Merging upstream version 1.73.0+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

4 files changed, 179 insertions, 130 deletions

diff --git a/compiler/rustc_monomorphize/src/collector.rs b/compiler/rustc_monomorphize/src/collector.rs
index 242269e9d..55b14ce1c 100644
--- a/compiler/rustc_monomorphize/src/collector.rs
+++ b/compiler/rustc_monomorphize/src/collector.rs
@@ -178,11 +178,11 @@ use rustc_middle::mir::{self, Local, Location};
 use rustc_middle::query::TyCtxtAt;
 use rustc_middle::ty::adjustment::{CustomCoerceUnsized, PointerCoercion};
 use rustc_middle::ty::print::with_no_trimmed_paths;
-use rustc_middle::ty::subst::{GenericArgKind, InternalSubsts};
 use rustc_middle::ty::{
     self, GenericParamDefKind, Instance, InstanceDef, Ty, TyCtxt, TypeFoldable, TypeVisitableExt,
     VtblEntry,
 };
+use rustc_middle::ty::{GenericArgKind, GenericArgs};
 use rustc_middle::{middle::codegen_fn_attrs::CodegenFnAttrFlags, mir::visit::TyContext};
 use rustc_session::config::EntryFnType;
 use rustc_session::lint::builtin::LARGE_ASSIGNMENTS;
@@ -384,7 +384,7 @@ fn collect_items_rec<'tcx>(
 
             if let Ok(alloc) = tcx.eval_static_initializer(def_id) {
                 for &id in alloc.inner().provenance().ptrs().values() {
-                    collect_miri(tcx, id, &mut used_items);
+                    collect_alloc(tcx, id, &mut used_items);
                 }
             }
 
@@ -393,7 +393,7 @@ fn collect_items_rec<'tcx>(
                     starting_item.span,
                     MonoItem::Fn(Instance {
                         def: InstanceDef::ThreadLocalShim(def_id),
-                        substs: InternalSubsts::empty(),
+                        args: GenericArgs::empty(),
                     }),
                 ));
             }
@@ -555,7 +555,7 @@ fn check_recursion_limit<'tcx>(
 
 fn check_type_length_limit<'tcx>(tcx: TyCtxt<'tcx>, instance: Instance<'tcx>) {
     let type_length = instance
-        .substs
+        .args
         .iter()
         .flat_map(|arg| arg.walk())
         .filter(|arg| match arg.unpack() {
@@ -659,11 +659,11 @@ impl<'a, 'tcx> MirVisitor<'tcx> for MirUsedCollector<'a, 'tcx> {
                 let source_ty = operand.ty(self.body, self.tcx);
                 let source_ty = self.monomorphize(source_ty);
                 match *source_ty.kind() {
-                    ty::Closure(def_id, substs) => {
+                    ty::Closure(def_id, args) => {
                         let instance = Instance::resolve_closure(
                             self.tcx,
                             def_id,
-                            substs,
+                            args,
                             ty::ClosureKind::FnOnce,
                         )
                         .expect("failed to normalize and resolve closure during codegen");
@@ -875,12 +875,11 @@ fn visit_fn_use<'tcx>(
     source: Span,
     output: &mut MonoItems<'tcx>,
 ) {
-    if let ty::FnDef(def_id, substs) = *ty.kind() {
+    if let ty::FnDef(def_id, args) = *ty.kind() {
         let instance = if is_direct_call {
-            ty::Instance::expect_resolve(tcx, ty::ParamEnv::reveal_all(), def_id, substs)
+            ty::Instance::expect_resolve(tcx, ty::ParamEnv::reveal_all(), def_id, args)
         } else {
-            match ty::Instance::resolve_for_fn_ptr(tcx, ty::ParamEnv::reveal_all(), def_id, substs)
-            {
+            match ty::Instance::resolve_for_fn_ptr(tcx, ty::ParamEnv::reveal_all(), def_id, args) {
                 Some(instance) => instance,
                 _ => bug!("failed to resolve instance for {ty}"),
             }
@@ -1043,7 +1042,7 @@ fn find_vtable_types_for_unsizing<'tcx>(
         // T as dyn* Trait
         (_, &ty::Dynamic(_, _, ty::DynStar)) => ptr_vtable(source_ty, target_ty),
 
