1 //! Implements threads.
3 use std::cell::RefCell;
4 use std::collections::hash_map::Entry;
5 use std::convert::TryFrom;
7 use std::num::TryFromIntError;
8 use std::time::{Duration, Instant, SystemTime};
12 use rustc_data_structures::fx::FxHashMap;
13 use rustc_hir::def_id::DefId;
14 use rustc_index::vec::{Idx, IndexVec};
16 use crate::sync::SynchronizationState;
19 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
20 pub enum SchedulingAction {
21 /// Execute step on the active thread.
23 /// Execute a timeout callback.
24 ExecuteTimeoutCallback,
25 /// Execute destructors of the active thread.
31 /// Timeout callbacks can be created by synchronization primitives to tell the
32 /// scheduler that they should be called once some period of time passes.
33 type TimeoutCallback<'mir, 'tcx> =
34 Box<dyn FnOnce(&mut InterpCx<'mir, 'tcx, Evaluator<'mir, 'tcx>>) -> InterpResult<'tcx> + 'tcx>;
36 /// A thread identifier.
37 #[derive(Clone, Copy, Debug, PartialOrd, Ord, PartialEq, Eq, Hash)]
38 pub struct ThreadId(u32);
40 /// The main thread. When it terminates, the whole application terminates.
41 const MAIN_THREAD: ThreadId = ThreadId(0);
44 pub fn to_u32(self) -> u32 {
49 impl Idx for ThreadId {
50 fn new(idx: usize) -> Self {
51 ThreadId(u32::try_from(idx).unwrap())
54 fn index(self) -> usize {
55 usize::try_from(self.0).unwrap()
59 impl TryFrom<u64> for ThreadId {
60 type Error = TryFromIntError;
61 fn try_from(id: u64) -> Result<Self, Self::Error> {
62 u32::try_from(id).map(|id_u32| Self(id_u32))
66 impl From<u32> for ThreadId {
67 fn from(id: u32) -> Self {
73 pub fn to_u32_scalar<'tcx>(&self) -> Scalar<Tag> {
74 Scalar::from_u32(u32::try_from(self.0).unwrap())
78 /// The state of a thread.
79 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
80 pub enum ThreadState {
81 /// The thread is enabled and can be executed.
83 /// The thread tried to join the specified thread and is blocked until that
84 /// thread terminates.
85 BlockedOnJoin(ThreadId),
86 /// The thread is blocked on some synchronization primitive. It is the
87 /// responsibility of the synchronization primitives to track threads that
88 /// are blocked by them.
90 /// The thread has terminated its execution. We do not delete terminated
91 /// threads (FIXME: why?).
95 /// The join status of a thread.
96 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
97 enum ThreadJoinStatus {
98 /// The thread can be joined.
100 /// A thread is detached if its join handle was destroyed and no other
101 /// thread can join it.
103 /// The thread was already joined by some thread and cannot be joined again.
108 pub struct Thread<'mir, 'tcx> {
111 /// Name of the thread.
112 thread_name: Option<Vec<u8>>,
114 /// The virtual call stack.
115 stack: Vec<Frame<'mir, 'tcx, Tag, FrameData<'tcx>>>,
118 join_status: ThreadJoinStatus,
120 /// The temporary used for storing the argument of
121 /// the call to `miri_start_panic` (the panic payload) when unwinding.
122 /// This is pointer-sized, and matches the `Payload` type in `src/libpanic_unwind/miri.rs`.
123 pub(crate) panic_payload: Option<Scalar<Tag>>,
125 /// Last OS error location in memory. It is a 32-bit integer.
126 pub(crate) last_error: Option<MPlaceTy<'tcx, Tag>>,
129 impl<'mir, 'tcx> Thread<'mir, 'tcx> {
130 /// Check if the thread is done executing (no more stack frames). If yes,
131 /// change the state to terminated and return `true`.
132 fn check_terminated(&mut self) -> bool {
133 if self.state == ThreadState::Enabled {
134 if self.stack.is_empty() {
135 self.state = ThreadState::Terminated;
142 /// Get the name of the current thread, or `<unnamed>` if it was not set.
