Auto merge of rust-lang#128408 - Bryanskiy:delegation-perf, r=<try>

Delegation: querify `sig_id` getter

Possible perf fix for rust-lang#125929

r? `@petrochenkov`

compiler/rustc_hir_analysis/src/collect/generics_of.rs

@@ -55,7 +55,7 @@ pub(super) fn generics_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Generics {
     }
 
     // For a delegation item inherit generics from callee.
-    if let Some(sig_id) = tcx.hir().opt_delegation_sig_id(def_id)
+    if let Some(sig_id) = tcx.opt_delegation_sig_id(def_id)
         && let Some(generics) = inherit_generics_for_delegation_item(tcx, def_id, sig_id)
     {
         return generics;

compiler/rustc_hir_analysis/src/collect/predicates_of.rs

@@ -116,7 +116,7 @@ fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Gen
     }
 
     // For a delegation item inherit predicates from callee.
-    if let Some(sig_id) = tcx.hir().opt_delegation_sig_id(def_id)
+    if let Some(sig_id) = tcx.opt_delegation_sig_id(def_id)
         && let Some(predicates) = inherit_predicates_for_delegation_item(tcx, def_id, sig_id)
     {
         return predicates;

compiler/rustc_hir_analysis/src/delegation.rs

@@ -1,6 +1,8 @@
 use rustc_data_structures::fx::FxHashMap;
+use rustc_hir as hir;
 use rustc_hir::def::DefKind;
 use rustc_hir::def_id::{DefId, LocalDefId};
+use rustc_middle::query::Providers;
 use rustc_middle::ty::fold::{TypeFoldable, TypeFolder, TypeSuperFoldable};
 use rustc_middle::ty::{self, Ty, TyCtxt};
 use rustc_span::ErrorGuaranteed;
@@ -217,7 +219,7 @@ fn check_constraints<'tcx>(
     }
 
     if let Some(local_sig_id) = sig_id.as_local()
-        && tcx.hir().opt_delegation_sig_id(local_sig_id).is_some()
+        && tcx.opt_delegation_sig_id(local_sig_id).is_some()
     {
         emit("recursive delegation is not supported yet");
     }
@@ -242,7 +244,7 @@ pub(crate) fn inherit_sig_for_delegation_item<'tcx>(
     tcx: TyCtxt<'tcx>,
     def_id: LocalDefId,
 ) -> &'tcx [Ty<'tcx>] {
-    let sig_id = tcx.hir().delegation_sig_id(def_id);
+    let sig_id = tcx.opt_delegation_sig_id(def_id).unwrap();
     let caller_sig = tcx.fn_sig(sig_id);
     if let Err(err) = check_constraints(tcx, def_id, sig_id) {
         let sig_len = caller_sig.instantiate_identity().skip_binder().inputs().len() + 1;
@@ -257,3 +259,17 @@ pub(crate) fn inherit_sig_for_delegation_item<'tcx>(
     let sig_iter = sig.inputs().iter().cloned().chain(std::iter::once(sig.output()));
     tcx.arena.alloc_from_iter(sig_iter)
 }
+
+pub(crate) fn opt_delegation_sig_id<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> Option<DefId> {
+    if let Some(ret) = tcx.hir().get_fn_output(def_id)
+        && let hir::FnRetTy::Return(ty) = ret
+        && let hir::TyKind::InferDelegation(sig_id, _) = ty.kind
+    {
+        return Some(sig_id);
+    }
+    None
+}
+
+pub fn provide(providers: &mut Providers) {
+    *providers = Providers { inherit_sig_for_delegation_item, opt_delegation_sig_id, ..*providers };
+}

compiler/rustc_hir_analysis/src/lib.rs

@@ -147,10 +147,7 @@ pub fn provide(providers: &mut Providers) {
     variance::provide(providers);
     outlives::provide(providers);
     hir_wf_check::provide(providers);
-    *providers = Providers {
-        inherit_sig_for_delegation_item: delegation::inherit_sig_for_delegation_item,
-        ..*providers
-    };
+    delegation::provide(providers);
 }
 
 pub fn check_crate(tcx: TyCtxt<'_>) {

compiler/rustc_middle/src/hir/map/mod.rs

@@ -746,21 +746,6 @@ impl<'hir> Map<'hir> {
         }
     }
 
-    pub fn opt_delegation_sig_id(self, def_id: LocalDefId) -> Option<DefId> {
-        if let Some(ret) = self.get_fn_output(def_id)
-            && let FnRetTy::Return(ty) = ret
-            && let TyKind::InferDelegation(sig_id, _) = ty.kind
-        {
-            return Some(sig_id);
-        }
-        None
-    }
-
-    #[inline]
-    pub fn delegation_sig_id(self, def_id: LocalDefId) -> DefId {
-        self.opt_delegation_sig_id(def_id).unwrap()
-    }
-
     #[inline]
     fn opt_ident(self, id: HirId) -> Option<Ident> {
         match self.tcx.hir_node(id) {

compiler/rustc_middle/src/query/mod.rs

@@ -1722,6 +1722,10 @@ rustc_queries! {
         desc { |tcx| "getting the native library for `{}`", tcx.def_path_str(def_id) }
     }
 
+    query opt_delegation_sig_id(def_id: LocalDefId) -> Option<DefId> {
+        desc { "getting the item from which the signature is inherited when delegating" }
+    }
+
     query inherit_sig_for_delegation_item(def_id: LocalDefId) -> &'tcx [Ty<'tcx>] {
         desc { "inheriting delegation signature" }
     }