refactor search graph even more!

compiler/rustc_middle/src/arena.rs

@@ -61,10 +61,6 @@ macro_rules! arena_types {
             [] dtorck_constraint: rustc_middle::traits::query::DropckConstraint<'tcx>,
             [] candidate_step: rustc_middle::traits::query::CandidateStep<'tcx>,
             [] autoderef_bad_ty: rustc_middle::traits::query::MethodAutoderefBadTy<'tcx>,
-            [] canonical_goal_evaluation:
-                rustc_type_ir::solve::inspect::CanonicalGoalEvaluationStep<
-                    rustc_middle::ty::TyCtxt<'tcx>
-                >,
             [] query_region_constraints: rustc_middle::infer::canonical::QueryRegionConstraints<'tcx>,
             [] type_op_subtype:
                 rustc_middle::infer::canonical::Canonical<'tcx,

compiler/rustc_middle/src/ty/context.rs

@@ -112,8 +112,6 @@ impl<'tcx> Interner for TyCtxt<'tcx> {
         self.mk_predefined_opaques_in_body(data)
     }
     type DefiningOpaqueTypes = &'tcx ty::List<LocalDefId>;
-    type CanonicalGoalEvaluationStepRef =
-        &'tcx solve::inspect::CanonicalGoalEvaluationStep<TyCtxt<'tcx>>;
     type CanonicalVars = CanonicalVarInfos<'tcx>;
     fn mk_canonical_var_infos(self, infos: &[ty::CanonicalVarInfo<Self>]) -> Self::CanonicalVars {
         self.mk_canonical_var_infos(infos)
@@ -282,13 +280,6 @@ impl<'tcx> Interner for TyCtxt<'tcx> {
         self.debug_assert_args_compatible(def_id, args);
     }
 
-    fn intern_canonical_goal_evaluation_step(
-        self,
-        step: solve::inspect::CanonicalGoalEvaluationStep<TyCtxt<'tcx>>,
-    ) -> &'tcx solve::inspect::CanonicalGoalEvaluationStep<TyCtxt<'tcx>> {
-        self.arena.alloc(step)
-    }
-
     fn mk_type_list_from_iter<I, T>(self, args: I) -> T::Output
     where
         I: Iterator<Item = T>,

compiler/rustc_next_trait_solver/src/solve/inspect/build.rs

@@ -5,10 +5,9 @@
 //! see the comment on [ProofTreeBuilder].
 
 use std::marker::PhantomData;
-use std::mem;
 
 use rustc_type_ir::inherent::*;
-use rustc_type_ir::{self as ty, search_graph, Interner};
+use rustc_type_ir::{self as ty, Interner};
 
 use crate::delegate::SolverDelegate;
 use crate::solve::eval_ctxt::canonical;
@@ -96,33 +95,11 @@ impl<I: Interner> WipGoalEvaluation<I> {
     }
 }
 
-#[derive(derivative::Derivative)]
-#[derivative(PartialEq(bound = ""), Eq(bound = ""))]
-pub(in crate::solve) enum WipCanonicalGoalEvaluationKind<I: Interner> {
-    Overflow,
-    CycleInStack,
-    ProvisionalCacheHit,
-    Interned { final_revision: I::CanonicalGoalEvaluationStepRef },
-}
-
-impl<I: Interner> std::fmt::Debug for WipCanonicalGoalEvaluationKind<I> {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        match self {
-            Self::Overflow => write!(f, "Overflow"),
-            Self::CycleInStack => write!(f, "CycleInStack"),
-            Self::ProvisionalCacheHit => write!(f, "ProvisionalCacheHit"),
-            Self::Interned { final_revision: _ } => {
-                f.debug_struct("Interned").finish_non_exhaustive()
-            }
-        }
-    }
-}
-
 #[derive(derivative::Derivative)]
 #[derivative(PartialEq(bound = ""), Eq(bound = ""), Debug(bound = ""))]
 struct WipCanonicalGoalEvaluation<I: Interner> {
     goal: CanonicalInput<I>,
-    kind: Option<WipCanonicalGoalEvaluationKind<I>>,
+    encountered_overflow: bool,
     /// Only used for uncached goals. After we finished evaluating
     /// the goal, this is interned and moved into `kind`.
     final_revision: Option<WipCanonicalGoalEvaluationStep<I>>,
@@ -131,25 +108,17 @@ struct WipCanonicalGoalEvaluation<I: Interner> {
 
