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::lint;
   8 use rustc::lint::LintStore;
   9 use rustc::session::config::{OutputFilenames, OutputType};
  10 use rustc::session::Session;
  11 use rustc::ty::steal::Steal;
  12 use rustc::ty::{AllArenas, GlobalCtxt, ResolverOutputs};
  13 use rustc::util::common::ErrorReported;
  14 use rustc_codegen_utils::codegen_backend::CodegenBackend;
  15 use rustc_data_structures::sync::{Lrc, Once, WorkerLocal};
  16 use rustc_hir::def_id::LOCAL_CRATE;
  17 use rustc_incremental::DepGraphFuture;
  18 use std::any::Any;
  19 use std::cell::{Ref, RefCell, RefMut};
  20 use std::mem;
  21 use std::rc::Rc;
  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.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: Once<GlobalCtxt<'tcx>>,
  69
  70     all_arenas: AllArenas,
  71     arena: WorkerLocal<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 map::Forest<'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: Once::new(),
  90             all_arenas: AllArenas::new(),
  91             arena: WorkerLocal::new(|_| 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 lint::LintStore) + Sync + Send) = &|_, _| {};
 137             let result = passes::register_plugins(
 138                 self.session(),
 139                 &*self.codegen_backend().metadata_loader(),
 140                 self.compiler.register_lints.as_ref().map(|p| &**p).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                     rustc_codegen_utils::link::find_crate_name(
 164                         Some(self.session()),
 165                         &krate.attrs,
 166                         &self.compiler.input,
 167                     )
 168                 }
 169             })
 170         })
 171     }
 172
 173     pub fn expansion(
 174         &self,
 175     ) -> Result<&Query<(ast::Crate, Steal<Rc<RefCell<BoxedResolver>>>, Lrc<LintStore>)>> {
 176         self.expansion.compute(|| {
 177             let crate_name = self.crate_name()?.peek().clone();
 178             let (krate, lint_store) = self.register_plugins()?.take();
 179             let _timer = self.session().timer("configure_and_expand");
 180             passes::configure_and_expand(
 181                 self.session().clone(),
 182                 lint_store.clone(),
 183                 self.codegen_backend().metadata_loader(),
 184                 krate,
 185                 &crate_name,
 186             )
 187             .map(|(krate, resolver)| {
 188                 (krate, Steal::new(Rc::new(RefCell::new(resolver))), lint_store)
 189             })
 190         })
 191     }
 192
 193     pub fn dep_graph(&self) -> Result<&Query<DepGraph>> {
 194         self.dep_graph.compute(|| {
 195             Ok(match self.dep_graph_future()?.take() {
 196                 None => DepGraph::new_disabled(),
 197                 Some(future) => {
 198                     let (prev_graph, prev_work_products) =
 199                         self.session().time("blocked_on_dep_graph_loading", || {
 200                             future
 201                                 .open()
 202                                 .unwrap_or_else(|e| rustc_incremental::LoadResult::Error {
 203                                     message: format!("could not decode incremental cache: {:?}", e),
 204                                 })
 205                                 .open(self.session())
 206                         });
 207                     DepGraph::new(prev_graph, prev_work_products)
 208                 }
 209             })
 210         })
 211     }
 212
 213     pub fn lower_to_hir(
 214         &'tcx self,
 215     ) -> Result<&Query<(&'tcx map::Forest<'tcx>, Steal<ResolverOutputs>)>> {
 216         self.lower_to_hir.compute(|| {
 217             let expansion_result = self.expansion()?;
 218             let peeked = expansion_result.peek();
 219             let krate = &peeked.0;
 220             let resolver = peeked.1.steal();
 221             let lint_store = &peeked.2;
 222             let hir = resolver.borrow_mut().access(|resolver| {
 223                 passes::lower_to_hir(
 224                     self.session(),
 225                     lint_store,
 226                     resolver,
 227                     &*self.dep_graph()?.peek(),
 228                     &krate,
 229                     &self.arena,
 230                 )
 231             })?;
 232             let hir = self.arena.alloc(hir);
 233             Ok((hir, Steal::new(BoxedResolver::to_resolver_outputs(resolver))))
 234         })
 235     }
 236
 237     pub fn prepare_outputs(&self) -> Result<&Query<OutputFilenames>> {
 238         self.prepare_outputs.compute(|| {
 239             let expansion_result = self.expansion()?;
 240             let (krate, boxed_resolver, _) = &*expansion_result.peek();
 241             let crate_name = self.crate_name()?;
 242             let crate_name = crate_name.peek();
 243             passes::prepare_outputs(
