1 use crate::hir::def_id::{DefId, CrateNum, LOCAL_CRATE};
3 use syntax::symbol::Symbol;
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, StableHasher};
12 use crate::ich::{Fingerprint, StableHashingContext, NodeIdHashingMode};
13 use crate::session::config::OptLevel;
17 /// Describes how a monomorphization will be instantiated in object files.
19 pub enum InstantiationMode {
20 /// There will be exactly one instance of the given MonoItem. It will have
21 /// external linkage so that it can be linked to from other codegen units.
23 /// In some compilation scenarios we may decide to take functions that
24 /// are typically `LocalCopy` and instead move them to `GloballyShared`
25 /// to avoid codegenning them a bunch of times. In this situation,
26 /// however, our local copy may conflict with other crates also
27 /// inlining the same function.
29 /// This flag indicates that this situation is occurring, and informs
30 /// symbol name calculation that some extra mangling is needed to
31 /// avoid conflicts. Note that this may eventually go away entirely if
32 /// ThinLTO enables us to *always* have a globally shared instance of a
33 /// function within one crate's compilation.
37 /// Each codegen unit containing a reference to the given MonoItem will
38 /// have its own private copy of the function (with internal linkage).
42 #[derive(PartialEq, Eq, Clone, Copy, Debug, Hash)]
43 pub enum MonoItem<'tcx> {
49 impl<'tcx> MonoItem<'tcx> {
50 pub fn size_estimate(&self, tcx: TyCtxt<'tcx>) -> usize {
52 MonoItem::Fn(instance) => {
53 // Estimate the size of a function based on how many statements
55 tcx.instance_def_size_estimate(instance.def)
57 // Conservatively estimate the size of a static declaration
58 // or assembly to be 1.
60 MonoItem::GlobalAsm(_) => 1,
64 pub fn is_generic_fn(&self) -> bool {
66 MonoItem::Fn(ref instance) => {
67 instance.substs.non_erasable_generics().next().is_some()
69 MonoItem::Static(..) |
70 MonoItem::GlobalAsm(..) => false,
74 pub fn symbol_name(&self, tcx: TyCtxt<'tcx>) -> SymbolName {
76 MonoItem::Fn(instance) => tcx.symbol_name(instance),
77 MonoItem::Static(def_id) => {
78 tcx.symbol_name(Instance::mono(tcx, def_id))
80 MonoItem::GlobalAsm(hir_id) => {
81 let def_id = tcx.hir().local_def_id(hir_id);
83 name: Symbol::intern(&format!("global_asm_{:?}", def_id))
89 pub fn instantiation_mode(&self, tcx: TyCtxt<'tcx>) -> InstantiationMode {
90 let inline_in_all_cgus =
91 tcx.sess.opts.debugging_opts.inline_in_all_cgus.unwrap_or_else(|| {
92 tcx.sess.opts.optimize != OptLevel::No
93 }) && !tcx.sess.opts.cg.link_dead_code;
96 MonoItem::Fn(ref instance) => {
97 let entry_def_id = tcx.entry_fn(LOCAL_CRATE).map(|(id, _)| id);
98 // If this function isn't inlined or otherwise has explicit
99 // linkage, then we'll be creating a globally shared version.
100 if self.explicit_linkage(tcx).is_some() ||
101 !instance.def.requires_local(tcx) ||
102 Some(instance.def_id()) == entry_def_id
104 return InstantiationMode::GloballyShared { may_conflict: false }
107 // At this point we don't have explicit linkage and we're an
108 // inlined function. If we're inlining into all CGUs then we'll
109 // be creating a local copy per CGU
110 if inline_in_all_cgus {
111 return InstantiationMode::LocalCopy
114 // Finally, if this is `#[inline(always)]` we're sure to respect
115 // that with an inline copy per CGU, but otherwise we'll be
116 // creating one copy of this `#[inline]` function which may
117 // conflict with upstream crates as it could be an exported
119 match tcx.codegen_fn_attrs(instance.def_id()).inline {
120 InlineAttr::Always => InstantiationMode::LocalCopy,
122 InstantiationMode::GloballyShared { may_conflict: true }
126 MonoItem::Static(..) |
127 MonoItem::GlobalAsm(..) => {
128 InstantiationMode::GloballyShared { may_conflict: false }
133 pub fn explicit_linkage(&self, tcx: TyCtxt<'tcx>) -> Option<Linkage> {
134 let def_id = match *self {
135 MonoItem::Fn(ref instance) => instance.def_id(),
136 MonoItem::Static(def_id) => def_id,
137 MonoItem::GlobalAsm(..) => return None,
140 let codegen_fn_attrs = tcx.codegen_fn_attrs(def_id);
141 codegen_fn_attrs.linkage
144 /// Returns `true` if this instance is instantiable - whether it has no unsatisfied
147 /// In order to codegen an item, all of its predicates must hold, because
148 /// otherwise the item does not make sense. Type-checking ensures that
149 /// the predicates of every item that is *used by* a valid item *do*
150 /// hold, so we can rely on that.