143 fn thread_name(&self) -> &[u8] {
144 if let Some(ref thread_name) = self.thread_name {
152 impl<'mir, 'tcx> std::fmt::Debug for Thread<'mir, 'tcx> {
153 fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
154 write!(f, "{}({:?}, {:?})", String::from_utf8_lossy(self.thread_name()), self.state, self.join_status)
158 impl<'mir, 'tcx> Default for Thread<'mir, 'tcx> {
159 fn default() -> Self {
161 state: ThreadState::Enabled,
164 join_status: ThreadJoinStatus::Joinable,
171 /// A specific moment in time.
175 RealTime(SystemTime),
179 /// How long do we have to wait from now until the specified time?
180 fn get_wait_time(&self) -> Duration {
182 Time::Monotonic(instant) => instant.saturating_duration_since(Instant::now()),
183 Time::RealTime(time) =>
184 time.duration_since(SystemTime::now()).unwrap_or(Duration::new(0, 0)),
189 /// Callbacks are used to implement timeouts. For example, waiting on a
190 /// conditional variable with a timeout creates a callback that is called after
191 /// the specified time and unblocks the thread. If another thread signals on the
192 /// conditional variable, the signal handler deletes the callback.
193 struct TimeoutCallbackInfo<'mir, 'tcx> {
194 /// The callback should be called no earlier than this time.
196 /// The called function.
197 callback: TimeoutCallback<'mir, 'tcx>,
200 impl<'mir, 'tcx> std::fmt::Debug for TimeoutCallbackInfo<'mir, 'tcx> {
201 fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
202 write!(f, "TimeoutCallback({:?})", self.call_time)
206 /// A set of threads.
208 pub struct ThreadManager<'mir, 'tcx> {
209 /// Identifier of the currently active thread.
210 active_thread: ThreadId,
211 /// Threads used in the program.
213 /// Note that this vector also contains terminated threads.
214 threads: IndexVec<ThreadId, Thread<'mir, 'tcx>>,
215 /// This field is pub(crate) because the synchronization primitives
216 /// (`crate::sync`) need a way to access it.
217 pub(crate) sync: SynchronizationState,
218 /// A mapping from a thread-local static to an allocation id of a thread
219 /// specific allocation.
220 thread_local_alloc_ids: RefCell<FxHashMap<(DefId, ThreadId), AllocId>>,
221 /// A flag that indicates that we should change the active thread.
222 yield_active_thread: bool,
223 /// Callbacks that are called once the specified time passes.
224 timeout_callbacks: FxHashMap<ThreadId, TimeoutCallbackInfo<'mir, 'tcx>>,
227 impl<'mir, 'tcx> Default for ThreadManager<'mir, 'tcx> {
228 fn default() -> Self {
229 let mut threads = IndexVec::new();
230 // Create the main thread and add it to the list of threads.
231 let mut main_thread = Thread::default();
232 // The main thread can *not* be joined on.
233 main_thread.join_status = ThreadJoinStatus::Detached;
234 threads.push(main_thread);
236 active_thread: ThreadId::new(0),
238 sync: SynchronizationState::default(),
239 thread_local_alloc_ids: Default::default(),
240 yield_active_thread: false,
241 timeout_callbacks: FxHashMap::default(),
246 impl<'mir, 'tcx: 'mir> ThreadManager<'mir, 'tcx> {
247 /// Check if we have an allocation for the given thread local static for the
249 fn get_thread_local_alloc_id(&self, def_id: DefId) -> Option<AllocId> {
250 self.thread_local_alloc_ids.borrow().get(&(def_id, self.active_thread)).cloned()
253 /// Set the allocation id as the allocation id of the given thread local
254 /// static for the active thread.
256 /// Panics if a thread local is initialized twice for the same thread.
257 fn set_thread_local_alloc_id(&self, def_id: DefId, new_alloc_id: AllocId) {
258 self.thread_local_alloc_ids
260 .insert((def_id, self.active_thread), new_alloc_id)
264 /// Borrow the stack of the active thread.
265 fn active_thread_stack(&self) -> &[Frame<'mir, 'tcx, Tag, FrameData<'tcx>>] {
266 &self.threads[self.active_thread].stack
269 /// Mutably borrow the stack of the active thread.
