6705887: Compressed Oops: generate x64 addressing and implicit null checks with narrow oops Summary: Generate addresses and implicit null checks with narrow oops to avoid decoding. Reviewed-by: jrose, never

1cc8dd79fd1cd13d36b385196271a29632c67c3b jdk7-b24
bf2517e15f0c0f950e5b3143c4ca11e2df73dcc1 jdk7-b25