1 use crate::hir::def_id::{DefId, CrateNum, LOCAL_CRATE};
3 use syntax::symbol::InternedString;
4 use syntax::attr::InlineAttr;
5 use syntax::source_map::Span;
6 use crate::ty::{Instance, InstanceDef, TyCtxt, SymbolName, subst::InternalSubsts};
7 use crate::util::nodemap::FxHashMap;
8 use crate::ty::print::obsolete::DefPathBasedNames;
9 use crate::dep_graph::{WorkProductId, DepNode, WorkProduct, DepConstructor};
10 use rustc_data_structures::base_n;
11 use rustc_data_structures::stable_hasher::{HashStable, StableHasherResult,
13 use crate::ich::{Fingerprint, StableHashingContext, NodeIdHashingMode};
14 use crate::session::config::OptLevel;
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.
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.
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.
38 /// Each codegen unit containing a reference to the given MonoItem will
39 /// have its own private copy of the function (with internal linkage).
43 #[derive(PartialEq, Eq, Clone, Copy, Debug, Hash)]
44 pub enum MonoItem<'tcx> {
50 impl<'tcx> MonoItem<'tcx> {
51 pub fn size_estimate(&self, tcx: TyCtxt<'tcx, 'tcx>) -> usize {
53 MonoItem::Fn(instance) => {
54 // Estimate the size of a function based on how many statements
56 tcx.instance_def_size_estimate(instance.def)
58 // Conservatively estimate the size of a static declaration
59 // or assembly to be 1.
61 MonoItem::GlobalAsm(_) => 1,
65 pub fn is_generic_fn(&self) -> bool {
67 MonoItem::Fn(ref instance) => {
68 instance.substs.non_erasable_generics().next().is_some()
70 MonoItem::Static(..) |
71 MonoItem::GlobalAsm(..) => false,
75 pub fn symbol_name(&self, tcx: TyCtxt<'tcx, 'tcx>) -> SymbolName {
77 MonoItem::Fn(instance) => tcx.symbol_name(instance),
78 MonoItem::Static(def_id) => {
79 tcx.symbol_name(Instance::mono(tcx, def_id))
81 MonoItem::GlobalAsm(hir_id) => {
82 let def_id = tcx.hir().local_def_id_from_hir_id(hir_id);
84 name: InternedString::intern(&format!("global_asm_{:?}", def_id))
90 pub fn instantiation_mode(&self, tcx: TyCtxt<'tcx, 'tcx>) -> InstantiationMode {
91 let inline_in_all_cgus =
92 tcx.sess.opts.debugging_opts.inline_in_all_cgus.unwrap_or_else(|| {
93 tcx.sess.opts.optimize != OptLevel::No
94 }) && !tcx.sess.opts.cg.link_dead_code;
97 MonoItem::Fn(ref instance) => {
98 let entry_def_id = tcx.entry_fn(LOCAL_CRATE).map(|(id, _)| id);
99 // If this function isn't inlined or otherwise has explicit
100 // linkage, then we'll be creating a globally shared version.
101 if self.explicit_linkage(tcx).is_some() ||
102 !instance.def.requires_local(tcx) ||
103 Some(instance.def_id()) == entry_def_id
105 return InstantiationMode::GloballyShared { may_conflict: false }
108 // At this point we don't have explicit linkage and we're an
109 // inlined function. If we're inlining into all CGUs then we'll
110 // be creating a local copy per CGU
111 if inline_in_all_cgus {
112 return InstantiationMode::LocalCopy
115 // Finally, if this is `#[inline(always)]` we're sure to respect
116 // that with an inline copy per CGU, but otherwise we'll be
117 // creating one copy of this `#[inline]` function which may
118 // conflict with upstream crates as it could be an exported
120 match tcx.codegen_fn_attrs(instance.def_id()).inline {
121 InlineAttr::Always => InstantiationMode::LocalCopy,
123 InstantiationMode::GloballyShared { may_conflict: true }
127 MonoItem::Static(..) |
128 MonoItem::GlobalAsm(..) => {
129 InstantiationMode::GloballyShared { may_conflict: false }
134 pub fn explicit_linkage(&self, tcx: TyCtxt<'tcx, 'tcx>) -> Option<Linkage> {
135 let def_id = match *self {
136 MonoItem::Fn(ref instance) => instance.def_id(),
137 MonoItem::Static(def_id) => def_id,
138 MonoItem::GlobalAsm(..) => return None,
141 let codegen_fn_attrs = tcx.codegen_fn_attrs(def_id);
142 codegen_fn_attrs.linkage
145 /// Returns `true` if this instance is instantiable - whether it has no unsatisfied
148 /// In order to codegen an item, all of its predicates must hold, because
149 /// otherwise the item does not make sense. Type-checking ensures that
150 /// the predicates of every item that is *used by* a valid item *do*
151 /// hold, so we can rely on that.
