Auto merge of rust-lang#98570 - SparrowLii:deadlock, r=cjgillot

get rid of `tcx` in deadlock handler when parallel compilation

This is a very obscure and hard-to-trace problem that affects thread scheduling. If we copy `tcx` to the deadlock handler thread, it will perform unpredictable behavior and cause very weird problems when executing `try_collect_active_jobs`(For example, the deadlock handler thread suddenly preempts the content of the blocked worker thread and executes the unknown judgment branch, like rust-lang#94654).
Fortunately we can avoid this behavior by precomputing `query_map`. This change fixes the following ui tests failure on my environment when set `parallel-compiler = true`:
```
    [ui] src/test\ui\async-await\no-const-async.rs
    [ui] src/test\ui\infinite\infinite-struct.rs
    [ui] src/test\ui\infinite\infinite-tag-type-recursion.rs
    [ui] src/test\ui\issues\issue-3008-1.rs
    [ui] src/test\ui\issues\issue-3008-2.rs
    [ui] src/test\ui\issues\issue-32326.rs
    [ui] src/test\ui\issues\issue-57271.rs
    [ui] src/test\ui\issues\issue-72554.rs
    [ui] src/test\ui\parser\fn-header-semantic-fail.rs
    [ui] src/test\ui\union\union-nonrepresentable.rs
```

Updates rust-lang#75760
Fixes rust-lang#94654

Author: bors

compiler/rustc_interface/src/util.rs

@@ -10,7 +10,7 @@ use rustc_errors::registry::Registry;
 use rustc_middle::ty::tls;
 use rustc_parse::validate_attr;
 #[cfg(parallel_compiler)]
-use rustc_query_impl::QueryCtxt;
+use rustc_query_impl::{QueryContext, QueryCtxt};
 use rustc_session as session;
 use rustc_session::config::CheckCfg;
 use rustc_session::config::{self, CrateType};
@@ -166,20 +166,12 @@ pub fn run_in_thread_pool_with_globals<F: FnOnce() -> R + Send, R: Send>(
 unsafe fn handle_deadlock() {
     let registry = rustc_rayon_core::Registry::current();
 
-    let context = tls::get_tlv();
-    assert!(context != 0);
-    rustc_data_structures::sync::assert_sync::<tls::ImplicitCtxt<'_, '_>>();
-    let icx: &tls::ImplicitCtxt<'_, '_> = &*(context as *const tls::ImplicitCtxt<'_, '_>);
-
-    let session_globals = rustc_span::with_session_globals(|sg| sg as *const _);
-    let session_globals = &*session_globals;
-    thread::spawn(move || {
-        tls::enter_context(icx, |_| {
-            rustc_span::set_session_globals_then(session_globals, || {
-                tls::with(|tcx| QueryCtxt::from_tcx(tcx).deadlock(&registry))
-            })
-        });
+    let query_map = tls::with(|tcx| {
+        QueryCtxt::from_tcx(tcx)
+            .try_collect_active_jobs()
+            .expect("active jobs shouldn't be locked in deadlock handler")
     });
+    thread::spawn(move || rustc_query_impl::deadlock(query_map, &registry));
 }
 
 #[cfg(parallel_compiler)]

compiler/rustc_query_impl/src/lib.rs

@@ -27,6 +27,8 @@ use rustc_span::Span;
 mod plumbing;
 pub use plumbing::QueryCtxt;
 use rustc_query_system::query::*;
+#[cfg(parallel_compiler)]
+pub use rustc_query_system::query::{deadlock, QueryContext};
 
 mod keys;
 use keys::Key;

compiler/rustc_query_impl/src/plumbing.rs

@@ -132,11 +132,6 @@ impl<'tcx> QueryCtxt<'tcx> {
         self.queries.on_disk_cache.as_ref()
     }
 
-    #[cfg(parallel_compiler)]
-    pub unsafe fn deadlock(self, registry: &rustc_rayon_core::Registry) {
-        rustc_query_system::query::deadlock(self, registry)
-    }
-
     pub(super) fn encode_query_results(
         self,
         encoder: &mut on_disk_cache::CacheEncoder<'_, 'tcx>,

compiler/rustc_query_system/src/query/job.rs

@@ -492,14 +492,13 @@ fn remove_cycle(
 /// There may be multiple cycles involved in a deadlock, so this searches
 /// all active queries for cycles before finally resuming all the waiters at once.
 #[cfg(parallel_compiler)]
-pub fn deadlock<CTX: QueryContext>(tcx: CTX, registry: &rayon_core::Registry) {
+pub fn deadlock(query_map: QueryMap, registry: &rayon_core::Registry) {
     let on_panic = OnDrop(|| {
         eprintln!("deadlock handler panicked, aborting process");
         process::abort();
     });
 
     let mut wakelist = Vec::new();
-    let query_map = tcx.try_collect_active_jobs().unwrap();
     let mut jobs: Vec<QueryJobId> = query_map.keys().cloned().collect();
 
     let mut found_cycle = false;