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