152 /// However, we codegen collector roots (reachable items) and functions
153 /// in vtables when they are seen, even if they are not used, and so they
154 /// might not be instantiable. For example, a programmer can define this
157 /// pub fn foo<'a>(s: &'a mut ()) where &'a mut (): Clone {
158 /// <&mut () as Clone>::clone(&s);
161 /// That function can't be codegened, because the method `<&mut () as Clone>::clone`
162 /// does not exist. Luckily for us, that function can't ever be used,
163 /// because that would require for `&'a mut (): Clone` to hold, so we
164 /// can just not emit any code, or even a linker reference for it.
166 /// Similarly, if a vtable method has such a signature, and therefore can't
167 /// be used, we can just not emit it and have a placeholder (a null pointer,
168 /// which will never be accessed) in its place.
169 pub fn is_instantiable(&self, tcx: TyCtxt<'tcx>) -> bool {
170 debug!("is_instantiable({:?})", self);
171 let (def_id, substs) = match *self {
172 MonoItem::Fn(ref instance) => (instance.def_id(), instance.substs),
173 MonoItem::Static(def_id) => (def_id, InternalSubsts::empty()),
174 // global asm never has predicates
175 MonoItem::GlobalAsm(..) => return true
178 tcx.substitute_normalize_and_test_predicates((def_id, &substs))
181 pub fn to_string(&self, tcx: TyCtxt<'tcx>, debug: bool) -> String {
183 MonoItem::Fn(instance) => {
184 to_string_internal(tcx, "fn ", instance, debug)
186 MonoItem::Static(def_id) => {
187 let instance = Instance::new(def_id, tcx.intern_substs(&[]));
188 to_string_internal(tcx, "static ", instance, debug)
190 MonoItem::GlobalAsm(..) => {
191 "global_asm".to_string()
195 fn to_string_internal<'tcx>(
198 instance: Instance<'tcx>,
201 let mut result = String::with_capacity(32);
202 result.push_str(prefix);
203 let printer = DefPathBasedNames::new(tcx, false, false);
204 printer.push_instance_as_string(instance, &mut result, debug);
209 pub fn local_span(&self, tcx: TyCtxt<'tcx>) -> Option<Span> {
211 MonoItem::Fn(Instance { def, .. }) => {
212 tcx.hir().as_local_hir_id(def.def_id())
214 MonoItem::Static(def_id) => {
215 tcx.hir().as_local_hir_id(def_id)
217 MonoItem::GlobalAsm(hir_id) => {
220 }.map(|hir_id| tcx.hir().span(hir_id))
224 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for MonoItem<'tcx> {
225 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
226 ::std::mem::discriminant(self).hash_stable(hcx, hasher);
229 MonoItem::Fn(ref instance) => {
230 instance.hash_stable(hcx, hasher);
232 MonoItem::Static(def_id) => {
233 def_id.hash_stable(hcx, hasher);
235 MonoItem::GlobalAsm(node_id) => {
236 hcx.with_node_id_hashing_mode(NodeIdHashingMode::HashDefPath, |hcx| {
237 node_id.hash_stable(hcx, hasher);
244 pub struct CodegenUnit<'tcx> {
245 /// A name for this CGU. Incremental compilation requires that
246 /// name be unique amongst **all** crates. Therefore, it should
247 /// contain something unique to this crate (e.g., a module path)
248 /// as well as the crate name and disambiguator.
