1 files changed, 402 insertions, 0 deletions
diff --git a/compiler/rustc_interface/src/queries.rs b/compiler/rustc_interface/src/queries.rs
new file mode 100644
index 000000000..73402ae08
--- /dev/null
+++ b/compiler/rustc_interface/src/queries.rs
@@ -0,0 +1,402 @@
+use crate::interface::{Compiler, Result};
+use crate::passes::{self, BoxedResolver, QueryContext};
+
+use rustc_ast as ast;
+use rustc_codegen_ssa::traits::CodegenBackend;
+use rustc_codegen_ssa::CodegenResults;
+use rustc_data_structures::svh::Svh;
+use rustc_data_structures::sync::{Lrc, OnceCell, WorkerLocal};
+use rustc_hir::def_id::LOCAL_CRATE;
+use rustc_incremental::DepGraphFuture;
+use rustc_lint::LintStore;
+use rustc_middle::arena::Arena;
+use rustc_middle::dep_graph::DepGraph;
+use rustc_middle::ty::{GlobalCtxt, TyCtxt};
+use rustc_query_impl::Queries as TcxQueries;
+use rustc_session::config::{self, OutputFilenames, OutputType};
+use rustc_session::{output::find_crate_name, Session};
+use rustc_span::symbol::sym;
+use std::any::Any;
+use std::cell::{Ref, RefCell, RefMut};
+use std::rc::Rc;
+
+/// Represent the result of a query.
+///
+/// This result can be stolen with the [`take`] method and generated with the [`compute`] method.
+///
+/// [`take`]: Self::take
+/// [`compute`]: Self::compute
+pub struct Query<T> {
+    result: RefCell<Option<Result<T>>>,
+}
+
+impl<T> Query<T> {
+    fn compute<F: FnOnce() -> Result<T>>(&self, f: F) -> Result<&Query<T>> {
+        let mut result = self.result.borrow_mut();
+        if result.is_none() {
+            *result = Some(f());
+        }
+        result.as_ref().unwrap().as_ref().map(|_| self).map_err(|err| *err)
+    }
+
+    /// Takes ownership of the query result. Further attempts to take or peek the query
+    /// result will panic unless it is generated by calling the `compute` method.
+    pub fn take(&self) -> T {
+        self.result.borrow_mut().take().expect("missing query result").unwrap()
+    }
+
+    /// Borrows the query result using the RefCell. Panics if the result is stolen.
+    pub fn peek(&self) -> Ref<'_, T> {
+        Ref::map(self.result.borrow(), |r| {
+            r.as_ref().unwrap().as_ref().expect("missing query result")
+        })
+    }
+
+    /// Mutably borrows the query result using the RefCell. Panics if the result is stolen.
+    pub fn peek_mut(&self) -> RefMut<'_, T> {
+        RefMut::map(self.result.borrow_mut(), |r| {
+            r.as_mut().unwrap().as_mut().expect("missing query result")
+        })
+    }
+}
+
+impl<T> Default for Query<T> {
+    fn default() -> Self {
+        Query { result: RefCell::new(None) }
+    }
+}
+
+pub struct Queries<'tcx> {
+    compiler: &'tcx Compiler,
+    gcx: OnceCell<GlobalCtxt<'tcx>>,
+    queries: OnceCell<TcxQueries<'tcx>>,
+
+    arena: WorkerLocal<Arena<'tcx>>,
+    hir_arena: WorkerLocal<rustc_hir::Arena<'tcx>>,
+
+    dep_graph_future: Query<Option<DepGraphFuture>>,
+    parse: Query<ast::Crate>,
+    crate_name: Query<String>,
+    register_plugins: Query<(ast::Crate, Lrc<LintStore>)>,
+    expansion: Query<(Lrc<ast::Crate>, Rc<RefCell<BoxedResolver>>, Lrc<LintStore>)>,