153 /// However, we codegen collector roots (reachable items) and functions
154 /// in vtables when they are seen, even if they are not used, and so they
155 /// might not be instantiable. For example, a programmer can define this
158 /// pub fn foo<'a>(s: &'a mut ()) where &'a mut (): Clone {
159 /// <&mut () as Clone>::clone(&s);
162 /// That function can't be codegened, because the method `<&mut () as Clone>::clone`
163 /// does not exist. Luckily for us, that function can't ever be used,
164 /// because that would require for `&'a mut (): Clone` to hold, so we
165 /// can just not emit any code, or even a linker reference for it.
167 /// Similarly, if a vtable method has such a signature, and therefore can't
168 /// be used, we can just not emit it and have a placeholder (a null pointer,
169 /// which will never be accessed) in its place.
170 pub fn is_instantiable(&self, tcx: TyCtxt<'tcx, 'tcx>) -> bool {
171 debug!("is_instantiable({:?})", self);
172 let (def_id, substs) = match *self {
173 MonoItem::Fn(ref instance) => (instance.def_id(), instance.substs),
174 MonoItem::Static(def_id) => (def_id, InternalSubsts::empty()),
175 // global asm never has predicates
176 MonoItem::GlobalAsm(..) => return true
179 tcx.substitute_normalize_and_test_predicates((def_id, &substs))
182 pub fn to_string(&self, tcx: TyCtxt<'tcx, 'tcx>, debug: bool) -> String {
184 MonoItem::Fn(instance) => {
185 to_string_internal(tcx, "fn ", instance, debug)
187 MonoItem::Static(def_id) => {
188 let instance = Instance::new(def_id, tcx.intern_substs(&[]));
189 to_string_internal(tcx, "static ", instance, debug)
191 MonoItem::GlobalAsm(..) => {
192 "global_asm".to_string()
196 fn to_string_internal<'tcx>(
197 tcx: TyCtxt<'tcx, 'tcx>,
199 instance: Instance<'tcx>,
202 let mut result = String::with_capacity(32);
203 result.push_str(prefix);
204 let printer = DefPathBasedNames::new(tcx, false, false);
205 printer.push_instance_as_string(instance, &mut result, debug);
210 pub fn local_span(&self, tcx: TyCtxt<'tcx, 'tcx>) -> Option<Span> {
212 MonoItem::Fn(Instance { def, .. }) => {
213 tcx.hir().as_local_hir_id(def.def_id())
215 MonoItem::Static(def_id) => {
216 tcx.hir().as_local_hir_id(def_id)
218 MonoItem::GlobalAsm(hir_id) => {
221 }.map(|hir_id| tcx.hir().span_by_hir_id(hir_id))
225 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for MonoItem<'tcx> {
226 fn hash_stable<W: StableHasherResult>(&self,
227 hcx: &mut StableHashingContext<'a>,
228 hasher: &mut StableHasher<W>) {
229 ::std::mem::discriminant(self).hash_stable(hcx, hasher);
232 MonoItem::Fn(ref instance) => {
233 instance.hash_stable(hcx, hasher);
235 MonoItem::Static(def_id) => {
236 def_id.hash_stable(hcx, hasher);
238 MonoItem::GlobalAsm(node_id) => {
239 hcx.with_node_id_hashing_mode(NodeIdHashingMode::HashDefPath, |hcx| {
240 node_id.hash_stable(hcx, hasher);
247 pub struct CodegenUnit<'tcx> {
248 /// A name for this CGU. Incremental compilation requires that
249 /// name be unique amongst **all** crates. Therefore, it should
250 /// contain something unique to this crate (e.g., a module path)
251 /// as well as the crate name and disambiguator.