-        (&ty::Adt(source_adt_def, source_substs), &ty::Adt(target_adt_def, target_substs)) => {
+        (&ty::Adt(source_adt_def, source_args), &ty::Adt(target_adt_def, target_args)) => {
             assert_eq!(source_adt_def, target_adt_def);
 
             let CustomCoerceUnsized::Struct(coerce_index) =
@@ -1059,8 +1058,8 @@ fn find_vtable_types_for_unsizing<'tcx>(
 
             find_vtable_types_for_unsizing(
                 tcx,
-                source_fields[coerce_index].ty(*tcx, source_substs),
-                target_fields[coerce_index].ty(*tcx, target_substs),
+                source_fields[coerce_index].ty(*tcx, source_args),
+                target_fields[coerce_index].ty(*tcx, target_args),
             )
         }
         _ => bug!(
@@ -1245,7 +1244,7 @@ impl<'v> RootCollector<'_, 'v> {
             self.tcx,
             ty::ParamEnv::reveal_all(),
             start_def_id,
-            self.tcx.mk_substs(&[main_ret_ty.into()]),
+            self.tcx.mk_args(&[main_ret_ty.into()]),
         )
         .unwrap()
         .unwrap();
@@ -1292,8 +1291,8 @@ fn create_mono_items_for_default_impls<'tcx>(
             )
         }
     };
-    let impl_substs = InternalSubsts::for_item(tcx, item.owner_id.to_def_id(), only_region_params);
-    let trait_ref = trait_ref.subst(tcx, impl_substs);
+    let impl_args = GenericArgs::for_item(tcx, item.owner_id.to_def_id(), only_region_params);
+    let trait_ref = trait_ref.instantiate(tcx, impl_args);
 
     // Unlike 'lazy' monomorphization that begins by collecting items transitively
     // called by `main` or other global items, when eagerly monomorphizing impl
@@ -1304,7 +1303,7 @@ fn create_mono_items_for_default_impls<'tcx>(
     // consider higher-ranked predicates such as `for<'a> &'a mut [u8]: Copy` to
     // be trivially false. We must now check that the impl has no impossible-to-satisfy
     // predicates.
-    if tcx.subst_and_check_impossible_predicates((item.owner_id.to_def_id(), impl_substs)) {
+    if tcx.subst_and_check_impossible_predicates((item.owner_id.to_def_id(), impl_args)) {
         return;
     }
 
@@ -1322,8 +1321,8 @@ fn create_mono_items_for_default_impls<'tcx>(
 
         // As mentioned above, the method is legal to eagerly instantiate if it
         // only has lifetime substitutions. This is validated by
-        let substs = trait_ref.substs.extend_to(tcx, method.def_id, only_region_params);
-        let instance = ty::Instance::expect_resolve(tcx, param_env, method.def_id, substs);
+        let args = trait_ref.args.extend_to(tcx, method.def_id, only_region_params);
+        let instance = ty::Instance::expect_resolve(tcx, param_env, method.def_id, args);
 
         let mono_item = create_fn_mono_item(tcx, instance, DUMMY_SP);
         if mono_item.node.is_instantiable(tcx) && should_codegen_locally(tcx, &instance) {
@@ -1332,8 +1331,8 @@ fn create_mono_items_for_default_impls<'tcx>(
     }
 }
 
-/// Scans the miri alloc in order to find function calls, closures, and drop-glue.
-fn collect_miri<'tcx>(tcx: TyCtxt<'tcx>, alloc_id: AllocId, output: &mut MonoItems<'tcx>) {
+/// Scans the CTFE alloc in order to find function calls, closures, and drop-glue.
+fn collect_alloc<'tcx>(tcx: TyCtxt<'tcx>, alloc_id: AllocId, output: &mut MonoItems<'tcx>) {
     match tcx.global_alloc(alloc_id) {
         GlobalAlloc::Static(def_id) => {
             assert!(!tcx.is_thread_local_static(def_id));
@@ -1347,7 +1346,7 @@ fn collect_miri<'tcx>(tcx: TyCtxt<'tcx>, alloc_id: AllocId, output: &mut MonoIte
             trace!("collecting {:?} with {:#?}", alloc_id, alloc);
             for &inner in alloc.inner().provenance().ptrs().values() {
                 rustc_data_structures::stack::ensure_sufficient_stack(|| {
-                    collect_miri(tcx, inner, output);
+                    collect_alloc(tcx, inner, output);
                 });
             }
         }
@@ -1359,7 +1358,7 @@ fn collect_miri<'tcx>(tcx: TyCtxt<'tcx>, alloc_id: AllocId, output: &mut MonoIte
         }
         GlobalAlloc::VTable(ty, trait_ref) => {
             let alloc_id = tcx.vtable_allocation((ty, trait_ref));
-            collect_miri(tcx, alloc_id, output)
+            collect_alloc(tcx, alloc_id, output)
         }
     }
 }
@@ -1382,10 +1381,10 @@ fn collect_const_value<'tcx>(
     output: &mut MonoItems<'tcx>,
 ) {
     match value {
-        ConstValue::Scalar(Scalar::Ptr(ptr, _size)) => collect_miri(tcx, ptr.provenance, output),
+        ConstValue::Scalar(Scalar::Ptr(ptr, _size)) => collect_alloc(tcx, ptr.provenance, output),
         ConstValue::Slice { data: alloc, start: _, end: _ } | ConstValue::ByRef { alloc, .. } => {
             for &id in alloc.inner().provenance().ptrs().values() {
-                collect_miri(tcx, id, output);
+                collect_alloc(tcx, id, output);
             }
         }
         _ => {}
diff --git a/compiler/rustc_monomorphize/src/partitioning.rs b/compiler/rustc_monomorphize/src/partitioning.rs
index da76cf223..de6db8ae6 100644
--- a/compiler/rustc_monomorphize/src/partitioning.rs
+++ b/compiler/rustc_monomorphize/src/partitioning.rs
@@ -107,7 +107,8 @@ use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrFlags;
 use rustc_middle::middle::exported_symbols::{SymbolExportInfo, SymbolExportLevel};
 use rustc_middle::mir;
 use rustc_middle::mir::mono::{
-    CodegenUnit, CodegenUnitNameBuilder, InstantiationMode, Linkage, MonoItem, Visibility,
+    CodegenUnit, CodegenUnitNameBuilder, InstantiationMode, Linkage, MonoItem, MonoItemData,
+    Visibility,
 };
 use rustc_middle::query::Providers;
 use rustc_middle::ty::print::{characteristic_def_id_of_type, with_no_trimmed_paths};
@@ -130,11 +131,6 @@ struct PlacedMonoItems<'tcx> {
     codegen_units: Vec<CodegenUnit<'tcx>>,
 
