Auto merge of rust-lang#117749 - aliemjay:perf-canon-cache, r=<try>

[perf] canonicalize param env only once

Canonicalize ParamEnv only once and store it. Then whenever we try to canonicalize `ParamEnvAnd<'tcx, T>` we only have to canonicalize `T` and then merge the results.

Prelimiary results show ~3-4% savings in diesel and serde benchmarks.

r? `@ghost`

Author: bors

compiler/rustc_infer/src/infer/canonical/canonicalizer.rs

@@ -35,13 +35,35 @@ impl<'tcx> InferCtxt<'tcx> {
     /// [c]: https://rust-lang.github.io/chalk/book/canonical_queries/canonicalization.html#canonicalizing-the-query
     pub fn canonicalize_query<V>(
         &self,
-        value: V,
+        value: ty::ParamEnvAnd<'tcx, V>,
         query_state: &mut OriginalQueryValues<'tcx>,
-    ) -> Canonical<'tcx, V>
+    ) -> Canonical<'tcx, ty::ParamEnvAnd<'tcx, V>>
     where
         V: TypeFoldable<TyCtxt<'tcx>>,
     {
-        Canonicalizer::canonicalize(value, self, self.tcx, &CanonicalizeAllFreeRegions, query_state)
+        let (param_env, value) = value.into_parts();
+        let base = self.tcx.canonical_param_env_cache.get_or_insert(
+            param_env,
+            query_state,
+            |query_state| {
+                Canonicalizer::canonicalize(
+                    param_env,
+                    self,
+                    self.tcx,
+                    &CanonicalizeFreeRegionsOtherThanStatic,
+                    query_state,
+                )
+            },
+        );
+        Canonicalizer::canonicalize_continue(
+            base,
+            value,
+            self,
+            self.tcx,
+            &CanonicalizeAllFreeRegions,
+            query_state,
+        )
+        .unchecked_map(|(param_env, value)| param_env.and(value))
     }
 
     /// Like [Self::canonicalize_query], but preserves distinct universes. For
@@ -126,19 +148,35 @@ impl<'tcx> InferCtxt<'tcx> {
     /// handling of `'static` regions (e.g. trait evaluation).
     pub fn canonicalize_query_keep_static<V>(
         &self,
-        value: V,
+        value: ty::ParamEnvAnd<'tcx, V>,
         query_state: &mut OriginalQueryValues<'tcx>,
-    ) -> Canonical<'tcx, V>
+    ) -> Canonical<'tcx, ty::ParamEnvAnd<'tcx, V>>
     where
         V: TypeFoldable<TyCtxt<'tcx>>,
     {
-        Canonicalizer::canonicalize(
+        let (param_env, value) = value.into_parts();
+        let base = self.tcx.canonical_param_env_cache.get_or_insert(
+            param_env,
+            query_state,
+            |query_state| {
+                Canonicalizer::canonicalize(
+                    param_env,
+                    self,
+                    self.tcx,
+                    &CanonicalizeFreeRegionsOtherThanStatic,
+                    query_state,
+                )
+            },
+        );
+        Canonicalizer::canonicalize_continue(
+            base,
             value,
             self,
             self.tcx,
             &CanonicalizeFreeRegionsOtherThanStatic,
             query_state,
         )
+        .unchecked_map(|(param_env, value)| param_env.and(value))
     }
 }
 
@@ -615,6 +653,66 @@ impl<'cx, 'tcx> Canonicalizer<'cx, 'tcx> {
         Canonical { max_universe, variables: canonical_variables, value: out_value }
     }
 
