diff options
Diffstat (limited to 'compiler/rustc_monomorphize/src')
| -rw-r--r-- | compiler/rustc_monomorphize/src/collector.rs | 378 | ||||
| -rw-r--r-- | compiler/rustc_monomorphize/src/partitioning.rs | 14 |
2 files changed, 282 insertions, 110 deletions
diff --git a/compiler/rustc_monomorphize/src/collector.rs b/compiler/rustc_monomorphize/src/collector.rs index d8bdbd8c442..1eb11cec6c5 100644 --- a/compiler/rustc_monomorphize/src/collector.rs +++ b/compiler/rustc_monomorphize/src/collector.rs @@ -137,21 +137,41 @@ //! just linked to and no node is created; which is exactly what we want, since //! no machine code should be generated in the current crate for such an item. //! -//! Eager and Lazy Collection Mode -//! ------------------------------ -//! Mono item collection can be performed in one of two modes: +//! Eager and Lazy Collection Strategy +//! ---------------------------------- +//! Mono item collection can be performed with one of two strategies: //! -//! - Lazy mode means that items will only be instantiated when actually +//! - Lazy strategy means that items will only be instantiated when actually //! used. The goal is to produce the least amount of machine code //! possible. //! -//! - Eager mode is meant to be used in conjunction with incremental compilation +//! - Eager strategy is meant to be used in conjunction with incremental compilation //! where a stable set of mono items is more important than a minimal -//! one. Thus, eager mode will instantiate drop-glue for every drop-able type +//! one. Thus, eager strategy will instantiate drop-glue for every drop-able type //! in the crate, even if no drop call for that type exists (yet). It will //! also instantiate default implementations of trait methods, something that //! otherwise is only done on demand. //! +//! Collection-time const evaluation and "mentioned" items +//! ------------------------------------------------------ +//! +//! One important role of collection is to evaluate all constants that are used by all the items +//! which are being collected. Codegen can then rely on only encountering constants that evaluate +//! successfully, and if a constant fails to evaluate, the collector has much better context to be +//! able to show where this constant comes up. +//! +//! However, the exact set of "used" items (collected as described above), and therefore the exact +//! set of used constants, can depend on optimizations. Optimizing away dead code may optimize away +//! a function call that uses a failing constant, so an unoptimized build may fail where an +//! optimized build succeeds. This is undesirable. +//! +//! To avoid this, the collector has the concept of "mentioned" items. Some time during the MIR +//! pipeline, before any optimization-level-dependent optimizations, we compute a list of all items +//! that syntactically appear in the code. These are considered "mentioned", and even if they are in +//! dead code and get optimized away (which makes them no longer "used"), they are still +//! "mentioned". For every used item, the collector ensures that all mentioned items, recursively, +//! do not use a failing constant. This is reflected via the [`CollectionMode`], which determines +//! whether we are visiting a used item or merely a mentioned item. //! //! Open Issues //! ----------- @@ -165,15 +185,16 @@ //! regardless of whether it is actually needed or not. use rustc_data_structures::fx::{FxHashMap, FxHashSet}; -use rustc_data_structures::sync::{par_for_each_in, MTLock, MTLockRef}; +use rustc_data_structures::sync::{par_for_each_in, LRef, MTLock}; use rustc_hir as hir; use rustc_hir::def::DefKind; 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::visit::Visitor