Mercurial > hg > graal-jvmci-8
diff src/share/vm/prims/unsafe.cpp @ 3249:e1162778c1c8
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
| author | johnc |
|---|---|
| date | Thu, 07 Apr 2011 09:53:20 -0700 |
| parents | c7f3d0b4570f |
| children | 92add02409c9 |
line wrap: on
line diff
--- a/src/share/vm/prims/unsafe.cpp Tue Apr 05 19:14:03 2011 -0700 +++ b/src/share/vm/prims/unsafe.cpp Thu Apr 07 09:53:20 2011 -0700 @@ -24,6 +24,9 @@ #include "precompiled.hpp" #include "classfile/vmSymbols.hpp" +#ifndef SERIALGC +#include "gc_implementation/g1/g1SATBCardTableModRefBS.hpp" +#endif // SERIALGC #include "memory/allocation.inline.hpp" #include "prims/jni.h" #include "prims/jvm.h" @@ -193,7 +196,32 @@ UnsafeWrapper("Unsafe_GetObject"); if (obj == NULL) THROW_0(vmSymbols::java_lang_NullPointerException()); GET_OOP_FIELD(obj, offset, v) - return JNIHandles::make_local(env, v); + jobject ret = JNIHandles::make_local(env, v); +#ifndef SERIALGC + // We could be accessing the referent field in a reference + // object. If G1 is enabled then we need to register a non-null + // referent with the SATB barrier. + if (UseG1GC) { + bool needs_barrier = false; + + if (ret != NULL) { + if (offset == java_lang_ref_Reference::referent_offset) { + oop o = JNIHandles::resolve_non_null(obj); + klassOop k = o->klass(); + if (instanceKlass::cast(k)->reference_type() != REF_NONE) { + assert(instanceKlass::cast(k)->is_subclass_of(SystemDictionary::Reference_klass()), "sanity"); + needs_barrier = true; + } + } + } + + if (needs_barrier) { + oop referent = JNIHandles::resolve(ret); + G1SATBCardTableModRefBS::enqueue(referent); + } + } +#endif // SERIALGC + return ret; UNSAFE_END UNSAFE_ENTRY(void, Unsafe_SetObject140(JNIEnv *env, jobject unsafe, jobject obj, jint offset, jobject x_h)) @@ -226,7 +254,32 @@ UNSAFE_ENTRY(jobject, Unsafe_GetObject(JNIEnv *env, jobject unsafe, jobject obj, jlong offset)) UnsafeWrapper("Unsafe_GetObject"); GET_OOP_FIELD(obj, offset, v) - return JNIHandles::make_local(env, v); + jobject ret = JNIHandles::make_local(env, v); +#ifndef SERIALGC + // We could be accessing the referent field in a reference + // object. If G1 is enabled then we need to register non-null + // referent with the SATB barrier. + if (UseG1GC) { + bool needs_barrier = false; + + if (ret != NULL) { + if (offset == java_lang_ref_Reference::referent_offset && obj != NULL) { + oop o = JNIHandles::resolve(obj); + klassOop k = o->klass(); + if (instanceKlass::cast(k)->reference_type() != REF_NONE) { + assert(instanceKlass::cast(k)->is_subclass_of(SystemDictionary::Reference_klass()), "sanity"); + needs_barrier = true; + } + } + } + + if (needs_barrier) { + oop referent = JNIHandles::resolve(ret); + G1SATBCardTableModRefBS::enqueue(referent); + } + } +#endif // SERIALGC + return ret; UNSAFE_END UNSAFE_ENTRY(void, Unsafe_SetObject(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jobject x_h))