Auto merge of #108638 - Zoxc:erase-query-values-map, r=cjgillot

Use dynamic dispatch for queries

This replaces most concrete query values `V` with `MaybeUninit<[u8; { size_of::<V>() }]>` reducing the code instantiated by queries. The compile time of `rustc_query_impl` is reduced by 27%. It is an alternative to https://github.com/rust-lang/rust/pull/107937 which uses unstable const generics while this uses a `EraseType` trait which maps query values to their erased variant.

This is achieved by introducing an `Erased` type which does sanity check with `cfg(debug_assertions)`. The query caches gets instantiated with these erased types leaving the code in `rustc_query_system` unaware of them. `rustc_query_system` is changed to use instances of `QueryConfig` so that `rustc_query_impl` can pass in `DynamicConfig` which holds a pointer to a virtual table.

<table><tr><td rowspan="2">Benchmark</td><td colspan="1"><b>Before</b></th><td colspan="2"><b>After</b></th></tr><tr><td align="right">Time</td><td align="right">Time</td><td align="right">%</th></tr><tr><td>🟣 <b>clap</b>:check</td><td align="right">1.7055s</td><td align="right">1.6949s</td><td align="right"> -0.62%</td></tr><tr><td>🟣 <b>hyper</b>:check</td><td align="right">0.2547s</td><td align="right">0.2528s</td><td align="right"> -0.73%</td></tr><tr><td>🟣 <b>regex</b>:check</td><td align="right">0.9590s</td><td align="right">0.9553s</td><td align="right"> -0.39%</td></tr><tr><td>🟣 <b>syn</b>:check</td><td align="right">1.5457s</td><td align="right">1.5440s</td><td align="right"> -0.11%</td></tr><tr><td>🟣 <b>syntex_syntax</b>:check</td><td align="right">5.9092s</td><td align="right">5.9009s</td><td align="right"> -0.14%</td></tr><tr><td>Total</td><td align="right">10.3741s</td><td align="right">10.3479s</td><td align="right"> -0.25%</td></tr><tr><td>Summary</td><td align="right">1.0000s</td><td align="right">0.9960s</td><td align="right"> -0.40%</td></tr></table>

<table><tr><td rowspan="2">Benchmark</td><td colspan="1"><b>Before</b></th><td colspan="2"><b>After</b></th></tr><tr><td align="right">Time</td><td align="right">Time</td><td align="right">%</th></tr><tr><td>🟣 <b>clap</b>:check:initial</td><td align="right">2.0605s</td><td align="right">2.0575s</td><td align="right"> -0.15%</td></tr><tr><td>🟣 <b>hyper</b>:check:initial</td><td align="right">0.3218s</td><td align="right">0.3216s</td><td align="right"> -0.07%</td></tr><tr><td>🟣 <b>regex</b>:check:initial</td><td align="right">1.1848s</td><td align="right">1.1839s</td><td align="right"> -0.07%</td></tr><tr><td>🟣 <b>syn</b>:check:initial</td><td align="right">1.9409s</td><td align="right">1.9376s</td><td align="right"> -0.17%</td></tr><tr><td>🟣 <b>syntex_syntax</b>:check:initial</td><td align="right">7.3105s</td><td align="right">7.2928s</td><td align="right"> -0.24%</td></tr><tr><td>Total</td><td align="right">12.8185s</td><td align="right">12.7935s</td><td align="right"> -0.20%</td></tr><tr><td>Summary</td><td align="right">1.0000s</td><td align="right">0.9986s</td><td align="right"> -0.14%</td></tr></table>

<table><tr><td rowspan="2">Benchmark</td><td colspan="1"><b>Before</b></th><td colspan="2"><b>After</b></th></tr><tr><td align="right">Time</td><td align="right">Time</td><td align="right">%</th></tr><tr><td>🟣 <b>clap</b>:check:unchanged</td><td align="right">0.4606s</td><td align="right">0.4617s</td><td align="right"> 0.24%</td></tr><tr><td>🟣 <b>hyper</b>:check:unchanged</td><td align="right">0.1335s</td><td align="right">0.1336s</td><td align="right"> 0.08%</td></tr><tr><td>🟣 <b>regex</b>:check:unchanged</td><td align="right">0.3324s</td><td align="right">0.3346s</td><td align="right"> 0.65%</td></tr><tr><td>🟣 <b>syn</b>:check:unchanged</td><td align="right">0.6268s</td><td align="right">0.6307s</td><td align="right"> 0.64%</td></tr><tr><td>🟣 <b>syntex_syntax</b>:check:unchanged</td><td align="right">1.8248s</td><td align="right">1.8508s</td><td align="right">💔  1.43%</td></tr><tr><td>Total</td><td align="right">3.3779s</td><td align="right">3.4113s</td><td align="right"> 0.99%</td></tr><tr><td>Summary</td><td align="right">1.0000s</td><td align="right">1.0061s</td><td align="right"> 0.61%</td></tr></table>