as MirVisitor; -use rustc_middle::mir::{self, Location}; +use rustc_middle::mir::{self, Location, MentionedItem}; use rustc_middle::query::TyCtxtAt; use rustc_middle::ty::adjustment::{CustomCoerceUnsized, PointerCoercion}; use rustc_middle::ty::layout::ValidityRequirement; @@ -183,7 +204,6 @@ use rustc_middle::ty::{ 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; use rustc_session::Limit; @@ -199,7 +219,7 @@ use crate::errors::{ }; #[derive(PartialEq)] -pub enum MonoItemCollectionMode { +pub enum MonoItemCollectionStrategy { Eager, Lazy, } @@ -214,6 +234,35 @@ pub struct UsageMap<'tcx> { type MonoItems<'tcx> = Vec<Spanned<MonoItem<'tcx>>>; +/// The state that is shared across the concurrent threads that are doing collection. +struct SharedState<'tcx> { + /// Items that have been or are currently being recursively collected. + visited: MTLock<FxHashSet<MonoItem<'tcx>>>, + /// Items that have been or are currently being recursively treated as "mentioned", i.e., their + /// consts are evaluated but nothing is added to the collection. + mentioned: MTLock<FxHashSet<MonoItem<'tcx>>>, + /// Which items are being used where, for better errors. + 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: FxHashMap::default(), user_map: FxHashMap::default() } @@ -253,25 +302,28 @@ impl<'tcx> UsageMap<'tcx> { } } -#[instrument(skip(tcx, mode), level = "debug")] +#[instrument(skip(tcx, strategy), level = "debug")] pub fn collect_crate_mono_items( tcx: TyCtxt<'_>, - mode: MonoItemCollectionMode, + strategy: MonoItemCollectionStrategy, ) -> (FxHashSet<MonoItem<'_>>, UsageMap<'_>) { let _prof_timer = tcx.prof.generic_activity("monomorphization_collector"); - let roots = - tcx.sess.time("monomorphization_collector_root_collections", || collect_roots(tcx, mode)); + let roots = tcx + .sess + .time("monomorphization_collector_root_collections", || collect_roots(tcx, strategy)); debug!("building mono item graph, beginning at roots"); - let mut visited = MTLock::new(FxHashSet::default()); - let mut usage_map = MTLock::new(UsageMap::new()); + let mut state = SharedState { + visited: MTLock::new(FxHashSet::default()), + mentioned: MTLock::new(FxHashSet::default()), + usage_map: MTLock::new(UsageMap::new()), + }; let recursion_limit = tcx.recursion_limit(); { - let visited: MTLockRef<'_, _> = &mut visited; - let usage_map: MTLockRef<'_, _> = &mut usage_map; + let state: LRef<'_, _> = &mut state; tcx.sess.time("monomorphization_collector_graph_walk", || { par_for_each_in(roots, |root| { @@ -279,22 +331,22 @@ pub fn collect_crate_mono_items( collect_items_rec( tcx, dummy_spanned(root), - visited, + state, &mut recursion_depths, recursion_limit, - usage_map, + CollectionMode::UsedItems, ); }); }); } - (visited.into_inner(), usage_map.into_inner()) + (state.visited.into_inner(), state.usage_map.into_inner()) } // Find all non-generic items by walking the HIR. These items serve as roots to // start monomorphizing from. #[instrument(skip(tcx, mode), level = "debug")] -fn collect_roots(tcx: TyCtxt<'_>, mode: MonoItemCollectionMode) -> Vec<MonoItem<'_>> { +fn collect_roots(tcx: TyCtxt<'_>, mode: MonoItemCollectionStrategy) -> Vec<MonoItem<'_>> { debug!("collecting roots"); let mut roots = Vec::new(); @@ -303,7 +355,7 @@ fn collect_roots(tcx: TyCtxt<'_>, mode: MonoItemCollectionMode) -> Vec<MonoItem< debug!("collect_roots: entry_fn = {:?