+    dep_graph: Query<DepGraph>,
+    prepare_outputs: Query<OutputFilenames>,
+    global_ctxt: Query<QueryContext<'tcx>>,
+    ongoing_codegen: Query<Box<dyn Any>>,
+}
+
+impl<'tcx> Queries<'tcx> {
+    pub fn new(compiler: &'tcx Compiler) -> Queries<'tcx> {
+        Queries {
+            compiler,
+            gcx: OnceCell::new(),
+            queries: OnceCell::new(),
+            arena: WorkerLocal::new(|_| Arena::default()),
+            hir_arena: WorkerLocal::new(|_| rustc_hir::Arena::default()),
+            dep_graph_future: Default::default(),
+            parse: Default::default(),
+            crate_name: Default::default(),
+            register_plugins: Default::default(),
+            expansion: Default::default(),
+            dep_graph: Default::default(),
+            prepare_outputs: Default::default(),
+            global_ctxt: Default::default(),
+            ongoing_codegen: Default::default(),
+        }
+    }
+
+    fn session(&self) -> &Lrc<Session> {
+        &self.compiler.sess
+    }
+    fn codegen_backend(&self) -> &Lrc<Box<dyn CodegenBackend>> {
+        self.compiler.codegen_backend()
+    }
+
+    fn dep_graph_future(&self) -> Result<&Query<Option<DepGraphFuture>>> {
+        self.dep_graph_future.compute(|| {
+            let sess = self.session();
+            Ok(sess.opts.build_dep_graph().then(|| rustc_incremental::load_dep_graph(sess)))
+        })
+    }
+
+    pub fn parse(&self) -> Result<&Query<ast::Crate>> {
+        self.parse.compute(|| {
+            passes::parse(self.session(), &self.compiler.input)
+                .map_err(|mut parse_error| parse_error.emit())
+        })
+    }
+
+    pub fn register_plugins(&self) -> Result<&Query<(ast::Crate, Lrc<LintStore>)>> {
+        self.register_plugins.compute(|| {
+            let crate_name = self.crate_name()?.peek().clone();
+            let krate = self.parse()?.take();
+
+            let empty: &(dyn Fn(&Session, &mut LintStore) + Sync + Send) = &|_, _| {};
+            let (krate, lint_store) = passes::register_plugins(
+                self.session(),
+                &*self.codegen_backend().metadata_loader(),
+                self.compiler.register_lints.as_deref().unwrap_or_else(|| empty),
+                krate,
+                &crate_name,
+            )?;
+
+            // Compute the dependency graph (in the background). We want to do
+            // this as early as possible, to give the DepGraph maximum time to
+            // load before dep_graph() is called, but it also can't happen
+            // until after rustc_incremental::prepare_session_directory() is
+            // called, which happens within passes::register_plugins().
+            self.dep_graph_future().ok();
+
+            Ok((krate, Lrc::new(lint_store)))
+        })
+    }
+
+    pub fn crate_name(&self) -> Result<&Query<String>> {
+        self.crate_name.compute(|| {
+            Ok({
+                let parse_result = self.parse()?;
+                let krate = parse_result.peek();
+                // parse `#[crate_name]` even if `--crate-name` was passed, to make sure it matches.