270 fn active_thread_stack_mut(&mut self) -> &mut Vec<Frame<'mir, 'tcx, Tag, FrameData<'tcx>>> {
271 &mut self.threads[self.active_thread].stack
274 /// Create a new thread and returns its id.
275 fn create_thread(&mut self) -> ThreadId {
276 let new_thread_id = ThreadId::new(self.threads.len());
277 self.threads.push(Default::default());
281 /// Set an active thread and return the id of the thread that was active before.
282 fn set_active_thread_id(&mut self, id: ThreadId) -> ThreadId {
283 let active_thread_id = self.active_thread;
284 self.active_thread = id;
285 assert!(self.active_thread.index() < self.threads.len());
289 /// Get the id of the currently active thread.
290 fn get_active_thread_id(&self) -> ThreadId {
294 /// Get the total number of threads that were ever spawn by this program.
295 fn get_total_thread_count(&self) -> usize {
299 /// Has the given thread terminated?
300 fn has_terminated(&self, thread_id: ThreadId) -> bool {
301 self.threads[thread_id].state == ThreadState::Terminated
304 /// Enable the thread for execution. The thread must be terminated.
305 fn enable_thread(&mut self, thread_id: ThreadId) {
306 assert!(self.has_terminated(thread_id));
307 self.threads[thread_id].state = ThreadState::Enabled;
310 /// Get a mutable borrow of the currently active thread.
311 fn active_thread_mut(&mut self) -> &mut Thread<'mir, 'tcx> {
312 &mut self.threads[self.active_thread]
315 /// Get a shared borrow of the currently active thread.
316 fn active_thread_ref(&self) -> &Thread<'mir, 'tcx> {
317 &self.threads[self.active_thread]
320 /// Mark the thread as detached, which means that no other thread will try
321 /// to join it and the thread is responsible for cleaning up.
322 fn detach_thread(&mut self, id: ThreadId) -> InterpResult<'tcx> {
323 if self.threads[id].join_status != ThreadJoinStatus::Joinable {
324 throw_ub_format!("trying to detach thread that was already detached or joined");
326 self.threads[id].join_status = ThreadJoinStatus::Detached;
330 /// Mark that the active thread tries to join the thread with `joined_thread_id`.
331 fn join_thread(&mut self, joined_thread_id: ThreadId, data_race: &Option<Rc<data_race::GlobalState>>) -> InterpResult<'tcx> {
332 if self.threads[joined_thread_id].join_status != ThreadJoinStatus::Joinable {
333 throw_ub_format!("trying to join a detached or already joined thread");
335 if joined_thread_id == self.active_thread {
336 throw_ub_format!("trying to join itself");
341 .all(|thread| thread.state != ThreadState::BlockedOnJoin(joined_thread_id)),
342 "a joinable thread already has threads waiting for its termination"
344 // Mark the joined thread as being joined so that we detect if other
345 // threads try to join it.
346 self.threads[joined_thread_id].join_status = ThreadJoinStatus::Joined;
347 if self.threads[joined_thread_id].state != ThreadState::Terminated {
348 // The joined thread is still running, we need to wait for it.
349 self.active_thread_mut().state = ThreadState::BlockedOnJoin(joined_thread_id);
351 "{:?} blocked on {:?} when trying to join",
356 // The thread has already terminated - mark join happens-before
357 if let Some(data_race) = data_race {
358 data_race.thread_joined(self.active_thread, joined_thread_id);
364 /// Set the name of the active thread.
365 fn set_thread_name(&mut self, new_thread_name: Vec<u8>) {
366 self.active_thread_mut().thread_name = Some(new_thread_name);
369 /// Get the name of the active thread.
370 fn get_thread_name(&self) -> &[u8] {
371 self.active_thread_ref().thread_name()
374 /// Put the thread into the blocked state.
375 fn block_thread(&mut self, thread: ThreadId) {
376 let state = &mut self.threads[thread].state;
377 assert_eq!(*state, ThreadState::Enabled);
378 *state = ThreadState::BlockedOnSync;
381 /// Put the blocked thread into the enabled state.
382 fn unblock_thread(&mut self, thread: ThreadId) {
383 let state = &mut self.threads[thread].state;
384 assert_eq!(*state, ThreadState::BlockedOnSync);
385 *state = ThreadState::Enabled;
388 /// Change the active thread to some enabled thread.
