src/librustc_interface/queries.rs

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