1 files changed, 238 insertions, 0 deletions
diff --git a/compiler/rustc_interface/src/queries.rs b/compiler/rustc_interface/src/queries.rs
new file mode 100644
index 00000000000..b6837ec764f
--- /dev/null
+++ b/compiler/rustc_interface/src/queries.rs
@@ -0,0 +1,238 @@
+use std::any::Any;
+use std::cell::{RefCell, RefMut};
+use std::sync::Arc;
+
+use rustc_ast as ast;
+use rustc_codegen_ssa::CodegenResults;
+use rustc_codegen_ssa::traits::CodegenBackend;
+use rustc_data_structures::steal::Steal;
+use rustc_data_structures::svh::Svh;
+use rustc_data_structures::sync::{OnceLock, WorkerLocal};
+use rustc_hir::def_id::LOCAL_CRATE;
+use rustc_middle::arena::Arena;
+use rustc_middle::dep_graph::DepGraph;
+use rustc_middle::ty::{GlobalCtxt, TyCtxt};
+use rustc_serialize::opaque::FileEncodeResult;
+use rustc_session::Session;
+use rustc_session::config::{self, OutputFilenames, OutputType};
+
+use crate::errors::FailedWritingFile;
+use crate::interface::{Compiler, Result};
+use crate::{errors, passes};
+
+/// Represent the result of a query.
+///
+/// This result can be stolen once with the [`steal`] method and generated with the [`compute`] method.
+///
+/// [`steal`]: Steal::steal
+/// [`compute`]: Self::compute
+pub struct Query<T> {
+    /// `None` means no value has been computed yet.
+    result: RefCell<Option<Result<Steal<T>>>>,
+}
+
+impl<T> Query<T> {
+    fn compute<F: FnOnce() -> Result<T>>(&self, f: F) -> Result<QueryResult<'_, T>> {
+        RefMut::filter_map(
+            self.result.borrow_mut(),
+            |r: &mut Option<Result<Steal<T>>>| -> Option<&mut Steal<T>> {
+                r.get_or_insert_with(|| f().map(Steal::new)).as_mut().ok()
+            },
+        )
+        .map_err(|r| *r.as_ref().unwrap().as_ref().map(|_| ()).unwrap_err())
+        .map(QueryResult)
+    }
+}
+
+pub struct QueryResult<'a, T>(RefMut<'a, Steal<T>>);
+
+impl<'a, T> std::ops::Deref for QueryResult<'a, T> {
+    type Target = RefMut<'a, Steal<T>>;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl<'a, T> std::ops::DerefMut for QueryResult<'a, T> {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.0
+    }
+}
+
+impl<'a, 'tcx> QueryResult<'a, &'tcx GlobalCtxt<'tcx>> {
+    pub fn enter<T>(&mut self, f: impl FnOnce(TyCtxt<'tcx>) -> T) -> T {
+        (*self.0).get_mut().enter(f)
+    }
+}
+
+pub struct Queries<'tcx> {
+    compiler: &'tcx Compiler,
+    gcx_cell: OnceLock<GlobalCtxt<'tcx>>,
+
+    arena: WorkerLocal<Arena<'tcx>>,
+    hir_arena: WorkerLocal<rustc_hir::Arena<'tcx>>,
+
+    parse: Query<ast::Crate>,
+    // This just points to what's in `gcx_cell`.
+    gcx: Query<&'tcx GlobalCtxt<'tcx>>,
+}
+
+impl<'tcx> Queries<'tcx> {
+    pub fn new(compiler: &'tcx Compiler) -> Queries<'tcx> {
+        Queries {
+            compiler,
+            gcx_cell: OnceLock::new(),
+            arena: WorkerLocal::new(|_| Arena::default()),
+            hir_arena: WorkerLocal::new(|_| rustc_hir::Arena::default()),
+            parse: Query { result: RefCell::new(None) },
+            gcx: Query { result: RefCell::new(None) },
+        }
+    }
+
+    pub fn finish(&self) -> FileEncodeResult {
+        if let Some(gcx) = self.gcx_cell.get() { gcx.finish() } else { Ok(0) }
+    }
+
+    pub fn parse(&self) -> Result<QueryResult<'_, ast::Crate>> {
+        self.parse.compute(|| passes::parse(&self.compiler.sess))
+    }
+
+    pub fn global_ctxt(&'tcx self) -> Result<QueryResult<'tcx, &'tcx GlobalCtxt<'tcx>>> {
+        self.gcx.compute(|| {
+            let krate = self.parse()?.steal();
+
+            passes::create_global_ctxt(
+                self.compiler,
+                krate,
+                &self.gcx_cell,
+                &self.arena,
+                &self.hir_arena,
+            )
+        })
+    }
+}
+
+pub struct Linker {
+    dep_graph: DepGraph,
+    output_filenames: Arc<OutputFilenames>,
+    // Only present when incr. comp. is enabled.
