src/librustc_interface/queries.rs

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