[K/N] Use already dereferenced weakReferee (KT-66371)
And prevent weak barriers from execution during STW
Merge-request: KT-MR-14797
Merged-by: Alexey Glushko <aleksei.glushko@jetbrains.com>diff --git a/kotlin-native/runtime/src/gc/cms/cpp/Barriers.cpp b/kotlin-native/runtime/src/gc/cms/cpp/Barriers.cpp
index 29105fe..df747e4 100644
--- a/kotlin-native/runtime/src/gc/cms/cpp/Barriers.cpp
+++ b/kotlin-native/runtime/src/gc/cms/cpp/Barriers.cpp
@@ -187,13 +187,19 @@
auto phase = currentPhase();
BarriersLogDebug(phase, "Weak read %p", weak);
+ // The weak read protector switches the thread state to native, thus making this code able to execute during STW.
+ // However, this is only possible with the disabled barriers.
+ // Be extra cautious not to access or modify heap structure here. e.g. do not allocate objects
+ AssertThreadState(ThreadState::kNative);
+ RuntimeAssert(!mm::IsThreadSuspensionRequested() || phase == BarriersPhase::kDisabled, "Unexpected barriers phase during STW: %s", toString(phase));
+
if (__builtin_expect(phase == BarriersPhase::kMarkClosure, false)) {
weakRefReadInMarkSlowPath(weak);
} else {
if (__builtin_expect(phase == BarriersPhase::kWeakProcessing, false)) {
// TODO reread the referee here under the barrier guard
// if `disableBarriers` would be possible outside of STW
- return weakRefReadInWeakSweepSlowPath(weakReferee);
+ return weakRefReadInWeakSweepSlowPath(weak);
}
}
return weak;
diff --git a/kotlin-native/runtime/src/gc/cms/cpp/ConcurrentMark.cpp b/kotlin-native/runtime/src/gc/cms/cpp/ConcurrentMark.cpp
index 26e8f09..7754e34 100644
--- a/kotlin-native/runtime/src/gc/cms/cpp/ConcurrentMark.cpp
+++ b/kotlin-native/runtime/src/gc/cms/cpp/ConcurrentMark.cpp
@@ -87,6 +87,9 @@
gc::processWeaks<DefaultProcessWeaksTraits>(gcHandle(), mm::SpecialRefRegistry::instance());
if (!terminateInSTW) {
+ // Mutator threads execute weak barrier in "native" state. This hack maes them stop with the rest of the world.
+ std::unique_lock markTerminationGuard(markTerminationMutex_);
+
stopTheWorld(gcHandle(), "GC stop the world #2: prepare to sweep");
}
