4965777: GC changes to support use of discovered field for pending references
Summary: If and when the reference handler thread is able to use the discovered field to link reference objects in its pending list, so will GC. In that case, GC will scan through this field once a reference object has been placed on the pending list, but not scan that field before that stage, as the field is used by the concurrent GC thread to link discovered objects. When ReferenceHandleR thread does not use the discovered field for the purpose of linking the elements in the pending list, as would be the case in older JDKs, the JVM will fall back to the old behaviour of using the next field for that purpose.
Reviewed-by: jcoomes, mchung, stefank
/*
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#ifndef SHARE_VM_MEMORY_SPECIALIZED_OOP_CLOSURES_HPP
#define SHARE_VM_MEMORY_SPECIALIZED_OOP_CLOSURES_HPP
#include "runtime/atomic.hpp"
#ifndef SERIALGC
#include "gc_implementation/g1/g1_specialized_oop_closures.hpp"
#endif
// The following OopClosure types get specialized versions of
// "oop_oop_iterate" that invoke the closures' do_oop methods
// non-virtually, using a mechanism defined in this file. Extend these
// macros in the obvious way to add specializations for new closures.
// Forward declarations.
class OopClosure;
class OopsInGenClosure;
// DefNew
class ScanClosure;
class FastScanClosure;
class FilteringClosure;
// ParNew
class ParScanWithBarrierClosure;
class ParScanWithoutBarrierClosure;
// CMS
class MarkRefsIntoAndScanClosure;
class Par_MarkRefsIntoAndScanClosure;
class PushAndMarkClosure;
class Par_PushAndMarkClosure;
class PushOrMarkClosure;
class Par_PushOrMarkClosure;
class CMSKeepAliveClosure;
class CMSInnerParMarkAndPushClosure;
// This macro applies an argument macro to all OopClosures for which we
// want specialized bodies of "oop_oop_iterate". The arguments to "f" are:
// "f(closureType, non_virtual)"
// where "closureType" is the name of the particular subclass of OopClosure,
// and "non_virtual" will be the string "_nv" if the closure type should
// have its "do_oop" method invoked non-virtually, or else the
// string "_v". ("OopClosure" itself will be the only class in the latter
// category.)
// This is split into several because of a Visual C++ 6.0 compiler bug
// where very long macros cause the compiler to crash
// Some other heap might define further specialized closures.
#ifndef FURTHER_SPECIALIZED_OOP_OOP_ITERATE_CLOSURES
#define FURTHER_SPECIALIZED_OOP_OOP_ITERATE_CLOSURES(f) \
/* None */
#endif
#define SPECIALIZED_OOP_OOP_ITERATE_CLOSURES_S(f) \
f(ScanClosure,_nv) \
f(FastScanClosure,_nv) \
f(FilteringClosure,_nv)
#ifndef SERIALGC
#define SPECIALIZED_OOP_OOP_ITERATE_CLOSURES_P(f) \
f(ParScanWithBarrierClosure,_nv) \
f(ParScanWithoutBarrierClosure,_nv)
#else // SERIALGC
#define SPECIALIZED_OOP_OOP_ITERATE_CLOSURES_P(f)
#endif // SERIALGC
#define SPECIALIZED_OOP_OOP_ITERATE_CLOSURES_1(f) \
SPECIALIZED_OOP_OOP_ITERATE_CLOSURES_S(f) \
SPECIALIZED_OOP_OOP_ITERATE_CLOSURES_P(f)
#ifndef SERIALGC
#define SPECIALIZED_OOP_OOP_ITERATE_CLOSURES_2(f) \
f(MarkRefsIntoAndScanClosure,_nv) \
f(Par_MarkRefsIntoAndScanClosure,_nv) \
f(PushAndMarkClosure,_nv) \
f(Par_PushAndMarkClosure,_nv) \
f(PushOrMarkClosure,_nv) \
f(Par_PushOrMarkClosure,_nv) \
f(CMSKeepAliveClosure,_nv) \
f(CMSInnerParMarkAndPushClosure,_nv) \
FURTHER_SPECIALIZED_OOP_OOP_ITERATE_CLOSURES(f)
#else // SERIALGC
#define SPECIALIZED_OOP_OOP_ITERATE_CLOSURES_2(f)
#endif // SERIALGC
// We separate these out, because sometime the general one has
// a different definition from the specialized ones, and sometimes it
// doesn't.
#define ALL_OOP_OOP_ITERATE_CLOSURES_1(f) \
f(OopClosure,_v) \
SPECIALIZED_OOP_OOP_ITERATE_CLOSURES_1(f)
#define ALL_OOP_OOP_ITERATE_CLOSURES_2(f) \
SPECIALIZED_OOP_OOP_ITERATE_CLOSURES_2(f)
#ifndef SERIALGC
// This macro applies an argument macro to all OopClosures for which we
// want specialized bodies of a family of methods related to
// "par_oop_iterate". The arguments to f are the same as above.
// The "root_class" is the most general class to define; this may be
// "OopClosure" in some applications and "OopsInGenClosure" in others.
