Give deadlock handler access to GlobalCtxt

Author: oli-obk

compiler/rustc_interface/src/interface.rs

@@ -24,6 +24,7 @@ use rustc_span::symbol::sym;
 use rustc_span::FileName;
 use std::path::PathBuf;
 use std::result;
+use std::sync::atomic::AtomicPtr;
 use std::sync::Arc;
 
 pub type Result<T> = result::Result<T, ErrorGuaranteed>;
@@ -39,6 +40,7 @@ pub struct Compiler {
     pub sess: Session,
     pub codegen_backend: Box<dyn CodegenBackend>,
     pub(crate) override_queries: Option<fn(&Session, &mut Providers)>,
+    pub compiler_for_deadlock_handler: Arc<AtomicPtr<()>>,
 }
 
 /// Converts strings provided as `--cfg [cfgspec]` into a `Cfg`.
@@ -328,23 +330,27 @@ pub fn run_compiler<R: Send>(config: Config, f: impl FnOnce(&Compiler) -> R + Se
     let early_dcx = EarlyDiagCtxt::new(config.opts.error_format);
     early_dcx.initialize_checked_jobserver();
 
+    let compiler_for_deadlock_handler = Arc::<AtomicPtr<_>>::default();
+
     util::run_in_thread_pool_with_globals(
         config.opts.edition,
         config.opts.unstable_opts.threads,
+        compiler_for_deadlock_handler.clone(),
         || {
             crate::callbacks::setup_callbacks();
 
             let early_dcx = EarlyDiagCtxt::new(config.opts.error_format);
 
-            let codegen_backend = if let Some(make_codegen_backend) = config.make_codegen_backend {
-                make_codegen_backend(&config.opts)
-            } else {
-                util::get_codegen_backend(
-                    &early_dcx,
-                    &config.opts.maybe_sysroot,
-                    config.opts.unstable_opts.codegen_backend.as_deref(),
-                )
-            };
+            let codegen_backend: Box<dyn CodegenBackend> =
+                if let Some(make_codegen_backend) = config.make_codegen_backend {
+                    make_codegen_backend(&config.opts)
+                } else {
+                    util::get_codegen_backend(
+                        &early_dcx,
+                        &config.opts.maybe_sysroot,
+                        config.opts.unstable_opts.codegen_backend.as_deref(),
+                    )
+                };
 
             let temps_dir = config.opts.unstable_opts.temps_dir.as_deref().map(PathBuf::from);
 
@@ -419,8 +425,12 @@ pub fn run_compiler<R: Send>(config: Config, f: impl FnOnce(&Compiler) -> R + Se
             }
             sess.lint_store = Some(Lrc::new(lint_store));
 
-            let compiler =
-                Compiler { sess, codegen_backend, override_queries: config.override_queries };
+            let compiler = Arc::new(Compiler {
+                sess,
+                codegen_backend,
+                override_queries: config.override_queries,
+                compiler_for_deadlock_handler,
+            });
 
             rustc_span::set_source_map(compiler.sess.parse_sess.clone_source_map(), move || {
                 // There are two paths out of `f`.

compiler/rustc_interface/src/queries.rs

@@ -24,6 +24,7 @@ use rustc_session::Session;
 use rustc_span::symbol::sym;
 use std::any::Any;
 use std::cell::{RefCell, RefMut};
+use std::sync::atomic::Ordering;
 use std::sync::Arc;
 
 /// Represent the result of a query.
@@ -160,6 +161,10 @@ impl<'tcx> Queries<'tcx> {
                 &self.hir_arena,
             );
 
+            self.compiler
+                .compiler_for_deadlock_handler
+                .store(qcx as *const _ as *mut _, Ordering::Relaxed);
+
             qcx.enter(|tcx| {
                 let feed = tcx.feed_local_crate();
                 feed.crate_name(crate_name);
@@ -311,6 +316,11 @@ impl Compiler {
     {
         // Must declare `_timer` first so that it is dropped after `queries`.
         let mut _timer = None;
+        let _guard = rustc_data_structures::defer(|| {
+            // If we got here, there was no deadlock, so we can't be in a situation where a deadlock handler
+            // is accessing the `GlobalCtxt`.
+            self.compiler_for_deadlock_handler.store(std::ptr::null_mut(), Ordering::Relaxed);
+        });
         let queries = Queries::new(self);
         let ret = f(&queries);
 

compiler/rustc_interface/src/util.rs

@@ -18,8 +18,8 @@ use session::EarlyDiagCtxt;
 use std::env;
 use std::env::consts::{DLL_PREFIX, DLL_SUFFIX};
 use std::path::{Path, PathBuf};
-use std::sync::atomic::{AtomicBool, Ordering};
-use std::sync::OnceLock;
+use std::sync::atomic::{AtomicBool, AtomicPtr, Ordering};
+use std::sync::{Arc, OnceLock};
 use std::thread;
 
 /// Function pointer type that constructs a new CodegenBackend.
@@ -90,6 +90,7 @@ pub(crate) fn run_in_thread_with_globals<F: FnOnce() -> R + Send, R: Send>(
 pub(crate) fn run_in_thread_pool_with_globals<F: FnOnce() -> R + Send, R: Send>(
     edition: Edition,
     _threads: usize,
+    _compiler: Arc<AtomicPtr<()>>,
     f: F,
 ) -> R {
     run_in_thread_with_globals(edition, f)
@@ -99,10 +100,11 @@ pub(crate) fn run_in_thread_pool_with_globals<F: FnOnce() -> R + Send, R: Send>(
 pub(crate) fn run_in_thread_pool_with_globals<F: FnOnce() -> R + Send, R: Send>(
     edition: Edition,
     threads: usize,
+    compiler: Arc<AtomicPtr<()>>,
     f: F,
 ) -> R {
     use rustc_data_structures::{jobserver, sync::FromDyn};
-    use rustc_middle::ty::tls;
+    use rustc_middle::ty::GlobalCtxt;
     use rustc_query_impl::QueryCtxt;
     use rustc_query_system::query::{deadlock, QueryContext};
 
@@ -122,11 +124,15 @@ pub(crate) fn run_in_thread_pool_with_globals<F: FnOnce() -> R + Send, R: Send>(
         .acquire_thread_handler(jobserver::acquire_thread)
         .release_thread_handler(jobserver::release_thread)
         .num_threads(threads)
-        .deadlock_handler(|| {
+        .deadlock_handler(move || {
+            let compiler = compiler.load(Ordering::Relaxed);
+            assert!(!compiler.is_null());
+            let compiler = compiler as *const GlobalCtxt<'_>;
             // On deadlock, creates a new thread and forwards information in thread
             // locals to it. The new thread runs the deadlock handler.
-            let query_map =
-                FromDyn::from(tls::with(|tcx| QueryCtxt::new(tcx).collect_active_jobs()));
+            let query_map = FromDyn::from(unsafe {
+                (*compiler).enter(|tcx| QueryCtxt::new(tcx).collect_active_jobs())
+            });
             let registry = rayon_core::Registry::current();
             thread::spawn(move || deadlock(query_map.into_inner(), &registry));
         });