     internalization_candidates: FxHashSet<MonoItem<'tcx>>,
-
-    /// These must be obtained when the iterator in `partition` runs. They
-    /// can't be obtained later because some inlined functions might not be
-    /// reachable.
-    unique_inlined_stats: (usize, usize),
 }
 
 // The output CGUs are sorted by name.
@@ -152,11 +148,11 @@ where
 
     // Place all mono items into a codegen unit. `place_mono_items` is
     // responsible for initializing the CGU size estimates.
-    let PlacedMonoItems { mut codegen_units, internalization_candidates, unique_inlined_stats } = {
+    let PlacedMonoItems { mut codegen_units, internalization_candidates } = {
         let _prof_timer = tcx.prof.generic_activity("cgu_partitioning_place_items");
         let placed = place_mono_items(cx, mono_items);
 
-        debug_dump(tcx, "PLACE", &placed.codegen_units, placed.unique_inlined_stats);
+        debug_dump(tcx, "PLACE", &placed.codegen_units);
 
         placed
     };
@@ -167,7 +163,7 @@ where
     {
         let _prof_timer = tcx.prof.generic_activity("cgu_partitioning_merge_cgus");
         merge_codegen_units(cx, &mut codegen_units);
-        debug_dump(tcx, "MERGE", &codegen_units, unique_inlined_stats);
+        debug_dump(tcx, "MERGE", &codegen_units);
     }
 
     // Make as many symbols "internal" as possible, so LLVM has more freedom to
@@ -176,7 +172,7 @@ where
         let _prof_timer = tcx.prof.generic_activity("cgu_partitioning_internalize_symbols");
         internalize_symbols(cx, &mut codegen_units, internalization_candidates);
 
-        debug_dump(tcx, "INTERNALIZE", &codegen_units, unique_inlined_stats);
+        debug_dump(tcx, "INTERNALIZE", &codegen_units);
     }
 
     // Mark one CGU for dead code, if necessary.
@@ -216,18 +212,12 @@ where
     let cgu_name_builder = &mut CodegenUnitNameBuilder::new(cx.tcx);
     let cgu_name_cache = &mut FxHashMap::default();
 
-    let mut num_unique_inlined_items = 0;
-    let mut unique_inlined_items_size = 0;
     for mono_item in mono_items {
         // Handle only root items directly here. Inlined items are handled at
         // the bottom of the loop based on reachability.
         match mono_item.instantiation_mode(cx.tcx) {
             InstantiationMode::GloballyShared { .. } => {}
-            InstantiationMode::LocalCopy => {
-                num_unique_inlined_items += 1;
-                unique_inlined_items_size += mono_item.size_estimate(cx.tcx);
-                continue;
-            }
+            InstantiationMode::LocalCopy => continue,
         }
 
         let characteristic_def_id = characteristic_def_id_of_mono_item(cx.tcx, mono_item);
@@ -256,8 +246,10 @@ where
         if visibility == Visibility::Hidden && can_be_internalized {
             internalization_candidates.insert(mono_item);
         }
+        let size_estimate = mono_item.size_estimate(cx.tcx);
 
-        cgu.items_mut().insert(mono_item, (linkage, visibility));
+        cgu.items_mut()
+            .insert(mono_item, MonoItemData { inlined: false, linkage, visibility, size_estimate });
 
         // Get all inlined items that are reachable from `mono_item` without
         // going via another root item. This includes drop-glue, functions from
@@ -271,7 +263,12 @@ where
         // the `insert` will be a no-op.
         for inlined_item in reachable_inlined_items {
             // This is a CGU-private copy.
-            cgu.items_mut().insert(inlined_item, (Linkage::Internal, Visibility::Default));
+            cgu.items_mut().entry(inlined_item).or_insert_with(|| MonoItemData {
+                inlined: true,
+                linkage: Linkage::Internal,
+                visibility: Visibility::Default,
+                size_estimate: inlined_item.size_estimate(cx.tcx),
+            });
         }
     }
 