252 name: InternedString,
253 items: FxHashMap<MonoItem<'tcx>, (Linkage, Visibility)>,
254 size_estimate: Option<usize>,
257 #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
272 impl_stable_hash_for!(enum self::Linkage {
286 #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
287 pub enum Visibility {
293 impl_stable_hash_for!(enum self::Visibility {
299 impl<'tcx> CodegenUnit<'tcx> {
300 pub fn new(name: InternedString) -> CodegenUnit<'tcx> {
303 items: Default::default(),
308 pub fn name(&self) -> &InternedString {
312 pub fn set_name(&mut self, name: InternedString) {
316 pub fn items(&self) -> &FxHashMap<MonoItem<'tcx>, (Linkage, Visibility)> {
320 pub fn items_mut(&mut self)
321 -> &mut FxHashMap<MonoItem<'tcx>, (Linkage, Visibility)>
326 pub fn mangle_name(human_readable_name: &str) -> String {
327 // We generate a 80 bit hash from the name. This should be enough to
328 // avoid collisions and is still reasonably short for filenames.
329 let mut hasher = StableHasher::new();
330 human_readable_name.hash(&mut hasher);
331 let hash: u128 = hasher.finish();
332 let hash = hash & ((1u128 << 80) - 1);
333 base_n::encode(hash, base_n::CASE_INSENSITIVE)
336 pub fn estimate_size(&mut self, tcx: TyCtxt<'tcx, 'tcx>) {
337 // Estimate the size of a codegen unit as (approximately) the number of MIR
338 // statements it corresponds to.
339 self.size_estimate = Some(self.items.keys().map(|mi| mi.size_estimate(tcx)).sum());
342 pub fn size_estimate(&self) -> usize {
343 // Should only be called if `estimate_size` has previously been called.
344 self.size_estimate.expect("estimate_size must be called before getting a size_estimate")
347 pub fn modify_size_estimate(&mut self, delta: usize) {
348 assert!(self.size_estimate.is_some());
349 if let Some(size_estimate) = self.size_estimate {
350 self.size_estimate = Some(size_estimate + delta);
354 pub fn contains_item(&self, item: &MonoItem<'tcx>) -> bool {
355 self.items().contains_key(item)
358 pub fn work_product_id(&self) -> WorkProductId {
359 WorkProductId::from_cgu_name(&self.name().as_str())
362 pub fn work_product(&self, tcx: TyCtxt<'_, '_>) -> WorkProduct {
363 let work_product_id = self.work_product_id();
365 .previous_work_product(&work_product_id)
367 panic!("Could not find work-product for CGU `{}`", self.name())
371 pub fn items_in_deterministic_order(
373 tcx: TyCtxt<'tcx, 'tcx>,
374 ) -> Vec<(MonoItem<'tcx>, (Linkage, Visibility))> {
375 // The codegen tests rely on items being process in the same order as
376 // they appear in the file, so for local items, we sort by node_id first
377 #[derive(PartialEq, Eq, PartialOrd, Ord)]
378 pub struct ItemSortKey(Option<HirId>, SymbolName);
380 fn item_sort_key<'tcx>(tcx: TyCtxt<'tcx, 'tcx>, item: MonoItem<'tcx>) -> ItemSortKey {
381 ItemSortKey(match item {
382 MonoItem::Fn(ref instance) => {
384 // We only want to take HirIds of user-defined
385 // instances into account. The others don't matter for
386 // the codegen tests and can even make item order
388 InstanceDef::Item(def_id) => {
389 tcx.hir().as_local_hir_id(def_id)
391 InstanceDef::VtableShim(..) |
392 InstanceDef::Intrinsic(..) |
393 InstanceDef::FnPtrShim(..) |
394 InstanceDef::Virtual(..) |
395 InstanceDef::ClosureOnceShim { .. } |
396 InstanceDef::DropGlue(..) |
397 InstanceDef::CloneShim(..) => {
402 MonoItem::Static(def_id) => {
403 tcx.hir().as_local_hir_id(def_id)
405 MonoItem::GlobalAsm(hir_id) => {
408 }, item.symbol_name(tcx))
411 let mut items: Vec<_> = self.items().iter().map(|(&i, &l)| (i, l)).collect();
412 items.sort_by_cached_key(|&(i, _)| item_sort_key(tcx, i));
