RFR (S) 8150465: Unsafe methods to produce uninitialized arrays

[Andrew Haley]

This is something of a loaded gun pointed at our feet.  We'll have to
be extremely careful that we can prove that such arrays are never
unsafely published.  It's the "generic case where a complicated
processing is done after the allocation" I'm worried about.

The only way to guarantee safety is to prove that the array reference
doesn't escape the thread until the array is fully initialized and a
release barrier has been executed.

I urge extreme caution.

Andrew.