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::{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     arena: WorkerLocal<Arena<'tcx>>,
  70
  71     dep_graph_future: Query<Option<DepGraphFuture>>,
  72     parse: Query<ast::Crate>,
  73     crate_name: Query<String>,
  74     register_plugins: Query<(ast::Crate, Lrc<LintStore>)>,
  75     expansion: Query<(ast::Crate, Steal<Rc<RefCell<BoxedResolver>>>, Lrc<LintStore>)>,
  76     dep_graph: Query<DepGraph>,
  77     lower_to_hir: Query<(&'tcx map::Forest<'tcx>, Steal<ResolverOutputs>)>,
  78     prepare_outputs: Query<OutputFilenames>,
  79     global_ctxt: Query<QueryContext<'tcx>>,
  80     ongoing_codegen: Query<Box<dyn Any>>,
  81 }
  82
  83 impl<'tcx> Queries<'tcx> {
  84     pub fn new(compiler: &'tcx Compiler) -> Queries<'tcx> {
  85         Queries {
  86             compiler,
  87             gcx: Once::new(),
  88             arena: WorkerLocal::new(|_| Arena::default()),
  89             dep_graph_future: Default::default(),
  90             parse: Default::default(),
  91             crate_name: Default::default(),
  92             register_plugins: Default::default(),
  93             expansion: Default::default(),
  94             dep_graph: Default::default(),
  95             lower_to_hir: Default::default(),
  96             prepare_outputs: Default::default(),
  97             global_ctxt: Default::default(),
  98             ongoing_codegen: Default::default(),
  99         }
 100     }
 101
 102     fn session(&self) -> &Lrc<Session> {
 103         &self.compiler.sess
 104     }
 105     fn codegen_backend(&self) -> &Lrc<Box<dyn CodegenBackend>> {
 106         &self.compiler.codegen_backend()
 107     }
 108
 109     pub fn dep_graph_future(&self) -> Result<&Query<Option<DepGraphFuture>>> {
 110         self.dep_graph_future.compute(|| {
 111             Ok(self
 112                 .session()
 113                 .opts
 114                 .build_dep_graph()
 115                 .then(|| rustc_incremental::load_dep_graph(self.session())))
 116         })
 117     }
 118
 119     pub fn parse(&self) -> Result<&Query<ast::Crate>> {
 120         self.parse.compute(|| {
 121             passes::parse(self.session(), &self.compiler.input).map_err(|mut parse_error| {
 122                 parse_error.emit();
 123                 ErrorReported
 124             })
 125         })
 126     }
 127
 128     pub fn register_plugins(&self) -> Result<&Query<(ast::Crate, Lrc<LintStore>)>> {
 129         self.register_plugins.compute(|| {
 130             let crate_name = self.crate_name()?.peek().clone();
 131             let krate = self.parse()?.take();
 132
 133             let empty: &(dyn Fn(&Session, &mut LintStore) + Sync + Send) = &|_, _| {};
 134             let result = passes::register_plugins(
 135                 self.session(),
 136                 &*self.codegen_backend().metadata_loader(),
 137                 self.compiler.register_lints.as_ref().map(|p| &**p).unwrap_or_else(|| empty),
 138                 krate,
 139                 &crate_name,
 140             );
 141
 142             // Compute the dependency graph (in the background). We want to do
 143             // this as early as possible, to give the DepGraph maximum time to
 144             // load before dep_graph() is called, but it also can't happen
 145             // until after rustc_incremental::prepare_session_directory() is
 146             // called, which happens within passes::register_plugins().
 147             self.dep_graph_future().ok();
 148
 149             result
 150         })
 151     }
 152
 153     pub fn crate_name(&self) -> Result<&Query<String>> {
 154         self.crate_name.compute(|| {
 155             Ok(match self.compiler.crate_name {
 156                 Some(ref crate_name) => crate_name.clone(),
 157                 None => {
 158                     let parse_result = self.parse()?;
 159                     let krate = parse_result.peek();
 160                     rustc_codegen_utils::link::find_crate_name(
 161                         Some(self.session()),
 162                         &krate.attrs,
 163                         &self.compiler.input,
 164                     )
 165                 }
 166             })
 167         })
 168     }
 169
 170     pub fn expansion(
 171         &self,
 172     ) -> Result<&Query<(ast::Crate, Steal<Rc<RefCell<BoxedResolver>>>, Lrc<LintStore>)>> {
 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(
 211         &'tcx self,
 212     ) -> Result<&Query<(&'tcx map::Forest<'tcx>, Steal<ResolverOutputs>)>> {
 213         self.lower_to_hir.compute(|| {
 214             let expansion_result = self.expansion()?;
 215             let peeked = expansion_result.peek();
 216             let krate = &peeked.0;
 217             let resolver = peeked.1.steal();
 218             let lint_store = &peeked.2;
 219             let hir = resolver.borrow_mut().access(|resolver| {
 220                 passes::lower_to_hir(
 221                     self.session(),
 222                     lint_store,
 223                     resolver,
