinds in generalize: {l:?}, {r:?}"), @@ -531,7 +528,7 @@ impl<'tcx> TypeRelation> for Generalizer<'_, 'tcx> { // Record that `vid` and `new_var_id` have to be subtypes // of each other. This is currently only used for diagnostics. // To see why, see the docs in the `type_variables` module. - inner.type_variables().sub_unify(vid, new_var_id); + inner.sub_unify_ty_vids(vid, new_var_id); // If we're in the new solver and create a new inference // variable inside of an alias we eagerly constrain that // inference variable to prevent unexpected ambiguity errors. @@ -551,7 +548,7 @@ impl<'tcx> TypeRelation> for Generalizer<'_, 'tcx> { && !self.infcx.typing_mode_raw().is_coherence() && self.in_alias { - inner.type_variables().equate(vid, new_var_id); + inner.equate_ty_vids(vid, new_var_id); } debug!("replacing original vid={:?} with new={:?}", vid, new_var_id); @@ -660,8 +657,8 @@ impl<'tcx> TypeRelation> for Generalizer<'_, 'tcx> { } let mut inner = self.infcx.inner.borrow_mut(); - let variable_table = &mut inner.const_unification_table(); - match variable_table.probe_value(vid) { + let vid_value = inner.const_unification_table().probe_value(vid); + match vid_value { ConstVariableValue::Known { value: u } => { drop(inner); self.relate(u, u) @@ -670,7 +667,8 @@ impl<'tcx> TypeRelation> for Generalizer<'_, 'tcx> { if self.for_universe.can_name(universe) { Ok(c) } else { - let new_var_id = variable_table + let new_var_id = inner + .const_unification_table() .new_key(ConstVariableValue::Unknown { origin, universe: self.for_universe, @@ -683,7 +681,7 @@ impl<'tcx> TypeRelation> for Generalizer<'_, 'tcx> { && !self.infcx.typing_mode_raw().is_coherence() && self.in_alias { - variable_table.union(vid, new_var_id); + inner.equate_const_vids(vid, new_var_id); } Ok(ty::Const::new_var(tcx, new_var_id)) } diff --git a/compiler/rustc_infer/src/infer/relate/type_relating.rs b/compiler/rustc_infer/src/infer/relate/type_relating.rs index 7c8e263db5582..d837b91bd492b 100644 --- a/compiler/rustc_infer/src/infer/relate/type_relating.rs +++ b/compiler/rustc_infer/src/infer/relate/type_relating.rs @@ -166,7 +166,7 @@ impl<'tcx> TypeRelation> for TypeRelating<'_, 'tcx> { )); } ty::Invariant => { - infcx.inner.borrow_mut().type_variables().equate(a_id, b_id); + infcx.inner.borrow_mut().equate_ty_vids(a_id, b_id); } ty::Bivariant => { unreachable!("Expected bivariance to be handled in relate_with_variance") diff --git a/compiler/rustc_infer/src/infer/snapshot/mod.rs b/compiler/rustc_infer/src/infer/snapshot/mod.rs index b16c80cf20143..3c2e12fe22916 100644 --- a/compiler/rustc_infer/src/infer/snapshot/mod.rs +++ b/compiler/rustc_infer/src/infer/snapshot/mod.rs @@ -51,7 +51,7 @@ impl<'tcx> InferCtxt<'tcx> { let mut inner = self.inner.borrow_mut(); CombinedSnapshot { - undo_snapshot: inner.undo_log.start_snapshot(), + undo_snapshot: inner.start_snapshot(), region_constraints_snapshot: inner.unwrap_region_constraints().start_snapshot(), universe: self.universe(), } diff --git a/compiler/rustc_infer/src/infer/snapshot/undo_log.rs b/compiler/rustc_infer/src/infer/snapshot/undo_log.rs index fe697eb4c01ac..90ebc5b1cd778 100644 --- a/compiler/rustc_infer/src/infer/snapshot/undo_log.rs +++ b/compiler/rustc_infer/src/infer/snapshot/undo_log.rs @@ -12,6 +12,7 @@ use crate::traits; pub struct Snapshot<'tcx> { pub(crate) undo_len: