RFR: 8252889: Obsolete -XX:+InsertMemBarAfterArraycopy

[Aleksey Shipilev]

On Tue, 8 Sep 2020 11:25:19 GMT, Tobias Hartmann <thartmann at openjdk.org> wrote:

>> src/hotspot/share/runtime/arguments.cpp line 556:
>> 
>>> 554:   { "UseSemaphoreGCThreadsSynchronization", JDK_Version::undefined(), JDK_Version::jdk(16), JDK_Version::jdk(17) },
>>> 555:   { "ForceNUMA",                     JDK_Version::jdk(15), JDK_Version::jdk(16), JDK_Version::jdk(17) },
>>> 556:   { "InsertMemBarAfterArraycopy",    JDK_Version::undefined(), JDK_Version::jdk(16), JDK_Version::jdk(17) },
>> 
>> This seems like a product flag, so needs to follow `ForceNUMA` example? E.g. 16 -> 17 -> 18? And a provisional CSR?
>
> Since the flag is broken, I think immediate obsoletion, rather than deprecation makes more sense. See also discussion
> in JDK-8252889. A CSR has been created (JDK-8252890).

Okay then!

>> src/hotspot/share/opto/macroArrayCopy.cpp line 1106:
>> 
>>> 1104:     RegionNode* slow_region = new RegionNode(1);
>>> 1105:     transform_later(slow_region);
>>> 1106:
>> 
>> This cleanup does not seem related?
>
> Yes but it does not seem justified to create a separate PR for removing dead code in the same file.

Okay then.

-------------

PR: https://git.openjdk.java.net/jdk/pull/69