@@ -286,14 +283,10 @@ where
     codegen_units.sort_by(|a, b| a.name().as_str().cmp(b.name().as_str()));
 
     for cgu in codegen_units.iter_mut() {
-        cgu.compute_size_estimate(cx.tcx);
+        cgu.compute_size_estimate();
     }
 
-    return PlacedMonoItems {
-        codegen_units,
-        internalization_candidates,
-        unique_inlined_stats: (num_unique_inlined_items, unique_inlined_items_size),
-    };
+    return PlacedMonoItems { codegen_units, internalization_candidates };
 
     fn get_reachable_inlined_items<'tcx>(
         tcx: TyCtxt<'tcx>,
@@ -325,6 +318,60 @@ fn merge_codegen_units<'tcx>(
     let mut cgu_contents: FxHashMap<Symbol, Vec<Symbol>> =
         codegen_units.iter().map(|cgu| (cgu.name(), vec![cgu.name()])).collect();
 
+    // If N is the maximum number of CGUs, and the CGUs are sorted from largest
+    // to smallest, we repeatedly find which CGU in codegen_units[N..] has the
+    // greatest overlap of inlined items with codegen_units[N-1], merge that
+    // CGU into codegen_units[N-1], then re-sort by size and repeat.
+    //
+    // We use inlined item overlap to guide this merging because it minimizes
+    // duplication of inlined items, which makes LLVM be faster and generate
+    // better and smaller machine code.
+    //
+    // Why merge into codegen_units[N-1]? We want CGUs to have similar sizes,
+    // which means we don't want codegen_units[0..N] (the already big ones)
+    // getting any bigger, if we can avoid it. When we have more than N CGUs
+    // then at least one of the biggest N will have to grow. codegen_units[N-1]
+    // is the smallest of those, and so has the most room to grow.
+    let max_codegen_units = cx.tcx.sess.codegen_units().as_usize();
+    while codegen_units.len() > max_codegen_units {
+        // Sort small CGUs to the back.
+        codegen_units.sort_by_key(|cgu| cmp::Reverse(cgu.size_estimate()));
+
+        let cgu_dst = &codegen_units[max_codegen_units - 1];
+
+        // Find the CGU that overlaps the most with `cgu_dst`. In the case of a
+        // tie, favour the earlier (bigger) CGU.
+        let mut max_overlap = 0;
+        let mut max_overlap_i = max_codegen_units;
+        for (i, cgu_src) in codegen_units.iter().enumerate().skip(max_codegen_units) {
+            if cgu_src.size_estimate() <= max_overlap {
+                // None of the remaining overlaps can exceed `max_overlap`, so
+                // stop looking.
+                break;
+            }
+
+            let overlap = compute_inlined_overlap(cgu_dst, cgu_src);
+            if overlap > max_overlap {
+                max_overlap = overlap;
+                max_overlap_i = i;
+            }
+        }
+
+        let mut cgu_src = codegen_units.swap_remove(max_overlap_i);
+        let cgu_dst = &mut codegen_units[max_codegen_units - 1];
+
+        // Move the items from `cgu_src` to `cgu_dst`. Some of them may be
+        // duplicate inlined items, in which case the destination CGU is
+        // unaffected. Recalculate size estimates afterwards.
+        cgu_dst.items_mut().extend(cgu_src.items_mut().drain());
+        cgu_dst.compute_size_estimate();
+
+        // Record that `cgu_dst` now contains all the stuff that was in
+        // `cgu_src` before.
+        let mut consumed_cgu_names = cgu_contents.remove(&cgu_src.name()).unwrap();
+        cgu_contents.get_mut(&cgu_dst.name()).unwrap().append(&mut consumed_cgu_names);
+    }
+
     // Having multiple CGUs can drastically speed up compilation. But for
     // non-incremental builds, tiny CGUs slow down compilation *and* result in
     // worse generated code. So we don't allow CGUs smaller than this (unless
@@ -332,24 +379,22 @@ fn merge_codegen_units<'tcx>(
     // common in larger programs, so this isn't all that large.
     const NON_INCR_MIN_CGU_SIZE: usize = 1800;
 
