1 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
2 use rustc_hir::def_id::CrateNum;
3 use rustc_hir::definitions::{DefPathData, DisambiguatedDefPathData};
4 use rustc_middle::ich::NodeIdHashingMode;
5 use rustc_middle::mir::interpret::{ConstValue, Scalar};
6 use rustc_middle::ty::print::{PrettyPrinter, Print, Printer};
7 use rustc_middle::ty::subst::{GenericArg, GenericArgKind};
8 use rustc_middle::ty::{self, Instance, Ty, TyCtxt, TypeFoldable};
9 use rustc_middle::util::common::record_time;
13 use std::fmt::{self, Write};
14 use std::mem::{self, discriminant};
18 instance: Instance<'tcx>,
19 instantiating_crate: Option<CrateNum>,
21 let def_id = instance.def_id();
23 // We want to compute the "type" of this item. Unfortunately, some
24 // kinds of items (e.g., closures) don't have an entry in the
25 // item-type array. So walk back up the find the closest parent
26 // that DOES have an entry.
27 let mut ty_def_id = def_id;
30 let key = tcx.def_key(ty_def_id);
31 match key.disambiguated_data.data {
32 DefPathData::TypeNs(_) | DefPathData::ValueNs(_) => {
33 instance_ty = tcx.type_of(ty_def_id);
37 // if we're making a symbol for something, there ought
38 // to be a value or type-def or something in there
40 ty_def_id.index = key.parent.unwrap_or_else(|| {
42 "finding type for {:?}, encountered def-id {:?} with no \
52 // Erase regions because they may not be deterministic when hashed
53 // and should not matter anyhow.
54 let instance_ty = tcx.erase_regions(&instance_ty);
56 let hash = get_symbol_hash(tcx, instance, instance_ty, instantiating_crate);
58 let mut printer = SymbolPrinter { tcx, path: SymbolPath::new(), keep_within_component: false }
59 .print_def_path(def_id, &[])
62 if let ty::InstanceDef::VtableShim(..) = instance.def {
63 let _ = printer.write_str("{{vtable-shim}}");
66 if let ty::InstanceDef::ReifyShim(..) = instance.def {
67 let _ = printer.write_str("{{reify-shim}}");
70 printer.path.finish(hash)
73 fn get_symbol_hash<'tcx>(
76 // instance this name will be for
77 instance: Instance<'tcx>,
79 // type of the item, without any generic
80 // parameters substituted; this is
81 // included in the hash as a kind of
85 instantiating_crate: Option<CrateNum>,
87 let def_id = instance.def_id();
88 let substs = instance.substs;
89 debug!("get_symbol_hash(def_id={:?}, parameters={:?})", def_id, substs);
91 let mut hasher = StableHasher::new();
92 let mut hcx = tcx.create_stable_hashing_context();
94 record_time(&tcx.sess.perf_stats.symbol_hash_time, || {
95 // the main symbol name is not necessarily unique; hash in the
96 // compiler's internal def-path, guaranteeing each symbol has a
98 tcx.def_path_hash(def_id).hash_stable(&mut hcx, &mut hasher);
100 // Include the main item-type. Note that, in this case, the
101 // assertions about `needs_subst` may not hold, but this item-type
102 // ought to be the same for every reference anyway.
103 assert!(!item_type.has_erasable_regions());
104 hcx.while_hashing_spans(false, |hcx| {
105 hcx.with_node_id_hashing_mode(NodeIdHashingMode::HashDefPath, |hcx| {
106 item_type.hash_stable(hcx, &mut hasher);
110 // If this is a function, we hash the signature as well.
111 // This is not *strictly* needed, but it may help in some
112 // situations, see the `run-make/a-b-a-linker-guard` test.
113 if let ty::FnDef(..) = item_type.kind {
114 item_type.fn_sig(tcx).hash_stable(&mut hcx, &mut hasher);
117 // also include any type parameters (for generic items)
118 assert!(!substs.has_erasable_regions());
119 assert!(!substs.needs_subst());
120 substs.hash_stable(&mut hcx, &mut hasher);
122 if let Some(instantiating_crate) = instantiating_crate {
123 tcx.original_crate_name(instantiating_crate)
125 .hash_stable(&mut hcx, &mut hasher);
126 tcx.crate_disambiguator(instantiating_crate).hash_stable(&mut hcx, &mut hasher);
129 // We want to avoid accidental collision between different types of instances.