389 fn yield_active_thread(&mut self) {
390 // We do not yield immediately, as swapping out the current stack while executing a MIR statement
391 // could lead to all sorts of confusion.
392 // We should only switch stacks between steps.
393 self.yield_active_thread = true;
396 /// Register the given `callback` to be called once the `call_time` passes.
398 /// The callback will be called with `thread` being the active thread, and
399 /// the callback may not change the active thread.
400 fn register_timeout_callback(
404 callback: TimeoutCallback<'mir, 'tcx>,
406 self.timeout_callbacks
407 .insert(thread, TimeoutCallbackInfo { call_time, callback })
411 /// Unregister the callback for the `thread`.
412 fn unregister_timeout_callback_if_exists(&mut self, thread: ThreadId) {
413 self.timeout_callbacks.remove(&thread);
416 /// Get a callback that is ready to be called.
417 fn get_ready_callback(&mut self) -> Option<(ThreadId, TimeoutCallback<'mir, 'tcx>)> {
418 // We iterate over all threads in the order of their indices because
419 // this allows us to have a deterministic scheduler.
420 for thread in self.threads.indices() {
421 match self.timeout_callbacks.entry(thread) {
422 Entry::Occupied(entry) =>
423 if entry.get().call_time.get_wait_time() == Duration::new(0, 0) {
424 return Some((thread, entry.remove().callback));
426 Entry::Vacant(_) => {}
432 /// Wakes up threads joining on the active one and deallocates thread-local statics.
433 /// The `AllocId` that can now be freed is returned.
434 fn thread_terminated(&mut self, data_race: &Option<Rc<data_race::GlobalState>>) -> Vec<AllocId> {
435 let mut free_tls_statics = Vec::new();
437 let mut thread_local_statics = self.thread_local_alloc_ids.borrow_mut();
438 thread_local_statics.retain(|&(_def_id, thread), &mut alloc_id| {
439 if thread != self.active_thread {
440 // Keep this static around.
443 // Delete this static from the map and from memory.
444 // We cannot free directly here as we cannot use `?` in this context.
445 free_tls_statics.push(alloc_id);
449 // Set the thread into a terminated state in the data-race detector
450 if let Some(data_race) = data_race {
451 data_race.thread_terminated();
453 // Check if we need to unblock any threads.
454 for (i, thread) in self.threads.iter_enumerated_mut() {
455 if thread.state == ThreadState::BlockedOnJoin(self.active_thread) {
456 // The thread has terminated, mark happens-before edge to joining thread
457 if let Some(data_race) = data_race {
458 data_race.thread_joined(i, self.active_thread);
460 trace!("unblocking {:?} because {:?} terminated", i, self.active_thread);
461 thread.state = ThreadState::Enabled;
464 return free_tls_statics;
467 /// Decide which action to take next and on which thread.
469 /// The currently implemented scheduling policy is the one that is commonly
470 /// used in stateless model checkers such as Loom: run the active thread as
471 /// long as we can and switch only when we have to (the active thread was
472 /// blocked, terminated, or has explicitly asked to be preempted).
473 fn schedule(&mut self, data_race: &Option<Rc<data_race::GlobalState>>) -> InterpResult<'tcx, SchedulingAction> {
474 // Check whether the thread has **just** terminated (`check_terminated`
475 // checks whether the thread has popped all its stack and if yes, sets
476 // the thread state to terminated).
477 if self.threads[self.active_thread].check_terminated() {
478 return Ok(SchedulingAction::ExecuteDtors);
480 if self.threads[MAIN_THREAD].state == ThreadState::Terminated {
481 // The main thread terminated; stop the program.
482 if self.threads.iter().any(|thread| thread.state != ThreadState::Terminated) {
483 // FIXME: This check should be either configurable or just emit
484 // a warning. For example, it seems normal for a program to
485 // terminate without waiting for its detached threads to
486 // terminate. However, this case is not trivial to support
487 // because we also probably do not want to consider the memory
488 // owned by these threads as leaked.
