RFR: 8205923: ZGC: Verification applies load barriers before verification

[Erik Osterlund]

Hi Stefan,

Looks good.

Thanks,
/Erik

> On 27 Jun 2018, at 15:15, Stefan Karlsson <stefan.karlsson at oracle.com> wrote:
> 
> Hi all,
> 
> Please review this patch to stop applying load barriers in the Mark End verification.
> 
> http://cr.openjdk.java.net/~stefank/8205923/webrev.01/
> https://bugs.openjdk.java.net/browse/JDK-8205923
> 
> The recent IN_CONCURRENT_ROOT changes introduced load barriers to our Mark End verification. These load barriers are unnecessary because all roots should have been fixed at that point.
> 
> The object oop field verification applied a load barrier to be able to load stale j.l.Reference::referents, and as an effect applied load barriers to all fields. This patch skips visiting the referents and uses RawAccess loads for all other fields.
> 
> This patch builds upon the JDK-8205922, which introduces the mechanism to skip visiting referents in oop_iterate calls.
> 
> Thanks,
> StefanK