-    // Repeatedly merge the two smallest codegen units as long as:
-    // - we have more CGUs than the upper limit, or
-    // - (Non-incremental builds only) the user didn't specify a CGU count, and
-    //   there are multiple CGUs, and some are below the minimum size.
+    // Repeatedly merge the two smallest codegen units as long as: it's a
+    // non-incremental build, and the user didn't specify a CGU count, and
+    // there are multiple CGUs, and some are below the minimum size.
     //
     // The "didn't specify a CGU count" condition is because when an explicit
     // count is requested we observe it as closely as possible. For example,
     // the `compiler_builtins` crate sets `codegen-units = 10000` and it's
     // critical they aren't merged. Also, some tests use explicit small values
     // and likewise won't work if small CGUs are merged.
-    while codegen_units.len() > cx.tcx.sess.codegen_units().as_usize()
-        || (cx.tcx.sess.opts.incremental.is_none()
-            && matches!(cx.tcx.sess.codegen_units(), CodegenUnits::Default(_))
-            && codegen_units.len() > 1
-            && codegen_units.iter().any(|cgu| cgu.size_estimate() < NON_INCR_MIN_CGU_SIZE))
+    while cx.tcx.sess.opts.incremental.is_none()
+        && matches!(cx.tcx.sess.codegen_units(), CodegenUnits::Default(_))
+        && codegen_units.len() > 1
+        && codegen_units.iter().any(|cgu| cgu.size_estimate() < NON_INCR_MIN_CGU_SIZE)
     {
         // Sort small cgus to the back.
-        codegen_units.sort_by_cached_key(|cgu| cmp::Reverse(cgu.size_estimate()));
+        codegen_units.sort_by_key(|cgu| cmp::Reverse(cgu.size_estimate()));
 
         let mut smallest = codegen_units.pop().unwrap();
         let second_smallest = codegen_units.last_mut().unwrap();
@@ -358,18 +403,9 @@ fn merge_codegen_units<'tcx>(
         // may be duplicate inlined items, in which case the destination CGU is
         // unaffected. Recalculate size estimates afterwards.
         second_smallest.items_mut().extend(smallest.items_mut().drain());
-        second_smallest.compute_size_estimate(cx.tcx);
-
-        // Record that `second_smallest` now contains all the stuff that was
-        // in `smallest` before.
-        let mut consumed_cgu_names = cgu_contents.remove(&smallest.name()).unwrap();
-        cgu_contents.get_mut(&second_smallest.name()).unwrap().append(&mut consumed_cgu_names);
+        second_smallest.compute_size_estimate();
 
-        debug!(
-            "CodegenUnit {} merged into CodegenUnit {}",
-            smallest.name(),
-            second_smallest.name()
-        );
+        // Don't update `cgu_contents`, that's only for incremental builds.
     }
 
     let cgu_name_builder = &mut CodegenUnitNameBuilder::new(cx.tcx);
@@ -448,6 +484,25 @@ fn merge_codegen_units<'tcx>(
     }
 }
 
+/// Compute the combined size of all inlined items that appear in both `cgu1`
+/// and `cgu2`.
+fn compute_inlined_overlap<'tcx>(cgu1: &CodegenUnit<'tcx>, cgu2: &CodegenUnit<'tcx>) -> usize {
+    // Either order works. We pick the one that involves iterating over fewer
+    // items.
+    let (src_cgu, dst_cgu) =
+        if cgu1.items().len() <= cgu2.items().len() { (cgu1, cgu2) } else { (cgu2, cgu1) };
+
+    let mut overlap = 0;
+    for (item, data) in src_cgu.items().iter() {
+        if data.inlined {
+            if dst_cgu.items().contains_key(item) {
+                overlap += data.size_estimate;
+            }
+        }
+    }
+    overlap
+}
+
 fn internalize_symbols<'tcx>(
     cx: &PartitioningCx<'_, 'tcx>,
     codegen_units: &mut [CodegenUnit<'tcx>],
@@ -492,7 +547,7 @@ fn internalize_symbols<'tcx>(
     for cgu in codegen_units {
         let home_cgu = MonoItemPlacement::SingleCgu(cgu.name());
 
-        for (item, linkage_and_visibility) in cgu.items_mut() {
+        for (item, data) in cgu.items_mut() {
             if !internalization_candidates.contains(item) {
                 // This item is no candidate for internalizing, so skip it.
                 continue;
@@ -520,7 +575,8 @@ fn internalize_symbols<'tcx>(
 
             // If we got here, we did not find any uses from other CGUs, so
             // it's fine to make this monomorphization internal.
-            *linkage_and_visibility = (Linkage::Internal, Visibility::Default);
+            data.linkage = Linkage::Internal;
+            data.visibility = Visibility::Default;
         }
     }
 }
@@ -537,7 +593,7 @@ fn mark_code_coverage_dead_code_cgu<'tcx>(codegen_units: &mut [CodegenUnit<'tcx>
     // function symbols to be included via `-u` or `/include` linker args.
     let dead_code_cgu = codegen_units
         .iter_mut()
-        .filter(|cgu| cgu.items().iter().any(|(_, (linkage, _))| *linkage == Linkage::External))
+        .filter(|cgu| cgu.items().iter().any(|(_, data)| data.linkage == Linkage::External))
         .min_by_key(|cgu| cgu.size_estimate());
 
     // If there are no CGUs that have externally linked items, then we just
@@ -572,7 +628,7 @@ fn characteristic_def_id_of_mono_item<'tcx>(
             // DefId, we use the location of the impl after all.
 
