RFR(XS) 8138891: C1: Missing release memory barrier in C1's CMS post-barrier

[Doerr, Martin]

Hi,

the dirty marking of the card table needs to be a releasing store for CMS. It's already there in template interpreter and C2 on PPC64. We have seen GC crashed when testing C1 on PPC64.
Unfortunately, C1 does currently not support releasing stores (or load-acquire) which could be exploited on aarch64 or ia64. Hence, we're using a membar_store_store.
This change is a prerequisite for our C1 on PPC64 contribution.

Webrev is here:
http://cr.openjdk.java.net/~mdoerr/8138891_c1_cms_membar/webrev.00



Please review this change.  I need a sponsor, please.


Best regards,
  Martin

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