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Commit | Line | Data |
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dc9dc135 | 1 | use rustc_data_structures::stable_hasher::{HashStable, StableHasher}; |
dfeec247 | 2 | use rustc_hir::def_id::CrateNum; |
ba9703b0 XL |
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; | |
dc9dc135 | 10 | |
3dfed10e | 11 | use tracing::debug; |
dc9dc135 XL |
12 | |
13 | use std::fmt::{self, Write}; | |
14 | use std::mem::{self, discriminant}; | |
15 | ||
16 | pub(super) fn mangle( | |
17 | tcx: TyCtxt<'tcx>, | |
18 | instance: Instance<'tcx>, | |
19 | instantiating_crate: Option<CrateNum>, | |
20 | ) -> String { | |
21 | let def_id = instance.def_id(); | |
22 | ||
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; | |
28 | let instance_ty; | |
29 | loop { | |
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); | |
34 | break; | |
35 | } | |
36 | _ => { | |
37 | // if we're making a symbol for something, there ought | |
38 | // to be a value or type-def or something in there | |
39 | // *somewhere* | |
40 | ty_def_id.index = key.parent.unwrap_or_else(|| { | |
41 | bug!( | |
42 | "finding type for {:?}, encountered def-id {:?} with no \ | |
43 | parent", | |
44 | def_id, | |
45 | ty_def_id | |
46 | ); | |
47 | }); | |
48 | } | |
49 | } | |
50 | } | |
51 | ||
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); | |
55 | ||
56 | let hash = get_symbol_hash(tcx, instance, instance_ty, instantiating_crate); | |
57 | ||
dfeec247 XL |
58 | let mut printer = SymbolPrinter { tcx, path: SymbolPath::new(), keep_within_component: false } |
59 | .print_def_path(def_id, &[]) | |
60 | .unwrap(); | |
dc9dc135 | 61 | |
ba9703b0 | 62 | if let ty::InstanceDef::VtableShim(..) = instance.def { |
dc9dc135 XL |
63 | let _ = printer.write_str("{{vtable-shim}}"); |
64 | } | |
65 | ||
ba9703b0 XL |
66 | if let ty::InstanceDef::ReifyShim(..) = instance.def { |
67 | let _ = printer.write_str("{{reify-shim}}"); | |
68 | } | |
69 | ||
dc9dc135 XL |
70 | printer.path.finish(hash) |
71 | } | |
72 | ||
73 | fn get_symbol_hash<'tcx>( | |
74 | tcx: TyCtxt<'tcx>, | |
75 | ||
76 | // instance this name will be for | |
77 | instance: Instance<'tcx>, | |
78 | ||
79 | // type of the item, without any generic | |
80 | // parameters substituted; this is | |
81 | // included in the hash as a kind of | |
82 | // safeguard. | |
83 | item_type: Ty<'tcx>, | |
84 | ||
85 | instantiating_crate: Option<CrateNum>, | |
86 | ) -> u64 { | |
87 | let def_id = instance.def_id(); | |
88 | let substs = instance.substs; | |
dfeec247 | 89 | debug!("get_symbol_hash(def_id={:?}, parameters={:?})", def_id, substs); |
dc9dc135 | 90 | |
e74abb32 | 91 | let mut hasher = StableHasher::new(); |
dc9dc135 XL |
92 | let mut hcx = tcx.create_stable_hashing_context(); |
93 | ||
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 | |
97 | // truly unique path | |
98 | tcx.def_path_hash(def_id).hash_stable(&mut hcx, &mut hasher); | |
99 | ||
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); | |
107 | }); | |
108 | }); | |
109 | ||
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. | |
1b1a35ee | 113 | if let ty::FnDef(..) = item_type.kind() { |
dc9dc135 XL |
114 | item_type.fn_sig(tcx).hash_stable(&mut hcx, &mut hasher); |
115 | } | |
116 | ||
117 | // also include any type parameters (for generic items) | |
dc9dc135 XL |
118 | substs.hash_stable(&mut hcx, &mut hasher); |
119 | ||
120 | if let Some(instantiating_crate) = instantiating_crate { | |
dfeec247 XL |
121 | tcx.original_crate_name(instantiating_crate) |
122 | .as_str() | |
dc9dc135 | 123 | .hash_stable(&mut hcx, &mut hasher); |
dfeec247 | 124 | tcx.crate_disambiguator(instantiating_crate).hash_stable(&mut hcx, &mut hasher); |
dc9dc135 XL |
125 | } |
126 | ||
