RFR: 8158854: Ensure release_store is paired with load_acquire in lock-free code

[David Holmes]

Bug: https://bugs.openjdk.java.net/browse/JDK-8158854

webrev: http://cr.openjdk.java.net/~dholmes/8158854/webrev/


Generally speaking release_store should be paired with load_acquire to 
ensure correct memory visibility and ordering in lock-free code (often 
the read path is what is lock-free). So based on some observations from 
earlier bug fixes this bug was intended to examine the use of 
release_store and see if we have the appropriate load_acquire as well. 
The bug report lists all of the cases that were examined - some clear 
cut correct, some complex correct, some fixed here and some split out 
into separate issues.

Here's a summary of the actual changes in the webrev:

  src/share/vm/classfile/classLoader.hpp

- next() accessor needs to use load_acquire.

---

src/share/vm/classfile/verifier.cpp

- load of _verify_byte_codes_fn needs to load_acquire to pair with use 
of release_store
- release_store of _is_new_verify_byte_codes_fn is not needed

---

src/share/vm/oops/arrayKlass.hpp
src/share/vm/oops/instanceKlass.cpp
src/share/vm/oops/instanceKlass.hpp
src/share/vm/oops/instanceKlass.inline.hpp
src/share/vm/oops/objArrayKlass.cpp
src/share/vm/oops/typeArrayKlass.cpp

The logic for storing dimensions values was using a storeStore barrier 
between the lower and higher dimensions. This is converted to use a 
release-store setter for higher-dimension, with paired load-acquire 
accessor. Plus the accessed fields are declared volatile.

The methods_jmethod_ids_acquire() and its paired 
release_set_methods_jmethod_ids(), are moved to the .inline.hpp file 
where they belong.

---

src/share/vm/runtime/vmStructs.cpp

Updated declaration for _array_klasses  now it is volatile.

---

Thanks,
David