 224                     &*self.dep_graph()?.peek(),
 225                     &krate,
 226                     &self.arena,
 227                 )
 228             })?;
 229             let hir = self.arena.alloc(hir);
 230             Ok((hir, Steal::new(BoxedResolver::to_resolver_outputs(resolver))))
 231         })
 232     }
 233
 234     pub fn prepare_outputs(&self) -> Result<&Query<OutputFilenames>> {
 235         self.prepare_outputs.compute(|| {
 236             let expansion_result = self.expansion()?;
 237             let (krate, boxed_resolver, _) = &*expansion_result.peek();
 238             let crate_name = self.crate_name()?;
 239             let crate_name = crate_name.peek();
 240             passes::prepare_outputs(
 241                 self.session(),
 242                 self.compiler,
 243                 &krate,
 244                 &boxed_resolver,
 245                 &crate_name,
 246             )
 247         })
 248     }
 249
 250     pub fn global_ctxt(&'tcx self) -> Result<&Query<QueryContext<'tcx>>> {
 251         self.global_ctxt.compute(|| {
 252             let crate_name = self.crate_name()?.peek().clone();
 253             let outputs = self.prepare_outputs()?.peek().clone();
 254             let lint_store = self.expansion()?.peek().2.clone();
 255             let hir = self.lower_to_hir()?.peek();
 256             let (ref hir_forest, ref resolver_outputs) = &*hir;
 257             let _timer = self.session().timer("create_global_ctxt");
 258             Ok(passes::create_global_ctxt(
 259                 self.compiler,
 260                 lint_store,
 261                 hir_forest,
 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                 Ok(passes::start_codegen(&***self.codegen_backend(), tcx, &*outputs.peek()))
 281             })
 282         })
 283     }
 284
 285     pub fn linker(&'tcx self) -> Result<Linker> {
 286         let dep_graph = self.dep_graph()?;
 287         let prepare_outputs = self.prepare_outputs()?;
 288         let ongoing_codegen = self.ongoing_codegen()?;
 289
 290         let sess = self.session().clone();
 291         let codegen_backend = self.codegen_backend().clone();
 292
 293         Ok(Linker {
 294             sess,
 295             dep_graph: dep_graph.peek().clone(),
 296             prepare_outputs: prepare_outputs.take(),
 297             ongoing_codegen: ongoing_codegen.take(),
 298             codegen_backend,
 299         })
 300     }
 301 }
 302
 303 pub struct Linker {
 304     sess: Lrc<Session>,
 305     dep_graph: DepGraph,
 306     prepare_outputs: OutputFilenames,
 307     ongoing_codegen: Box<dyn Any>,
 308     codegen_backend: Lrc<Box<dyn CodegenBackend>>,
 309 }
 310
 311 impl Linker {
 312     pub fn link(self) -> Result<()> {
 313         let r = self
 314             .codegen_backend
 315             .join_codegen_and_link(
 316                 self.ongoing_codegen,
 317                 &self.sess,
 318                 &self.dep_graph,
 319                 &self.prepare_outputs,
 320             )
 321             .map_err(|_| ErrorReported);
 322         let prof = self.sess.prof.clone();
 323         let dep_graph = self.dep_graph;
 324         prof.generic_activity("drop_dep_graph").run(move || drop(dep_graph));
 325         r
 326     }
 327 }
 328
 329 impl Compiler {
 330     pub fn enter<F, T>(&self, f: F) -> T
 331     where
 332         F: for<'tcx> FnOnce(&'tcx Queries<'tcx>) -> T,
 333     {
 334         let mut _timer = None;
 335         let queries = Queries::new(&self);
 336         let ret = f(&queries);
 337
 338         if self.session().opts.debugging_opts.query_stats {
 339             if let Ok(gcx) = queries.global_ctxt() {
 340                 gcx.peek().print_stats();
 341             }
 342         }
 343
 344         _timer = Some(self.session().timer("free_global_ctxt"));
 345
 346         ret
 347     }
 348
 349     // This method is different to all the other methods in `Compiler` because
 350     // it lacks a `Queries` entry. It's also not currently used. It does serve
 351     // as an example of how `Compiler` can be used, with additional steps added
 352     // between some passes. And see `rustc_driver::run_compiler` for a more
 353     // complex example.
 354     pub fn compile(&self) -> Result<()> {
 355         let linker = self.enter(|queries| {
 356             queries.prepare_outputs()?;
 357
 358             if self.session().opts.output_types.contains_key(&OutputType::DepInfo)
 359                 && self.session().opts.output_types.len() == 1
 360             {
 361                 return Ok(None);
 362             }
 363
 364             queries.global_ctxt()?;
 365
 366             // Drop AST after creating GlobalCtxt to free memory.
 367             mem::drop(queries.expansion()?.take());
 368
 369             queries.ongoing_codegen()?;
 370
 371             let linker = queries.linker()?;
 372             Ok(Some(linker))
 373         })?;
 374
 375         if let Some(linker) = linker {
 376             linker.link()?
 377         }
 378
 379         Ok(())
 380     }
 381 }