416 pub fn codegen_dep_node(&self, tcx: TyCtxt<'tcx, 'tcx>) -> DepNode {
417 DepNode::new(tcx, DepConstructor::CompileCodegenUnit(self.name().clone()))
421 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for CodegenUnit<'tcx> {
422 fn hash_stable<W: StableHasherResult>(&self,
423 hcx: &mut StableHashingContext<'a>,
424 hasher: &mut StableHasher<W>) {
428 // The size estimate is not relevant to the hash
432 name.hash_stable(hcx, hasher);
434 let mut items: Vec<(Fingerprint, _)> = items.iter().map(|(mono_item, &attrs)| {
435 let mut hasher = StableHasher::new();
436 mono_item.hash_stable(hcx, &mut hasher);
437 let mono_item_fingerprint = hasher.finish();
438 (mono_item_fingerprint, attrs)
441 items.sort_unstable_by_key(|i| i.0);
442 items.hash_stable(hcx, hasher);
446 pub struct CodegenUnitNameBuilder<'gcx, 'tcx> {
447 tcx: TyCtxt<'gcx, 'tcx>,
448 cache: FxHashMap<CrateNum, String>,
451 impl CodegenUnitNameBuilder<'gcx, 'tcx> {
452 pub fn new(tcx: TyCtxt<'gcx, 'tcx>) -> Self {
453 CodegenUnitNameBuilder {
455 cache: Default::default(),
459 /// CGU names should fulfill the following requirements:
460 /// - They should be able to act as a file name on any kind of file system
461 /// - They should not collide with other CGU names, even for different versions
462 /// of the same crate.
464 /// Consequently, we don't use special characters except for '.' and '-' and we
465 /// prefix each name with the crate-name and crate-disambiguator.
467 /// This function will build CGU names of the form:
470 /// <crate-name>.<crate-disambiguator>[-in-<local-crate-id>](-<component>)*[.<special-suffix>]
471 /// <local-crate-id> = <local-crate-name>.<local-crate-disambiguator>
474 /// The '.' before `<special-suffix>` makes sure that names with a special
475 /// suffix can never collide with a name built out of regular Rust
476 /// identifiers (e.g., module paths).
477 pub fn build_cgu_name<I, C, S>(&mut self,
480 special_suffix: Option<S>)
482 where I: IntoIterator<Item=C>,
486 let cgu_name = self.build_cgu_name_no_mangle(cnum,
490 if self.tcx.sess.opts.debugging_opts.human_readable_cgu_names {
493 let cgu_name = &cgu_name.as_str()[..];
494 InternedString::intern(&CodegenUnit::mangle_name(cgu_name))
498 /// Same as `CodegenUnit::build_cgu_name()` but will never mangle the
500 pub fn build_cgu_name_no_mangle<I, C, S>(&mut self,
503 special_suffix: Option<S>)
505 where I: IntoIterator<Item=C>,
511 let mut cgu_name = String::with_capacity(64);
513 // Start out with the crate name and disambiguator
515 let crate_prefix = self.cache.entry(cnum).or_insert_with(|| {
516 // Whenever the cnum is not LOCAL_CRATE we also mix in the
517 // local crate's ID. Otherwise there can be collisions between CGUs
518 // instantiating stuff for upstream crates.
519 let local_crate_id = if cnum != LOCAL_CRATE {
520 let local_crate_disambiguator =
521 format!("{}", tcx.crate_disambiguator(LOCAL_CRATE));
523 tcx.crate_name(LOCAL_CRATE),
524 &local_crate_disambiguator[0 .. 8])
529 let crate_disambiguator = tcx.crate_disambiguator(cnum).to_string();
530 // Using a shortened disambiguator of about 40 bits
532 tcx.crate_name(cnum),
533 &crate_disambiguator[0 .. 8],
537 write!(cgu_name, "{}", crate_prefix).unwrap();
539 // Add the components
540 for component in components {
541 write!(cgu_name, "-{}", component).unwrap();
544 if let Some(special_suffix) = special_suffix {
545 // We add a dot in here so it cannot clash with anything in a regular
547 write!(cgu_name, ".{}", special_suffix).unwrap();
550 InternedString::intern(&cgu_name[..])