On Thu, 28 Oct 2021 07:41:59 GMT, Aleksey Shipilev <[email protected]> wrote:
>> Thanks for clarifying. Now we have all the intrinsics in place we have the
>> choice of delegating either at the Java level or the native level, where
>> previously we had to delegate at the Java level to get the benefit of the
>> storeFence intrinsic. But it is fine as-is.
>
> Now I am actually thinking to drop `Unsafe_{Load|Store}Fence` entry points
> and delegate `Unsafe.{load|store}Fence()` to `Unsafe.fullFence()` as the
> fallback, in a similar way. It looks to me calling all the way to
> `unsafe.cpp` for a single barrier is not that useful. That's something for a
> separate PR.
>
> So it would be something like:
> - `storeStore` intrinsifies efficiently, or falls back to `release`
> - `loadLoad` always falls back to `acquire` (seems to be little sense to
> intrinsify this, as all platforms alias it to `acquire`)
> - `acquire` intrinsifies efficiently, or falls back to `full`
> - `release` intrinsifies efficiently, or falls back to `full`
> - `full` intrinsifies efficiently, or falls back to `Unsafe_FullFence`,
> which calls `OrderAccess::fullFence()`.
Doing it here: #6149, JDK-8276096.
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PR: https://git.openjdk.java.net/jdk/pull/6136