+    fn canonicalize_continue<U, V>(
+        base: Canonical<'tcx, U>,
+        value: V,
+        infcx: &InferCtxt<'tcx>,
+        tcx: TyCtxt<'tcx>,
+        canonicalize_region_mode: &dyn CanonicalizeMode,
+        query_state: &mut OriginalQueryValues<'tcx>,
+    ) -> Canonical<'tcx, (U, V)>
+    where
+        V: TypeFoldable<TyCtxt<'tcx>>,
+    {
+        let needs_canonical_flags = if canonicalize_region_mode.any() {
+            TypeFlags::HAS_INFER | TypeFlags::HAS_PLACEHOLDER | TypeFlags::HAS_FREE_REGIONS
+        } else {
+            TypeFlags::HAS_INFER | TypeFlags::HAS_PLACEHOLDER
+        };
+
+        // Fast path: nothing that needs to be canonicalized.
+        if !value.has_type_flags(needs_canonical_flags) {
+            return base.unchecked_map(|b| (b, value));
+        }
+
+        let mut canonicalizer = Canonicalizer {
+            infcx,
+            tcx,
+            canonicalize_mode: canonicalize_region_mode,
+            needs_canonical_flags,
+            variables: SmallVec::from_slice(base.variables),
+            query_state,
+            indices: FxHashMap::default(),
+            binder_index: ty::INNERMOST,
+        };
+        if canonicalizer.query_state.var_values.spilled() {
+            canonicalizer.indices = canonicalizer
+                .query_state
+                .var_values
+                .iter()
+                .enumerate()
+                .map(|(i, &kind)| (kind, BoundVar::new(i)))
+                .collect();
+        }
+        let out_value = value.fold_with(&mut canonicalizer);
+
+        // Once we have canonicalized `out_value`, it should not
+        // contain anything that ties it to this inference context
+        // anymore.
+        debug_assert!(!out_value.has_infer() && !out_value.has_placeholders());
+
+        let canonical_variables =
+            tcx.mk_canonical_var_infos(&canonicalizer.universe_canonicalized_variables());
+
+        let max_universe = canonical_variables
+            .iter()
+            .map(|cvar| cvar.universe())
+            .max()
+            .unwrap_or(ty::UniverseIndex::ROOT);
+
+        Canonical { max_universe, variables: canonical_variables, value: (base.value, out_value) }
+    }
+
     /// Creates a canonical variable replacing `kind` from the input,
     /// or returns an existing variable if `kind` has already been
     /// seen. `kind` is expected to be an unbound variable (or

compiler/rustc_infer/src/infer/combine.rs

@@ -171,7 +171,7 @@ impl<'tcx> InferCtxt<'tcx> {
             // two const param's types are able to be equal has to go through a canonical query with the actual logic
             // in `rustc_trait_selection`.
             let canonical = self.canonicalize_query(
-                (relation.param_env(), a.ty(), b.ty()),
+                relation.param_env().and((a.ty(), b.ty())),
                 &mut OriginalQueryValues::default(),
             );
             self.tcx.check_tys_might_be_eq(canonical).map_err(|_| {

compiler/rustc_middle/src/infer/canonical.rs

@@ -291,3 +291,39 @@ impl<'tcx> Index<BoundVar> for CanonicalVarValues<'tcx> {
         &self.var_values[value.as_usize()]
     }
 }
+
+use rustc_data_structures::fx::FxHashMap;
+use rustc_data_structures::sync::Lock;
+
+#[derive(Default)]
+pub struct CanonicalParamEnvCache<'tcx> {
+    map: Lock<
+        FxHashMap<
+            ty::ParamEnv<'tcx>,
+            (Canonical<'tcx, ty::ParamEnv<'tcx>>, OriginalQueryValues<'tcx>),
+        >,
+    >,
+}
+
+impl<'tcx> CanonicalParamEnvCache<'tcx> {
+    pub fn get_or_insert(
+        &self,
+        key: ty::ParamEnv<'tcx>,
+        vals: &mut OriginalQueryValues<'tcx>,
+        f: impl FnOnce(&mut OriginalQueryValues<'tcx>) -> Canonical<'tcx, ty::ParamEnv<'tcx>>,
+    ) -> Canonical<'tcx, ty::ParamEnv<'tcx>> {
+        use std::collections::hash_map::Entry;
+        match self.map.borrow().entry(key) {
+            Entry::Occupied(e) => {
+                let (canonical, vals2) = e.get();
+                vals.clone_from(vals2);
+                canonical.clone()
+            }
+            Entry::Vacant(e) => {
+                let canonical = f(vals);
+                e.insert((canonical.clone(), vals.clone()));
+                canonical
+            }
+        }
+    }
+}

