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8212184: Incorrect oop ref strength used for referents in FinalReference

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Reviewed-by: eosterlund, kbarrett
This commit is contained in:
Per Lidén 2018-11-02 07:58:22 +01:00
parent ca91f514d8
commit 54d4acf73f
3 changed files with 13 additions and 1 deletions
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1
src/hotspot/share/classfile/javaClasses.hpp
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@ -912,6 +912,7 @@ class java_lang_ref_Reference: AllStatic {
static inline oop queue(oop ref); static inline oop queue(oop ref);
static inline void set_queue(oop ref, oop value); static inline void set_queue(oop ref, oop value);
static bool is_referent_field(oop obj, ptrdiff_t offset); static bool is_referent_field(oop obj, ptrdiff_t offset);
static inline bool is_final(oop ref);
static inline bool is_phantom(oop ref); static inline bool is_phantom(oop ref);
}; };

3
src/hotspot/share/classfile/javaClasses.inline.hpp
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@ -127,6 +127,9 @@ void java_lang_ref_Reference::set_discovered_raw(oop ref, oop value) {
HeapWord* java_lang_ref_Reference::discovered_addr_raw(oop ref) { HeapWord* java_lang_ref_Reference::discovered_addr_raw(oop ref) {
return ref->obj_field_addr_raw<HeapWord>(discovered_offset); return ref->obj_field_addr_raw<HeapWord>(discovered_offset);
} }
bool java_lang_ref_Reference::is_final(oop ref) {
return InstanceKlass::cast(ref->klass())->reference_type() == REF_FINAL;
}
bool java_lang_ref_Reference::is_phantom(oop ref) { bool java_lang_ref_Reference::is_phantom(oop ref) {
return InstanceKlass::cast(ref->klass())->reference_type() == REF_PHANTOM; return InstanceKlass::cast(ref->klass())->reference_type() == REF_PHANTOM;
} }

10
src/hotspot/share/gc/shared/accessBarrierSupport.cpp
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@ -28,8 +28,16 @@
#include "oops/access.hpp" #include "oops/access.hpp"
DecoratorSet AccessBarrierSupport::resolve_unknown_oop_ref_strength(DecoratorSet decorators, oop base, ptrdiff_t offset) { DecoratorSet AccessBarrierSupport::resolve_unknown_oop_ref_strength(DecoratorSet decorators, oop base, ptrdiff_t offset) {
// Note that the referent in a FinalReference is technically not strong.
// However, it always behaves like one in practice. The two cases are:
// 1) A mutator calls Reference.get(). However, a mutator can only ever
// see inactive FinalReferences, whose referents really are strong.
// 2) A GC heap walking operation. In this case the GC can see active
// FinalReferences, but the GC always wants to follow the referent
// as if it was strong.
DecoratorSet ds = decorators & ~ON_UNKNOWN_OOP_REF; DecoratorSet ds = decorators & ~ON_UNKNOWN_OOP_REF;
if (!java_lang_ref_Reference::is_referent_field(base, offset)) { if (!java_lang_ref_Reference::is_referent_field(base, offset) ||
java_lang_ref_Reference::is_final(base)) {
ds |= ON_STRONG_OOP_REF; ds |= ON_STRONG_OOP_REF;
} else if (java_lang_ref_Reference::is_phantom(base)) { } else if (java_lang_ref_Reference::is_phantom(base)) {
ds |= ON_PHANTOM_OOP_REF; ds |= ON_PHANTOM_OOP_REF;