}", entry_fn); - let mut collector = RootCollector { tcx, mode, entry_fn, output: &mut roots }; + let mut collector = RootCollector { tcx, strategy: mode, entry_fn, output: &mut roots }; let crate_items = tcx.hir_crate_items(()); @@ -331,21 +383,38 @@ fn collect_roots(tcx: TyCtxt<'_>, mode: MonoItemCollectionMode) -> Vec<MonoItem< /// Collect all monomorphized items reachable from `starting_point`, and emit a note diagnostic if a /// post-monomorphization error is encountered during a collection step. -#[instrument(skip(tcx, visited, recursion_depths, recursion_limit, usage_map), level = "debug")] +/// +/// `mode` determined whether we are scanning for [used items][CollectionMode::UsedItems] +/// or [mentioned items][CollectionMode::MentionedItems]. +#[instrument(skip(tcx, state, recursion_depths, recursion_limit), level = "debug")] fn collect_items_rec<'tcx>( tcx: TyCtxt<'tcx>, starting_item: Spanned<MonoItem<'tcx>>, - visited: MTLockRef<'_, FxHashSet<MonoItem<'tcx>>>, + state: LRef<'_, SharedState<'tcx>>, recursion_depths: &mut DefIdMap<usize>, recursion_limit: Limit, - usage_map: MTLockRef<'_, UsageMap<'tcx>>, + mode: CollectionMode, ) { - if !visited.lock_mut().insert(starting_item.node) { - // We've been here already, no need to search again. - return; + if mode == CollectionMode::UsedItems { + if !state.visited.lock_mut().insert(starting_item.node) { + // We've been here already, no need to search again. + return; + } + } else { + if state.visited.lock().contains(&starting_item.node) { + // We've already done a *full* visit on this one, no need to do the "mention" visit. + return; + } + if !state.mentioned.lock_mut().insert(starting_item.node) { + // We've been here already, no need to search again. + return; + } + // There's some risk that we first do a 'mention' visit and then a full visit. But there's no + // harm in that, the mention visit will trigger all the queries and the results are cached. } - let mut used_items = Vec::new(); + let mut used_items = MonoItems::new(); + let mut mentioned_items = MonoItems::new(); let recursion_depth_reset; // Post-monomorphization errors MVP @@ -373,37 +442,48 @@ fn collect_items_rec<'tcx>( // FIXME: don't rely on global state, instead bubble up errors. Note: this is very hard to do. let error_count = tcx.dcx().err_count(); + // In `mentioned_items` we collect items that were mentioned in this MIR but possibly do not + // need to be monomorphized. This is done to ensure that optimizing away function calls does not + // hide const-eval errors that those calls would otherwise have triggered. match starting_item.node { MonoItem::Static(def_id) => { - let instance = Instance::mono(tcx, def_id); + recursion_depth_reset = None; - // Sanity check whether this ended up being collected accidentally - debug_assert!(should_codegen_locally(tcx, &instance)); + // Statics always get evaluted (which is possible because they can't be generic), so for + // `MentionedItems` collection there's nothing to do here. + if mode == CollectionMode::UsedItems { + let instance = Instance::mono(tcx, def_id); - let DefKind::Static { nested, .. } = tcx.def_kind(def_id) else { bug!() }; - // Nested statics have no type. - if !nested { - let ty = instance.ty(tcx, ty::ParamEnv::reveal_all()); - visit_drop_use(tcx, ty, true, starting_item.span, &mut used_items); - } + // Sanity check whether this ended up being collected accidentally + debug_assert!(should_codegen_locally(tcx, &instance)); - recursion_depth_reset = None; + let DefKind::Static { nested, .. } = tcx.def_kind(def_id) else { bug!