1 use crate::monomorphize::Instance;
3 use rustc::hir::def_id::{DefId, LOCAL_CRATE};
4 use rustc::mir::interpret::ConstValue;
5 use rustc::session::config::OptLevel;
6 use rustc::ty::{self, Ty, TyCtxt, Const, ClosureSubsts, GeneratorSubsts};
7 use rustc::ty::subst::{SubstsRef, InternalSubsts};
9 use syntax::attr::InlineAttr;
10 use std::fmt::{self, Write};
12 use rustc::mir::mono::Linkage;
13 use syntax_pos::symbol::InternedString;
14 use syntax::source_map::Span;
15 pub use rustc::mir::mono::MonoItem;
17 /// Describes how a monomorphization will be instantiated in object files.
18 #[derive(PartialEq, Eq, Clone, Copy, Debug, Hash)]
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 pub trait MonoItemExt<'a, 'tcx>: fmt::Debug {
43 fn as_mono_item(&self) -> &MonoItem<'tcx>;
45 fn is_generic_fn(&self) -> bool {
46 match *self.as_mono_item() {
47 MonoItem::Fn(ref instance) => {
48 instance.substs.non_erasable_generics().next().is_some()
50 MonoItem::Static(..) |
51 MonoItem::GlobalAsm(..) => false,
55 fn symbol_name(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> ty::SymbolName {
56 match *self.as_mono_item() {
57 MonoItem::Fn(instance) => tcx.symbol_name(instance),
58 MonoItem::Static(def_id) => {
59 tcx.symbol_name(Instance::mono(tcx, def_id))
61 MonoItem::GlobalAsm(hir_id) => {
62 let def_id = tcx.hir().local_def_id_from_hir_id(hir_id);
64 name: InternedString::intern(&format!("global_asm_{:?}", def_id))
69 fn instantiation_mode(&self,
70 tcx: TyCtxt<'a, 'tcx, 'tcx>)
71 -> InstantiationMode {
72 let inline_in_all_cgus =
73 tcx.sess.opts.debugging_opts.inline_in_all_cgus.unwrap_or_else(|| {
74 tcx.sess.opts.optimize != OptLevel::No
75 }) && !tcx.sess.opts.cg.link_dead_code;
77 match *self.as_mono_item() {
78 MonoItem::Fn(ref instance) => {
79 let entry_def_id = tcx.entry_fn(LOCAL_CRATE).map(|(id, _)| id);
80 // If this function isn't inlined or otherwise has explicit
81 // linkage, then we'll be creating a globally shared version.
82 if self.explicit_linkage(tcx).is_some() ||
83 !instance.def.requires_local(tcx) ||
84 Some(instance.def_id()) == entry_def_id
86 return InstantiationMode::GloballyShared { may_conflict: false }
89 // At this point we don't have explicit linkage and we're an
90 // inlined function. If we're inlining into all CGUs then we'll
91 // be creating a local copy per CGU
92 if inline_in_all_cgus {
93 return InstantiationMode::LocalCopy
96 // Finally, if this is `#[inline(always)]` we're sure to respect
97 // that with an inline copy per CGU, but otherwise we'll be
98 // creating one copy of this `#[inline]` function which may
99 // conflict with upstream crates as it could be an exported
101 match tcx.codegen_fn_attrs(instance.def_id()).inline {
102 InlineAttr::Always => InstantiationMode::LocalCopy,
104 InstantiationMode::GloballyShared { may_conflict: true }
108 MonoItem::Static(..) |
109 MonoItem::GlobalAsm(..) => {
110 InstantiationMode::GloballyShared { may_conflict: false }
115 fn explicit_linkage(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> Option<Linkage> {
116 let def_id = match *self.as_mono_item() {
117 MonoItem::Fn(ref instance) => instance.def_id(),
118 MonoItem::Static(def_id) => def_id,
119 MonoItem::GlobalAsm(..) => return None,
122 let codegen_fn_attrs = tcx.codegen_fn_attrs(def_id);
123 codegen_fn_attrs.linkage
126 /// Returns `true` if this instance is instantiable - whether it has no unsatisfied
129 /// In order to codegen an item, all of its predicates must hold, because
130 /// otherwise the item does not make sense. Type-checking ensures that
131 /// the predicates of every item that is *used by* a valid item *do*
132 /// hold, so we can rely on that.
134 /// However, we codegen collector roots (reachable items) and functions
135 /// in vtables when they are seen, even if they are not used, and so they
136 /// might not be instantiable. For example, a programmer can define this
139 /// pub fn foo<'a>(s: &'a mut ()) where &'a mut (): Clone {
140 /// <&mut () as Clone>::clone(&s);
143 /// That function can't be codegened, because the method `<&mut () as Clone>::clone`
144 /// does not exist. Luckily for us, that function can't ever be used,
145 /// because that would require for `&'a mut (): Clone` to hold, so we
146 /// can just not emit any code, or even a linker reference for it.
148 /// Similarly, if a vtable method has such a signature, and therefore can't
149 /// be used, we can just not emit it and have a placeholder (a null pointer,
150 /// which will never be accessed) in its place.
