Release store in C2 putfield
aph at redhat.com
Thu Sep 4 13:13:37 UTC 2014
On 09/04/2014 11:36 AM, David Holmes wrote:
> On 4/09/2014 8:22 PM, Andrew Haley wrote:
>> On 09/04/2014 11:15 AM, David Holmes wrote:
>>> I'll also add that a "barrier" at the end of construction is not
>>> necessarily sufficient as Bertrand has already mentioned, if 'this' can
>> Can you provide us with an example of this which isn't a Java
>> programmer error?
> To clarify there are two sets of object state we are concerned with:
> - internal VM state that ensures the platform safety guarantees are met
> (ie all fields default initialized, valid vtable and object header seen)
> - Java level state
> The first requires a suitable "barrier" before Java constructor code is
> executed so that Java programmer errors do not lead to crashes. So a
> barrier at the end of construction is not sufficient.
Yes, I've got both of those.
> If you have the barrier at the start of construction then you don't need
> a barrier at the end except potentially as part of the freeze semantic
> for final fields. (Though updated JMM in Java 9 may indeed require such
> a barrier.)
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