250 items: FxHashMap<MonoItem<'tcx>, (Linkage, Visibility)>,
251 size_estimate: Option<usize>,
254 #[derive(Copy, Clone, PartialEq, Debug, RustcEncodable, RustcDecodable)]
269 impl_stable_hash_for!(enum self::Linkage {
283 #[derive(Copy, Clone, PartialEq, Debug)]
284 pub enum Visibility {
290 impl_stable_hash_for!(enum self::Visibility {
296 impl<'tcx> CodegenUnit<'tcx> {
297 pub fn new(name: Symbol) -> CodegenUnit<'tcx> {
300 items: Default::default(),
305 pub fn name(&self) -> Symbol {
309 pub fn set_name(&mut self, name: Symbol) {
313 pub fn items(&self) -> &FxHashMap<MonoItem<'tcx>, (Linkage, Visibility)> {
317 pub fn items_mut(&mut self)
318 -> &mut FxHashMap<MonoItem<'tcx>, (Linkage, Visibility)>
323 pub fn mangle_name(human_readable_name: &str) -> String {
324 // We generate a 80 bit hash from the name. This should be enough to
325 // avoid collisions and is still reasonably short for filenames.
326 let mut hasher = StableHasher::new();
327 human_readable_name.hash(&mut hasher);
328 let hash: u128 = hasher.finish();
329 let hash = hash & ((1u128 << 80) - 1);
330 base_n::encode(hash, base_n::CASE_INSENSITIVE)
333 pub fn estimate_size(&mut self, tcx: TyCtxt<'tcx>) {
334 // Estimate the size of a codegen unit as (approximately) the number of MIR
335 // statements it corresponds to.
336 self.size_estimate = Some(self.items.keys().map(|mi| mi.size_estimate(tcx)).sum());
339 pub fn size_estimate(&self) -> usize {
340 // Should only be called if `estimate_size` has previously been called.
341 self.size_estimate.expect("estimate_size must be called before getting a size_estimate")
344 pub fn modify_size_estimate(&mut self, delta: usize) {
345 assert!(self.size_estimate.is_some());
346 if let Some(size_estimate) = self.size_estimate {
347 self.size_estimate = Some(size_estimate + delta);
351 pub fn contains_item(&self, item: &MonoItem<'tcx>) -> bool {
352 self.items().contains_key(item)
355 pub fn work_product_id(&self) -> WorkProductId {
356 WorkProductId::from_cgu_name(&self.name().as_str())
359 pub fn work_product(&self, tcx: TyCtxt<'_>) -> WorkProduct {
360 let work_product_id = self.work_product_id();
362 .previous_work_product(&work_product_id)
364 panic!("Could not find work-product for CGU `{}`", self.name())
368 pub fn items_in_deterministic_order(
371 ) -> Vec<(MonoItem<'tcx>, (Linkage, Visibility))> {
372 // The codegen tests rely on items being process in the same order as
373 // they appear in the file, so for local items, we sort by node_id first
374 #[derive(PartialEq, Eq, PartialOrd, Ord)]
375 pub struct ItemSortKey(Option<HirId>, SymbolName);
377 fn item_sort_key<'tcx>(tcx: TyCtxt<'tcx>, item: MonoItem<'tcx>) -> ItemSortKey {
378 ItemSortKey(match item {
379 MonoItem::Fn(ref instance) => {
381 // We only want to take HirIds of user-defined
382 // instances into account. The others don't matter for
383 // the codegen tests and can even make item order
385 InstanceDef::Item(def_id) => {
386 tcx.hir().as_local_hir_id(def_id)
388 InstanceDef::VtableShim(..) |
389 InstanceDef::ReifyShim(..) |
390 InstanceDef::Intrinsic(..) |
391 InstanceDef::FnPtrShim(..) |
392 InstanceDef::Virtual(..) |
393 InstanceDef::ClosureOnceShim { .. } |
394 InstanceDef::DropGlue(..) |
395 InstanceDef::CloneShim(..) => {
400 MonoItem::Static(def_id) => {
401 tcx.hir().as_local_hir_id(def_id)
403 MonoItem::GlobalAsm(hir_id) => {
406 }, item.symbol_name(tcx))
409 let mut items: Vec<_> = self.items().iter().map(|(&i, &l)| (i, l)).collect();
