Querify MonoItem collection

Author: saethlin

compiler/rustc_middle/src/mir/mono.rs

@@ -556,3 +556,21 @@ impl<'tcx> CodegenUnitNameBuilder<'tcx> {
         Symbol::intern(&cgu_name)
     }
 }
+
+/// See module-level docs on some contect for "mentioned" items.
+#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, HashStable)]
+pub enum CollectionMode {
+    /// Collect items that are used, i.e., actually needed for codegen.
+    ///
+    /// Which items are used can depend on optimization levels, as MIR optimizations can remove
+    /// uses.
+    UsedItems,
+    /// Collect items that are mentioned. The goal of this mode is that it is independent of
+    /// optimizations: the set of "mentioned" items is computed before optimizations are run.
+    ///
+    /// The exact contents of this set are *not* a stable guarantee. (For instance, it is currently
+    /// computed after drop-elaboration. If we ever do some optimizations even in debug builds, we
+    /// might decide to run them before computing mentioned items.) The key property of this set is
+    /// that it is optimization-independent.
+    MentionedItems,
+}

compiler/rustc_middle/src/query/erase.rs

@@ -218,6 +218,10 @@ impl<T0, T1> EraseType for (&'_ T0, &'_ [T1]) {
     type Result = [u8; size_of::<(&'static (), &'static [()])>()];
 }
 
+impl<T0, T1> EraseType for (&'_ [T0], &'_ [T1]) {
+    type Result = [u8; size_of::<(&'static [()], &'static [()])>()];
+}
+
 impl<T0> EraseType for (&'_ T0, Result<(), ErrorGuaranteed>) {
     type Result = [u8; size_of::<(&'static (), Result<(), ErrorGuaranteed>)>()];
 }

compiler/rustc_middle/src/query/keys.rs

@@ -8,6 +8,7 @@ use rustc_span::{DUMMY_SP, Span};
 use rustc_target::abi;
 
 use crate::infer::canonical::CanonicalQueryInput;
+use crate::mir::mono::CollectionMode;
 use crate::ty::fast_reject::SimplifiedType;
 use crate::ty::layout::{TyAndLayout, ValidityRequirement};
 use crate::ty::{self, GenericArg, GenericArgsRef, Ty, TyCtxt};
@@ -591,3 +592,11 @@ impl<'tcx> Key for (ValidityRequirement, ty::ParamEnvAnd<'tcx, Ty<'tcx>>) {
         }
     }
 }
+
+impl<'tcx> Key for (ty::Instance<'tcx>, CollectionMode) {
+    type Cache<V> = DefaultCache<Self, V>;
+
+    fn default_span(&self, _: TyCtxt<'_>) -> Span {
+        DUMMY_SP
+    }
+}

compiler/rustc_middle/src/query/mod.rs

@@ -40,6 +40,7 @@ use rustc_session::cstore::{
 };
 use rustc_session::lint::LintExpectationId;
 use rustc_span::def_id::LOCAL_CRATE;
+use rustc_span::source_map::Spanned;
 use rustc_span::symbol::Symbol;
 use rustc_span::{DUMMY_SP, Span};
 use rustc_target::abi;
@@ -60,7 +61,7 @@ use crate::mir::interpret::{
     EvalStaticInitializerRawResult, EvalToAllocationRawResult, EvalToConstValueResult,
     EvalToValTreeResult, GlobalId, LitToConstError, LitToConstInput,
 };
-use crate::mir::mono::CodegenUnit;
+use crate::mir::mono::{CodegenUnit, CollectionMode, MonoItem};
 use crate::query::erase::{Erase, erase, restore};
 use crate::query::plumbing::{
     CyclePlaceholder, DynamicQuery, query_ensure, query_ensure_error_guaranteed, query_get_at,
@@ -2315,6 +2316,11 @@ rustc_queries! {
         desc { "whether the item should be made inlinable across crates" }
         separate_provide_extern
     }
+
+    query items_of_instance(key: (ty::Instance<'tcx>, CollectionMode)) -> (&'tcx [Spanned<MonoItem<'tcx>>], &'tcx [Spanned<MonoItem<'tcx>>]) {
+        desc { "collecting used items" }
+        cache_on_disk_if { true }
+    }
 }
 
