[aarch64-port-dev ] RFR(S): aarch64 Fix loading ConstantPoolCacheEntry._indices with load acquire

[Andrew Haley]

On 11/23/2015 03:07 PM, Edward Nevill wrote:
> 
> On Fri, 2015-11-20 at 22:07 +0800, Hui Shi wrote:
>> Hi,
>>
>> Could someone help review and sponsor this fix for aarch64 runtime?
>>
>> Bug:  https://bugs.openjdk.java.net/browse/JDK-8143285
>> webrev:  http://cr.openjdk.java.net/~hshi/8143285/webrev/
> 
> Hi Shi Hui,
> 
> Thanks for finding this.
> 
> Do you think this should be predicated on 'UseBarriersForVolatile'

No, this is fine.  This isn't a Java volatile, it's VM-internal.
AArch64 ldar/stlr work just fine for it on all hardware.

> IE.
> 
>    if (UseBarrieresForVolatile) {
>      <ldar as you suggest>
>    } else {
>      <ldr>/<membar>
>    }
> 
> This seems to be the only code in the Template Interpreter or C1
> that uses acquire release. The only place acquire release is used
> otherwise is in C2.
> 
> Do you think we should just use membar to fix this problem and then
> as a separate issue look at whether we augment the membars in
> Template Interpreter / C1 to load acquire / store release when
> possible.

No, this is fine.  The wider question of changing the Template
Interpreter / C1 to load acquire / store release can wait.  I think
it's just moving the furniture around for no good reason.

Andrew.