src/librustc_interface/queries.rs

   1 use crate::interface::{Compiler, Result};
   2 use crate::passes::{self, BoxedResolver, QueryContext};
   3
   4 use rustc_ast::{self, ast};
   5 use rustc_codegen_ssa::traits::CodegenBackend;
   6 use rustc_data_structures::sync::{Lrc, OnceCell, WorkerLocal};
   7 use rustc_errors::ErrorReported;
   8 use rustc_hir::def_id::LOCAL_CRATE;
   9 use rustc_hir::Crate;
  10 use rustc_incremental::DepGraphFuture;
  11 use rustc_lint::LintStore;
  12 use rustc_middle::arena::Arena;
  13 use rustc_middle::dep_graph::DepGraph;
  14 use rustc_middle::ty::steal::Steal;
  15 use rustc_middle::ty::{GlobalCtxt, ResolverOutputs, TyCtxt};
  16 use rustc_session::config::{OutputFilenames, OutputType};
  17 use rustc_session::{output::find_crate_name, Session};
  18 use rustc_span::symbol::sym;
  19 use std::any::Any;
  20 use std::cell::{Ref, RefCell, RefMut};
  21 use std::mem;
  22 use std::rc::Rc;
  23
  24 /// Represent the result of a query.
  25 /// This result can be stolen with the `take` method and generated with the `compute` method.
  26 pub struct Query<T> {
  27     result: RefCell<Option<Result<T>>>,
  28 }
  29
  30 impl<T> Query<T> {
  31     fn compute<F: FnOnce() -> Result<T>>(&self, f: F) -> Result<&Query<T>> {
  32         let mut result = self.result.borrow_mut();
  33         if result.is_none() {
  34             *result = Some(f());
  35         }
  36         result.as_ref().unwrap().as_ref().map(|_| self).map_err(|err| *err)
  37     }
  38
  39     /// Takes ownership of the query result. Further attempts to take or peek the query
  40     /// result will panic unless it is generated by calling the `compute` method.
  41     pub fn take(&self) -> T {
  42         self.result.borrow_mut().take().expect("missing query result").unwrap()
  43     }
  44
  45     /// Borrows the query result using the RefCell. Panics if the result is stolen.
  46     pub fn peek(&self) -> Ref<'_, T> {
  47         Ref::map(self.result.borrow(), |r| {
  48             r.as_ref().unwrap().as_ref().expect("missing query result")
  49         })
  50     }
  51
  52     /// Mutably borrows the query result using the RefCell. Panics if the result is stolen.
  53     pub fn peek_mut(&self) -> RefMut<'_, T> {
  54         RefMut::map(self.result.borrow_mut(), |r| {
  55             r.as_mut().unwrap().as_mut().expect("missing query result")
  56         })
  57     }
  58 }
  59
  60 impl<T> Default for Query<T> {
  61     fn default() -> Self {
  62         Query { result: RefCell::new(None) }
  63     }
  64 }
  65
  66 pub struct Queries<'tcx> {
  67     compiler: &'tcx Compiler,
  68     gcx: OnceCell<GlobalCtxt<'tcx>>,
  69
  70     arena: WorkerLocal<Arena<'tcx>>,
  71     hir_arena: WorkerLocal<rustc_ast_lowering::Arena<'tcx>>,
  72
  73     dep_graph_future: Query<Option<DepGraphFuture>>,
  74     parse: Query<ast::Crate>,
  75     crate_name: Query<String>,
  76     register_plugins: Query<(ast::Crate, Lrc<LintStore>)>,
  77     expansion: Query<(ast::Crate, Steal<Rc<RefCell<BoxedResolver>>>, Lrc<LintStore>)>,
  78     dep_graph: Query<DepGraph>,
  79     lower_to_hir: Query<(&'tcx Crate<'tcx>, Steal<ResolverOutputs>)>,
  80     prepare_outputs: Query<OutputFilenames>,
  81     global_ctxt: Query<QueryContext<'tcx>>,
  82     ongoing_codegen: Query<Box<dyn Any>>,
  83 }
  84
  85 impl<'tcx> Queries<'tcx> {
  86     pub fn new(compiler: &'tcx Compiler) -> Queries<'tcx> {
  87         Queries {
  88             compiler,
  89             gcx: OnceCell::new(),
  90             arena: WorkerLocal::new(|_| Arena::default()),
  91             hir_arena: WorkerLocal::new(|_| rustc_ast_lowering::Arena::default()),
  92             dep_graph_future: Default::default(),
  93             parse: Default::default(),
  94             crate_name: Default::default(),
  95             register_plugins: Default::default(),
  96             expansion: Default::default(),
  97             dep_graph: Default::default(),
  98             lower_to_hir: Default::default(),
  99             prepare_outputs: Default::default(),
 100             global_ctxt: Default::default(),
 101             ongoing_codegen: Default::default(),
 102         }
 103     }
 104
 105     fn session(&self) -> &Lrc<Session> {
