x86: Enable dual TLH by default

[BradleyWood]

No description provided.

[vijaysun-omr]

I would appreciate a review from @0xdaryl on this to make sure we have considered what we need to, before making this change

[vijaysun-omr]

I would also advise a small unit test in this case where you have an allocation of each kind, one that needs zeroing and one that does not, and check the generated code sequences to make sure that it is all as expected (i.e. we use the two TLHs in the expected way).

[vijaysun-omr]

Also FYI, @mpirvu for any memory footprint impacts

[vijaysun-omr]

I am only approving the fact that the enablement looks okay. I'll wait for Daryl's review and run tests.

[vijaysun-omr]

jenkins build all

[BradleyWood]

MacOS failure is #7181

Windows Failed due to:

ChannelClosedException: Channel "hudson.remoting.Channel@4b2b57a4:win2019x64-openj9-2": Remote call on win2019x64-openj9-2 failed. The channel is closing down or has closed down

[knn-k]

Dual TLH is disabled by default on AArch64 now. PR #7243.

[vijaysun-omr]

Is batch clearing enabled by default on AArch64 ? If not, is it being considered to be enabled by default ?

[knn-k]

@vijaysun-omr TLH batch clearing is enabled by default on AArch64. See my comment in eclipse-openj9/openj9#18870 (comment).