151 fn is_instantiable(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> bool {
152 debug!("is_instantiable({:?})", self);
153 let (def_id, substs) = match *self.as_mono_item() {
154 MonoItem::Fn(ref instance) => (instance.def_id(), instance.substs),
155 MonoItem::Static(def_id) => (def_id, InternalSubsts::empty()),
156 // global asm never has predicates
157 MonoItem::GlobalAsm(..) => return true
160 tcx.substitute_normalize_and_test_predicates((def_id, &substs))
163 fn to_string(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>, debug: bool) -> String {
164 return match *self.as_mono_item() {
165 MonoItem::Fn(instance) => {
166 to_string_internal(tcx, "fn ", instance, debug)
168 MonoItem::Static(def_id) => {
169 let instance = Instance::new(def_id, tcx.intern_substs(&[]));
170 to_string_internal(tcx, "static ", instance, debug)
172 MonoItem::GlobalAsm(..) => {
173 "global_asm".to_string()
177 fn to_string_internal<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
179 instance: Instance<'tcx>,
182 let mut result = String::with_capacity(32);
183 result.push_str(prefix);
184 let printer = DefPathBasedNames::new(tcx, false, false);
185 printer.push_instance_as_string(instance, &mut result, debug);
190 fn local_span(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> Option<Span> {
191 match *self.as_mono_item() {
192 MonoItem::Fn(Instance { def, .. }) => {
193 tcx.hir().as_local_hir_id(def.def_id())
195 MonoItem::Static(def_id) => {
196 tcx.hir().as_local_hir_id(def_id)
198 MonoItem::GlobalAsm(hir_id) => {
201 }.map(|hir_id| tcx.hir().span_by_hir_id(hir_id))
205 impl<'a, 'tcx> MonoItemExt<'a, 'tcx> for MonoItem<'tcx> {
206 fn as_mono_item(&self) -> &MonoItem<'tcx> {
211 //=-----------------------------------------------------------------------------
212 // MonoItem String Keys
213 //=-----------------------------------------------------------------------------
215 // The code below allows for producing a unique string key for a mono item.
216 // These keys are used by the handwritten auto-tests, so they need to be
217 // predictable and human-readable.
219 // Note: A lot of this could looks very similar to what's already in `ty::print`.
220 // FIXME(eddyb) implement a custom `PrettyPrinter` for this.
222 /// Same as `unique_type_name()` but with the result pushed onto the given
223 /// `output` parameter.
224 pub struct DefPathBasedNames<'a, 'tcx: 'a> {
225 tcx: TyCtxt<'a, 'tcx, 'tcx>,
226 omit_disambiguators: bool,
227 omit_local_crate_name: bool,
230 impl<'a, 'tcx> DefPathBasedNames<'a, 'tcx> {
231 pub fn new(tcx: TyCtxt<'a, 'tcx, 'tcx>,
232 omit_disambiguators: bool,
233 omit_local_crate_name: bool)
238 omit_local_crate_name,
242 // Pushes the type name of the specified type to the provided string.
243 // If `debug` is true, printing normally unprintable types is allowed
244 // (e.g. `ty::GeneratorWitness`). This parameter should only be set when
245 // this method is being used for logging purposes (e.g. with `debug!` or `info!`)
246 // When being used for codegen purposes, `debug` should be set to `false`
247 // in order to catch unexpected types that should never end up in a type name.
248 pub fn push_type_name(&self, t: Ty<'tcx>, output: &mut String, debug: bool) {
250 ty::Bool => output.push_str("bool"),
251 ty::Char => output.push_str("char"),
252 ty::Str => output.push_str("str"),
253 ty::Never => output.push_str("!"),
254 ty::Int(ast::IntTy::Isize) => output.push_str("isize"),
255 ty::Int(ast::IntTy::I8) => output.push_str("i8"),
256 ty::Int(ast::IntTy::I16) => output.push_str("i16"),
257 ty::Int(ast::IntTy::I32) => output.push_str("i32"),
258 ty::Int(ast::IntTy::I64) => output.push_str("i64"),
259 ty::Int(ast::IntTy::I128) => output.push_str("i128"),
260 ty::Uint(ast::UintTy::Usize) => output.push_str("usize"),
261 ty::Uint(ast::UintTy::U8) => output.push_str("u8"),
262 ty::Uint(ast::UintTy::U16) => output.push_str("u16"),
263 ty::Uint(ast::UintTy::U32) => output.push_str("u32"),
264 ty::Uint(ast::UintTy::U64) => output.push_str("u64"),
265 ty::Uint(ast::UintTy::U128) => output.push_str("u128"),
266 ty::Float(ast::FloatTy::F32) => output.push_str("f32"),
267 ty::Float(ast::FloatTy::F64) => output.push_str("f64"),
268 ty::Adt(adt_def, substs) => {
269 self.push_def_path(adt_def.did, output);
270 self.push_generic_params(substs, iter::empty(), output, debug);
272 ty::Tuple(component_types) => {
274 for &component_type in component_types {
275 self.push_type_name(component_type.expect_ty(), output, debug);
276 output.push_str(", ");
278 if !component_types.is_empty() {