+    crate_hash: Option<Svh>,
+    ongoing_codegen: Box<dyn Any>,
+}
+
+impl Linker {
+    pub fn codegen_and_build_linker(
+        tcx: TyCtxt<'_>,
+        codegen_backend: &dyn CodegenBackend,
+    ) -> Result<Linker> {
+        let ongoing_codegen = passes::start_codegen(codegen_backend, tcx)?;
+
+        // This must run after monomorphization so that all generic types
+        // have been instantiated.
+        if tcx.sess.opts.unstable_opts.print_type_sizes {
+            tcx.sess.code_stats.print_type_sizes();
+        }
+
+        if tcx.sess.opts.unstable_opts.print_vtable_sizes {
+            let crate_name = tcx.crate_name(LOCAL_CRATE);
+
+            tcx.sess.code_stats.print_vtable_sizes(crate_name);
+        }
+
+        Ok(Linker {
+            dep_graph: tcx.dep_graph.clone(),
+            output_filenames: Arc::clone(tcx.output_filenames(())),
+            crate_hash: if tcx.needs_crate_hash() {
+                Some(tcx.crate_hash(LOCAL_CRATE))
+            } else {
+                None
+            },
+            ongoing_codegen,
+        })
+    }
+
+    pub fn link(self, sess: &Session, codegen_backend: &dyn CodegenBackend) -> Result<()> {
+        let (codegen_results, work_products) =
+            codegen_backend.join_codegen(self.ongoing_codegen, sess, &self.output_filenames);
+
+        if let Some(guar) = sess.dcx().has_errors() {
+            return Err(guar);
+        }
+
+        sess.time("serialize_work_products", || {
+            rustc_incremental::save_work_product_index(sess, &self.dep_graph, work_products)
+        });
+
+        let prof = sess.prof.clone();
+        prof.generic_activity("drop_dep_graph").run(move || drop(self.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(sess, self.crate_hash);
+
+        if !sess
+            .opts
+            .output_types
+            .keys()
+            .any(|&i| i == OutputType::Exe || i == OutputType::Metadata)
+        {
+            return Ok(());
+        }
+
+        if sess.opts.unstable_opts.no_link {
+            let rlink_file = self.output_filenames.with_extension(config::RLINK_EXT);
+            CodegenResults::serialize_rlink(
+                sess,
+                &rlink_file,
+                &codegen_results,
+                &*self.output_filenames,
+            )
+            .map_err(|error| {
+                sess.dcx().emit_fatal(FailedWritingFile { path: &rlink_file, error })
+            })?;
+            return Ok(());
+        }
+
+        let _timer = sess.prof.verbose_generic_activity("link_crate");
+        codegen_backend.link(sess, codegen_results, &self.output_filenames)
+    }
+}
+
+impl Compiler {
+    pub fn enter<F, T>(&self, f: F) -> T
+    where
+        F: for<'tcx> FnOnce(&'tcx Queries<'tcx>) -> T,
+    {
+        // Must declare `_timer` first so that it is dropped after `queries`.
+        let _timer;
+        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.gcx.result.borrow_mut() {
+            let gcx = gcx.get_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.compiler.sess.prof.generic_activity("self_profile_alloc_query_strings");
+                gcx.enter(rustc_query_impl::alloc_self_profile_query_strings);
+            }
+
+            self.sess.time("serialize_dep_graph", || gcx.enter(rustc_incremental::save_dep_graph));
+
+            gcx.enter(rustc_query_impl::query_key_hash_verify_all);
+        }
+
+        // The timer's lifetime spans the dropping of `queries`, which contains
+        // the global context.
+        _timer = self.sess.timer("free_global_ctxt");
+        if let Err((path, error)) = queries.finish() {
+            self.sess.dcx().emit_fatal(errors::FailedWritingFile { path: &path, error });
+        }
+
+        ret
+    }
+}