usize, + stalled_goal_generation: Option, _marker: PhantomData<&'tcx ()>, } @@ -158,6 +159,7 @@ impl<'tcx> InferCtxtInner<'tcx> { } self.type_variable_storage.finalize_rollback(); + self.stalled_goal_generation = snapshot.stalled_goal_generation; if self.undo_log.num_open_snapshots == 1 { // After the root snapshot the undo log should be empty. @@ -184,9 +186,12 @@ impl<'tcx> InferCtxtInner<'tcx> { } impl<'tcx> InferCtxtUndoLogs<'tcx> { - pub(crate) fn start_snapshot(&mut self) -> Snapshot<'tcx> { + pub(crate) fn start_snapshot( + &mut self, + stalled_goal_generation: Option, + ) -> Snapshot<'tcx> { self.num_open_snapshots += 1; - Snapshot { undo_len: self.logs.len(), _marker: PhantomData } + Snapshot { undo_len: self.logs.len(), stalled_goal_generation, _marker: PhantomData } } pub(crate) fn region_constraints_in_snapshot( diff --git a/compiler/rustc_infer/src/infer/type_variable.rs b/compiler/rustc_infer/src/infer/type_variable.rs index be0ac72d85675..c5b17c24ed491 100644 --- a/compiler/rustc_infer/src/infer/type_variable.rs +++ b/compiler/rustc_infer/src/infer/type_variable.rs @@ -178,6 +178,7 @@ impl<'tcx> TypeVariableTable<'_, 'tcx> { pub(crate) fn equate(&mut self, a: ty::TyVid, b: ty::TyVid) { debug_assert!(self.probe(a).is_unknown()); debug_assert!(self.probe(b).is_unknown()); + self.eq_relations().union(a, b); self.sub_unification_table().union(a, b); } @@ -189,6 +190,7 @@ impl<'tcx> TypeVariableTable<'_, 'tcx> { pub(crate) fn sub_unify(&mut self, a: ty::TyVid, b: ty::TyVid) { debug_assert!(self.probe(a).is_unknown()); debug_assert!(self.probe(b).is_unknown()); + self.sub_unification_table().union(a, b); } @@ -204,6 +206,7 @@ impl<'tcx> TypeVariableTable<'_, 'tcx> { "instantiating type variable `{vid:?}` twice: new-value = {ty:?}, old-value={:?}", self.eq_relations().probe_value(vid) ); + self.eq_relations().union_value(vid, TypeVariableValue::Known { value: ty }); } diff --git a/compiler/rustc_trait_selection/src/solve/fulfill.rs b/compiler/rustc_trait_selection/src/solve/fulfill.rs index f7eb76bbe72b5..5d1b7c077a3a5 100644 --- a/compiler/rustc_trait_selection/src/solve/fulfill.rs +++ b/compiler/rustc_trait_selection/src/solve/fulfill.rs @@ -9,7 +9,8 @@ use rustc_infer::traits::{ use rustc_middle::ty::{self, TyCtxt, TypeVisitableExt, TypingMode}; use rustc_next_trait_solver::solve::fast_path::compute_goal_fast_path; use rustc_next_trait_solver::solve::{ - GoalEvaluation, GoalStalledOn, HasChanged, SolverDelegateEvalExt as _, StalledOnCoroutines, + GoalEvaluation, GoalStalledOn, GoalStalledOnOpaques, HasChanged, SolverDelegateEvalExt as _, + StalledOnCoroutines, }; use thin_vec::ThinVec; use tracing::instrument; @@ -48,6 +49,17 @@ pub struct FulfillmentCtxt<'tcx, E: 'tcx> { /// gets rolled back. Because of this we explicitly check that we only /// use the context in exactly this snapshot. usable_in_snapshot: usize, + + last_stalled_goal_generation: u64, + + /// Whether any trackable stalled obligation requires the opaque + /// type storage to remain empty. + stalled_on_empty_opaques: bool, + + /// Whether every pending obligation can use the context-wide + /// stalled-goal fast path. + all_pending_trackable: bool, + _errors: PhantomData, } @@ -133,13 +145,33 @@ impl<'tcx, E: 'tcx> FulfillmentCtxt<'tcx, E> { "new trait solver fulfillment context created when \ infcx