127 | // We want to avoid accidental collision between different types of instances. | |
ba9703b0 XL |
128 | // Especially, `VtableShim`s and `ReifyShim`s may overlap with their original |
129 | // instances without this. | |
dc9dc135 XL |
130 | discriminant(&instance.def).hash_stable(&mut hcx, &mut hasher); |
131 | }); | |
132 | ||
133 | // 64 bits should be enough to avoid collisions. | |
e74abb32 | 134 | hasher.finish::<u64>() |
dc9dc135 XL |
135 | } |
136 | ||
137 | // Follow C++ namespace-mangling style, see | |
3dfed10e | 138 | // https://en.wikipedia.org/wiki/Name_mangling for more info. |
dc9dc135 XL |
139 | // |
140 | // It turns out that on macOS you can actually have arbitrary symbols in | |
141 | // function names (at least when given to LLVM), but this is not possible | |
142 | // when using unix's linker. Perhaps one day when we just use a linker from LLVM | |
143 | // we won't need to do this name mangling. The problem with name mangling is | |
144 | // that it seriously limits the available characters. For example we can't | |
145 | // have things like &T in symbol names when one would theoretically | |
146 | // want them for things like impls of traits on that type. | |
147 | // | |
148 | // To be able to work on all platforms and get *some* reasonable output, we | |
149 | // use C++ name-mangling. | |
150 | #[derive(Debug)] | |
151 | struct SymbolPath { | |
152 | result: String, | |
153 | temp_buf: String, | |
154 | } | |
155 | ||
156 | impl SymbolPath { | |
157 | fn new() -> Self { | |
dfeec247 XL |
158 | let mut result = |
159 | SymbolPath { result: String::with_capacity(64), temp_buf: String::with_capacity(16) }; | |
dc9dc135 XL |
160 | result.result.push_str("_ZN"); // _Z == Begin name-sequence, N == nested |
161 | result | |
162 | } | |
163 | ||
164 | fn finalize_pending_component(&mut self) { | |
165 | if !self.temp_buf.is_empty() { | |
166 | let _ = write!(self.result, "{}{}", self.temp_buf.len(), self.temp_buf); | |
167 | self.temp_buf.clear(); | |
168 | } | |
169 | } | |
170 | ||
171 | fn finish(mut self, hash: u64) -> String { | |
172 | self.finalize_pending_component(); | |
173 | // E = end name-sequence | |
174 | let _ = write!(self.result, "17h{:016x}E", hash); | |
175 | self.result | |
176 | } | |
177 | } | |
178 | ||
179 | struct SymbolPrinter<'tcx> { | |
180 | tcx: TyCtxt<'tcx>, | |
181 | path: SymbolPath, | |
182 | ||
183 | // When `true`, `finalize_pending_component` isn't used. | |
184 | // This is needed when recursing into `path_qualified`, | |
185 | // or `path_generic_args`, as any nested paths are | |
186 | // logically within one component. | |
187 | keep_within_component: bool, | |
188 | } | |
189 | ||
190 | // HACK(eddyb) this relies on using the `fmt` interface to get | |
191 | // `PrettyPrinter` aka pretty printing of e.g. types in paths, | |
192 | // symbol names should have their own printing machinery. | |
193 | ||
194 | impl Printer<'tcx> for SymbolPrinter<'tcx> { | |
195 | type Error = fmt::Error; | |
196 | ||
197 | type Path = Self; | |
198 | type Region = Self; | |
199 | type Type = Self; | |
200 | type DynExistential = Self; | |
201 | type Const = Self; | |
202 | ||
203 | fn tcx(&self) -> TyCtxt<'tcx> { | |
204 | self.tcx | |
205 | } | |
206 | ||
dfeec247 | 207 | fn print_region(self, _region: ty::Region<'_>) -> Result<Self::Region, Self::Error> { |
dc9dc135 XL |
208 | Ok(self) |
209 | } | |
210 | ||
dfeec247 | 211 | fn print_type(self, ty: Ty<'tcx>) -> Result<Self::Type, Self::Error> { |
1b1a35ee | 212 | match *ty.kind() { |
dc9dc135 | 213 | // Print all nominal types as paths (unlike `pretty_print_type`). |
dfeec247 XL |
214 | ty::FnDef(def_id, substs) |
215 | | ty::Opaque(def_id, substs) | |
216 | | ty::Projection(ty::ProjectionTy { item_def_id: def_id, substs }) | |
dfeec247 XL |
217 | | ty::Closure(def_id, substs) |
