RFR: 8234563: Harmonize parameter order in Atomic

[Stefan Karlsson]

Hi all,

I'd like to propose a restructuring of the parameter order in Atomic.

https://bugs.openjdk.java.net/browse/JDK-8234563

These are some of the functions used to concurrently write memory from 
HotSpot C++ code:

  Atomic::store(value, destination);
  OrderAccess::release_store(destination, value)
  OrderAccess::release_store_fence(destination, value)
  Atomic::add(value, destination);
  Atomic::sub(value, destination);
  Atomic::xchg(exchange_value, destination);
  Atomic::cmpxchg(exchange_value, destination, compare_value);

With the proposed JDK-8234562 change, this would look like:

  Atomic::store(value, destination);
  Atomic::release_store(destination, value)
  Atomic::release_store_fence(destination, value)
  Atomic::add(value, destination);
  Atomic::sub(value, destination);
  Atomic::xchg(exchange_value, destination);
  Atomic::cmpxchg(exchange_value, destination, compare_value);

I'd like to propose that we move the destination parameter over to the 
left, and the new value to the right. This would look like this:

  Atomic::store(destination, value);
  Atomic::release_store(destination, value)
  Atomic::release_store_fence(destination, value)
  Atomic::add(destination, value);
  Atomic::sub(destination, value);
  Atomic::xchg(destination, exchange_value);
  Atomic::cmpxchg(destination, compare_value, exchange_value);

This would bring the Atomic API more in-line with the order for a normal 
store:

*destination = value;

I've split this up into separate patches, each dealing with a separate 
operation:

Atomic::store:
  https://cr.openjdk.java.net/~stefank/8234563/webrev.01.01.store/

Atomic::add:
  https://cr.openjdk.java.net/~stefank/8234563/webrev.01.02.add/

Atomic::sub:
  https://cr.openjdk.java.net/~stefank/8234563/webrev.01.03.sub/

Atomic::xchg:
  https://cr.openjdk.java.net/~stefank/8234563/webrev.01.04.xchg/

Atomic::cmpxchg:
  https://cr.openjdk.java.net/~stefank/8234563/webrev.01.05.cmpxchg/

All sub-patches combined:
  https://cr.openjdk.java.net/~stefank/8234563/webrev.01.all/

The patches applies on-top of the patch for JDK-8234562:
  https://cr.openjdk.java.net/~stefank/8234562/webrev.01/

I've tested this patch with tier1-7. I've also built fastdebug on the 
following configs: aarch64, arm32, ppc64le, s390x, shenandoah, zero, 
minimal, just to minimize any disruptions. However, this is a moving 
target and latest rebase of this has only been run on tier1.

Thanks,
StefanK