 106         &self.compiler.sess
 107     }
 108     fn codegen_backend(&self) -> &Lrc<Box<dyn CodegenBackend>> {
 109         &self.compiler.codegen_backend()
 110     }
 111
 112     pub fn dep_graph_future(&self) -> Result<&Query<Option<DepGraphFuture>>> {
 113         self.dep_graph_future.compute(|| {
 114             Ok(self
 115                 .session()
 116                 .opts
 117                 .build_dep_graph()
 118                 .then(|| rustc_incremental::load_dep_graph(self.session())))
 119         })
 120     }
 121
 122     pub fn parse(&self) -> Result<&Query<ast::Crate>> {
 123         self.parse.compute(|| {
 124             passes::parse(self.session(), &self.compiler.input).map_err(|mut parse_error| {
 125                 parse_error.emit();
 126                 ErrorReported
 127             })
 128         })
 129     }
 130
 131     pub fn register_plugins(&self) -> Result<&Query<(ast::Crate, Lrc<LintStore>)>> {
 132         self.register_plugins.compute(|| {
 133             let crate_name = self.crate_name()?.peek().clone();
 134             let krate = self.parse()?.take();
 135
 136             let empty: &(dyn Fn(&Session, &mut LintStore) + Sync + Send) = &|_, _| {};
 137             let result = passes::register_plugins(
 138                 self.session(),
 139                 &*self.codegen_backend().metadata_loader(),
 140                 self.compiler.register_lints.as_deref().unwrap_or_else(|| empty),
 141                 krate,
 142                 &crate_name,
 143             );
 144
 145             // Compute the dependency graph (in the background). We want to do
 146             // this as early as possible, to give the DepGraph maximum time to
 147             // load before dep_graph() is called, but it also can't happen
 148             // until after rustc_incremental::prepare_session_directory() is
 149             // called, which happens within passes::register_plugins().
 150             self.dep_graph_future().ok();
 151
 152             result
 153         })
 154     }
 155
 156     pub fn crate_name(&self) -> Result<&Query<String>> {
 157         self.crate_name.compute(|| {
 158             Ok(match self.compiler.crate_name {
 159                 Some(ref crate_name) => crate_name.clone(),
 160                 None => {
 161                     let parse_result = self.parse()?;
 162                     let krate = parse_result.peek();
 163                     find_crate_name(Some(self.session()), &krate.attrs, &self.compiler.input)
 164                 }
 165             })
 166         })
 167     }
 168
 169     pub fn expansion(
 170         &self,
 171     ) -> Result<&Query<(ast::Crate, Steal<Rc<RefCell<BoxedResolver>>>, Lrc<LintStore>)>> {
 172         log::trace!("expansion");
 173         self.expansion.compute(|| {
 174             let crate_name = self.crate_name()?.peek().clone();
 175             let (krate, lint_store) = self.register_plugins()?.take();
 176             let _timer = self.session().timer("configure_and_expand");
 177             passes::configure_and_expand(
 178                 self.session().clone(),
 179                 lint_store.clone(),
 180                 self.codegen_backend().metadata_loader(),
 181                 krate,
 182                 &crate_name,
 183             )
 184             .map(|(krate, resolver)| {
 185                 (krate, Steal::new(Rc::new(RefCell::new(resolver))), lint_store)
 186             })
 187         })
 188     }
 189
 190     pub fn dep_graph(&self) -> Result<&Query<DepGraph>> {
 191         self.dep_graph.compute(|| {
 192             Ok(match self.dep_graph_future()?.take() {
 193                 None => DepGraph::new_disabled(),
 194                 Some(future) => {
 195                     let (prev_graph, prev_work_products) =
 196                         self.session().time("blocked_on_dep_graph_loading", || {
 197                             future
 198                                 .open()
 199                                 .unwrap_or_else(|e| rustc_incremental::LoadResult::Error {
 200                                     message: format!("could not decode incremental cache: {:?}", e),
 201                                 })
 202                                 .open(self.session())