218 | | ty::Generator(def_id, substs, _) => self.print_def_path(def_id, substs), | |
dc9dc135 XL |
219 | _ => self.pretty_print_type(ty), |
220 | } | |
221 | } | |
222 | ||
223 | fn print_dyn_existential( | |
224 | mut self, | |
225 | predicates: &'tcx ty::List<ty::ExistentialPredicate<'tcx>>, | |
226 | ) -> Result<Self::DynExistential, Self::Error> { | |
227 | let mut first = true; | |
228 | for p in predicates { | |
229 | if !first { | |
230 | write!(self, "+")?; | |
231 | } | |
232 | first = false; | |
233 | self = p.print(self)?; | |
234 | } | |
235 | Ok(self) | |
236 | } | |
237 | ||
dfeec247 | 238 | fn print_const(mut self, ct: &'tcx ty::Const<'tcx>) -> Result<Self::Const, Self::Error> { |
dc9dc135 | 239 | // only print integers |
29967ef6 | 240 | if let ty::ConstKind::Value(ConstValue::Scalar(Scalar::Int { .. })) = ct.val { |
dc9dc135 | 241 | if ct.ty.is_integral() { |
dfeec247 | 242 | return self.pretty_print_const(ct, true); |
dc9dc135 XL |
243 | } |
244 | } | |
245 | self.write_str("_")?; | |
246 | Ok(self) | |
247 | } | |
248 | ||
dfeec247 | 249 | fn path_crate(mut self, cnum: CrateNum) -> Result<Self::Path, Self::Error> { |
dc9dc135 XL |
250 | self.write_str(&self.tcx.original_crate_name(cnum).as_str())?; |
251 | Ok(self) | |
252 | } | |
253 | fn path_qualified( | |
254 | self, | |
255 | self_ty: Ty<'tcx>, | |
256 | trait_ref: Option<ty::TraitRef<'tcx>>, | |
257 | ) -> Result<Self::Path, Self::Error> { | |
258 | // Similar to `pretty_path_qualified`, but for the other | |
259 | // types that are printed as paths (see `print_type` above). | |
1b1a35ee | 260 | match self_ty.kind() { |
dfeec247 XL |
261 | ty::FnDef(..) |
262 | | ty::Opaque(..) | |
263 | | ty::Projection(_) | |
dfeec247 XL |
264 | | ty::Closure(..) |
265 | | ty::Generator(..) | |
dc9dc135 XL |
266 | if trait_ref.is_none() => |
267 | { | |
268 | self.print_type(self_ty) | |
269 | } | |
270 | ||
dfeec247 | 271 | _ => self.pretty_path_qualified(self_ty, trait_ref), |
dc9dc135 XL |
272 | } |
273 | } | |
274 | ||
275 | fn path_append_impl( | |
276 | self, | |
277 | print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>, | |
278 | _disambiguated_data: &DisambiguatedDefPathData, | |
279 | self_ty: Ty<'tcx>, | |
280 | trait_ref: Option<ty::TraitRef<'tcx>>, | |
281 | ) -> Result<Self::Path, Self::Error> { | |
282 | self.pretty_path_append_impl( | |
283 | |mut cx| { | |
284 | cx = print_prefix(cx)?; | |
285 | ||
286 | if cx.keep_within_component { | |
287 | // HACK(eddyb) print the path similarly to how `FmtPrinter` prints it. | |
288 | cx.write_str("::")?; | |
289 | } else { | |
290 | cx.path.finalize_pending_component(); | |
291 | } | |
292 | ||
293 | Ok(cx) | |
294 | }, | |
295 | self_ty, | |
296 | trait_ref, | |
297 | ) | |
298 | } | |
299 | fn path_append( | |
300 | mut self, | |
301 | print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>, | |
302 | disambiguated_data: &DisambiguatedDefPathData, | |
303 | ) -> Result<Self::Path, Self::Error> { | |
304 | self = print_prefix(self)?; | |
305 | ||
306 | // Skip `::{{constructor}}` on tuple/unit structs. | |
ba9703b0 XL |
307 | if let DefPathData::Ctor = disambiguated_data.data { |
308 | return Ok(self); | |
dc9dc135 XL |
309 | } |
310 | ||
311 | if self.keep_within_component { | |
312 | // HACK(eddyb) print the path similarly to how `FmtPrinter` prints it. | |
313 | self.write_str("::")?; | |
314 | } else { | |
315 | self.path.finalize_pending_component(); | |
316 | } | |
317 | ||
1b1a35ee XL |
318 | write!(self, "{}", disambiguated_data.data)?; |
319 | ||
dc9dc135 XL |
320 | Ok(self) |
321 | } | |
322 | fn path_generic_args( | |
323 | mut self, | |
324 | print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>, | |
e74abb32 | 325 | args: &[GenericArg<'tcx>], |
dfeec247 | 326 | ) -> Result<Self::Path, Self::Error> { |