 impl<I: Interner> WipCanonicalGoalEvaluation<I> {
     fn finalize(self) -> inspect::CanonicalGoalEvaluation<I> {
-        // We've already interned the final revision in
-        // `fn finalize_canonical_goal_evaluation`.
-        assert!(self.final_revision.is_none());
-        let kind = match self.kind.unwrap() {
-            WipCanonicalGoalEvaluationKind::Overflow => {
+        inspect::CanonicalGoalEvaluation {
+            goal: self.goal,
+            kind: if self.encountered_overflow {
+                assert!(self.final_revision.is_none());
                 inspect::CanonicalGoalEvaluationKind::Overflow
-            }
-            WipCanonicalGoalEvaluationKind::CycleInStack => {
-                inspect::CanonicalGoalEvaluationKind::CycleInStack
-            }
-            WipCanonicalGoalEvaluationKind::ProvisionalCacheHit => {
-                inspect::CanonicalGoalEvaluationKind::ProvisionalCacheHit
-            }
-            WipCanonicalGoalEvaluationKind::Interned { final_revision } => {
+            } else {
+                let final_revision = self.final_revision.unwrap().finalize();
                 inspect::CanonicalGoalEvaluationKind::Evaluation { final_revision }
-            }
-        };
-
-        inspect::CanonicalGoalEvaluation { goal: self.goal, kind, result: self.result.unwrap() }
+            },
+            result: self.result.unwrap(),
+        }
     }
 }
 
@@ -315,7 +284,7 @@ impl<D: SolverDelegate<Interner = I>, I: Interner> ProofTreeBuilder<D> {
     ) -> ProofTreeBuilder<D> {
         self.nested(|| WipCanonicalGoalEvaluation {
             goal,
-            kind: None,
+            encountered_overflow: false,
             final_revision: None,
             result: None,
         })
@@ -336,11 +305,11 @@ impl<D: SolverDelegate<Interner = I>, I: Interner> ProofTreeBuilder<D> {
         }
     }
 
-    pub fn canonical_goal_evaluation_kind(&mut self, kind: WipCanonicalGoalEvaluationKind<I>) {
+    pub fn canonical_goal_evaluation_overflow(&mut self) {
         if let Some(this) = self.as_mut() {
             match this {
                 DebugSolver::CanonicalGoalEvaluation(canonical_goal_evaluation) => {
-                    assert_eq!(canonical_goal_evaluation.kind.replace(kind), None);
+                    canonical_goal_evaluation.encountered_overflow = true;
                 }
                 _ => unreachable!(),
             };
@@ -554,51 +523,3 @@ impl<D: SolverDelegate<Interner = I>, I: Interner> ProofTreeBuilder<D> {
         }
     }
 }
-
-impl<D, I> search_graph::ProofTreeBuilder<I> for ProofTreeBuilder<D>
-where
-    D: SolverDelegate<Interner = I>,
-    I: Interner,
-{
-    fn try_apply_proof_tree(
-        &mut self,
-        proof_tree: Option<I::CanonicalGoalEvaluationStepRef>,
-    ) -> bool {
-        if !self.is_noop() {
-            if let Some(final_revision) = proof_tree {
-                let kind = WipCanonicalGoalEvaluationKind::Interned { final_revision };
-                self.canonical_goal_evaluation_kind(kind);
-                true
-            } else {
-                false
-            }
-        } else {
-            true
-        }
-    }
-
-    fn on_provisional_cache_hit(&mut self) {
-        self.canonical_goal_evaluation_kind(WipCanonicalGoalEvaluationKind::ProvisionalCacheHit);
-    }
-
-    fn on_cycle_in_stack(&mut self) {
-        self.canonical_goal_evaluation_kind(WipCanonicalGoalEvaluationKind::CycleInStack);
-    }
-
-    fn finalize_canonical_goal_evaluation(
-        &mut self,
-        tcx: I,
-    ) -> Option<I::CanonicalGoalEvaluationStepRef> {
-        self.as_mut().map(|this| match this {
-            DebugSolver::CanonicalGoalEvaluation(evaluation) => {
-                let final_revision = mem::take(&mut evaluation.final_revision).unwrap();
-                let final_revision =
-                    tcx.intern_canonical_goal_evaluation_step(final_revision.finalize());
-                let kind = WipCanonicalGoalEvaluationKind::Interned { final_revision };
-                assert_eq!(evaluation.kind.replace(kind), None);
-                final_revision
-            }
-            _ => unreachable!(),
-        })
-    }
-}