 rustc_query_append! { define_callbacks! }

compiler/rustc_monomorphize/src/collector.rs

@@ -218,7 +218,7 @@ use rustc_hir::def_id::{DefId, DefIdMap, LocalDefId};
 use rustc_hir::lang_items::LangItem;
 use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrFlags;
 use rustc_middle::mir::interpret::{AllocId, ErrorHandled, GlobalAlloc, Scalar};
-use rustc_middle::mir::mono::{InstantiationMode, MonoItem};
+use rustc_middle::mir::mono::{CollectionMode, InstantiationMode, MonoItem};
 use rustc_middle::mir::visit::Visitor as MirVisitor;
 use rustc_middle::mir::{self, Location, MentionedItem, traversal};
 use rustc_middle::query::TyCtxtAt;
@@ -268,24 +268,6 @@ struct SharedState<'tcx> {
     usage_map: MTLock<UsageMap<'tcx>>,
 }
 
-/// See module-level docs on some contect for "mentioned" items.
-#[derive(Copy, Clone, Debug, PartialEq)]
-enum CollectionMode {
-    /// Collect items that are used, i.e., actually needed for codegen.
-    ///
-    /// Which items are used can depend on optimization levels, as MIR optimizations can remove
-    /// uses.
-    UsedItems,
-    /// Collect items that are mentioned. The goal of this mode is that it is independent of
-    /// optimizations: the set of "mentioned" items is computed before optimizations are run.
-    ///
-    /// The exact contents of this set are *not* a stable guarantee. (For instance, it is currently
-    /// computed after drop-elaboration. If we ever do some optimizations even in debug builds, we
-    /// might decide to run them before computing mentioned items.) The key property of this set is
-    /// that it is optimization-independent.
-    MentionedItems,
-}
-
 impl<'tcx> UsageMap<'tcx> {
     fn new() -> UsageMap<'tcx> {
         UsageMap { used_map: Default::default(), user_map: Default::default() }
@@ -447,13 +429,9 @@ fn collect_items_rec<'tcx>(
             ));
 
             rustc_data_structures::stack::ensure_sufficient_stack(|| {
-                collect_items_of_instance(
-                    tcx,
-                    instance,
-                    &mut used_items,
-                    &mut mentioned_items,
-                    mode,
-                )
+                let (used, mentioned) = tcx.items_of_instance((instance, mode));
+                used_items.extend(used);
+                mentioned_items.extend(mentioned);
             });
         }
         MonoItem::GlobalAsm(item_id) => {
@@ -1253,6 +1231,16 @@ fn collect_items_of_instance<'tcx>(
     }
 }
 
+fn items_of_instance<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    (instance, mode): (Instance<'tcx>, CollectionMode),
+) -> (&'tcx [Spanned<MonoItem<'tcx>>], &'tcx [Spanned<MonoItem<'tcx>>]) {
+    let mut used_items = MonoItems::default();
+    let mut mentioned_items = MonoItems::default();
+    collect_items_of_instance(tcx, instance, &mut used_items, &mut mentioned_items, mode);
+    (tcx.arena.alloc_slice(&used_items), tcx.arena.alloc_slice(&mentioned_items))
+}
+
 /// `item` must be already monomorphized.
 #[instrument(skip(tcx, span, output), level = "debug")]
 fn visit_mentioned_item<'tcx>(
@@ -1623,4 +1611,5 @@ pub(crate) fn collect_crate_mono_items<'tcx>(
 
 pub(crate) fn provide(providers: &mut Providers) {
     providers.hooks.should_codegen_locally = should_codegen_locally;
+    providers.items_of_instance = items_of_instance;
 }