 244                 self.session(),
 245                 self.compiler,
 246                 &krate,
 247                 &boxed_resolver,
 248                 &crate_name,
 249             )
 250         })
 251     }
 252
 253     pub fn global_ctxt(&'tcx self) -> Result<&Query<QueryContext<'tcx>>> {
 254         self.global_ctxt.compute(|| {
 255             let crate_name = self.crate_name()?.peek().clone();
 256             let outputs = self.prepare_outputs()?.peek().clone();
 257             let lint_store = self.expansion()?.peek().2.clone();
 258             let hir = self.lower_to_hir()?.peek();
 259             let (ref hir_forest, ref resolver_outputs) = &*hir;
 260             let _timer = self.session().timer("create_global_ctxt");
 261             Ok(passes::create_global_ctxt(
 262                 self.compiler,
 263                 lint_store,
 264                 hir_forest,
 265                 resolver_outputs.steal(),
 266                 outputs,
 267                 &crate_name,
 268                 &self.gcx,
 269                 &self.all_arenas,
 270                 &self.arena,
 271             ))
 272         })
 273     }
 274
 275     pub fn ongoing_codegen(&'tcx self) -> Result<&Query<Box<dyn Any>>> {
 276         self.ongoing_codegen.compute(|| {
 277             let outputs = self.prepare_outputs()?;
 278             self.global_ctxt()?.peek_mut().enter(|tcx| {
 279                 tcx.analysis(LOCAL_CRATE).ok();
 280
 281                 // Don't do code generation if there were any errors
 282                 self.session().compile_status()?;
 283
 284                 Ok(passes::start_codegen(&***self.codegen_backend(), tcx, &*outputs.peek()))
 285             })
 286         })
 287     }
 288
 289     pub fn linker(&'tcx self) -> Result<Linker> {
 290         let dep_graph = self.dep_graph()?;
 291         let prepare_outputs = self.prepare_outputs()?;
 292         let ongoing_codegen = self.ongoing_codegen()?;
 293
 294         let sess = self.session().clone();
 295         let codegen_backend = self.codegen_backend().clone();
 296
 297         Ok(Linker {
 298             sess,
 299             dep_graph: dep_graph.peek().clone(),
 300             prepare_outputs: prepare_outputs.take(),
 301             ongoing_codegen: ongoing_codegen.take(),
 302             codegen_backend,
 303         })
 304     }
 305 }
 306
 307 pub struct Linker {
 308     sess: Lrc<Session>,
 309     dep_graph: DepGraph,
 310     prepare_outputs: OutputFilenames,
 311     ongoing_codegen: Box<dyn Any>,
 312     codegen_backend: Lrc<Box<dyn CodegenBackend>>,
 313 }
 314
 315 impl Linker {
 316     pub fn link(self) -> Result<()> {
 317         let r = self
 318             .codegen_backend
 319             .join_codegen_and_link(
 320                 self.ongoing_codegen,
 321                 &self.sess,
 322                 &self.dep_graph,
 323                 &self.prepare_outputs,
 324             )
 325             .map_err(|_| ErrorReported);
 326         let prof = self.sess.prof.clone();
 327         let dep_graph = self.dep_graph;
 328         prof.generic_activity("drop_dep_graph").run(move || drop(dep_graph));
 329         r
 330     }
 331 }
 332
 333 impl Compiler {
 334     pub fn enter<F, T>(&self, f: F) -> T
 335     where
 336         F: for<'tcx> FnOnce(&'tcx Queries<'tcx>) -> T,
 337     {
 338         let mut _timer = None;
 339         let queries = Queries::new(&self);
 340         let ret = f(&queries);
 341
 342         if self.session().opts.debugging_opts.query_stats {
 343             if let Ok(gcx) = queries.global_ctxt() {
 344                 gcx.peek().print_stats();
 345             }
 346         }
 347
 348         _timer = Some(self.session().timer("free_global_ctxt"));
 349
 350         ret
 351     }
 352
 353     // This method is different to all the other methods in `Compiler` because
 354     // it lacks a `Queries` entry. It's also not currently used. It does serve
 355     // as an example of how `Compiler` can be used, with additional steps added
 356     // between some passes. And see `rustc_driver::run_compiler` for a more
 357     // complex example.
 358     pub fn compile(&self) -> Result<()> {
 359         let linker = self.enter(|queries| {
 360             queries.prepare_outputs()?;
 361
 362             if self.session().opts.output_types.contains_key(&OutputType::DepInfo)
 363                 && self.session().opts.output_types.len() == 1
 364             {
 365                 return Ok(None);
 366             }
 367
 368             queries.global_ctxt()?;
 369
 370             // Drop AST after creating GlobalCtxt to free memory.
 371             mem::drop(queries.expansion()?.take());
 372
 373             queries.ongoing_codegen()?;
 374
 375             let linker = queries.linker()?;
 376             Ok(Some(linker))
 377         })?;
 378
 379         if let Some(linker) = linker {
 380             linker.link()?
 381         }
 382
 383         Ok(())
 384     }
 385 }