compiler/rustc_next_trait_solver/src/solve/search_graph.rs

@@ -5,7 +5,7 @@ use rustc_type_ir::search_graph::{self, CycleKind, UsageKind};
 use rustc_type_ir::solve::{CanonicalInput, Certainty, QueryResult};
 use rustc_type_ir::Interner;
 
-use super::inspect::{self, ProofTreeBuilder};
+use super::inspect::ProofTreeBuilder;
 use super::FIXPOINT_STEP_LIMIT;
 use crate::delegate::SolverDelegate;
 
@@ -25,6 +25,9 @@ where
     const FIXPOINT_STEP_LIMIT: usize = FIXPOINT_STEP_LIMIT;
 
     type ProofTreeBuilder = ProofTreeBuilder<D>;
+    fn inspect_is_noop(inspect: &mut Self::ProofTreeBuilder) -> bool {
+        inspect.is_noop()
+    }
 
     fn recursion_limit(cx: I) -> usize {
         cx.recursion_limit()
@@ -68,7 +71,7 @@ where
         inspect: &mut ProofTreeBuilder<D>,
         input: CanonicalInput<I>,
     ) -> QueryResult<I> {
-        inspect.canonical_goal_evaluation_kind(inspect::WipCanonicalGoalEvaluationKind::Overflow);
+        inspect.canonical_goal_evaluation_overflow();
         response_no_constraints(cx, input, Certainty::overflow(true))
     }
 

compiler/rustc_trait_selection/src/solve/inspect/analyse.rs

@@ -332,13 +332,9 @@ impl<'a, 'tcx> InspectGoal<'a, 'tcx> {
 
     pub fn candidates(&'a self) -> Vec<InspectCandidate<'a, 'tcx>> {
         let mut candidates = vec![];
-        let last_eval_step = match self.evaluation_kind {
-            inspect::CanonicalGoalEvaluationKind::Overflow
-            | inspect::CanonicalGoalEvaluationKind::CycleInStack
-            | inspect::CanonicalGoalEvaluationKind::ProvisionalCacheHit => {
-                warn!("unexpected root evaluation: {:?}", self.evaluation_kind);
-                return vec![];
-            }
+        let last_eval_step = match &self.evaluation_kind {
+            // An annoying edge case in case the recursion limit is 0.
+            inspect::CanonicalGoalEvaluationKind::Overflow => return vec![],
             inspect::CanonicalGoalEvaluationKind::Evaluation { final_revision } => final_revision,
         };
 

compiler/rustc_type_ir/src/interner.rs

@@ -11,7 +11,6 @@ use crate::ir_print::IrPrint;
 use crate::lang_items::TraitSolverLangItem;
 use crate::relate::Relate;
 use crate::search_graph;
-use crate::solve::inspect::CanonicalGoalEvaluationStep;
 use crate::solve::{
     CanonicalInput, ExternalConstraintsData, PredefinedOpaquesData, QueryResult, SolverMode,
 };
@@ -63,11 +62,6 @@ pub trait Interner:
         + Eq
         + TypeVisitable<Self>
         + SliceLike<Item = Self::LocalDefId>;
-    type CanonicalGoalEvaluationStepRef: Copy
-        + Debug
-        + Hash
-        + Eq
-        + Deref<Target = CanonicalGoalEvaluationStep<Self>>;
 
     type CanonicalVars: Copy
         + Debug
@@ -175,11 +169,6 @@ pub trait Interner:
 
     fn debug_assert_args_compatible(self, def_id: Self::DefId, args: Self::GenericArgs);
 