compiler/rustc_middle/src/query/mod.rs

@@ -2177,7 +2177,9 @@ rustc_queries! {
     /// Used in `super_combine_consts` to ICE if the type of the two consts are definitely not going to end up being
     /// equal to eachother. This might return `Ok` even if the types are not equal, but will never return `Err` if
     /// the types might be equal.
-    query check_tys_might_be_eq(arg: Canonical<'tcx, (ty::ParamEnv<'tcx>, Ty<'tcx>, Ty<'tcx>)>) -> Result<(), NoSolution> {
+    query check_tys_might_be_eq(
+        arg: Canonical<'tcx, ty::ParamEnvAnd<'tcx, (Ty<'tcx>, Ty<'tcx>)>>
+    ) -> Result<(), NoSolution> {
         desc { "check whether two const param are definitely not equal to eachother"}
     }
 

compiler/rustc_middle/src/ty/context.rs

@@ -6,7 +6,7 @@ pub mod tls;
 
 use crate::arena::Arena;
 use crate::dep_graph::{DepGraph, DepKindStruct};
-use crate::infer::canonical::{CanonicalVarInfo, CanonicalVarInfos};
+use crate::infer::canonical::{CanonicalParamEnvCache, CanonicalVarInfo, CanonicalVarInfos};
 use crate::lint::struct_lint_level;
 use crate::metadata::ModChild;
 use crate::middle::codegen_fn_attrs::CodegenFnAttrs;
@@ -615,6 +615,8 @@ pub struct GlobalCtxt<'tcx> {
     pub new_solver_evaluation_cache: solve::EvaluationCache<'tcx>,
     pub new_solver_coherence_evaluation_cache: solve::EvaluationCache<'tcx>,
 
+    pub canonical_param_env_cache: CanonicalParamEnvCache<'tcx>,
+
     /// Data layout specification for the current target.
     pub data_layout: TargetDataLayout,
 
@@ -779,6 +781,7 @@ impl<'tcx> TyCtxt<'tcx> {
             evaluation_cache: Default::default(),
             new_solver_evaluation_cache: Default::default(),
             new_solver_coherence_evaluation_cache: Default::default(),
+            canonical_param_env_cache: Default::default(),
             data_layout,
             alloc_map: Lock::new(interpret::AllocMap::new()),
         }

compiler/rustc_trait_selection/src/traits/misc.rs

@@ -9,7 +9,7 @@ use rustc_infer::infer::canonical::Canonical;
 use rustc_infer::infer::{RegionResolutionError, TyCtxtInferExt};
 use rustc_infer::traits::query::NoSolution;
 use rustc_infer::{infer::outlives::env::OutlivesEnvironment, traits::FulfillmentError};
-use rustc_middle::ty::{self, AdtDef, GenericArg, List, ParamEnv, Ty, TyCtxt, TypeVisitableExt};
+use rustc_middle::ty::{self, AdtDef, GenericArg, List, Ty, TyCtxt, TypeVisitableExt};
 use rustc_span::DUMMY_SP;
 
 use super::outlives_bounds::InferCtxtExt;
@@ -209,10 +209,10 @@ pub fn all_fields_implement_trait<'tcx>(
 
 pub fn check_tys_might_be_eq<'tcx>(
     tcx: TyCtxt<'tcx>,
-    canonical: Canonical<'tcx, (ParamEnv<'tcx>, Ty<'tcx>, Ty<'tcx>)>,
+    canonical: Canonical<'tcx, ty::ParamEnvAnd<'tcx, (Ty<'tcx>, Ty<'tcx>)>>,
 ) -> Result<(), NoSolution> {
-    let (infcx, (param_env, ty_a, ty_b), _) =
-        tcx.infer_ctxt().build_with_canonical(DUMMY_SP, &canonical);
+    let (infcx, key, _) = tcx.infer_ctxt().build_with_canonical(DUMMY_SP, &canonical);
+    let (param_env, (ty_a, ty_b)) = key.into_parts();
     let ocx = ObligationCtxt::new(&infcx);
 
     let result = ocx.eq(&ObligationCause::dummy(), param_env, ty_a, ty_b);