8026049: (bf) Intrinsify ByteBuffer.put{Int, Double, Float, ...} methods

[Andrew Haley]

I've tried to address all the points that have been made.

I haven't changed the way the sub-words are read and written because
the code I'm seeing is fairly nearly optimal right now and anything
more complex runs the risk of tripping inlining limits, thus
pessimizing performance.  We need a general solution which isn't
optimized for special cases but is decent on average and often very
good.  I think it's close to the best compromise we're going to get.

I have changed the javadoc as requested and I have fixed the code in
HeapByteBuffer so that it doesn't check the index twice for floating-
point put() and get() operations.

I have added a jtreg test for HeapByteBuffer which tests it pretty
thoroughly.  It also, as a consequence, tests the underlying Unsafe
methods.  I wasn't sure what a separate test for the Unsafe methods
would achieve so I didn't write one.

OK?

http://cr.openjdk.java.net/~aph/unaligned.hotspot.6/
http://cr.openjdk.java.net/~aph/unaligned.jdk.6/

Andrew.