             if tcx.trait_of_item(def_id).is_some() {
-                let self_ty = instance.substs.type_at(0);
+                let self_ty = instance.args.type_at(0);
                 // This is a default implementation of a trait method.
                 return characteristic_def_id_of_type(self_ty).or(Some(def_id));
             }
@@ -592,7 +648,7 @@ fn characteristic_def_id_of_mono_item<'tcx>(
                 if !tcx.sess.opts.unstable_opts.polymorphize || !instance.has_param() {
                     // This is a method within an impl, find out what the self-type is:
                     let impl_self_ty = tcx.subst_and_normalize_erasing_regions(
-                        instance.substs,
+                        instance.args,
                         ty::ParamEnv::reveal_all(),
                         tcx.type_of(impl_def_id),
                     );
@@ -745,7 +801,7 @@ fn mono_item_visibility<'tcx>(
         return Visibility::Hidden;
     }
 
-    let is_generic = instance.substs.non_erasable_generics().next().is_some();
+    let is_generic = instance.args.non_erasable_generics().next().is_some();
 
     // Upstream `DefId` instances get different handling than local ones.
     let Some(def_id) = def_id.as_local() else {
@@ -851,12 +907,7 @@ fn default_visibility(tcx: TyCtxt<'_>, id: DefId, is_generic: bool) -> Visibilit
     }
 }
 
-fn debug_dump<'a, 'tcx: 'a>(
-    tcx: TyCtxt<'tcx>,
-    label: &str,
-    cgus: &[CodegenUnit<'tcx>],
-    (unique_inlined_items, unique_inlined_size): (usize, usize),
-) {
+fn debug_dump<'a, 'tcx: 'a>(tcx: TyCtxt<'tcx>, label: &str, cgus: &[CodegenUnit<'tcx>]) {
     let dump = move || {
         use std::fmt::Write;
 
@@ -865,29 +916,34 @@ fn debug_dump<'a, 'tcx: 'a>(
 
         // Note: every unique root item is placed exactly once, so the number
         // of unique root items always equals the number of placed root items.
+        //
+        // Also, unreached inlined items won't be counted here. This is fine.
+
+        let mut inlined_items = FxHashSet::default();
 
         let mut root_items = 0;
-        // unique_inlined_items is passed in above.
+        let mut unique_inlined_items = 0;
         let mut placed_inlined_items = 0;
 
         let mut root_size = 0;
-        // unique_inlined_size is passed in above.
+        let mut unique_inlined_size = 0;
         let mut placed_inlined_size = 0;
 
         for cgu in cgus.iter() {
             num_cgus += 1;
             all_cgu_sizes.push(cgu.size_estimate());
 
-            for (item, _) in cgu.items() {
-                match item.instantiation_mode(tcx) {
-                    InstantiationMode::GloballyShared { .. } => {
-                        root_items += 1;
-                        root_size += item.size_estimate(tcx);
-                    }
-                    InstantiationMode::LocalCopy => {
-                        placed_inlined_items += 1;
-                        placed_inlined_size += item.size_estimate(tcx);
+            for (item, data) in cgu.items() {
+                if !data.inlined {
+                    root_items += 1;
+                    root_size += data.size_estimate;
+                } else {
+                    if inlined_items.insert(item) {
+                        unique_inlined_items += 1;
+                        unique_inlined_size += data.size_estimate;
                     }
+                    placed_inlined_items += 1;
+                    placed_inlined_size += data.size_estimate;
                 }
             }
         }
@@ -928,7 +984,7 @@ fn debug_dump<'a, 'tcx: 'a>(
             let mean_size = size as f64 / num_items as f64;
 
             let mut placed_item_sizes: Vec<_> =
-                cgu.items().iter().map(|(item, _)| item.size_estimate(tcx)).collect();
+                cgu.items().values().map(|data| data.size_estimate).collect();
             placed_item_sizes.sort_unstable_by_key(|&n| cmp::Reverse(n));
             let sizes = list(&placed_item_sizes);
 
@@ -937,15 +993,13 @@ fn debug_dump<'a, 'tcx: 'a>(
             let _ =
                 writeln!(s, "  - items: {num_items}, mean size: {mean_size:.1}, sizes: {sizes}",);
 
-            for (item, linkage) in cgu.items_in_deterministic_order(tcx) {
+            for (item, data) in cgu.items_in_deterministic_order(tcx) {
+                let linkage = data.linkage;
                 let symbol_name = item.symbol_name(tcx).name;
                 let symbol_hash_start = symbol_name.rfind('h');
                 let symbol_hash = symbol_hash_start.map_or("<no hash>", |i| &symbol_name[i..]);
-                let size = item.size_estimate(tcx);
-                let kind = match item.instantiation_mode(tcx) {
-                    InstantiationMode::GloballyShared { .. } => "root",
-                    InstantiationMode::LocalCopy => "inlined",
-                };
+                let kind = if !data.inlined { "root" } else { "inlined" };
+                let size = data.size_estimate;
                 let _ = with_no_trimmed_paths!(writeln!(
                     s,
                     "  - {item} [{linkage:?}] [{symbol_hash}] ({kind}, size: {size})"
@@ -987,10 +1041,7 @@ fn debug_dump<'a, 'tcx: 'a>(
             }
             elem(curr, curr_count);
 