 203                         });
 204                     DepGraph::new(prev_graph, prev_work_products)
 205                 }
 206             })
 207         })
 208     }
 209
 210     pub fn lower_to_hir(&'tcx self) -> Result<&Query<(&'tcx Crate<'tcx>, Steal<ResolverOutputs>)>> {
 211         self.lower_to_hir.compute(|| {
 212             let expansion_result = self.expansion()?;
 213             let peeked = expansion_result.peek();
 214             let krate = &peeked.0;
 215             let resolver = peeked.1.steal();
 216             let lint_store = &peeked.2;
 217             let hir = resolver.borrow_mut().access(|resolver| {
 218                 Ok(passes::lower_to_hir(
 219                     self.session(),
 220                     lint_store,
 221                     resolver,
 222                     &*self.dep_graph()?.peek(),
 223                     &krate,
 224                     &self.hir_arena,
 225                 ))
 226             })?;
 227             let hir = self.hir_arena.alloc(hir);
 228             Ok((hir, Steal::new(BoxedResolver::to_resolver_outputs(resolver))))
 229         })
 230     }
 231
 232     pub fn prepare_outputs(&self) -> Result<&Query<OutputFilenames>> {
 233         self.prepare_outputs.compute(|| {
 234             let expansion_result = self.expansion()?;
 235             let (krate, boxed_resolver, _) = &*expansion_result.peek();
 236             let crate_name = self.crate_name()?;
 237             let crate_name = crate_name.peek();
 238             passes::prepare_outputs(
 239                 self.session(),
 240                 self.compiler,
 241                 &krate,
 242                 &boxed_resolver,
 243                 &crate_name,
 244             )
 245         })
 246     }
 247
 248     pub fn global_ctxt(&'tcx self) -> Result<&Query<QueryContext<'tcx>>> {
 249         self.global_ctxt.compute(|| {
 250             let crate_name = self.crate_name()?.peek().clone();
 251             let outputs = self.prepare_outputs()?.peek().clone();
 252             let lint_store = self.expansion()?.peek().2.clone();
 253             let hir = self.lower_to_hir()?.peek();
 254             let dep_graph = self.dep_graph()?.peek().clone();
 255             let (ref krate, ref resolver_outputs) = &*hir;
 256             let _timer = self.session().timer("create_global_ctxt");
 257             Ok(passes::create_global_ctxt(
 258                 self.compiler,
 259                 lint_store,
 260                 krate,
 261                 dep_graph,
 262                 resolver_outputs.steal(),
 263                 outputs,
 264                 &crate_name,
 265                 &self.gcx,
 266                 &self.arena,
 267             ))
 268         })
 269     }
 270
 271     pub fn ongoing_codegen(&'tcx self) -> Result<&Query<Box<dyn Any>>> {
 272         self.ongoing_codegen.compute(|| {
 273             let outputs = self.prepare_outputs()?;
 274             self.global_ctxt()?.peek_mut().enter(|tcx| {
 275                 tcx.analysis(LOCAL_CRATE).ok();
 276
 277                 // Don't do code generation if there were any errors
 278                 self.session().compile_status()?;
 279
 280                 // Hook for compile-fail tests.
 281                 Self::check_for_rustc_errors_attr(tcx);
 282
 283                 Ok(passes::start_codegen(&***self.codegen_backend(), tcx, &*outputs.peek()))
 284             })
 285         })
 286     }
 287
 288     /// Check for the `#[rustc_error]` annotation, which forces an error in codegen. This is used
 289     /// to write compile-fail tests that actually test that compilation succeeds without reporting
 290     /// an error.
 291     fn check_for_rustc_errors_attr(tcx: TyCtxt<'_>) {
 292         let def_id = match tcx.entry_fn(LOCAL_CRATE) {
 293             Some((def_id, _)) => def_id,
 294             _ => return,
 295         };
 296
 297         let attrs = &*tcx.get_attrs(def_id.to_def_id());
 298         let attrs = attrs.iter().filter(|attr| attr.check_name(sym::rustc_error));
 299         for attr in attrs {
 300             match attr.meta_item_list() {
 301                 // Check if there is a `#[rustc_error(delay_span_bug_from_inside_query)]`.
