11use crate::hir::def_id::{DefId, CrateNum, LOCAL_CRATE};
22use crate::hir::HirId;
33use syntax::symbol::InternedString;
4- use crate::ty::{Instance, TyCtxt};
4+ use syntax::attr::InlineAttr;
5+ use syntax::source_map::Span;
6+ use crate::ty::{Instance, InstanceDef, TyCtxt, SymbolName, subst::InternalSubsts};
57use crate::util::nodemap::FxHashMap;
8+ use crate::ty::print::obsolete::DefPathBasedNames;
9+ use crate::dep_graph::{WorkProductId, DepNode, WorkProduct, DepConstructor};
610use rustc_data_structures::base_n;
711use rustc_data_structures::stable_hasher::{HashStable, StableHasherResult,
812 StableHasher};
913use crate::ich::{Fingerprint, StableHashingContext, NodeIdHashingMode};
14+ use crate::session::config::OptLevel;
1015use std::fmt;
1116use std::hash::Hash;
1217
18+ /// Describes how a monomorphization will be instantiated in object files.
19+ #[derive(PartialEq, Eq, Clone, Copy, Debug, Hash)]
20+ pub enum InstantiationMode {
21+ /// There will be exactly one instance of the given MonoItem. It will have
22+ /// external linkage so that it can be linked to from other codegen units.
23+ GloballyShared {
24+ /// In some compilation scenarios we may decide to take functions that
25+ /// are typically `LocalCopy` and instead move them to `GloballyShared`
26+ /// to avoid codegenning them a bunch of times. In this situation,
27+ /// however, our local copy may conflict with other crates also
28+ /// inlining the same function.
29+ ///
30+ /// This flag indicates that this situation is occurring, and informs
31+ /// symbol name calculation that some extra mangling is needed to
32+ /// avoid conflicts. Note that this may eventually go away entirely if
33+ /// ThinLTO enables us to *always* have a globally shared instance of a
34+ /// function within one crate's compilation.
35+ may_conflict: bool,
36+ },
37+
38+ /// Each codegen unit containing a reference to the given MonoItem will
39+ /// have its own private copy of the function (with internal linkage).
40+ LocalCopy,
41+ }
42+
1343#[derive(PartialEq, Eq, Clone, Copy, Debug, Hash)]
1444pub enum MonoItem<'tcx> {
1545 Fn(Instance<'tcx>),
@@ -31,6 +61,166 @@ impl<'tcx> MonoItem<'tcx> {
3161 MonoItem::GlobalAsm(_) => 1,
3262 }
3363 }
64+
65+ pub fn is_generic_fn(&self) -> bool {
66+ match *self {
67+ MonoItem::Fn(ref instance) => {
68+ instance.substs.non_erasable_generics().next().is_some()
69+ }
70+ MonoItem::Static(..) |
71+ MonoItem::GlobalAsm(..) => false,
72+ }
73+ }
74+
75+ pub fn symbol_name(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> SymbolName {
76+ match *self {
77+ MonoItem::Fn(instance) => tcx.symbol_name(instance),
78+ MonoItem::Static(def_id) => {
79+ tcx.symbol_name(Instance::mono(tcx, def_id))
80+ }
81+ MonoItem::GlobalAsm(hir_id) => {
82+ let def_id = tcx.hir().local_def_id_from_hir_id(hir_id);
83+ SymbolName {
84+ name: InternedString::intern(&format!("global_asm_{:?}", def_id))
85+ }
86+ }
87+ }
88+ }
89+
90+ pub fn instantiation_mode(&self,
91+ tcx: TyCtxt<'a, 'tcx, 'tcx>)
92+ -> InstantiationMode {
93+ let inline_in_all_cgus =
94+ tcx.sess.opts.debugging_opts.inline_in_all_cgus.unwrap_or_else(|| {
95+ tcx.sess.opts.optimize != OptLevel::No
96+ }) && !tcx.sess.opts.cg.link_dead_code;
97+
98+ match *self {
99+ MonoItem::Fn(ref instance) => {
100+ let entry_def_id = tcx.entry_fn(LOCAL_CRATE).map(|(id, _)| id);
101+ // If this function isn't inlined or otherwise has explicit
102+ // linkage, then we'll be creating a globally shared version.