-            let mut s = "[".to_string();
-            s.push_str(&v.join(", "));
-            s.push_str("]");
-            s
+            format!("[{}]", v.join(", "))
         }
     };
 
@@ -1100,8 +1151,8 @@ fn collect_and_partition_mono_items(tcx: TyCtxt<'_>, (): ()) -> (&DefIdSet, &[Co
         let mut item_to_cgus: FxHashMap<_, Vec<_>> = Default::default();
 
         for cgu in codegen_units {
-            for (&mono_item, &linkage) in cgu.items() {
-                item_to_cgus.entry(mono_item).or_default().push((cgu.name(), linkage));
+            for (&mono_item, &data) in cgu.items() {
+                item_to_cgus.entry(mono_item).or_default().push((cgu.name(), data.linkage));
             }
         }
 
@@ -1114,7 +1165,7 @@ fn collect_and_partition_mono_items(tcx: TyCtxt<'_>, (): ()) -> (&DefIdSet, &[Co
                 let cgus = item_to_cgus.get_mut(i).unwrap_or(&mut empty);
                 cgus.sort_by_key(|(name, _)| *name);
                 cgus.dedup();
-                for &(ref cgu_name, (linkage, _)) in cgus.iter() {
+                for &(ref cgu_name, linkage) in cgus.iter() {
                     output.push(' ');
                     output.push_str(cgu_name.as_str());
 
@@ -1175,12 +1226,13 @@ fn dump_mono_items_stats<'tcx>(
     // Gather instantiated mono items grouped by def_id
     let mut items_per_def_id: FxHashMap<_, Vec<_>> = Default::default();
     for cgu in codegen_units {
-        for (&mono_item, _) in cgu.items() {
+        cgu.items()
+            .keys()
             // Avoid variable-sized compiler-generated shims
-            if mono_item.is_user_defined() {
+            .filter(|mono_item| mono_item.is_user_defined())
+            .for_each(|mono_item| {
                 items_per_def_id.entry(mono_item.def_id()).or_default().push(mono_item);
-            }
-        }
+            });
     }
 
     #[derive(serde::Serialize)]
@@ -1233,7 +1285,7 @@ fn codegened_and_inlined_items(tcx: TyCtxt<'_>, (): ()) -> &DefIdSet {
     let mut result = items.clone();
 
