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::{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     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             arena: WorkerLocal::new(|_| Arena::default()),
  90             dep_graph_future: Default::default(),
  91             parse: Default::default(),
  92             crate_name: Default::default(),
  93             register_plugins: Default::default(),
  94             expansion: Default::default(),
  95             dep_graph: Default::default(),
  96             lower_to_hir: Default::default(),
  97             prepare_outputs: Default::default(),
  98             global_ctxt: Default::default(),
  99             ongoing_codegen: Default::default(),
 100         }
 101     }
 102
 103     fn session(&self) -> &Lrc<Session> {
 104         &self.compiler.sess
 105     }
 106     fn codegen_backend(&self) -> &Lrc<Box<dyn CodegenBackend>> {
 107         &self.compiler.codegen_backend()
 108     }
 109
 110     pub fn dep_graph_future(&self) -> Result<&Query<Option<DepGraphFuture>>> {
 111         self.dep_graph_future.compute(|| {
 112             Ok(self
 113                 .session()
 114                 .opts
 115                 .build_dep_graph()
 116                 .then(|| rustc_incremental::load_dep_graph(self.session())))
 117         })
 118     }
 119
 120     pub fn parse(&self) -> Result<&Query<ast::Crate>> {
 121         self.parse.compute(|| {
 122             passes::parse(self.session(), &self.compiler.input).map_err(|mut parse_error| {
 123                 parse_error.emit();
 124                 ErrorReported
 125             })
 126         })
 127     }
 128
 129     pub fn register_plugins(&self) -> Result<&Query<(ast::Crate, Lrc<LintStore>)>> {
 130         self.register_plugins.compute(|| {
 131             let crate_name = self.crate_name()?.peek().clone();
 132             let krate = self.parse()?.take();
 133
 134             let empty: &(dyn Fn(&Session, &mut lint::LintStore) + Sync + Send) = &|_, _| {};
 135             let result = passes::register_plugins(
 136                 self.session(),
 137                 &*self.codegen_backend().metadata_loader(),
 138                 self.compiler.register_lints.as_ref().map(|p| &**p).unwrap_or_else(|| empty),
 139                 krate,
 140                 &crate_name,
 141             );
 142
 143             // Compute the dependency graph (in the background). We want to do
 144             // this as early as possible, to give the DepGraph maximum time to
 145             // load before dep_graph() is called, but it also can't happen
 146             // until after rustc_incremental::prepare_session_directory() is
 147             // called, which happens within passes::register_plugins().
 148             self.dep_graph_future().ok();
 149
 150             result
 151         })
 152     }
 153
 154     pub fn crate_name(&self) -> Result<&Query<String>> {
 155         self.crate_name.compute(|| {
 156             Ok(match self.compiler.crate_name {
 157                 Some(ref crate_name) => crate_name.clone(),
 158                 None => {
 159                     let parse_result = self.parse()?;
 160                     let krate = parse_result.peek();
 161                     rustc_codegen_utils::link::find_crate_name(
 162                         Some(self.session()),
 163                         &krate.attrs,
 164                         &self.compiler.input,
 165                     )
 166                 }
 167             })
 168         })
 169     }
 170
 171     pub fn expansion(
 172         &self,
 173     ) -> Result<&Query<(ast::Crate, Steal<Rc<RefCell<BoxedResolver>>>, Lrc<LintStore>)>> {
 174         self.expansion.compute(|| {
 175             let crate_name = self.crate_name()?.peek().clone();
 176             let (krate, lint_store) = self.register_plugins()?.take();
 177             let _timer = self.session().timer("configure_and_expand");
 178             passes::configure_and_expand(
 179                 self.session().clone(),
 180                 lint_store.clone(),
 181                 self.codegen_backend().metadata_loader(),
 182                 krate,
 183                 &crate_name,
 184             )
 185             .map(|(krate, resolver)| {
 186                 (krate, Steal::new(Rc::new(RefCell::new(resolver))), lint_store)
 187             })
 188         })
 189     }
 190
 191     pub fn dep_graph(&self) -> Result<&Query<DepGraph>> {
 192         self.dep_graph.compute(|| {
 193             Ok(match self.dep_graph_future()?.take() {
 194                 None => DepGraph::new_disabled(),
 195                 Some(future) => {
 196                     let (prev_graph, prev_work_products) =
 197                         self.session().time("blocked_on_dep_graph_loading", || {
 198                             future
 199                                 .open()
 200                                 .unwrap_or_else(|e| rustc_incremental::LoadResult::Error {
 201                                     message: format!("could not decode incremental cache: {:?}", e),
 202                                 })
 203                                 .open(self.session())
 204                         });
 205                     DepGraph::new(prev_graph, prev_work_products)
 206                 }
 207             })
 208         })
 209     }
 210
 211     pub fn lower_to_hir(
 212         &'tcx self,
 213     ) -> Result<&Query<(&'tcx map::Forest<'tcx>, Steal<ResolverOutputs>)>> {
 214         self.lower_to_hir.compute(|| {
 215             let expansion_result = self.expansion()?;
 216             let peeked = expansion_result.peek();
 217             let krate = &peeked.0;