103+ if self.explicit_linkage(tcx).is_some() ||
104+ !instance.def.requires_local(tcx) ||
105+ Some(instance.def_id()) == entry_def_id
106+ {
107+ return InstantiationMode::GloballyShared { may_conflict: false }
108+ }
109+
110+ // At this point we don't have explicit linkage and we're an
111+ // inlined function. If we're inlining into all CGUs then we'll
112+ // be creating a local copy per CGU
113+ if inline_in_all_cgus {
114+ return InstantiationMode::LocalCopy
115+ }
116+
117+ // Finally, if this is `#[inline(always)]` we're sure to respect
118+ // that with an inline copy per CGU, but otherwise we'll be
119+ // creating one copy of this `#[inline]` function which may
120+ // conflict with upstream crates as it could be an exported
121+ // symbol.
122+ match tcx.codegen_fn_attrs(instance.def_id()).inline {
123+ InlineAttr::Always => InstantiationMode::LocalCopy,
124+ _ => {
125+ InstantiationMode::GloballyShared { may_conflict: true }
126+ }
127+ }
128+ }
129+ MonoItem::Static(..) |
130+ MonoItem::GlobalAsm(..) => {
131+ InstantiationMode::GloballyShared { may_conflict: false }
132+ }
133+ }
134+ }
135+
136+ pub fn explicit_linkage(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> Option<Linkage> {
137+ let def_id = match *self {
138+ MonoItem::Fn(ref instance) => instance.def_id(),
139+ MonoItem::Static(def_id) => def_id,
140+ MonoItem::GlobalAsm(..) => return None,
141+ };
142+
143+ let codegen_fn_attrs = tcx.codegen_fn_attrs(def_id);
144+ codegen_fn_attrs.linkage
145+ }
146+
147+ /// Returns `true` if this instance is instantiable - whether it has no unsatisfied
148+ /// predicates.
149+ ///
150+ /// In order to codegen an item, all of its predicates must hold, because
151+ /// otherwise the item does not make sense. Type-checking ensures that
152+ /// the predicates of every item that is *used by* a valid item *do*
153+ /// hold, so we can rely on that.
154+ ///
155+ /// However, we codegen collector roots (reachable items) and functions
156+ /// in vtables when they are seen, even if they are not used, and so they
157+ /// might not be instantiable. For example, a programmer can define this
158+ /// public function:
159+ ///
160+ /// pub fn foo<'a>(s: &'a mut ()) where &'a mut (): Clone {
161+ /// <&mut () as Clone>::clone(&s);
162+ /// }
163+ ///
164+ /// That function can't be codegened, because the method `<&mut () as Clone>::clone`
165+ /// does not exist. Luckily for us, that function can't ever be used,
166+ /// because that would require for `&'a mut (): Clone` to hold, so we
167+ /// can just not emit any code, or even a linker reference for it.
168+ ///
169+ /// Similarly, if a vtable method has such a signature, and therefore can't
170+ /// be used, we can just not emit it and have a placeholder (a null pointer,
171+ /// which will never be accessed) in its place.