() }; + // Nested statics have no type. + if !nested { + let ty = instance.ty(tcx, ty::ParamEnv::reveal_all()); + visit_drop_use(tcx, ty, true, starting_item.span, &mut used_items); + } - if let Ok(alloc) = tcx.eval_static_initializer(def_id) { - for &prov in alloc.inner().provenance().ptrs().values() { - collect_alloc(tcx, prov.alloc_id(), &mut used_items); + if let Ok(alloc) = tcx.eval_static_initializer(def_id) { + for &prov in alloc.inner().provenance().ptrs().values() { + collect_alloc(tcx, prov.alloc_id(), &mut used_items); + } } - } - if tcx.needs_thread_local_shim(def_id) { - used_items.push(respan( - starting_item.span, - MonoItem::Fn(Instance { - def: InstanceDef::ThreadLocalShim(def_id), - args: GenericArgs::empty(), - }), - )); + if tcx.needs_thread_local_shim(def_id) { + used_items.push(respan( + starting_item.span, + MonoItem::Fn(Instance { + def: InstanceDef::ThreadLocalShim(def_id), + args: GenericArgs::empty(), + }), + )); + } } + + // mentioned_items stays empty since there's no codegen for statics. statics don't get + // optimized, and if they did then the const-eval interpreter would have to worry about + // mentioned_items. } MonoItem::Fn(instance) => { // Sanity check whether this ended up being collected accidentally @@ -420,10 +500,20 @@ fn collect_items_rec<'tcx>( check_type_length_limit(tcx, instance); rustc_data_structures::stack::ensure_sufficient_stack(|| { - collect_used_items(tcx, instance, &mut used_items); + collect_items_of_instance( + tcx, + instance, + &mut used_items, + &mut mentioned_items, + mode, + ) }); } MonoItem::GlobalAsm(item_id) => { + assert!( + mode == CollectionMode::UsedItems, + "should never encounter global_asm when collecting mentioned items" + ); recursion_depth_reset = None; let item = tcx.hir().item(item_id); @@ -459,8 +549,10 @@ fn collect_items_rec<'tcx>( } else { span_bug!(item.span, "Mismatch between hir::Item type and MonoItem type") } + + // mention_items stays empty as nothing gets optimized here. } - } + }; // Check for PMEs and emit a diagnostic if one happened. To try to show relevant edges of the // mono item graph. @@ -474,10 +566,41 @@ fn collect_items_rec<'tcx>( formatted_item, }); } - usage_map.lock_mut().record_used(starting_item.node, &used_items); + // Only updating `usage_map` for used items as otherwise we may be inserting the same item + // multiple times (if it is first 'mentioned' and then later actuall used), and the usage map + // logic does not like that. + // This is part of the output of collection and hence only relevant for "used" items. + // ("Mentioned" items are only considered internally during collection.) + if mode == CollectionMode::UsedItems { + state.usage_map.lock_mut().record_used(starting_item.node, &used_items); + } - for used_item in used_items { - collect_items_rec(tcx, used_item, visited, recursion_depths, recursion_limit, usage_map); + if mode == CollectionMode::MentionedItems { + assert!(used_items.is_empty(), "'mentioned' collection should never encounter used items"); + } else { + for used_item in used_items { + collect_items_rec( + tcx, + used_item, + state, + recursion_depths, + recursion_limit, + CollectionMode::UsedItems, + ); + } + } + + // Walk over mentioned items *after* used items, so that if an item is both mentioned and used then + // the loop above has fully collected it, so this loop will skip it. + for mentioned_item in mentioned_items { + collect_items_rec( + tcx, + mentioned_item, + state, + recursion_depths, + recursion_limit, + CollectionMode::MentionedItems, + ); } if let Some((def_id, depth)) = recursion_depth_reset { @@ -596,7 +719,7 @@ fn check_type_length_limit<'tcx>(tcx: TyCtxt<'tcx>, instance: Instance<'tcx>) { struct MirUsedCollector<'a, 'tcx> { tcx: TyCtxt<'tcx>, body: &'a mir::Body<'tcx>, - output: &'a mut MonoItems<'tcx>, + used_items: &'a mut MonoItems<'tcx>, instance: Instance<'tcx>, /// Spans for move size lints already emitted. Helps avoid duplicate lints. move_size_spans: Vec<Span>, @@ -735,6 +858,31 @@ impl<'a, 'tcx> MirUsedCollector<'a, 'tcx> { ); self.move_size_spans.push(span); } + + /// Evaluates a *not yet