284 ty::RawPtr(ty::TypeAndMut { ty: inner_type, mutbl } ) => {
287 hir::MutImmutable => output.push_str("const "),
288 hir::MutMutable => output.push_str("mut "),
291 self.push_type_name(inner_type, output, debug);
293 ty::Ref(_, inner_type, mutbl) => {
295 if mutbl == hir::MutMutable {
296 output.push_str("mut ");
299 self.push_type_name(inner_type, output, debug);
301 ty::Array(inner_type, len) => {
303 self.push_type_name(inner_type, output, debug);
304 write!(output, "; {}", len.unwrap_usize(self.tcx)).unwrap();
307 ty::Slice(inner_type) => {
309 self.push_type_name(inner_type, output, debug);
312 ty::Dynamic(ref trait_data, ..) => {
313 if let Some(principal) = trait_data.principal() {
314 self.push_def_path(principal.def_id(), output);
315 self.push_generic_params(
316 principal.skip_binder().substs,
317 trait_data.projection_bounds(),
322 output.push_str("dyn '_");
325 ty::Foreign(did) => self.push_def_path(did, output),
328 let sig = t.fn_sig(self.tcx);
329 if sig.unsafety() == hir::Unsafety::Unsafe {
330 output.push_str("unsafe ");
334 if abi != ::rustc_target::spec::abi::Abi::Rust {
335 output.push_str("extern \"");
336 output.push_str(abi.name());
337 output.push_str("\" ");
340 output.push_str("fn(");
342 let sig = self.tcx.normalize_erasing_late_bound_regions(
343 ty::ParamEnv::reveal_all(),
347 if !sig.inputs().is_empty() {
348 for ¶meter_type in sig.inputs() {
349 self.push_type_name(parameter_type, output, debug);
350 output.push_str(", ");
357 if !sig.inputs().is_empty() {
358 output.push_str(", ...");
360 output.push_str("...");
366 if !sig.output().is_unit() {
367 output.push_str(" -> ");
368 self.push_type_name(sig.output(), output, debug);
371 ty::Generator(def_id, GeneratorSubsts { ref substs }, _) |
372 ty::Closure(def_id, ClosureSubsts { ref substs }) => {
373 self.push_def_path(def_id, output);
374 let generics = self.tcx.generics_of(self.tcx.closure_base_def_id(def_id));
375 let substs = substs.truncate_to(self.tcx, generics);
376 self.push_generic_params(substs, iter::empty(), output, debug);
381 ty::Placeholder(..) |
382 ty::UnnormalizedProjection(..) |
385 ty::GeneratorWitness(_) |
388 output.push_str(&format!("`{:?}`", t));
391 "DefPathBasedNames: trying to create type name for unexpected type: {:?}",
399 // Pushes the the name of the specified const to the provided string.
400 // If `debug` is true, usually-unprintable consts (such as `Infer`) will be printed,
401 // as well as the unprintable types of constants (see `push_type_name` for more details).
402 pub fn push_const_name(&self, c: &Const<'tcx>, output: &mut String, debug: bool) {
404 ConstValue::Scalar(..) | ConstValue::Slice { .. } | ConstValue::ByRef(..) => {
405 // FIXME(const_generics): we could probably do a better job here.
406 write!(output, "{:?}", c).unwrap()
410 write!(output, "{:?}", c).unwrap()
413 "DefPathBasedNames: trying to create const name for unexpected const: {:?}",
419 output.push_str(": ");
420 self.push_type_name(c.ty, output, debug);
423 pub fn push_def_path(&self,
425 output: &mut String) {
426 let def_path = self.tcx.def_path(def_id);
429 if !(self.omit_local_crate_name && def_id.is_local()) {
430 output.push_str(&self.tcx.crate_name(def_path.krate).as_str());
431 output.push_str("::");
434 // foo::bar::ItemName::
435 for part in self.tcx.def_path(def_id).data {
436 if self.omit_disambiguators {
437 write!(output, "{}::", part.data.as_interned_str()).unwrap();
439 write!(output, "{}[{}]::",
440 part.data.as_interned_str(),
441 part.disambiguator).unwrap();
450 fn push_generic_params<I>(
452 substs: SubstsRef<'tcx>,
456 ) where I: Iterator<Item=ty::PolyExistentialProjection<'tcx>> {
457 let mut projections = projections.peekable();
458 if substs.non_erasable_generics().next().is_none() && projections.peek().is_none() {
464 for type_parameter in substs.types() {
465 self.push_type_name(type_parameter, output, debug);
466 output.push_str(", ");
469 for projection in projections {
470 let projection = projection.skip_binder();
471 let name = &self.tcx.associated_item(projection.item_def_id).ident.as_str();
472 output.push_str(name);
473 output.push_str("=");
474 self.push_type_name(projection.ty, output, debug);
475 output.push_str(", ");
478 for const_parameter in substs.consts() {
479 self.push_const_name(const_parameter, output, debug);
480 output.push_str(", ");
489 pub fn push_instance_as_string(&self,
490 instance: Instance<'tcx>,
493 self.push_def_path(instance.def_id(), output);
494 self.push_generic_params(instance.substs, iter::empty(), output, debug);