dc9dc135 XL |
327 | self = print_prefix(self)?; |
328 | ||
29967ef6 XL |
329 | let args = |
330 | args.iter().cloned().filter(|arg| !matches!(arg.unpack(), GenericArgKind::Lifetime(_))); | |
dc9dc135 XL |
331 | |
332 | if args.clone().next().is_some() { | |
333 | self.generic_delimiters(|cx| cx.comma_sep(args)) | |
334 | } else { | |
335 | Ok(self) | |
336 | } | |
337 | } | |
338 | } | |
339 | ||
340 | impl PrettyPrinter<'tcx> for SymbolPrinter<'tcx> { | |
dfeec247 | 341 | fn region_should_not_be_omitted(&self, _region: ty::Region<'_>) -> bool { |
dc9dc135 XL |
342 | false |
343 | } | |
344 | fn comma_sep<T>(mut self, mut elems: impl Iterator<Item = T>) -> Result<Self, Self::Error> | |
345 | where | |
346 | T: Print<'tcx, Self, Output = Self, Error = Self::Error>, | |
347 | { | |
348 | if let Some(first) = elems.next() { | |
349 | self = first.print(self)?; | |
350 | for elem in elems { | |
351 | self.write_str(",")?; | |
352 | self = elem.print(self)?; | |
353 | } | |
354 | } | |
355 | Ok(self) | |
356 | } | |
357 | ||
358 | fn generic_delimiters( | |
359 | mut self, | |
360 | f: impl FnOnce(Self) -> Result<Self, Self::Error>, | |
361 | ) -> Result<Self, Self::Error> { | |
362 | write!(self, "<")?; | |
363 | ||
dfeec247 | 364 | let kept_within_component = mem::replace(&mut self.keep_within_component, true); |
dc9dc135 XL |
365 | self = f(self)?; |
366 | self.keep_within_component = kept_within_component; | |
367 | ||
368 | write!(self, ">")?; | |
369 | ||
370 | Ok(self) | |
371 | } | |
372 | } | |
373 | ||
374 | impl fmt::Write for SymbolPrinter<'_> { | |
375 | fn write_str(&mut self, s: &str) -> fmt::Result { | |
376 | // Name sanitation. LLVM will happily accept identifiers with weird names, but | |
377 | // gas doesn't! | |
378 | // gas accepts the following characters in symbols: a-z, A-Z, 0-9, ., _, $ | |
379 | // NVPTX assembly has more strict naming rules than gas, so additionally, dots | |
380 | // are replaced with '$' there. | |
381 | ||
382 | for c in s.chars() { | |
383 | if self.path.temp_buf.is_empty() { | |
384 | match c { | |
385 | 'a'..='z' | 'A'..='Z' | '_' => {} | |
386 | _ => { | |
387 | // Underscore-qualify anything that didn't start as an ident. | |
388 | self.path.temp_buf.push('_'); | |
389 | } | |
390 | } | |
391 | } | |
392 | match c { | |
393 | // Escape these with $ sequences | |
394 | '@' => self.path.temp_buf.push_str("$SP$"), | |
395 | '*' => self.path.temp_buf.push_str("$BP$"), | |
396 | '&' => self.path.temp_buf.push_str("$RF$"), | |
397 | '<' => self.path.temp_buf.push_str("$LT$"), | |
398 | '>' => self.path.temp_buf.push_str("$GT$"), | |
399 | '(' => self.path.temp_buf.push_str("$LP$"), | |
400 | ')' => self.path.temp_buf.push_str("$RP$"), | |
401 | ',' => self.path.temp_buf.push_str("$C$"), | |
402 | ||
403 | '-' | ':' | '.' if self.tcx.has_strict_asm_symbol_naming() => { | |
404 | // NVPTX doesn't support these characters in symbol names. | |
405 | self.path.temp_buf.push('$') | |
406 | } | |
407 | ||
408 | // '.' doesn't occur in types and functions, so reuse it | |
409 | // for ':' and '-' | |
410 | '-' | ':' => self.path.temp_buf.push('.'), | |
411 | ||
412 | // Avoid crashing LLVM in certain (LTO-related) situations, see #60925. | |
413 | 'm' if self.path.temp_buf.ends_with(".llv") => self.path.temp_buf.push_str("$u6d$"), | |
414 | ||
415 | // These are legal symbols | |
416 | 'a'..='z' | 'A'..='Z' | '0'..='9' | '_' | '.' | '$' => self.path.temp_buf.push(c), | |
417 | ||
418 | _ => { | |
419 | self.path.temp_buf.push('$'); | |
420 | for c in c.escape_unicode().skip(1) { | |
421 | match c { | |
422 | '{' => {} | |
423 | '}' => self.path.temp_buf.push('$'), | |
424 | c => self.path.temp_buf.push(c), | |
425 | } | |
426 | } | |
427 | } | |
428 | } | |
429 | } | |
430 | ||
431 | Ok(()) | |
432 | } | |
433 | } |