172+ pub fn is_instantiable(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> bool {
173+ debug!("is_instantiable({:?})", self);
174+ let (def_id, substs) = match *self {
175+ MonoItem::Fn(ref instance) => (instance.def_id(), instance.substs),
176+ MonoItem::Static(def_id) => (def_id, InternalSubsts::empty()),
177+ // global asm never has predicates
178+ MonoItem::GlobalAsm(..) => return true
179+ };
180+
181+ tcx.substitute_normalize_and_test_predicates((def_id, &substs))
182+ }
183+
184+ pub fn to_string(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>, debug: bool) -> String {
185+ return match *self {
186+ MonoItem::Fn(instance) => {
187+ to_string_internal(tcx, "fn ", instance, debug)
188+ },
189+ MonoItem::Static(def_id) => {
190+ let instance = Instance::new(def_id, tcx.intern_substs(&[]));
191+ to_string_internal(tcx, "static ", instance, debug)
192+ },
193+ MonoItem::GlobalAsm(..) => {
194+ "global_asm".to_string()
195+ }
196+ };
197+
198+ fn to_string_internal<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
199+ prefix: &str,
200+ instance: Instance<'tcx>,
201+ debug: bool)
202+ -> String {
203+ let mut result = String::with_capacity(32);
204+ result.push_str(prefix);
205+ let printer = DefPathBasedNames::new(tcx, false, false);
206+ printer.push_instance_as_string(instance, &mut result, debug);
207+ result
208+ }
209+ }
210+
211+ pub fn local_span(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> Option<Span> {
212+ match *self {
213+ MonoItem::Fn(Instance { def, .. }) => {
214+ tcx.hir().as_local_hir_id(def.def_id())
215+ }
216+ MonoItem::Static(def_id) => {
217+ tcx.hir().as_local_hir_id(def_id)
218+ }
219+ MonoItem::GlobalAsm(hir_id) => {
220+ Some(hir_id)
221+ }
222+ }.map(|hir_id| tcx.hir().span_by_hir_id(hir_id))
223+ }
34224}
35225
36226impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for MonoItem<'tcx> {
@@ -161,6 +351,73 @@ impl<'tcx> CodegenUnit<'tcx> {
161351 self.size_estimate = Some(size_estimate + delta);
162352 }
163353 }
354+
355+ pub fn contains_item(&self, item: &MonoItem<'tcx>) -> bool {
356+ self.items().contains_key(item)
357+ }
358+
359+ pub fn work_product_id(&self) -> WorkProductId {
360+ WorkProductId::from_cgu_name(&self.name().as_str())
361+ }
362+
363+ pub fn work_product(&self, tcx: TyCtxt<'_, '_, '_>) -> WorkProduct {
364+ let work_product_id = self.work_product_id();
365+ tcx.dep_graph
366+ .previous_work_product(&work_product_id)
367+ .unwrap_or_else(|| {
368+ panic!("Could not find work-product for CGU `{}`", self.name())
369+ })
370+ }
371+
372+ pub fn items_in_deterministic_order<'a>(&self,
373+ tcx: TyCtxt<'a, 'tcx, 'tcx>)
374+ -> Vec<(MonoItem<'tcx>,
375+ (Linkage, Visibility))> {
376+ // The codegen tests rely on items being process in the same order as
377+ // they appear in the file, so for local items, we sort by node_id first
378+ #[derive(PartialEq, Eq, PartialOrd, Ord)]
379+ pub struct ItemSortKey(Option<HirId>, SymbolName);
380+
381+ fn item_sort_key<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
382+ item: MonoItem<'tcx>) -> ItemSortKey {
383+ ItemSortKey(match item {
384+ MonoItem::Fn(ref instance) => {
385+ match instance.def {
386+ // We only want to take HirIds of user-defined
387+ // instances into account. The others don't matter for
388+ // the codegen tests and can even make item order
389+ // unstable.
390+ InstanceDef::Item(def_id) => {
391+ tcx.hir().as_local_hir_id(def_id)
392+ }
393+ InstanceDef::VtableShim(..) |
394+ InstanceDef::Intrinsic(..) |
395+ InstanceDef::FnPtrShim(..) |
396+ InstanceDef::Virtual(..) |
397+ InstanceDef::ClosureOnceShim { .. } |
398+ InstanceDef::DropGlue(..) |
399+ InstanceDef::CloneShim(..) => {
400+ None
401+ }
402+ }
403+ }
404+ MonoItem::Static(def_id) => {
405+ tcx.hir().as_local_hir_id(def_id)
406+ }
407+ MonoItem::GlobalAsm(hir_id) => {
408+ Some(hir_id)
409+ }
410+ }, item.symbol_name(tcx))
411+ }
412+
413+ let mut items: Vec<_> = self.items().iter().map(|(&i, &l)| (i, l)).collect();
414+ items.sort_by_cached_key(|&(i, _)| item_sort_key(tcx, i));
415+ items
416+ }
417+
418+ pub fn codegen_dep_node(&self, tcx: TyCtxt<'_, 'tcx, 'tcx>) -> DepNode {
419+ DepNode::new(tcx, DepConstructor::CompileCodegenUnit(self.name().clone()))
420+ }
164421}
165422
166423impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for CodegenUnit<'tcx> {
0 commit comments