It's based on https://github.com/rust-lang/rust/pull/108167.

r? `@cjgillot`

1 files changed, 182 insertions, 19 deletions

diff --git a/compiler/rustc_query_impl/src/lib.rs b/compiler/rustc_query_impl/src/lib.rs
index 82b335f4b4b..39ca4659541 100644
--- a/compiler/rustc_query_impl/src/lib.rs
+++ b/compiler/rustc_query_impl/src/lib.rs
@@ -3,11 +3,12 @@
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 // this shouldn't be necessary, but the check for `&mut _` is too naive and denies returning a function pointer that takes a mut ref
 #![feature(const_mut_refs)]
+#![feature(const_refs_to_cell)]
 #![feature(min_specialization)]
 #![feature(never_type)]
 #![feature(rustc_attrs)]
 #![recursion_limit = "256"]
-#![allow(rustc::potential_query_instability)]
+#![allow(rustc::potential_query_instability, unused_parens)]
 #![deny(rustc::untranslatable_diagnostic)]
 #![deny(rustc::diagnostic_outside_of_impl)]
 
@@ -15,16 +16,27 @@
 extern crate rustc_middle;
 
 use crate::plumbing::{encode_all_query_results, try_mark_green};
+use field_offset::offset_of;
+use rustc_data_structures::stable_hasher::HashStable;
+use rustc_data_structures::sync::AtomicU64;
 use rustc_middle::arena::Arena;
+use rustc_middle::dep_graph::DepNodeIndex;
 use rustc_middle::dep_graph::{self, DepKind, DepKindStruct};
 use rustc_middle::query::erase::{erase, restore, Erase};
+use rustc_middle::query::on_disk_cache::OnDiskCache;
 use rustc_middle::query::AsLocalKey;
 use rustc_middle::ty::query::{
     query_keys, query_provided, query_provided_to_value, query_storage, query_values,
+    DynamicQueries, DynamicQuery, ExternProviders, Providers, QueryCaches, QueryEngine,
+    QueryStates, QuerySystem, QuerySystemFns,
 };
-use rustc_middle::ty::query::{ExternProviders, Providers, QueryEngine, QuerySystemFns};
 use rustc_middle::ty::TyCtxt;
 use rustc_query_system::dep_graph::SerializedDepNodeIndex;
+use rustc_query_system::ich::StableHashingContext;
+use rustc_query_system::query::{
+    get_query, HashResult, QueryCache, QueryConfig, QueryInfo, QueryMap, QueryMode, QueryState,
+};
+use rustc_query_system::HandleCycleError;
 use rustc_query_system::Value;
 use rustc_span::Span;
 
@@ -32,31 +44,182 @@ use rustc_span::Span;
 mod plumbing;
 pub use crate::plumbing::QueryCtxt;
 
-pub use rustc_query_system::query::QueryConfig;
-use rustc_query_system::query::*;
-
 mod profiling_support;
 pub use self::profiling_support::alloc_self_profile_query_strings;
 
-/// This is implemented per query and restoring query values from their erased state.
-trait QueryConfigRestored<'tcx>: QueryConfig<QueryCtxt<'tcx>> + Default {
-    type RestoredValue;
+struct DynamicConfig<
+    'tcx,
+    C: QueryCache,
+    const ANON: bool,
+    const DEPTH_LIMIT: bool,
+    const FEEDABLE: bool,
+> {
+    dynamic: &'tcx DynamicQuery<'tcx, C>,
+}
 
-    fn restore(value: <Self as QueryConfig<QueryCtxt<'tcx>>>::Value) -> Self::RestoredValue;
+impl<'tcx, C: QueryCache, const ANON: bool, const DEPTH_LIMIT: bool, const FEEDABLE: bool> Copy
+    for DynamicConfig<'tcx, C, ANON, DEPTH_LIMIT, FEEDABLE>
+{
+}
+impl<'tcx, C: QueryCache, const ANON: bool, const DEPTH_LIMIT: bool, const FEEDABLE: bool> Clone
+    for DynamicConfig<'tcx, C, ANON, DEPTH_LIMIT, FEEDABLE>
+{
+    fn clone(&self) -> Self {
+        DynamicConfig { dynamic: self.dynamic }
+    }
 }
 