-    fn intern_canonical_goal_evaluation_step(
-        self,
-        step: CanonicalGoalEvaluationStep<Self>,
-    ) -> Self::CanonicalGoalEvaluationStepRef;
-
     fn mk_type_list_from_iter<I, T>(self, args: I) -> T::Output
     where
         I: Iterator<Item = T>,
@@ -388,7 +377,6 @@ impl<T, R, E> CollectAndApply<T, R> for Result<T, E> {
 }
 
 impl<I: Interner> search_graph::Cx for I {
-    type ProofTree = Option<I::CanonicalGoalEvaluationStepRef>;
     type Input = CanonicalInput<I>;
     type Result = QueryResult<I>;
 

compiler/rustc_type_ir/src/search_graph/global_cache.rs

@@ -3,15 +3,8 @@ use rustc_index::IndexVec;
 use super::{AvailableDepth, Cx, StackDepth, StackEntry};
 use crate::data_structures::{HashMap, HashSet};
 
-#[derive(derivative::Derivative)]
-#[derivative(Debug(bound = ""), Clone(bound = ""), Copy(bound = ""))]
-struct QueryData<X: Cx> {
-    result: X::Result,
-    proof_tree: X::ProofTree,
-}
-
 struct Success<X: Cx> {
-    data: X::Tracked<QueryData<X>>,
+    result: X::Tracked<X::Result>,
     additional_depth: usize,
 }
 
@@ -29,14 +22,13 @@ struct CacheEntry<X: Cx> {
     /// See the doc comment of `StackEntry::cycle_participants` for more
     /// details.
     nested_goals: HashSet<X::Input>,
-    with_overflow: HashMap<usize, X::Tracked<QueryData<X>>>,
+    with_overflow: HashMap<usize, X::Tracked<X::Result>>,
 }
 
 #[derive(derivative::Derivative)]
 #[derivative(Debug(bound = ""))]
 pub(super) struct CacheData<'a, X: Cx> {
     pub(super) result: X::Result,
-    pub(super) proof_tree: X::ProofTree,
     pub(super) additional_depth: usize,
     pub(super) encountered_overflow: bool,
     // FIXME: This is currently unused, but impacts the design
@@ -58,20 +50,19 @@ impl<X: Cx> GlobalCache<X> {
         input: X::Input,
 
         result: X::Result,
-        proof_tree: X::ProofTree,
         dep_node: X::DepNodeIndex,
 
         additional_depth: usize,
         encountered_overflow: bool,
         nested_goals: &HashSet<X::Input>,
     ) {
-        let data = cx.mk_tracked(QueryData { result, proof_tree }, dep_node);
+        let result = cx.mk_tracked(result, dep_node);
         let entry = self.map.entry(input).or_default();
         entry.nested_goals.extend(nested_goals);
         if encountered_overflow {
-            entry.with_overflow.insert(additional_depth, data);
+            entry.with_overflow.insert(additional_depth, result);
         } else {
-            entry.success = Some(Success { data, additional_depth });
+            entry.success = Some(Success { result, additional_depth });
         }
     }
 
@@ -93,26 +84,20 @@ impl<X: Cx> GlobalCache<X> {
 
         if let Some(ref success) = entry.success {
             if available_depth.cache_entry_is_applicable(success.additional_depth) {
-                let QueryData { result, proof_tree } = cx.get_tracked(&success.data);
                 return Some(CacheData {
-                    result,
-                    proof_tree,
+                    result: cx.get_tracked(&success.result),
                     additional_depth: success.additional_depth,
                     encountered_overflow: false,
                     nested_goals: &entry.nested_goals,
                 });
             }
         }
 
-        entry.with_overflow.get(&available_depth.0).map(|e| {
-            let QueryData { result, proof_tree } = cx.get_tracked(e);
-            CacheData {
-                result,
-                proof_tree,
-                additional_depth: available_depth.0,
-                encountered_overflow: true,
-                nested_goals: &entry.nested_goals,
-            }
+        entry.with_overflow.get(&available_depth.0).map(|e| CacheData {
+            result: cx.get_tracked(e),
+            additional_depth: available_depth.0,
+            encountered_overflow: true,
+            nested_goals: &entry.nested_goals,
         })
     }
 }