+                find_crate_name(self.session(), &krate.attrs, &self.compiler.input)
+            })
+        })
+    }
+
+    pub fn expansion(
+        &self,
+    ) -> Result<&Query<(Lrc<ast::Crate>, Rc<RefCell<BoxedResolver>>, Lrc<LintStore>)>> {
+        tracing::trace!("expansion");
+        self.expansion.compute(|| {
+            let crate_name = self.crate_name()?.peek().clone();
+            let (krate, lint_store) = self.register_plugins()?.take();
+            let _timer = self.session().timer("configure_and_expand");
+            let sess = self.session();
+            let mut resolver = passes::create_resolver(
+                sess.clone(),
+                self.codegen_backend().metadata_loader(),
+                &krate,
+                &crate_name,
+            );
+            let krate = resolver.access(|resolver| {
+                passes::configure_and_expand(sess, &lint_store, krate, &crate_name, resolver)
+            })?;
+            Ok((Lrc::new(krate), Rc::new(RefCell::new(resolver)), lint_store))
+        })
+    }
+
+    fn dep_graph(&self) -> Result<&Query<DepGraph>> {
+        self.dep_graph.compute(|| {
+            let sess = self.session();
+            let future_opt = self.dep_graph_future()?.take();
+            let dep_graph = future_opt
+                .and_then(|future| {
+                    let (prev_graph, prev_work_products) =
+                        sess.time("blocked_on_dep_graph_loading", || future.open().open(sess));
+
+                    rustc_incremental::build_dep_graph(sess, prev_graph, prev_work_products)
+                })
+                .unwrap_or_else(DepGraph::new_disabled);
+            Ok(dep_graph)
+        })
+    }
+
+    pub fn prepare_outputs(&self) -> Result<&Query<OutputFilenames>> {
+        self.prepare_outputs.compute(|| {
+            let (krate, boxed_resolver, _) = &*self.expansion()?.peek();
+            let crate_name = self.crate_name()?.peek();
+            passes::prepare_outputs(
+                self.session(),
+                self.compiler,
+                krate,
+                &*boxed_resolver,
+                &crate_name,
+            )
+        })
+    }
+
+    pub fn global_ctxt(&'tcx self) -> Result<&Query<QueryContext<'tcx>>> {
+        self.global_ctxt.compute(|| {
+            let crate_name = self.crate_name()?.peek().clone();
+            let outputs = self.prepare_outputs()?.peek().clone();
+            let dep_graph = self.dep_graph()?.peek().clone();
+            let (krate, resolver, lint_store) = self.expansion()?.take();
+            Ok(passes::create_global_ctxt(
+                self.compiler,
+                lint_store,
+                krate,
+                dep_graph,
+                resolver,
+                outputs,
+                &crate_name,
+                &self.queries,
+                &self.gcx,
+                &self.arena,
+                &self.hir_arena,
+            ))
+        })
+    }
+
+    pub fn ongoing_codegen(&'tcx self) -> Result<&Query<Box<dyn Any>>> {
+        self.ongoing_codegen.compute(|| {
+            let outputs = self.prepare_outputs()?;
+            self.global_ctxt()?.peek_mut().enter(|tcx| {
+                tcx.analysis(()).ok();
+
+                // Don't do code generation if there were any errors
+                self.session().compile_status()?;
+
+                // Hook for UI tests.
+                Self::check_for_rustc_errors_attr(tcx);
+
+                Ok(passes::start_codegen(&***self.codegen_backend(), tcx, &*outputs.peek()))
+            })
+        })
+    }
+
+    /// Check for the `#[rustc_error]` annotation, which forces an error in codegen. This is used
+    /// to write UI tests that actually test that compilation succeeds without reporting
+    /// an error.
+    fn check_for_rustc_errors_attr(tcx: TyCtxt<'_>) {
+        let Some((def_id, _)) = tcx.entry_fn(()) else { return };
+        for attr in tcx.get_attrs(def_id, sym::rustc_error) {
+            match attr.meta_item_list() {
+                // Check if there is a `#[rustc_error(delay_span_bug_from_inside_query)]`.
+                Some(list)
+                    if list.iter().any(|list_item| {
+                        matches!(
+                            list_item.ident().map(|i| i.name),
+                            Some(sym::delay_span_bug_from_inside_query)
+                        )
+                    }) =>
+                {
+                    tcx.ensure().trigger_delay_span_bug(def_id);
+                }
+
+                // Bare `#[rustc_error]`.
+                None => {
+                    tcx.sess.span_fatal(
+                        tcx.def_span(def_id),
+                        "fatal error triggered by #[rustc_error]",
+                    );
+                }
+
+                // Some other attribute.
