RFR: 8166651: OrderAccess::load_acquire &etc should have const parameters

[Erik Österlund]

Hi Kim,

Thanks for doing this. It looks good to me.

/Erik

On 2017-05-25 01:42, Kim Barrett wrote:
> Please review this change to Atomic::load and OrderAccess::load_acquire
> overloads to make their source const qualified, e.g. instead of
> "volatile T*" make them "const volatile T*".  This eliminates the need
> for casting away const when, for example, applying one of these
> operations to a member variable when in a const-qualified method.
>
> There are probably places that previously required casting away const
> but now do not. Similarly, there are probably places where values
> couldn't be const or member functions couldn't be const qualified, but
> now can be. I did a little searching and found a few candidates, but
> none that were otherwise trivial to add to this change, so haven't
> included any.
>
> This change touches platform-specific code for non-Oracle supported
> platforms that I can't test, so I'd like reviews from the respective
> platform owners.
>
> Aside regarding aarch64: I don't know why gcc's __atomic_load doesn't
> const-qualify the source argument; that seems like a bug.  Or maybe
> they are, but not documented that way.  And I wonder why the aarch64
> port uses __atomic_load rather than __atomic_load_n.
>
> CR:
> https://bugs.openjdk.java.net/browse/JDK-8166651
>
> Webrev:
> http://cr.openjdk.java.net/~kbarrett/8166651/hotspot.00
>
> Testing:
> JPRT
>