489 throw_unsup_format!("the main thread terminated without waiting for other threads");
491 return Ok(SchedulingAction::Stop);
493 // At least for `pthread_cond_timedwait` we need to report timeout when
494 // the function is called already after the specified time even if a
495 // signal is received before the thread gets scheduled. Therefore, we
496 // need to schedule all timeout callbacks before we continue regular
500 // https://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_cond_timedwait.html#
501 let potential_sleep_time =
502 self.timeout_callbacks.values().map(|info| info.call_time.get_wait_time()).min();
503 if potential_sleep_time == Some(Duration::new(0, 0)) {
504 return Ok(SchedulingAction::ExecuteTimeoutCallback);
506 // No callbacks scheduled, pick a regular thread to execute.
507 if self.threads[self.active_thread].state == ThreadState::Enabled
508 && !self.yield_active_thread
510 // The currently active thread is still enabled, just continue with it.
511 return Ok(SchedulingAction::ExecuteStep);
513 // We need to pick a new thread for execution.
514 for (id, thread) in self.threads.iter_enumerated() {
515 if thread.state == ThreadState::Enabled {
516 if !self.yield_active_thread || id != self.active_thread {
517 self.active_thread = id;
518 if let Some(data_race) = data_race {
519 data_race.thread_set_active(self.active_thread);
525 self.yield_active_thread = false;
526 if self.threads[self.active_thread].state == ThreadState::Enabled {
527 return Ok(SchedulingAction::ExecuteStep);
529 // We have not found a thread to execute.
530 if self.threads.iter().all(|thread| thread.state == ThreadState::Terminated) {
531 unreachable!("all threads terminated without the main thread terminating?!");
532 } else if let Some(sleep_time) = potential_sleep_time {
533 // All threads are currently blocked, but we have unexecuted
534 // timeout_callbacks, which may unblock some of the threads. Hence,
535 // sleep until the first callback.
536 std::thread::sleep(sleep_time);
537 Ok(SchedulingAction::ExecuteTimeoutCallback)
539 throw_machine_stop!(TerminationInfo::Deadlock);
544 // Public interface to thread management.
545 impl<'mir, 'tcx: 'mir> EvalContextExt<'mir, 'tcx> for crate::MiriEvalContext<'mir, 'tcx> {}
546 pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx> {
547 /// Get a thread-specific allocation id for the given thread-local static.
548 /// If needed, allocate a new one.
549 fn get_or_create_thread_local_alloc_id(&mut self, def_id: DefId) -> InterpResult<'tcx, AllocId> {
550 let this = self.eval_context_mut();
552 if let Some(new_alloc_id) = this.machine.threads.get_thread_local_alloc_id(def_id) {
553 // We already have a thread-specific allocation id for this
554 // thread-local static.
557 // We need to allocate a thread-specific allocation id for this
558 // thread-local static.
559 // First, we compute the initial value for this static.
560 if tcx.is_foreign_item(def_id) {
561 throw_unsup_format!("foreign thread-local statics are not supported");
563 let allocation = tcx.eval_static_initializer(def_id)?;
564 // Create a fresh allocation with this content.
565 let new_alloc_id = this.memory.allocate_with(allocation.clone(), MiriMemoryKind::Tls.into()).alloc_id;
566 this.machine.threads.set_thread_local_alloc_id(def_id, new_alloc_id);
572 fn create_thread(&mut self) -> ThreadId {
573 let this = self.eval_context_mut();
574 let id = this.machine.threads.create_thread();
575 if let Some(data_race) = &this.memory.extra.data_race {
576 data_race.thread_created(id);
582 fn detach_thread(&mut self, thread_id: ThreadId) -> InterpResult<'tcx> {
583 let this = self.eval_context_mut();
584 this.machine.threads.detach_thread(thread_id)
588 fn join_thread(&mut self, joined_thread_id: ThreadId) -> InterpResult<'tcx> {
589 let this = self.eval_context_mut();
590 let data_race = &this.memory.extra.data_race;
591 this.machine.threads.join_thread(joined_thread_id, data_race)?;
596 fn set_active_thread(&mut self, thread_id: ThreadId) -> ThreadId {
597 let this = self.eval_context_mut();
