src/librustc_interface/queries.rs

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