 218             let resolver = peeked.1.steal();
 219             let lint_store = &peeked.2;
 220             let hir = resolver.borrow_mut().access(|resolver| {
 221                 passes::lower_to_hir(
 222                     self.session(),
 223                     lint_store,
 224                     resolver,
 225                     &*self.dep_graph()?.peek(),
 226                     &krate,
 227                     &self.arena,
 228                 )
 229             })?;
 230             let hir = self.arena.alloc(hir);
 231             Ok((hir, Steal::new(BoxedResolver::to_resolver_outputs(resolver))))
 232         })
 233     }
 234
 235     pub fn prepare_outputs(&self) -> Result<&Query<OutputFilenames>> {
 236         self.prepare_outputs.compute(|| {
 237             let expansion_result = self.expansion()?;
 238             let (krate, boxed_resolver, _) = &*expansion_result.peek();
 239             let crate_name = self.crate_name()?;
 240             let crate_name = crate_name.peek();
 241             passes::prepare_outputs(
 242                 self.session(),
 243                 self.compiler,
 244                 &krate,
 245                 &boxed_resolver,
 246                 &crate_name,
 247             )
 248         })
 249     }
 250
 251     pub fn global_ctxt(&'tcx self) -> Result<&Query<QueryContext<'tcx>>> {
 252         self.global_ctxt.compute(|| {
 253             let crate_name = self.crate_name()?.peek().clone();
 254             let outputs = self.prepare_outputs()?.peek().clone();
 255             let lint_store = self.expansion()?.peek().2.clone();
 256             let hir = self.lower_to_hir()?.peek();
 257             let (ref hir_forest, ref resolver_outputs) = &*hir;
 258             let _timer = self.session().timer("create_global_ctxt");
 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.arena,
 268             ))
 269         })
 270     }
 271
 272     pub fn ongoing_codegen(&'tcx self) -> Result<&Query<Box<dyn Any>>> {
 273         self.ongoing_codegen.compute(|| {
 274             let outputs = self.prepare_outputs()?;
 275             self.global_ctxt()?.peek_mut().enter(|tcx| {
 276                 tcx.analysis(LOCAL_CRATE).ok();
 277
 278                 // Don't do code generation if there were any errors
 279                 self.session().compile_status()?;
 280
 281                 Ok(passes::start_codegen(&***self.codegen_backend(), tcx, &*outputs.peek()))
 282             })
 283         })
 284     }
 285
 286     pub fn linker(&'tcx self) -> Result<Linker> {
 287         let dep_graph = self.dep_graph()?;
 288         let prepare_outputs = self.prepare_outputs()?;
 289         let ongoing_codegen = self.ongoing_codegen()?;
 290
 291         let sess = self.session().clone();
 292         let codegen_backend = self.codegen_backend().clone();
 293
 294         Ok(Linker {
 295             sess,
 296             dep_graph: dep_graph.peek().clone(),
 297             prepare_outputs: prepare_outputs.take(),
 298             ongoing_codegen: ongoing_codegen.take(),
 299             codegen_backend,
 300         })
 301     }
 302 }
 303
 304 pub struct Linker {
 305     sess: Lrc<Session>,
 306     dep_graph: DepGraph,
 307     prepare_outputs: OutputFilenames,
 308     ongoing_codegen: Box<dyn Any>,
 309     codegen_backend: Lrc<Box<dyn CodegenBackend>>,
 310 }
 311
 312 impl Linker {
 313     pub fn link(self) -> Result<()> {
 314         let r = self
 315             .codegen_backend
 316             .join_codegen_and_link(
 317                 self.ongoing_codegen,
 318                 &self.sess,
 319                 &self.dep_graph,
 320                 &self.prepare_outputs,
 321             )
 322             .map_err(|_| ErrorReported);
 323         let prof = self.sess.prof.clone();
 324         let dep_graph = self.dep_graph;
 325         prof.generic_activity("drop_dep_graph").run(move || drop(dep_graph));
 326         r
 327     }
 328 }
 329
 330 impl Compiler {
 331     pub fn enter<F, T>(&self, f: F) -> T
 332     where
 333         F: for<'tcx> FnOnce(&'tcx Queries<'tcx>) -> T,
 334     {
 335         let mut _timer = None;
 336         let queries = Queries::new(&self);
 337         let ret = f(&queries);
 338
 339         if self.session().opts.debugging_opts.query_stats {
 340             if let Ok(gcx) = queries.global_ctxt() {
 341                 gcx.peek().print_stats();
 342             }
 343         }
 344
 345         _timer = Some(self.session().timer("free_global_ctxt"));
 346
 347         ret
 348     }
 349
 350     // This method is different to all the other methods in `Compiler` because
 351     // it lacks a `Queries` entry. It's also not currently used. It does serve
 352     // as an example of how `Compiler` can be used, with additional steps added
 353     // between some passes. And see `rustc_driver::run_compiler` for a more
 354     // complex example.
 355     pub fn compile(&self) -> Result<()> {
 356         let linker = self.enter(|queries| {
 357             queries.prepare_outputs()?;
 358
 359             if self.session().opts.output_types.contains_key(&OutputType::DepInfo)
 360                 && self.session().opts.output_types.len() == 1
 361             {
 362                 return Ok(None);
 363             }
 364
 365             queries.global_ctxt()?;
 366
 367             // Drop AST after creating GlobalCtxt to free memory.
 368             mem::drop(queries.expansion()?.take());
 369
 370             queries.ongoing_codegen()?;
 371
 372             let linker = queries.linker()?;
 373             Ok(Some(linker))
 374         })?;
 375
 376         if let Some(linker) = linker {
 377             linker.link()?
 378         }
 379
 380         Ok(())
 381     }
 382 }