598 if let Some(data_race) = &this.memory.extra.data_race {
599 data_race.thread_set_active(thread_id);
601 this.machine.threads.set_active_thread_id(thread_id)
605 fn get_active_thread(&self) -> ThreadId {
606 let this = self.eval_context_ref();
607 this.machine.threads.get_active_thread_id()
611 fn active_thread_mut(&mut self) -> &mut Thread<'mir, 'tcx> {
612 let this = self.eval_context_mut();
613 this.machine.threads.active_thread_mut()
617 fn active_thread_ref(&self) -> &Thread<'mir, 'tcx> {
618 let this = self.eval_context_ref();
619 this.machine.threads.active_thread_ref()
623 fn get_total_thread_count(&self) -> usize {
624 let this = self.eval_context_ref();
625 this.machine.threads.get_total_thread_count()
629 fn has_terminated(&self, thread_id: ThreadId) -> bool {
630 let this = self.eval_context_ref();
631 this.machine.threads.has_terminated(thread_id)
635 fn enable_thread(&mut self, thread_id: ThreadId) {
636 let this = self.eval_context_mut();
637 this.machine.threads.enable_thread(thread_id);
641 fn active_thread_stack(&self) -> &[Frame<'mir, 'tcx, Tag, FrameData<'tcx>>] {
642 let this = self.eval_context_ref();
643 this.machine.threads.active_thread_stack()
647 fn active_thread_stack_mut(&mut self) -> &mut Vec<Frame<'mir, 'tcx, Tag, FrameData<'tcx>>> {
648 let this = self.eval_context_mut();
649 this.machine.threads.active_thread_stack_mut()
653 fn set_active_thread_name(&mut self, new_thread_name: Vec<u8>) {
654 let this = self.eval_context_mut();
655 if let Some(data_race) = &this.memory.extra.data_race {
656 if let Ok(string) = String::from_utf8(new_thread_name.clone()) {
657 data_race.thread_set_name(
658 this.machine.threads.active_thread, string
662 this.machine.threads.set_thread_name(new_thread_name);
666 fn get_active_thread_name<'c>(&'c self) -> &'c [u8]
670 let this = self.eval_context_ref();
671 this.machine.threads.get_thread_name()
675 fn block_thread(&mut self, thread: ThreadId) {
676 let this = self.eval_context_mut();
677 this.machine.threads.block_thread(thread);
681 fn unblock_thread(&mut self, thread: ThreadId) {
682 let this = self.eval_context_mut();
683 this.machine.threads.unblock_thread(thread);
687 fn yield_active_thread(&mut self) {
688 let this = self.eval_context_mut();
689 this.machine.threads.yield_active_thread();
693 fn register_timeout_callback(
697 callback: TimeoutCallback<'mir, 'tcx>,
699 let this = self.eval_context_mut();
700 this.machine.threads.register_timeout_callback(thread, call_time, callback);
704 fn unregister_timeout_callback_if_exists(&mut self, thread: ThreadId) {
705 let this = self.eval_context_mut();
706 this.machine.threads.unregister_timeout_callback_if_exists(thread);
709 /// Execute a timeout callback on the callback's thread.
711 fn run_timeout_callback(&mut self) -> InterpResult<'tcx> {
712 let this = self.eval_context_mut();
713 let (thread, callback) =
714 this.machine.threads.get_ready_callback().expect("no callback found");
715 // This back-and-forth with `set_active_thread` is here because of two
717 // 1. Make the caller and not the callback responsible for changing
719 // 2. Make the scheduler the only place that can change the active
721 let old_thread = this.set_active_thread(thread);
723 this.set_active_thread(old_thread);
727 /// Decide which action to take next and on which thread.
729 fn schedule(&mut self) -> InterpResult<'tcx, SchedulingAction> {
730 let this = self.eval_context_mut();
731 let data_race = &this.memory.extra.data_race;
732 this.machine.threads.schedule(data_race)
735 /// Handles thread termination of the active thread: wakes up threads joining on this one,
736 /// and deallocated thread-local statics.
738 /// This is called from `tls.rs` after handling the TLS dtors.
740 fn thread_terminated(&mut self) -> InterpResult<'tcx> {
741 let this = self.eval_context_mut();
742 let data_race = &this.memory.extra.data_race;
743 for alloc_id in this.machine.threads.thread_terminated(data_race) {
744 let ptr = this.memory.global_base_pointer(alloc_id.into())?;
745 this.memory.deallocate(ptr, None, MiriMemoryKind::Tls.into())?;