Thu, 07 Apr 2011 09:53:20 -0700
7009266: G1: assert(obj->is_oop_or_null(true )) failed: Error
Summary: A referent object that is only weakly reachable at the start of concurrent marking but is re-attached to the strongly reachable object graph during marking may not be marked as live. This can cause the reference object to be processed prematurely and leave dangling pointers to the referent object. Implement a read barrier for the java.lang.ref.Reference::referent field by intrinsifying the Reference.get() method, and intercepting accesses though JNI, reflection, and Unsafe, so that when a non-null referent object is read it is also logged in an SATB buffer.
Reviewed-by: kvn, iveresov, never, tonyp, dholmes
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25 #ifndef SHARE_VM_OOPS_COMPILEDICHOLDEROOP_HPP
26 #define SHARE_VM_OOPS_COMPILEDICHOLDEROOP_HPP
28 #include "oops/oop.hpp"
30 // A compiledICHolderOop is a helper object for the inline cache implementation.
31 // It holds an intermediate value (method+klass pair) used when converting from
32 // compiled to an interpreted call.
33 //
34 // compiledICHolderOops are always allocated permanent (to avoid traversing the
35 // codeCache during scavenge).
38 class compiledICHolderOopDesc : public oopDesc {
39 friend class VMStructs;
40 private:
41 methodOop _holder_method;
42 klassOop _holder_klass; // to avoid name conflict with oopDesc::_klass
43 public:
44 // accessors
45 methodOop holder_method() const { return _holder_method; }
46 klassOop holder_klass() const { return _holder_klass; }
48 void set_holder_method(methodOop m) { oop_store_without_check((oop*)&_holder_method, (oop)m); }
49 void set_holder_klass(klassOop k) { oop_store_without_check((oop*)&_holder_klass, (oop)k); }
51 static int header_size() { return sizeof(compiledICHolderOopDesc)/HeapWordSize; }
52 static int object_size() { return align_object_size(header_size()); }
54 // interpreter support (offsets in bytes)
55 static int holder_method_offset() { return offset_of(compiledICHolderOopDesc, _holder_method); }
56 static int holder_klass_offset() { return offset_of(compiledICHolderOopDesc, _holder_klass); }
58 // GC support
59 oop* adr_holder_method() const { return (oop*)&_holder_method; }
60 oop* adr_holder_klass() const { return (oop*)&_holder_klass; }
61 };
63 #endif // SHARE_VM_OOPS_COMPILEDICHOLDEROOP_HPP