+                Some(_) => {
+                    tcx.sess.span_warn(
+                        tcx.def_span(def_id),
+                        "unexpected annotation used with `#[rustc_error(...)]!",
+                    );
+                }
+            }
+        }
+    }
+
+    pub fn linker(&'tcx self) -> Result<Linker> {
+        let sess = self.session().clone();
+        let codegen_backend = self.codegen_backend().clone();
+
+        let dep_graph = self.dep_graph()?.peek().clone();
+        let prepare_outputs = self.prepare_outputs()?.take();
+        let crate_hash = self.global_ctxt()?.peek_mut().enter(|tcx| tcx.crate_hash(LOCAL_CRATE));
+        let ongoing_codegen = self.ongoing_codegen()?.take();
+
+        Ok(Linker {
+            sess,
+            codegen_backend,
+
+            dep_graph,
+            prepare_outputs,
+            crate_hash,
+            ongoing_codegen,
+        })
+    }
+}
+
+pub struct Linker {
+    // compilation inputs
+    sess: Lrc<Session>,
+    codegen_backend: Lrc<Box<dyn CodegenBackend>>,
+
+    // compilation outputs
+    dep_graph: DepGraph,
+    prepare_outputs: OutputFilenames,
+    crate_hash: Svh,
+    ongoing_codegen: Box<dyn Any>,
+}
+
+impl Linker {
+    pub fn link(self) -> Result<()> {
+        let (codegen_results, work_products) = self.codegen_backend.join_codegen(
+            self.ongoing_codegen,
+            &self.sess,
+            &self.prepare_outputs,
+        )?;
+
+        self.sess.compile_status()?;
+
+        let sess = &self.sess;
+        let dep_graph = self.dep_graph;
+        sess.time("serialize_work_products", || {
+            rustc_incremental::save_work_product_index(sess, &dep_graph, work_products)
+        });
+
+        let prof = self.sess.prof.clone();
+        prof.generic_activity("drop_dep_graph").run(move || drop(dep_graph));
+
+        // Now that we won't touch anything in the incremental compilation directory
+        // any more, we can finalize it (which involves renaming it)
+        rustc_incremental::finalize_session_directory(&self.sess, self.crate_hash);
+
+        if !self
+            .sess
+            .opts
+            .output_types
+            .keys()
+            .any(|&i| i == OutputType::Exe || i == OutputType::Metadata)
+        {
+            return Ok(());
+        }
+
+        if sess.opts.unstable_opts.no_link {
+            let encoded = CodegenResults::serialize_rlink(&codegen_results);
+            let rlink_file = self.prepare_outputs.with_extension(config::RLINK_EXT);
+            std::fs::write(&rlink_file, encoded).map_err(|err| {
+                sess.fatal(&format!("failed to write file {}: {}", rlink_file.display(), err));
+            })?;
+            return Ok(());
+        }
+
+        let _timer = sess.prof.verbose_generic_activity("link_crate");
+        self.codegen_backend.link(&self.sess, codegen_results, &self.prepare_outputs)
+    }
+}
+
+impl Compiler {
+    pub fn enter<F, T>(&self, f: F) -> T
+    where
+        F: for<'tcx> FnOnce(&'tcx Queries<'tcx>) -> T,
+    {
+        let mut _timer = None;
+        let queries = Queries::new(self);
+        let ret = f(&queries);
+
+        // NOTE: intentionally does not compute the global context if it hasn't been built yet,
+        // since that likely means there was a parse error.
+        if let Some(Ok(gcx)) = &mut *queries.global_ctxt.result.borrow_mut() {
+            // We assume that no queries are run past here. If there are new queries
+            // after this point, they'll show up as "<unknown>" in self-profiling data.
+            {
+                let _prof_timer =
+                    queries.session().prof.generic_activity("self_profile_alloc_query_strings");
+                gcx.enter(rustc_query_impl::alloc_self_profile_query_strings);
+            }
+
+            self.session()
+                .time("serialize_dep_graph", || gcx.enter(rustc_incremental::save_dep_graph));
+        }
+
+        _timer = Some(self.session().timer("free_global_ctxt"));
+
+        ret
+    }
+}