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8371284: GenShen: Avoid unnecessary card marking #28204

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8371284: GenShen: Avoid unnecessary card marking #28204

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47612c0
exclude young-yong, old-old and honor UseCondCardMark in dirty card m…
Nov 7, 2025
fac569b
Merge branch 'openjdk:master' into 8371284
nityarai08 Nov 7, 2025
154a509
minor cleanup
Nov 7, 2025
09ad25a
clean whitespace
Nov 7, 2025
59f7a0d
early return of oop is null
Nov 7, 2025
1c85da7
Apply suggestions from code review
nityarai08 Nov 10, 2025
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21 changes: 20 additions & 1 deletion src/hotspot/share/gc/shenandoah/shenandoahBarrierSet.inline.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -191,8 +191,27 @@ inline void ShenandoahBarrierSet::keep_alive_if_weak(DecoratorSet decorators, oo
template <DecoratorSet decorators, typename T>
inline void ShenandoahBarrierSet::write_ref_field_post(T* field) {
assert(ShenandoahCardBarrier, "Should have been checked by caller");
if (_heap->is_in_young(field)) {
// Young field stores do not require card mark.
return;
}
T heap_oop = RawAccess<>::oop_load(field);
if (CompressedOops::is_null(heap_oop)) {
return;
}
oop obj = CompressedOops::decode_not_null(heap_oop);
if (!_heap->is_in_young(obj)) {
// Young object -> old field stores do not require card mark.
return;
}
volatile CardTable::CardValue* byte = card_table()->byte_for(field);
*byte = CardTable::dirty_card_val();
if (UseCondCardMark) {
if (*byte != CardTable::dirty_card_val()) {
*byte = CardTable::dirty_card_val();
}
} else {
*byte = CardTable::dirty_card_val();
}
}

template <typename T>
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