RFR: 8253843: AArch64: Use ishst for storestore barrier

[Alan Hayward]

On Wed, 30 Sep 2020 08:44:37 GMT, Alan Hayward <github.com+4146708+a74nh at openjdk.org> wrote:

>> AArch64 orderAccess uses gcc built in atomic functions, which expand
>> inline to DMB barrier instructions.  Specifically, they call the following:
>> 
>> FULL_MEM_BARRIER -> DMB ISH
>> READ_MEM_BARRIER -> DMB ISHLD
>> WRITE_MEM_BARRIER -> DMB ISH
>> 
>> However, storestore should be optimised to use ISHST.
>> 
>> In addition, __sync_synchronize is marked as legacy. See:
>> https://gcc.gnu.org/onlinedocs/gcc/_005f_005fatomic-Builtins.html
>> 
>> In order for the code to match, I switched everything to call dmbs directly.
>> 
>> Also, add AArch64 to the orderAccess documentation table.
>
>> /signed
> 
> this was a mistake. Meant to do /covered

There doesn't seem to be an AArch64-port label. Is there any way to get AArch64 patches posted to the AArch64-port-dev
mailing list?

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PR: https://git.openjdk.java.net/jdk/pull/427