[13u] RFR: 8230565: ZGC: Redesign C2 load barrier to expand on the MachNode level

[Per Liden]

Thanks Nils!

/Per

On 10/14/19 10:11 PM, Nils Eliasson wrote:
> Hi Per,
> 
> Looks good!
> 
> // Nils
> 
> On 2019-10-14 23:43, Per Liden wrote:
>> Hi,
>>
>> Please review this back port of JDK-8230565 to 13u. This fix 
>> significantly improves stability of ZGC (or more specifically ZGC's C2 
>> load barrier). The back port was trivial, but not completely clean, as 
>> it required manual merge to resolve 4 simple conflicts.
>>
>> Original bug: https://bugs.openjdk.java.net/browse/JDK-8230565
>> Original commit: https://hg.openjdk.java.net/jdk/jdk/rev/d376d86b0a01
>>
>> JDK 13u webrev: http://cr.openjdk.java.net/~pliden/8230565/webrev.jdk13u
>>
>> Testing:
>> - Tier1-3 on all Oracle platforms.
>> - Tier1-6 on Linux/x64.
>> - Multiple iterations of gc-test-suite on Linux/x64.
>> - Builds on Linux/AArch64.
>>
>> /Per