monomorphized* constant. + fn eval_constant( + &mut self, + constant: &mir::ConstOperand<'tcx>, + ) -> Option<mir::ConstValue<'tcx>> { + let const_ = self.monomorphize(constant.const_); + let param_env = ty::ParamEnv::reveal_all(); + // Evaluate the constant. This makes const eval failure a collection-time error (rather than + // a codegen-time error). rustc stops after collection if there was an error, so this + // ensures codegen never has to worry about failing consts. + // (codegen relies on this and ICEs will happen if this is violated.) + match const_.eval(self.tcx, param_env, constant.span) { + Ok(v) => Some(v), + Err(ErrorHandled::TooGeneric(..)) => span_bug!( + constant.span, + "collection encountered polymorphic constant: {:?}", + const_ + ), + Err(err @ ErrorHandled::Reported(..)) => { + err.emit_note(self.tcx); + return None; + } + } + } } impl<'a, 'tcx> MirVisitor<'tcx> for MirUsedCollector<'a, 'tcx> { @@ -769,7 +917,7 @@ impl<'a, 'tcx> MirVisitor<'tcx> for MirUsedCollector<'a, 'tcx> { target_ty, source_ty, span, - self.output, + self.used_items, ); } } @@ -780,7 +928,7 @@ impl<'a, 'tcx> MirVisitor<'tcx> for MirUsedCollector<'a, 'tcx> { ) => { let fn_ty = operand.ty(self.body, self.tcx); let fn_ty = self.monomorphize(fn_ty); - visit_fn_use(self.tcx, fn_ty, false, span, self.output); + visit_fn_use(self.tcx, fn_ty, false, span, self.used_items); } mir::Rvalue::Cast( mir::CastKind::PointerCoercion(PointerCoercion::ClosureFnPointer(_)), @@ -798,7 +946,7 @@ impl<'a, 'tcx> MirVisitor<'tcx> for MirUsedCollector<'a, 'tcx> { ty::ClosureKind::FnOnce, ); if should_codegen_locally(self.tcx, &instance) { - self.output.push(create_fn_mono_item(self.tcx, instance, span)); + self.used_items.push(create_fn_mono_item(self.tcx, instance, span)); } } _ => bug!(), @@ -809,7 +957,7 @@ impl<'a, 'tcx> MirVisitor<'tcx> for MirUsedCollector<'a, 'tcx> { let instance = Instance::mono(self.tcx, def_id); if should_codegen_locally(self.tcx, &instance) { trace!("collecting thread-local static {:?}", def_id); - self.output.push(respan(span, MonoItem::Static(def_id))); + self.used_items.push(respan(span, MonoItem::Static(def_id))); } } _ => { /* not interesting */ } @@ -822,26 +970,9 @@ impl<'a, 'tcx> MirVisitor<'tcx> for MirUsedCollector<'a, 'tcx> { /// to ensure that the constant evaluates successfully and walk the result. #[instrument(skip(self), level = "debug")] fn visit_constant(&mut self, constant: &mir::ConstOperand<'tcx>, location: Location) { - let const_ = self.monomorphize(constant.const_); - let param_env = ty::ParamEnv::reveal_all(); - // Evaluate the constant. This makes const eval failure a collection-time error (rather than - // a codegen-time error). rustc stops after collection if there was an error, so this - // ensures codegen never has to worry about failing consts. - // (codegen relies on this and ICEs will happen if this is violated.) - let val = match const_.eval(self.tcx, param_env, constant.span) { - Ok(v) => v, - Err(ErrorHandled::TooGeneric(..)) => span_bug!( - self.body.source_info(location).span, - "collection encountered polymorphic constant: {:?}", - const_ - ), - Err(err @ ErrorHandled::Reported(..)) => { - err.emit_note(self.tcx); - return; - } - }; - collect_const_value(self.tcx, val, self.output); - MirVisitor::visit_ty(self, const_.ty(), TyContext::Location(location)); + // No `super_constant` as we don't care about `visit_ty`/`visit_ty_const`. + let Some(val) = self.eval_constant(constant) else { return }; + collect_const_value(self.tcx, val, self.used_items); } fn visit_terminator(&mut self, terminator: &mir::Terminator<'tcx>, location: Location) { @@ -852,7 +983,7 @@ impl<'a, 'tcx> MirVisitor<'tcx> for MirUsedCollector<'a, 