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         self.expansion.compute(|| {
 173             let crate_name = self.crate_name()?.peek().clone();
 174             let (krate, lint_store) = self.register_plugins()?.take();
 175             let _timer = self.session().timer("configure_and_expand");
 176             passes::configure_and_expand(
 177                 self.session().clone(),
 178                 lint_store.clone(),
 179                 self.codegen_backend().metadata_loader(),
 180                 krate,
 181                 &crate_name,
 182             )
 183             .map(|(krate, resolver)| {
 184                 (krate, Steal::new(Rc::new(RefCell::new(resolver))), lint_store)
 185             })
 186         })
 187     }
 188
 189     pub fn dep_graph(&self) -> Result<&Query<DepGraph>> {
 190         self.dep_graph.compute(|| {
 191             Ok(match self.dep_graph_future()?.take() {
 192                 None => DepGraph::new_disabled(),
 193                 Some(future) => {
 194                     let (prev_graph, prev_work_products) =
 195                         self.session().time("blocked_on_dep_graph_loading", || {
 196                             future
 197                                 .open()
 198                                 .unwrap_or_else(|e| rustc_incremental::LoadResult::Error {
 199                                     message: format!("could not decode incremental cache: {:?}", e),
 200                                 })
 201                                 .open(self.session())
 202                         });
 203                     DepGraph::new(prev_graph, prev_work_products)
 204                 }
 205             })
 206         })
 207     }
 208
 209     pub fn lower_to_hir(&'tcx self) -> Result<&Query<(&'tcx Crate<'tcx>, Steal<ResolverOutputs>)>> {
 210         self.lower_to_hir.compute(|| {
 211             let expansion_result = self.expansion()?;
 212             let peeked = expansion_result.peek();
 213             let krate = &peeked.0;
 214             let resolver = peeked.1.steal();
 215             let lint_store = &peeked.2;
 216             let hir = resolver.borrow_mut().access(|resolver| {
 217                 Ok(passes::lower_to_hir(
 218                     self.session(),
 219                     lint_store,
 220                     resolver,
 221                     &*self.dep_graph()?.peek(),
 222                     &krate,
 223                     &self.hir_arena,
 224                 ))
 225             })?;
 226             let hir = self.hir_arena.alloc(hir);
 227             Ok((hir, Steal::new(BoxedResolver::to_resolver_outputs(resolver))))
 228         })
 229     }
 230
 231     pub fn prepare_outputs(&self) -> Result<&Query<OutputFilenames>> {
 232         self.prepare_outputs.compute(|| {
 233             let expansion_result = self.expansion()?;
 234             let (krate, boxed_resolver, _) = &*expansion_result.peek();
 235             let crate_name = self.crate_name()?;
 236             let crate_name = crate_name.peek();
 237             passes::prepare_outputs(
 238                 self.session(),
 239                 self.compiler,
 240                 &krate,
 241                 &boxed_resolver,
 242                 &crate_name,
 243             )
 244         })
 245     }
 246
 247     pub fn global_ctxt(&'tcx self) -> Result<&Query<QueryContext<'tcx>>> {
 248         self.global_ctxt.compute(|| {
 249             let crate_name = self.crate_name()?.peek().clone();
 250             let outputs = self.prepare_outputs()?.peek().clone();
 251             let lint_store = self.expansion()?.peek().2.clone();
 252             let hir = self.lower_to_hir()?.peek();
 253             let dep_graph = self.dep_graph()?.peek().clone();
 254             let (ref krate, ref resolver_outputs) = &*hir;
 255             let _timer = self.session().timer("create_global_ctxt");
 256             Ok(passes::create_global_ctxt(
 257                 self.compiler,
 258                 lint_store,
 259                 krate,
 260                 dep_graph,
 261                 resolver_outputs.steal(),
 262                 outputs,
 263                 &crate_name,
 264                 &self.gcx,
 265                 &self.arena,
 266             ))
 267         })
 268     }
 269
 270     pub fn ongoing_codegen(&'tcx self) -> Result<&Query<Box<dyn Any>>> {
 271         self.ongoing_codegen.compute(|| {
 272             let outputs = self.prepare_outputs()?;
 273             self.global_ctxt()?.peek_mut().enter(|tcx| {
 274                 tcx.analysis(LOCAL_CRATE).ok();
 275
 276                 // Don't do code generation if there were any errors
 277                 self.session().compile_status()?;
 278
 279                 // Hook for compile-fail tests.
 280                 Self::check_for_rustc_errors_attr(tcx);
 281
 282                 Ok(passes::start_codegen(&***self.codegen_backend(), tcx, &*outputs.peek()))
 283             })
 284         })
 285     }
 286
 287     /// Check for the `#[rustc_error]` annotation, which forces an error in codegen. This is used
 288     /// to write compile-fail tests that actually test that compilation succeeds without reporting
 289     /// an error.