 302                 Some(list)
 303                     if list.iter().any(|list_item| {
 304                         matches!(
 305                             list_item.ident().map(|i| i.name),
 306                             Some(sym::delay_span_bug_from_inside_query)
 307                         )
 308                     }) =>
 309                 {
 310                     tcx.ensure().trigger_delay_span_bug(def_id);
 311                 }
 312
 313                 // Bare `#[rustc_error]`.
 314                 None => {
 315                     tcx.sess.span_fatal(
 316                         tcx.def_span(def_id),
 317                         "fatal error triggered by #[rustc_error]",
 318                     );
 319                 }
 320
 321                 // Some other attribute.
 322                 Some(_) => {
 323                     tcx.sess.span_warn(
 324                         tcx.def_span(def_id),
 325                         "unexpected annotation used with `#[rustc_error(...)]!",
 326                     );
 327                 }
 328             }
 329         }
 330     }
 331
 332     pub fn linker(&'tcx self) -> Result<Linker> {
 333         let dep_graph = self.dep_graph()?;
 334         let prepare_outputs = self.prepare_outputs()?;
 335         let ongoing_codegen = self.ongoing_codegen()?;
 336
 337         let sess = self.session().clone();
 338         let codegen_backend = self.codegen_backend().clone();
 339
 340         Ok(Linker {
 341             sess,
 342             dep_graph: dep_graph.peek().clone(),
 343             prepare_outputs: prepare_outputs.take(),
 344             ongoing_codegen: ongoing_codegen.take(),
 345             codegen_backend,
 346         })
 347     }
 348 }
 349
 350 pub struct Linker {
 351     sess: Lrc<Session>,
 352     dep_graph: DepGraph,
 353     prepare_outputs: OutputFilenames,
 354     ongoing_codegen: Box<dyn Any>,
 355     codegen_backend: Lrc<Box<dyn CodegenBackend>>,
 356 }
 357
 358 impl Linker {
 359     pub fn link(self) -> Result<()> {
 360         let codegen_results =
 361             self.codegen_backend.join_codegen(self.ongoing_codegen, &self.sess, &self.dep_graph)?;
 362         let prof = self.sess.prof.clone();
 363         let dep_graph = self.dep_graph;
 364         prof.generic_activity("drop_dep_graph").run(move || drop(dep_graph));
 365
 366         if !self
 367             .sess
 368             .opts
 369             .output_types
 370             .keys()
 371             .any(|&i| i == OutputType::Exe || i == OutputType::Metadata)
 372         {
 373             return Ok(());
 374         }
 375         self.codegen_backend.link(&self.sess, codegen_results, &self.prepare_outputs)
 376     }
 377 }
 378
 379 impl Compiler {
 380     pub fn enter<F, T>(&self, f: F) -> T
 381     where
 382         F: for<'tcx> FnOnce(&'tcx Queries<'tcx>) -> T,
 383     {
 384         let mut _timer = None;
 385         let queries = Queries::new(&self);
 386         let ret = f(&queries);
 387
 388         if self.session().opts.debugging_opts.query_stats {
 389             if let Ok(gcx) = queries.global_ctxt() {
 390                 gcx.peek_mut().print_stats();
 391             }
 392         }
 393
 394         _timer = Some(self.session().timer("free_global_ctxt"));
 395
 396         ret
 397     }
 398
 399     // This method is different to all the other methods in `Compiler` because
 400     // it lacks a `Queries` entry. It's also not currently used. It does serve
 401     // as an example of how `Compiler` can be used, with additional steps added
 402     // between some passes. And see `rustc_driver::run_compiler` for a more
 403     // complex example.
 404     pub fn compile(&self) -> Result<()> {
 405         let linker = self.enter(|queries| {
 406             queries.prepare_outputs()?;
 407
 408             if self.session().opts.output_types.contains_key(&OutputType::DepInfo)
 409                 && self.session().opts.output_types.len() == 1
 410             {
 411                 return Ok(None);
 412             }
 413
 414             queries.global_ctxt()?;
 415
 416             // Drop AST after creating GlobalCtxt to free memory.
 417             mem::drop(queries.expansion()?.take());
 418
 419             queries.ongoing_codegen()?;
 420
 421             let linker = queries.linker()?;
 422             Ok(Some(linker))
 423         })?;
 424
 425         if let Some(linker) = linker {
 426             linker.link()?
 427         }
 428
 429         Ok(())
 430     }
 431 }