Integrated: 8253469: ARM32 Zero: replace usages of __sync_synchronize() with OrderAccess::fence

[Aleksey Shipilev]

On Tue, 22 Sep 2020 12:41:02 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> In `atomic_bsd_zero.hpp` and `atomic_linux_zero.hpp` there are uses of __sync_synchronize(). However,
> `orderAccess_*_zero.hpp` calls the kernel helper, because:
> /*
>  * ARM Kernel helper for memory barrier.
>  * Using __asm __volatile ("":::"memory") does not work reliable on ARM
>  * and gcc __sync_synchronize(); implementation does not use the kernel
>  * helper for all gcc versions so it is unreliable to use as well.
>  */
> 
> We need to clean this up to use `OrderAccess::fence()` to gain access to the kernel helper.
> 
> This depends on JDK-8253464 being fixed first.
> 
> Attention @bulasevich.
> 
> Testing:
>  - [x] ARM32 Zero jcstress
>  - [x] Mac OS x86_64 Zero jcstress

This pull request has now been integrated.

Changeset: f62eefc0
Author:    Aleksey Shipilev <shade at openjdk.org>
URL:       https://git.openjdk.java.net/jdk/commit/f62eefc0
Stats:     10 lines in 2 files changed: 4 ins; 0 del; 6 mod

8253469: ARM32 Zero: replace usages of __sync_synchronize() with OrderAccess::fence

Reviewed-by: dholmes

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PR: https://git.openjdk.java.net/jdk/pull/298