130 // Especially, `VtableShim`s and `ReifyShim`s may overlap with their original
131 // instances without this.
132 discriminant(&instance.def).hash_stable(&mut hcx, &mut hasher);
135 // 64 bits should be enough to avoid collisions.
136 hasher.finish::<u64>()
139 // Follow C++ namespace-mangling style, see
140 // http://en.wikipedia.org/wiki/Name_mangling for more info.
142 // It turns out that on macOS you can actually have arbitrary symbols in
143 // function names (at least when given to LLVM), but this is not possible
144 // when using unix's linker. Perhaps one day when we just use a linker from LLVM
145 // we won't need to do this name mangling. The problem with name mangling is
146 // that it seriously limits the available characters. For example we can't
147 // have things like &T in symbol names when one would theoretically
148 // want them for things like impls of traits on that type.
150 // To be able to work on all platforms and get *some* reasonable output, we
151 // use C++ name-mangling.
161 SymbolPath { result: String::with_capacity(64), temp_buf: String::with_capacity(16) };
162 result.result.push_str("_ZN"); // _Z == Begin name-sequence, N == nested
166 fn finalize_pending_component(&mut self) {
167 if !self.temp_buf.is_empty() {
168 let _ = write!(self.result, "{}{}", self.temp_buf.len(), self.temp_buf);
169 self.temp_buf.clear();
173 fn finish(mut self, hash: u64) -> String {
174 self.finalize_pending_component();
175 // E = end name-sequence
176 let _ = write!(self.result, "17h{:016x}E", hash);
181 struct SymbolPrinter<'tcx> {
185 // When `true`, `finalize_pending_component` isn't used.
186 // This is needed when recursing into `path_qualified`,
187 // or `path_generic_args`, as any nested paths are
188 // logically within one component.
189 keep_within_component: bool,
192 // HACK(eddyb) this relies on using the `fmt` interface to get
193 // `PrettyPrinter` aka pretty printing of e.g. types in paths,
194 // symbol names should have their own printing machinery.
196 impl Printer<'tcx> for SymbolPrinter<'tcx> {
197 type Error = fmt::Error;
202 type DynExistential = Self;
205 fn tcx(&self) -> TyCtxt<'tcx> {
209 fn print_region(self, _region: ty::Region<'_>) -> Result<Self::Region, Self::Error> {
213 fn print_type(self, ty: Ty<'tcx>) -> Result<Self::Type, Self::Error> {
215 // Print all nominal types as paths (unlike `pretty_print_type`).
216 ty::FnDef(def_id, substs)
217 | ty::Opaque(def_id, substs)
218 | ty::Projection(ty::ProjectionTy { item_def_id: def_id, substs })
219 | ty::Closure(def_id, substs)
220 | ty::Generator(def_id, substs, _) => self.print_def_path(def_id, substs),
221 _ => self.pretty_print_type(ty),
225 fn print_dyn_existential(
227 predicates: &'tcx ty::List<ty::ExistentialPredicate<'tcx>>,
228 ) -> Result<Self::DynExistential, Self::Error> {
229 let mut first = true;
230 for p in predicates {
235 self = p.print(self)?;
240 fn print_const(mut self, ct: &'tcx ty::Const<'tcx>) -> Result<Self::Const, Self::Error> {
241 // only print integers
242 if let ty::ConstKind::Value(ConstValue::Scalar(Scalar::Raw { .. })) = ct.val {
243 if ct.ty.is_integral() {
244 return self.pretty_print_const(ct, true);
247 self.write_str("_")?;
251 fn path_crate(mut self, cnum: CrateNum) -> Result<Self::Path, Self::Error> {
252 self.write_str(&self.tcx.original_crate_name(cnum).as_str())?;
258 trait_ref: Option<ty::TraitRef<'tcx>>,
259 ) -> Result<Self::Path, Self::Error> {
260 // Similar to `pretty_path_qualified`, but for the other
261 // types that are printed as paths (see `print_type` above).
