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8189871: Refactor GC barriers to use declarative semantics

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Reviewed-by: pliden, rkennke, coleenp, dholmes, kbarrett, stefank
This commit is contained in:
Erik Österlund 2017-11-20 13:07:44 +01:00
parent 63122ba705
commit 3e5e2f03b1
45 changed files with 3458 additions and 806 deletions
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21
src/hotspot/share/prims/jvm.cpp
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@ -35,12 +35,12 @@
#include "classfile/stringTable.hpp"
#include "classfile/systemDictionary.hpp"
#include "classfile/vmSymbols.hpp"
#include "gc/shared/barrierSet.inline.hpp"
#include "gc/shared/collectedHeap.inline.hpp"
#include "interpreter/bytecode.hpp"
#include "memory/oopFactory.hpp"
#include "memory/resourceArea.hpp"
#include "memory/universe.inline.hpp"
#include "oops/access.inline.hpp"
#include "oops/fieldStreams.hpp"
#include "oops/instanceKlass.hpp"
#include "oops/method.hpp"
@ -652,24 +652,7 @@ JVM_ENTRY(jobject, JVM_Clone(JNIEnv* env, jobject handle))
new_obj_oop = CollectedHeap::obj_allocate(klass, size, CHECK_NULL);
}
// 4839641 (4840070): We must do an oop-atomic copy, because if another thread
// is modifying a reference field in the clonee, a non-oop-atomic copy might
// be suspended in the middle of copying the pointer and end up with parts
// of two different pointers in the field. Subsequent dereferences will crash.
// 4846409: an oop-copy of objects with long or double fields or arrays of same
// won't copy the longs/doubles atomically in 32-bit vm's, so we copy jlongs instead
// of oops. We know objects are aligned on a minimum of an jlong boundary.
// The same is true of StubRoutines::object_copy and the various oop_copy
// variants, and of the code generated by the inline_native_clone intrinsic.
assert(MinObjAlignmentInBytes >= BytesPerLong, "objects misaligned");
Copy::conjoint_jlongs_atomic((jlong*)obj(), (jlong*)new_obj_oop,
align_object_size(size) / HeapWordsPerLong);
// Clear the header
new_obj_oop->init_mark();
// Store check (mark entire object and let gc sort it out)
BarrierSet* bs = Universe::heap()->barrier_set();
bs->write_region(MemRegion((HeapWord*)new_obj_oop, size));
HeapAccess<>::clone(obj(), new_obj_oop, size);
Handle new_obj(THREAD, new_obj_oop);
// Caution: this involves a java upcall, so the clone should be