#define SPECIALIZED_PAR_OOP_ITERATE_CLOSURES(f) \
f(MarkRefsIntoAndScanClosure,_nv) \
f(PushAndMarkClosure,_nv) \
f(Par_MarkRefsIntoAndScanClosure,_nv) \
f(Par_PushAndMarkClosure,_nv)
#define ALL_PAR_OOP_ITERATE_CLOSURES(f) \
f(OopClosure,_v) \
SPECIALIZED_PAR_OOP_ITERATE_CLOSURES(f)
#endif // SERIALGC
// This macro applies an argument macro to all OopClosures for which we
// want specialized bodies of a family of methods related to
// "oops_since_save_marks_do". The arguments to f are the same as above.
// The "root_class" is the most general class to define; this may be
// "OopClosure" in some applications and "OopsInGenClosure" in others.
// Some other heap might define further specialized closures.
#ifndef FURTHER_SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES
#define FURTHER_SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES(f) \
/* None */
#endif
#define SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES_YOUNG_S(f) \
f(ScanClosure,_nv) \
f(FastScanClosure,_nv)
#ifndef SERIALGC
#define SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES_YOUNG_P(f) \
f(ParScanWithBarrierClosure,_nv) \
f(ParScanWithoutBarrierClosure,_nv) \
FURTHER_SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES(f)
#else // SERIALGC
#define SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES_YOUNG_P(f)
#endif // SERIALGC
#define SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES_YOUNG(f) \
SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES_YOUNG_S(f) \
SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES_YOUNG_P(f)
#define SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES(f) \
SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES_YOUNG(f)
// We separate these out, because sometime the general one has
// a different definition from the specialized ones, and sometimes it
// doesn't.
// NOTE: One of the valid criticisms of this
// specialize-oop_oop_iterate-for-specific-closures idiom is that it is
// easy to have a silent performance bug: if you fail to de-virtualize,
// things still work, just slower. The "SpecializationStats" mode is
// intended to at least make such a failure easy to detect.
// *Not* using the ALL_SINCE_SAVE_MARKS_CLOSURES(f) macro defined
// below means that *only* closures for which oop_oop_iterate specializations
// exist above may be applied to "oops_since_save_marks". That is,
// this form of the performance bug is caught statically. When you add
// a definition for the general type, this property goes away.
// Make sure you test with SpecializationStats to find such bugs
// when introducing a new closure where you don't want virtual dispatch.
#define ALL_SINCE_SAVE_MARKS_CLOSURES(f) \
f(OopsInGenClosure,_v) \
SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES(f)
// For keeping stats on effectiveness.
#define ENABLE_SPECIALIZATION_STATS 0
class SpecializationStats {
public:
enum Kind {
ik, // instanceKlass
irk, // instanceRefKlass
oa, // objArrayKlass
NUM_Kinds
};
#if ENABLE_SPECIALIZATION_STATS
private:
static bool _init;
static bool _wrapped;
static jint _numCallsAll;
static jint _numCallsTotal[NUM_Kinds];
static jint _numCalls_nv[NUM_Kinds];
static jint _numDoOopCallsTotal[NUM_Kinds];
static jint _numDoOopCalls_nv[NUM_Kinds];
public:
#endif
static void clear() PRODUCT_RETURN;
static inline void record_call() PRODUCT_RETURN;
static inline void record_iterate_call_v(Kind k) PRODUCT_RETURN;
static inline void record_iterate_call_nv(Kind k) PRODUCT_RETURN;
static inline void record_do_oop_call_v(Kind k) PRODUCT_RETURN;
static inline void record_do_oop_call_nv(Kind k) PRODUCT_RETURN;
static void print() PRODUCT_RETURN;
};
#ifndef PRODUCT
#if ENABLE_SPECIALIZATION_STATS
inline void SpecializationStats::record_call() {
Atomic::inc(&_numCallsAll);
}
inline void SpecializationStats::record_iterate_call_v(Kind k) {
Atomic::inc(&_numCallsTotal[k]);
}
inline void SpecializationStats::record_iterate_call_nv(Kind k) {
Atomic::inc(&_numCallsTotal[k]);
Atomic::inc(&_numCalls_nv[k]);
}
inline void SpecializationStats::record_do_oop_call_v(Kind k) {
Atomic::inc(&_numDoOopCallsTotal[k]);
}
inline void SpecializationStats::record_do_oop_call_nv(Kind k) {
Atomic::inc(&_numDoOopCallsTotal[k]);
Atomic::inc(&_numDoOopCalls_nv[k]);
}
#else // !ENABLE_SPECIALIZATION_STATS
inline void SpecializationStats::record_call() {}
inline void SpecializationStats::record_iterate_call_v(Kind k) {}
inline void SpecializationStats::record_iterate_call_nv(Kind k) {}
inline void SpecializationStats::record_do_oop_call_v(Kind k) {}
inline void SpecializationStats::record_do_oop_call_nv(Kind k) {}
inline void SpecializationStats::clear() {}
inline void SpecializationStats::print() {}
#endif // ENABLE_SPECIALIZATION_STATS
#endif // !PRODUCT
#endif // SHARE_VM_MEMORY_SPECIALIZED_OOP_CLOSURES_HPP