is set up for old trait solver" ); + let generation = infcx.stalled_goal_generation(); + FulfillmentCtxt { obligations: Default::default(), usable_in_snapshot: infcx.num_open_snapshots(), + last_stalled_goal_generation: generation, + stalled_on_empty_opaques: false, + all_pending_trackable: true, _errors: PhantomData, } } + fn record_trackable_stalled_on( + stalled_on: &GoalStalledOn>, + stalled_on_empty_opaques: &mut bool, + ) -> bool { + match stalled_on.opaques { + GoalStalledOnOpaques::No => {} + GoalStalledOnOpaques::Yes { num_opaques_in_storage: 0, .. } => { + *stalled_on_empty_opaques = true; + } + GoalStalledOnOpaques::Yes { .. } => return false, + } + + true + } + fn inspect_evaluated_obligation( infcx: &InferCtxt<'tcx>, obligation: &PredicateObligation<'tcx>, @@ -176,10 +208,22 @@ where match certainty { Certainty::Yes => {} Certainty::Maybe(_) => { + if let Some(stalled_on) = &stalled_on { + if !Self::record_trackable_stalled_on( + stalled_on, + &mut self.stalled_on_empty_opaques, + ) { + self.all_pending_trackable = false; + } + } else { + self.all_pending_trackable = false; + } + self.obligations.register(obligation, stalled_on); } } } else { + self.all_pending_trackable = false; self.obligations.register(obligation, None); } } @@ -199,9 +243,35 @@ where assert_eq!(self.usable_in_snapshot, infcx.num_open_snapshots()); let mut errors = TraitErrors::NoErrors; let delegate = <&SolverDelegate<'tcx>>::from(infcx); + + let generation = infcx.stalled_goal_generation(); + + if self.obligations.pending.is_empty() { + self.last_stalled_goal_generation = generation; + self.stalled_on_empty_opaques = false; + self.all_pending_trackable = true; + return errors; + } + + if !infcx.tcx.disable_trait_solver_fast_paths() + && self.all_pending_trackable + && self.last_stalled_goal_generation == generation + { + let opaques_unchanged = !self.stalled_on_empty_opaques + || infcx.inner.borrow_mut().opaque_types().is_empty(); + + if opaques_unchanged { + return errors; + } + } + loop { + let pass_generation = infcx.stalled_goal_generation(); + let mut any_changed = false; let mut overflowed = false; + let mut all_pending_trackable = true; + let mut stalled_on_empty_opaques = false; self.obligations.pending.retain_mut(|(obligation, opt_stalled_on)| { if overflowed { @@ -213,6 +283,11 @@ where if let Some(stalled_on) = opt_stalled_on && delegate.goal_remains_stalled(stalled_on) { + if !Self::record_trackable_stalled_on(stalled_on, &mut stalled_on_empty_opaques) + { + all_pending_trackable = false; + } + return true; } @@ -283,17 +358,33 @@ where // Update `opt_stalled_on` goal, for the next retain_mut, because we are // running until a fixpoint. *opt_stalled_on = stalled_on; + + if let Some(stalled_on) = opt_stalled_on { + if !Self::record_trackable_stalled_on( + stalled_on, + &mut stalled_on_empty_opaques, + ) { + all_pending_trackable = false; + } + } else { + all_pending_trackable = false; + } + true } } }); if overflowed { + self.all_pending_trackable = false; self.obligations.on_fulfillment_overflow(infcx); // Only return true errors that we have accumulated while processing. return errors; } if !any_changed { + self.all_pending_trackable = all_pending_trackable; + self.stalled_on_empty_opaques = stalled_on_empty_opaques; + self.last_stalled_goal_generation = pass_generation; break; } }