-rustc_query_append! { define_queries! }
+impl<'tcx, C: QueryCache, const ANON: bool, const DEPTH_LIMIT: bool, const FEEDABLE: bool>
+    QueryConfig<QueryCtxt<'tcx>> for DynamicConfig<'tcx, C, ANON, DEPTH_LIMIT, FEEDABLE>
+where
+    for<'a> C::Key: HashStable<StableHashingContext<'a>>,
+{
+    type Key = C::Key;
+    type Value = C::Value;
+    type Cache = C;
+
+    #[inline(always)]
+    fn name(self) -> &'static str {
+        self.dynamic.name
+    }
+
+    #[inline(always)]
+    fn cache_on_disk(self, tcx: TyCtxt<'tcx>, key: &Self::Key) -> bool {
+        (self.dynamic.cache_on_disk)(tcx, key)
+    }
+
+    #[inline(always)]
+    fn query_state<'a>(self, qcx: QueryCtxt<'tcx>) -> &'a QueryState<Self::Key, DepKind>
+    where
+        QueryCtxt<'tcx>: 'a,
+    {
+        self.dynamic.query_state.apply(&qcx.tcx.query_system.states)
+    }
+
+    #[inline(always)]
+    fn query_cache<'a>(self, qcx: QueryCtxt<'tcx>) -> &'a Self::Cache
+    where
+        'tcx: 'a,
+    {
+        self.dynamic.query_cache.apply(&qcx.tcx.query_system.caches)
+    }
+
+    #[inline(always)]
+    fn execute_query(self, tcx: TyCtxt<'tcx>, key: Self::Key) -> Self::Value {
+        (self.dynamic.execute_query)(tcx, key)
+    }
+
+    #[inline(always)]
+    fn compute(self, qcx: QueryCtxt<'tcx>, key: Self::Key) -> Self::Value {
+        (self.dynamic.compute)(qcx.tcx, key)
+    }
+
+    #[inline(always)]
+    fn try_load_from_disk(
+        self,
+        qcx: QueryCtxt<'tcx>,
+        key: &Self::Key,
+        prev_index: SerializedDepNodeIndex,
+        index: DepNodeIndex,
+    ) -> Option<Self::Value> {
+        if self.dynamic.can_load_from_disk {
+            (self.dynamic.try_load_from_disk)(qcx.tcx, key, prev_index, index)
+        } else {
+            None
+        }
+    }
+
+    #[inline]
+    fn loadable_from_disk(
+        self,
+        qcx: QueryCtxt<'tcx>,
+        key: &Self::Key,
+        index: SerializedDepNodeIndex,
+    ) -> bool {
+        (self.dynamic.loadable_from_disk)(qcx.tcx, key, index)
+    }
+
+    fn value_from_cycle_error(
+        self,
+        tcx: TyCtxt<'tcx>,
+        cycle: &[QueryInfo<DepKind>],
+    ) -> Self::Value {
+        (self.dynamic.value_from_cycle_error)(tcx, cycle)
+    }
+
+    #[inline(always)]
+    fn format_value(self) -> fn(&Self::Value) -> String {
+        self.dynamic.format_value
+    }
+
+    #[inline(always)]
+    fn anon(self) -> bool {
+        ANON
+    }
+
+    #[inline(always)]
+    fn eval_always(self) -> bool {
+        self.dynamic.eval_always
+    }
+
+    #[inline(always)]
+    fn depth_limit(self) -> bool {
+        DEPTH_LIMIT
+    }
+
+    #[inline(always)]
+    fn feedable(self) -> bool {
+        FEEDABLE
+    }
+
+    #[inline(always)]
+    fn dep_kind(self) -> DepKind {
+        self.dynamic.dep_kind
+    }
+
+    #[inline(always)]
+    fn handle_cycle_error(self) -> HandleCycleError {
+        self.dynamic.handle_cycle_error
+    }
+
+    #[inline(always)]
+    fn hash_result(self) -> HashResult<Self::Value> {
+        self.dynamic.hash_result
+    }
+}
 
-pub fn query_system_fns<'tcx>(
+/// This is implemented per query. It allows restoring query values from their erased state
+/// and constructing a QueryConfig.
+trait QueryConfigRestored<'tcx> {
+    type RestoredValue;
+    type Config: QueryConfig<QueryCtxt<'tcx>>;
+
+    fn config(tcx: TyCtxt<'tcx>) -> Self::Config;
+    fn restore(value: <Self::Config as QueryConfig<QueryCtxt<'tcx>>>::Value)
+    -> Self::RestoredValue;
+}
+
+pub fn query_system<'tcx>(
     local_providers: Providers,
     extern_providers: ExternProviders,
-) -> QuerySystemFns<'tcx> {
-    QuerySystemFns {
-        engine: engine(),
-        local_providers,
-        extern_providers,
-        query_structs: make_dep_kind_array!(query_structs).to_vec(),
-        encode_query_results: encode_all_query_results,
-        try_mark_green: try_mark_green,
+    on_disk_cache: Option<OnDiskCache<'tcx>>,
+) -> QuerySystem<'tcx> {
+    QuerySystem {
+        states: Default::default(),
+        arenas: Default::default(),
+        caches: Default::default(),
+        dynamic_queries: dynamic_queries(),
+        on_disk_cache,
+        fns: QuerySystemFns {
+            engine: engine(),
+            local_providers,
+            extern_providers,
+            query_structs: make_dep_kind_array!(query_structs).to_vec(),
+            encode_query_results: encode_all_query_results,
+            try_mark_green: try_mark_green,
+        },
+        jobs: AtomicU64::new(1),
     }
 }
+
+rustc_query_append! { define_queries! }