     for cgu in cgus {
-        for (item, _) in cgu.items() {
+        for item in cgu.items().keys() {
             if let MonoItem::Fn(ref instance) = item {
                 let did = instance.def_id();
                 if !visited.insert(did) {
diff --git a/compiler/rustc_monomorphize/src/polymorphize.rs b/compiler/rustc_monomorphize/src/polymorphize.rs
index 88a3e0285..a8b7a0dbb 100644
--- a/compiler/rustc_monomorphize/src/polymorphize.rs
+++ b/compiler/rustc_monomorphize/src/polymorphize.rs
@@ -14,9 +14,8 @@ use rustc_middle::mir::{
 use rustc_middle::query::Providers;
 use rustc_middle::ty::{
     self,
-    subst::SubstsRef,
     visit::{TypeSuperVisitable, TypeVisitable, TypeVisitableExt, TypeVisitor},
-    Const, Ty, TyCtxt, UnusedGenericParams,
+    Const, GenericArgsRef, Ty, TyCtxt, UnusedGenericParams,
 };
 use rustc_span::symbol::sym;
 use std::ops::ControlFlow;
@@ -144,7 +143,7 @@ fn mark_used_by_default_parameters<'tcx>(
         | DefKind::Enum
         | DefKind::Variant
         | DefKind::Trait
-        | DefKind::TyAlias
+        | DefKind::TyAlias { .. }
         | DefKind::ForeignTy
         | DefKind::TraitAlias
         | DefKind::AssocTy
@@ -163,7 +162,6 @@ fn mark_used_by_default_parameters<'tcx>(
         | DefKind::AnonConst
         | DefKind::InlineConst
         | DefKind::OpaqueTy
-        | DefKind::ImplTraitPlaceholder
         | DefKind::Field
         | DefKind::LifetimeParam
         | DefKind::GlobalAsm
@@ -230,12 +228,12 @@ struct MarkUsedGenericParams<'a, 'tcx> {
 impl<'a, 'tcx> MarkUsedGenericParams<'a, 'tcx> {
     /// Invoke `unused_generic_params` on a body contained within the current item (e.g.
     /// a closure, generator or constant).
-    #[instrument(level = "debug", skip(self, def_id, substs))]
-    fn visit_child_body(&mut self, def_id: DefId, substs: SubstsRef<'tcx>) {
+    #[instrument(level = "debug", skip(self, def_id, args))]
+    fn visit_child_body(&mut self, def_id: DefId, args: GenericArgsRef<'tcx>) {
         let instance = ty::InstanceDef::Item(def_id);
         let unused = self.tcx.unused_generic_params(instance);
         debug!(?self.unused_parameters, ?unused);
-        for (i, arg) in substs.iter().enumerate() {
+        for (i, arg) in args.iter().enumerate() {
             let i = i.try_into().unwrap();
             if unused.is_used(i) {
                 arg.visit_with(self);
@@ -253,9 +251,9 @@ impl<'a, 'tcx> Visitor<'tcx> for MarkUsedGenericParams<'a, 'tcx> {
             if matches!(def_kind, DefKind::Closure | DefKind::Generator) {
                 // Skip visiting the closure/generator that is currently being processed. This only
                 // happens because the first argument to the closure is a reference to itself and
-                // that will call `visit_substs`, resulting in each generic parameter captured being
+                // that will call `visit_args`, resulting in each generic parameter captured being
                 // considered used by default.
-                debug!("skipping closure substs");
+                debug!("skipping closure args");
                 return;
             }
         }
@@ -268,12 +266,12 @@ impl<'a, 'tcx> Visitor<'tcx> for MarkUsedGenericParams<'a, 'tcx> {
             ConstantKind::Ty(c) => {
                 c.visit_with(self);
             }
-            ConstantKind::Unevaluated(mir::UnevaluatedConst { def, substs: _, promoted }, ty) => {
+            ConstantKind::Unevaluated(mir::UnevaluatedConst { def, args: _, promoted }, ty) => {
                 // Avoid considering `T` unused when constants are of the form:
                 //   `<Self as Foo<T>>::foo::promoted[p]`
                 if let Some(p) = promoted {
                     if self.def_id == def && !self.tcx.generics_of(def).has_self {
-                        // If there is a promoted, don't look at the substs - since it will always contain
+                        // If there is a promoted, don't look at the args - since it will always contain
                         // the generic parameters, instead, traverse the promoted MIR.
                         let promoted = self.tcx.promoted_mir(def);
                         self.visit_body(&promoted[p]);
@@ -304,10 +302,10 @@ impl<'a, 'tcx> TypeVisitor<TyCtxt<'tcx>> for MarkUsedGenericParams<'a, 'tcx> {
                 self.unused_parameters.mark_used(param.index);
                 ControlFlow::Continue(())
             }
-            ty::ConstKind::Unevaluated(ty::UnevaluatedConst { def, substs })
+            ty::ConstKind::Unevaluated(ty::UnevaluatedConst { def, args })
                 if matches!(self.tcx.def_kind(def), DefKind::AnonConst) =>
             {
-                self.visit_child_body(def, substs);
+                self.visit_child_body(def, args);
                 ControlFlow::Continue(())
             }
             _ => c.super_visit_with(self),
@@ -321,7 +319,7 @@ impl<'a, 'tcx> TypeVisitor<TyCtxt<'tcx>> for MarkUsedGenericParams<'a, 'tcx> {
         }
 
         match *ty.kind() {
-            ty::Closure(def_id, substs) | ty::Generator(def_id, substs, ..) => {
+            ty::Closure(def_id, args) | ty::Generator(def_id, args, ..) => {
                 debug!(?def_id);
                 // Avoid cycle errors with generators.
                 if def_id == self.def_id {
@@ -330,7 +328,7 @@ impl<'a, 'tcx> TypeVisitor<TyCtxt<'tcx>> for MarkUsedGenericParams<'a, 'tcx> {
 
                 // Consider any generic parameters used by any closures/generators as used in the
                 // parent.
-                self.visit_child_body(def_id, substs);
+                self.visit_child_body(def_id, args);
                 ControlFlow::Continue(())
             }
             ty::Param(param) => {
diff --git a/compiler/rustc_monomorphize/src/util.rs b/compiler/rustc_monomorphize/src/util.rs
index f6a80b043..a3433d3d1 100644
--- a/compiler/rustc_monomorphize/src/util.rs
+++ b/compiler/rustc_monomorphize/src/util.rs
@@ -27,12 +27,12 @@ pub(crate) fn dump_closure_profile<'tcx>(tcx: TyCtxt<'tcx>, closure_instance: In
             typeck_results.closure_size_eval[&closure_def_id];
 
         let before_feature_tys = tcx.subst_and_normalize_erasing_regions(
-            closure_instance.substs,
+            closure_instance.args,
             param_env,
             ty::EarlyBinder::bind(before_feature_tys),
         );
         let after_feature_tys = tcx.subst_and_normalize_erasing_regions(
-            closure_instance.substs,
+            closure_instance.args,
             param_env,
             ty::EarlyBinder::bind(after_feature_tys),
         );