Rollup merge of #67797 - Aaron1011:feature/instance-query, r=nikomatsakis

Query-ify Instance::resolve

Split off from #65989

Instance::resolve is now a wrapper for a new `resolve_instance` query.
This greatly improves performance on several benchmarks

src/librustc_interface/callbacks.rs

@@ -58,5 +58,4 @@ pub fn setup_callbacks() {
     rustc_span::SPAN_DEBUG.swap(&(span_debug as fn(_, &mut fmt::Formatter<'_>) -> _));
     rustc_hir::def_id::DEF_ID_DEBUG.swap(&(def_id_debug as fn(_, &mut fmt::Formatter<'_>) -> _));
     TRACK_DIAGNOSTICS.swap(&(track_diagnostic as fn(&_)));
-    rustc_middle::ty::RESOLVE_INSTANCE.swap(&(rustc_ty::instance::resolve_instance as _));
 }

src/librustc_middle/query/mod.rs

@@ -1257,5 +1257,9 @@ fn describe_as_module(def_id: DefId, tcx: TyCtxt<'_>) -> String {
             eval_always
             desc { "looking up enabled feature gates" }
         }
+
+        query resolve_instance(key: (ty::ParamEnv<'tcx>, DefId, SubstsRef<'tcx>)) -> Option<ty::Instance<'tcx>> {
+            desc { "resolving instance `{:?}` `{:?}` with {:?}", key.1, key.2, key.0 }
+        }
     }
 }

src/librustc_middle/ty/instance.rs

@@ -1,7 +1,6 @@
 use crate::middle::codegen_fn_attrs::CodegenFnAttrFlags;
 use crate::ty::print::{FmtPrinter, Printer};
 use crate::ty::{self, SubstsRef, Ty, TyCtxt, TypeFoldable};
-use rustc_data_structures::AtomicRef;
 use rustc_hir::def::Namespace;
 use rustc_hir::def_id::{CrateNum, DefId};
 use rustc_hir::lang_items::DropInPlaceFnLangItem;
@@ -289,7 +288,9 @@ pub fn resolve(
         def_id: DefId,
         substs: SubstsRef<'tcx>,
     ) -> Option<Instance<'tcx>> {
-        (*RESOLVE_INSTANCE)(tcx, param_env, def_id, substs)
+        // All regions in the result of this query are erased, so it's
+        // fine to erase all of the input regions.
+        tcx.resolve_instance((tcx.erase_regions(&param_env), def_id, tcx.erase_regions(&substs)))
     }
 
     pub fn resolve_for_fn_ptr(
@@ -440,21 +441,3 @@ fn needs_fn_once_adapter_shim(
         (ty::ClosureKind::FnMut, _) | (ty::ClosureKind::FnOnce, _) => Err(()),
     }
 }
-
-fn resolve_instance_default(
-    _tcx: TyCtxt<'tcx>,
-    _param_env: ty::ParamEnv<'tcx>,
-    _def_id: DefId,
-    _substs: SubstsRef<'tcx>,
-) -> Option<Instance<'tcx>> {
-    unimplemented!()
-}
-
-pub static RESOLVE_INSTANCE: AtomicRef<
-    for<'tcx> fn(
-        TyCtxt<'tcx>,
-        ty::ParamEnv<'tcx>,
-        DefId,
-        SubstsRef<'tcx>,
-    ) -> Option<Instance<'tcx>>,
-> = AtomicRef::new(&(resolve_instance_default as _));

src/librustc_middle/ty/mod.rs

@@ -81,7 +81,6 @@
     CtxtInterners, GeneratorInteriorTypeCause, GlobalCtxt, Lift, TypeckTables,
 };
 
-pub use self::instance::RESOLVE_INSTANCE;
 pub use self::instance::{Instance, InstanceDef};
 
 pub use self::trait_def::TraitDef;

src/librustc_middle/ty/query/keys.rs

@@ -296,3 +296,14 @@ fn default_span(&self, _tcx: TyCtxt<'_>) -> Span {
         DUMMY_SP
     }
 }
+
+impl<'tcx> Key for (ty::ParamEnv<'tcx>, DefId, SubstsRef<'tcx>) {
+    type CacheSelector = DefaultCacheSelector;
+
+    fn query_crate(&self) -> CrateNum {
+        self.1.krate
+    }
+    fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
+        tcx.def_span(self.1)
+    }
+}

src/librustc_ty/instance.rs

@@ -11,9 +11,7 @@
 
 pub fn resolve_instance<'tcx>(
     tcx: TyCtxt<'tcx>,
-    param_env: ty::ParamEnv<'tcx>,
-    def_id: DefId,
-    substs: SubstsRef<'tcx>,
+    (param_env, def_id, substs): (ty::ParamEnv<'tcx>, DefId, SubstsRef<'tcx>),
 ) -> Option<Instance<'tcx>> {
     debug!("resolve(def_id={:?}, substs={:?})", def_id, substs);
     let result = if let Some(trait_def_id) = tcx.trait_of_item(def_id) {
@@ -199,3 +197,7 @@ fn resolve_associated_item<'tcx>(
         traits::VtableAutoImpl(..) | traits::VtableParam(..) | traits::VtableTraitAlias(..) => None,
     }
 }
+
+pub fn provide(providers: &mut ty::query::Providers<'_>) {
+    *providers = ty::query::Providers { resolve_instance, ..*providers };
+}

src/librustc_ty/lib.rs

@@ -25,4 +25,5 @@ pub fn provide(providers: &mut Providers<'_>) {
     common_traits::provide(providers);
     needs_drop::provide(providers);
     ty::provide(providers);
+    instance::provide(providers);
 }