'tcx> { let push_mono_lang_item = |this: &mut Self, lang_item: LangItem| { let instance = Instance::mono(tcx, tcx.require_lang_item(lang_item, Some(source))); if should_codegen_locally(tcx, &instance) { - this.output.push(create_fn_mono_item(tcx, instance, source)); + this.used_items.push(create_fn_mono_item(tcx, instance, source)); } }; @@ -861,25 +992,25 @@ impl<'a, 'tcx> MirVisitor<'tcx> for MirUsedCollector<'a, 'tcx> { let callee_ty = func.ty(self.body, tcx); let callee_ty = self.monomorphize(callee_ty); self.check_fn_args_move_size(callee_ty, args, *fn_span, location); - visit_fn_use(self.tcx, callee_ty, true, source, &mut self.output) + visit_fn_use(self.tcx, callee_ty, true, source, &mut self.used_items) } mir::TerminatorKind::Drop { ref place, .. } => { let ty = place.ty(self.body, self.tcx).ty; let ty = self.monomorphize(ty); - visit_drop_use(self.tcx, ty, true, source, self.output); + visit_drop_use(self.tcx, ty, true, source, self.used_items); } mir::TerminatorKind::InlineAsm { ref operands, .. } => { for op in operands { match *op { mir::InlineAsmOperand::SymFn { ref value } => { let fn_ty = self.monomorphize(value.const_.ty()); - visit_fn_use(self.tcx, fn_ty, false, source, self.output); + visit_fn_use(self.tcx, fn_ty, false, source, self.used_items); } mir::InlineAsmOperand::SymStatic { def_id } => { let instance = Instance::mono(self.tcx, def_id); if should_codegen_locally(self.tcx, &instance) { trace!("collecting asm sym static {:?}", def_id); - self.output.push(respan(source, MonoItem::Static(def_id))); + self.used_items.push(respan(source, MonoItem::Static(def_id))); } } _ => {} @@ -1239,7 +1370,7 @@ fn create_mono_items_for_vtable_methods<'tcx>( struct RootCollector<'a, 'tcx> { tcx: TyCtxt<'tcx>, - mode: MonoItemCollectionMode, + strategy: MonoItemCollectionStrategy, output: &'a mut MonoItems<'tcx>, entry_fn: Option<(DefId, EntryFnType)>, } @@ -1248,7 +1379,7 @@ impl<'v> RootCollector<'_, 'v> { fn process_item(&mut self, id: hir::ItemId) { match self.tcx.def_kind(id.owner_id) { DefKind::Enum | DefKind::Struct | DefKind::Union => { - if self.mode == MonoItemCollectionMode::Eager + if self.strategy == MonoItemCollectionStrategy::Eager && self.tcx.generics_of(id.owner_id).count() == 0 { debug!("RootCollector: ADT drop-glue for `{id:?}`",); @@ -1279,7 +1410,7 @@ impl<'v> RootCollector<'_, 'v> { } } DefKind::Impl { .. } => { - if self.mode == MonoItemCollectionMode::Eager { + if self.strategy == MonoItemCollectionStrategy::Eager { create_mono_items_for_default_impls(self.tcx, id, self.output); } } @@ -1298,9 +1429,9 @@ impl<'v> RootCollector<'_, 'v> { fn is_root(&self, def_id: LocalDefId) -> bool { !self.tcx.generics_of(def_id).requires_monomorphization(self.tcx) - && match self.mode { - MonoItemCollectionMode::Eager => true, - MonoItemCollectionMode::Lazy => { + && match self.strategy { + MonoItemCollectionStrategy::Eager => true, + MonoItemCollectionStrategy::Lazy => { self.entry_fn.and_then(|(id, _)| id.as_local()) == Some(def_id) || self.tcx.is_reachable_non_generic(def_id) || self @@ -1497,26 +1628,67 @@ fn build_skip_move_check_fns(tcx: TyCtxt<'_>) -> Vec<DefId> { } /// Scans the MIR in order to find function calls, closures, and drop-glue. -#[instrument(skip(tcx, output), level = "debug")] -fn collect_used_items<'tcx>( +/// +/// Anything that's found is added to `output`. Furthermore the "mentioned items" of the MIR are returned. +#[instrument(skip(tcx, used_items, mentioned_items), level = "debug")] +fn collect_items_of_instance<'tcx>( tcx: TyCtxt<'tcx>, instance: Instance<'tcx>, - output: &mut MonoItems<'tcx>, + used_items: &mut MonoItems<'tcx>, + mentioned_items: &mut MonoItems<'tcx>, + mode: CollectionMode, ) { let body = tcx.instance_mir(instance.def); - - // Here we rely on the visitor also visiting `required_consts`, so that we evaluate them - // and abort compilation if any of them errors. - MirUsedCollector { + let mut collector = MirUsedCollector { tcx, - body: body, - output, + body, + used_items, instance, move_size_spans: vec![], visiting_call_terminator: false, skip_move_check_fns: None, + }; + + if mode == CollectionMode::UsedItems { + // Visit everything. Here we rely on the visitor also visiting `required_consts`, so that we + // evaluate them and abort compilation if any of them errors. + collector.visit_body(body); + } else { + // We only need to evaluate all constants, but can ignore the rest of the MIR. + for const_op in &body.required_consts { + if let Some(val) = collector.eval_constant(const_op) { + collect_const_value(tcx, val, mentioned_items); + } + } + } + + // Always gather mentioned items. + for item in &body.mentioned_items { + let item_mono = collector.monomorphize(item.node); + visit_mentioned_item(tcx, &item_mono, item.span, mentioned_items); + } +} + +/// `item` must be already monomorphized +fn visit_mentioned_item<'tcx>( + tcx: TyCtxt<'tcx>, + item: &MentionedItem<'tcx>, + span: Span, + output: &mut MonoItems<'tcx>, +) { + match *item { + MentionedItem::Fn(def_id, args) => { + let instance = Instance::expect_resolve(tcx, ty::ParamEnv::reveal_all(), def_id, args); + // `visit_instance_use` was written for "used" item collection but works just as well + // for "mentioned" item collection. + // We can set `is_direct_call`; that just means we'll skip a bunch of shims that anyway + // can't have their own failing constants. + visit_instance_use(tcx, instance, /*is_direct_call*/ true, span, output); + } + MentionedItem::Drop(ty) => { + visit_drop_use(tcx, ty, /*is_direct_call*/ true, span, output); + } } - .visit_body(body); } #[instrument(skip(tcx, output), level = "debug")] diff --git a/compiler/rustc_monomorphize/src/partitioning.rs b/compiler/rustc_monomorphize/src/partitioning.rs index 15041b9cd41..5a92657cb40 100644 --- a/compiler/rustc_monomorphize/src/partitioning.rs +++ b/compiler/rustc_monomorphize/src/partitioning.rs @@ -117,7 +117,7 @@ use rustc_session::CodegenUnits; use rustc_span::symbol::Symbol; use crate::collector::UsageMap; -use crate::collector::{self, MonoItemCollectionMode}; +use crate::collector::{self, MonoItemCollectionStrategy}; use crate::errors::{CouldntDumpMonoStats, SymbolAlreadyDefined, UnknownCguCollectionMode}; struct PartitioningCx<'a, 'tcx> { @@ -1087,30 +1087,30 @@ where } fn collect_and_partition_mono_items(tcx: TyCtxt<'_>, (): ()) -> (&DefIdSet, &[CodegenUnit<'_>]) { - let collection_mode = match tcx.sess.opts.unstable_opts.print_mono_items { + let collection_strategy = match tcx.sess.opts.unstable_opts.print_mono_items { Some(ref s) => { let mode = s.to_lowercase(); let mode = mode.trim(); if mode == "eager" { - MonoItemCollectionMode::Eager + MonoItemCollectionStrategy::Eager } else { if mode != "lazy" { tcx.dcx().emit_warn(UnknownCguCollectionMode { mode }); } - MonoItemCollectionMode::Lazy + MonoItemCollectionStrategy::Lazy } } None => { if tcx.sess.link_dead_code() { - MonoItemCollectionMode::Eager + MonoItemCollectionStrategy::Eager } else { - MonoItemCollectionMode::Lazy + MonoItemCollectionStrategy::Lazy } } }; - let (items, usage_map) = collector::collect_crate_mono_items(tcx, collection_mode); + let (items, usage_map) = collector::collect_crate_mono_items(tcx, collection_strategy); // If there was an error during collection (e.g. from one of the constants we evaluated), // then we stop here. This way codegen does not have to worry about failing constants. |