268 if trait_ref.is_none() =>
270 self.print_type(self_ty)
273 _ => self.pretty_path_qualified(self_ty, trait_ref),
279 print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
280 _disambiguated_data: &DisambiguatedDefPathData,
282 trait_ref: Option<ty::TraitRef<'tcx>>,
283 ) -> Result<Self::Path, Self::Error> {
284 self.pretty_path_append_impl(
286 cx = print_prefix(cx)?;
288 if cx.keep_within_component {
289 // HACK(eddyb) print the path similarly to how `FmtPrinter` prints it.
292 cx.path.finalize_pending_component();
303 print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
304 disambiguated_data: &DisambiguatedDefPathData,
305 ) -> Result<Self::Path, Self::Error> {
306 self = print_prefix(self)?;
308 // Skip `::{{constructor}}` on tuple/unit structs.
309 if let DefPathData::Ctor = disambiguated_data.data {
313 if self.keep_within_component {
314 // HACK(eddyb) print the path similarly to how `FmtPrinter` prints it.
315 self.write_str("::")?;
317 self.path.finalize_pending_component();
320 self.write_str(&disambiguated_data.data.as_symbol().as_str())?;
323 fn path_generic_args(
325 print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
326 args: &[GenericArg<'tcx>],
327 ) -> Result<Self::Path, Self::Error> {
328 self = print_prefix(self)?;
330 let args = args.iter().cloned().filter(|arg| match arg.unpack() {
331 GenericArgKind::Lifetime(_) => false,
335 if args.clone().next().is_some() {
336 self.generic_delimiters(|cx| cx.comma_sep(args))
343 impl PrettyPrinter<'tcx> for SymbolPrinter<'tcx> {
344 fn region_should_not_be_omitted(&self, _region: ty::Region<'_>) -> bool {
347 fn comma_sep<T>(mut self, mut elems: impl Iterator<Item = T>) -> Result<Self, Self::Error>
349 T: Print<'tcx, Self, Output = Self, Error = Self::Error>,
351 if let Some(first) = elems.next() {
352 self = first.print(self)?;
354 self.write_str(",")?;
355 self = elem.print(self)?;
361 fn generic_delimiters(
363 f: impl FnOnce(Self) -> Result<Self, Self::Error>,
364 ) -> Result<Self, Self::Error> {
367 let kept_within_component = mem::replace(&mut self.keep_within_component, true);
369 self.keep_within_component = kept_within_component;
377 impl fmt::Write for SymbolPrinter<'_> {
378 fn write_str(&mut self, s: &str) -> fmt::Result {
379 // Name sanitation. LLVM will happily accept identifiers with weird names, but
381 // gas accepts the following characters in symbols: a-z, A-Z, 0-9, ., _, $
382 // NVPTX assembly has more strict naming rules than gas, so additionally, dots
383 // are replaced with '$' there.
386 if self.path.temp_buf.is_empty() {
388 'a'..='z' | 'A'..='Z' | '_' => {}
390 // Underscore-qualify anything that didn't start as an ident.
391 self.path.temp_buf.push('_');
396 // Escape these with $ sequences
397 '@' => self.path.temp_buf.push_str("$SP$"),
398 '*' => self.path.temp_buf.push_str("$BP$"),
399 '&' => self.path.temp_buf.push_str("$RF$"),
400 '<' => self.path.temp_buf.push_str("$LT$"),
401 '>' => self.path.temp_buf.push_str("$GT$"),
402 '(' => self.path.temp_buf.push_str("$LP$"),
403 ')' => self.path.temp_buf.push_str("$RP$"),
404 ',' => self.path.temp_buf.push_str("$C$"),
406 '-' | ':' | '.' if self.tcx.has_strict_asm_symbol_naming() => {
407 // NVPTX doesn't support these characters in symbol names.
408 self.path.temp_buf.push('$')
411 // '.' doesn't occur in types and functions, so reuse it
413 '-' | ':' => self.path.temp_buf.push('.'),
415 // Avoid crashing LLVM in certain (LTO-related) situations, see #60925.
416 'm' if self.path.temp_buf.ends_with(".llv") => self.path.temp_buf.push_str("$u6d$"),
418 // These are legal symbols
419 'a'..='z' | 'A'..='Z' | '0'..='9' | '_' | '.' | '$' => self.path.temp_buf.push(c),
422 self.path.temp_buf.push('$');
423 for c in c.escape_unicode().skip(1) {
426 '}' => self.path.temp_buf.push('$'),
427 c => self.path.temp_buf.push(c),