410 items.sort_by_cached_key(|&(i, _)| item_sort_key(tcx, i));
414 pub fn codegen_dep_node(&self, tcx: TyCtxt<'tcx>) -> DepNode {
415 DepNode::new(tcx, DepConstructor::CompileCodegenUnit(self.name().clone()))
419 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for CodegenUnit<'tcx> {
420 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
424 // The size estimate is not relevant to the hash
428 name.hash_stable(hcx, hasher);
430 let mut items: Vec<(Fingerprint, _)> = items.iter().map(|(mono_item, &attrs)| {
431 let mut hasher = StableHasher::new();
432 mono_item.hash_stable(hcx, &mut hasher);
433 let mono_item_fingerprint = hasher.finish();
434 (mono_item_fingerprint, attrs)
437 items.sort_unstable_by_key(|i| i.0);
438 items.hash_stable(hcx, hasher);
442 pub struct CodegenUnitNameBuilder<'tcx> {
444 cache: FxHashMap<CrateNum, String>,
447 impl CodegenUnitNameBuilder<'tcx> {
448 pub fn new(tcx: TyCtxt<'tcx>) -> Self {
449 CodegenUnitNameBuilder {
451 cache: Default::default(),
455 /// CGU names should fulfill the following requirements:
456 /// - They should be able to act as a file name on any kind of file system
457 /// - They should not collide with other CGU names, even for different versions
458 /// of the same crate.
460 /// Consequently, we don't use special characters except for '.' and '-' and we
461 /// prefix each name with the crate-name and crate-disambiguator.
463 /// This function will build CGU names of the form:
466 /// <crate-name>.<crate-disambiguator>[-in-<local-crate-id>](-<component>)*[.<special-suffix>]
467 /// <local-crate-id> = <local-crate-name>.<local-crate-disambiguator>
470 /// The '.' before `<special-suffix>` makes sure that names with a special
471 /// suffix can never collide with a name built out of regular Rust
472 /// identifiers (e.g., module paths).
473 pub fn build_cgu_name<I, C, S>(&mut self,
476 special_suffix: Option<S>)
478 where I: IntoIterator<Item=C>,
482 let cgu_name = self.build_cgu_name_no_mangle(cnum,
486 if self.tcx.sess.opts.debugging_opts.human_readable_cgu_names {
489 let cgu_name = &cgu_name.as_str();
490 Symbol::intern(&CodegenUnit::mangle_name(cgu_name))
494 /// Same as `CodegenUnit::build_cgu_name()` but will never mangle the
496 pub fn build_cgu_name_no_mangle<I, C, S>(&mut self,
499 special_suffix: Option<S>)
501 where I: IntoIterator<Item=C>,
507 let mut cgu_name = String::with_capacity(64);
509 // Start out with the crate name and disambiguator
511 let crate_prefix = self.cache.entry(cnum).or_insert_with(|| {
512 // Whenever the cnum is not LOCAL_CRATE we also mix in the
513 // local crate's ID. Otherwise there can be collisions between CGUs
514 // instantiating stuff for upstream crates.
515 let local_crate_id = if cnum != LOCAL_CRATE {
516 let local_crate_disambiguator =
517 format!("{}", tcx.crate_disambiguator(LOCAL_CRATE));
519 tcx.crate_name(LOCAL_CRATE),
520 &local_crate_disambiguator[0 .. 8])
525 let crate_disambiguator = tcx.crate_disambiguator(cnum).to_string();
526 // Using a shortened disambiguator of about 40 bits
528 tcx.crate_name(cnum),
529 &crate_disambiguator[0 .. 8],
533 write!(cgu_name, "{}", crate_prefix).unwrap();
535 // Add the components
536 for component in components {
537 write!(cgu_name, "-{}", component).unwrap();
540 if let Some(special_suffix) = special_suffix {
541 // We add a dot in here so it cannot clash with anything in a regular
543 write!(cgu_name, ".{}", special_suffix).unwrap();
546 Symbol::intern(&cgu_name[..])