[8u] RFR: nativeInstruction atomicity and correctness of patching

[Anton Kozlov]

Hi, All!

Could you review a patch that should fix nativeInst in several aspects?

* macroassembler trampoline_call generates code, which loads call
target from memory just after trampoline. That constant could be
patched atomically and in mt_safe way. NativeTrampolineCall class was
introduced.

* NativeGeneralJump not falls to undefined behavior conditions now,
only imm branches swapped with imm branches. It used only by C1
patching facultiles, so there should be no harm that the implementation
depends on C1 implementation. It is a part of C1 patching that triggers
deoptimisation on aarch64, http://mail.openjdk.java.net/pipermail/aarch
64-port-dev/2013-September/000273.html. Note, that quote about
concurrent modification and execution in discussion applies to aarch32
as well.

* Atomic::store, Atomic::load for jlongs made really atomic.

Sorry for missing testcase.

Thanks,
Anton
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