RFR: 8180197: Failing assert: id must be initialized

[Kim Barrett]

> On Jun 2, 2017, at 5:45 AM, Rickard Bäckman <rickard.backman at oracle.com> wrote:
> 
> Hi,
> 
> there is a locking / race in ciObjectFactory. The variables
> _shared_ident_limit and _shared_ci_metadata are supposed to be protected
> by the volatile _initialized. However since we do double checked locking
> on at least some platforms we can have a race where _initialized is true
> but _shared_ident_limit has not yet been updated.
> 
> Since this code is only run when the compiler threads are starting,
> replacing the double checked locking with just check under lock would
> solve the problem. The code runs once per thread and can't be considered
> performance critical.
> 
> webrev: http://cr.openjdk.java.net/~rbackman/8180197/
> bug: https://bugs.openjdk.java.net/browse/JDK-8180197
> 
> /R

Looks good.