RFR 8158039 VarHandle float/double field/array access should support CAS/set/add atomics

[Paul Sandoz]

> On 6 Jul 2016, at 13:01, Andrew Haley <aph at redhat.com> wrote:
> 
> I'm baffled by
> 
>    @ForceInline
>    public final float compareAndExchangeFloatAcquire(Object o, long offset,
>                                                  float expected,
>                                                  float x) {
>        int w = compareAndExchangeIntVolatile(o, offset,
>                                              Float.floatToRawIntBits(expected),
>                                              Float.floatToRawIntBits(x));
>        return Float.intBitsToFloat(w);
>    }
> 
> Why does it use compareAndExchangeIntVolatile?  It's a minor
> inefficiency, but it does generate an unnecessary write fence on a
> machine with relaxed memory consistency.
> 

Opps, that’s an oversight (probably a copy/paste one, since the other methods are as expected). Thanks for noticing that.

I’ll fix once the changes get integrated into jdk9/dev (which i hope should occur soon).

  https://bugs.openjdk.java.net/browse/JDK-8160885 <https://bugs.openjdk.java.net/browse/JDK-8160885>

Paul.