 290     fn check_for_rustc_errors_attr(tcx: TyCtxt<'_>) {
 291         let def_id = match tcx.entry_fn(LOCAL_CRATE) {
 292             Some((def_id, _)) => def_id,
 293             _ => return,
 294         };
 295
 296         let attrs = &*tcx.get_attrs(def_id.to_def_id());
 297         let attrs = attrs.iter().filter(|attr| attr.check_name(sym::rustc_error));
 298         for attr in attrs {
 299             match attr.meta_item_list() {
 300                 // Check if there is a `#[rustc_error(delay_span_bug_from_inside_query)]`.
 301                 Some(list)
 302                     if list.iter().any(|list_item| {
 303                         matches!(
 304                             list_item.ident().map(|i| i.name),
 305                             Some(sym::delay_span_bug_from_inside_query)
 306                         )
 307                     }) =>
 308                 {
 309                     tcx.ensure().trigger_delay_span_bug(def_id);
 310                 }
 311
 312                 // Bare `#[rustc_error]`.
 313                 None => {
 314                     tcx.sess.span_fatal(
 315                         tcx.def_span(def_id),
 316                         "fatal error triggered by #[rustc_error]",
 317                     );
 318                 }
 319
 320                 // Some other attribute.
 321                 Some(_) => {
 322                     tcx.sess.span_warn(
 323                         tcx.def_span(def_id),
 324                         "unexpected annotation used with `#[rustc_error(...)]!",
 325                     );
 326                 }
 327             }
 328         }
 329     }
 330
 331     pub fn linker(&'tcx self) -> Result<Linker> {
 332         let dep_graph = self.dep_graph()?;
 333         let prepare_outputs = self.prepare_outputs()?;
 334         let ongoing_codegen = self.ongoing_codegen()?;
 335
 336         let sess = self.session().clone();
 337         let codegen_backend = self.codegen_backend().clone();
 338
 339         Ok(Linker {
 340             sess,
 341             dep_graph: dep_graph.peek().clone(),
 342             prepare_outputs: prepare_outputs.take(),
 343             ongoing_codegen: ongoing_codegen.take(),
 344             codegen_backend,
 345         })
 346     }
 347 }
 348
 349 pub struct Linker {
 350     sess: Lrc<Session>,
 351     dep_graph: DepGraph,
 352     prepare_outputs: OutputFilenames,
 353     ongoing_codegen: Box<dyn Any>,
 354     codegen_backend: Lrc<Box<dyn CodegenBackend>>,
 355 }
 356
 357 impl Linker {
 358     pub fn link(self) -> Result<()> {
 359         let codegen_results =
 360             self.codegen_backend.join_codegen(self.ongoing_codegen, &self.sess, &self.dep_graph)?;
 361         let prof = self.sess.prof.clone();
 362         let dep_graph = self.dep_graph;
 363         prof.generic_activity("drop_dep_graph").run(move || drop(dep_graph));
 364
 365         if !self
 366             .sess
 367             .opts
 368             .output_types
 369             .keys()
 370             .any(|&i| i == OutputType::Exe || i == OutputType::Metadata)
 371         {
 372             return Ok(());
 373         }
 374         self.codegen_backend.link(&self.sess, codegen_results, &self.prepare_outputs)
 375     }
 376 }
 377
 378 impl Compiler {
 379     pub fn enter<F, T>(&self, f: F) -> T
 380     where
 381         F: for<'tcx> FnOnce(&'tcx Queries<'tcx>) -> T,
 382     {
 383         let mut _timer = None;
 384         let queries = Queries::new(&self);
 385         let ret = f(&queries);
 386
 387         if self.session().opts.debugging_opts.query_stats {
 388             if let Ok(gcx) = queries.global_ctxt() {
 389                 gcx.peek_mut().print_stats();
 390             }
 391         }
 392
 393         _timer = Some(self.session().timer("free_global_ctxt"));
 394
 395         ret
 396     }
 397
 398     // This method is different to all the other methods in `Compiler` because
 399     // it lacks a `Queries` entry. It's also not currently used. It does serve
 400     // as an example of how `Compiler` can be used, with additional steps added
 401     // between some passes. And see `rustc_driver::run_compiler` for a more
 402     // complex example.
 403     pub fn compile(&self) -> Result<()> {
 404         let linker = self.enter(|queries| {
 405             queries.prepare_outputs()?;
 406
 407             if self.session().opts.output_types.contains_key(&OutputType::DepInfo)
 408                 && self.session().opts.output_types.len() == 1
 409             {
 410                 return Ok(None);
 411             }
 412
 413             queries.global_ctxt()?;
 414
 415             // Drop AST after creating GlobalCtxt to free memory.
 416             mem::drop(queries.expansion()?.take());
 417
 418             queries.ongoing_codegen()?;
 419
 420             let linker = queries.linker()?;
 421             Ok(Some(linker))
 422         })?;
 423
 424         if let Some(linker) = linker {
 425             linker.link()?
 426         }
 427
 428         Ok(())
 429     }
 430 }