RFR: 8376472: Shenandoah: Assembler store barriers read destination memory despite the decorators [v2]

[Aleksey Shipilev]

On Fri, 30 Jan 2026 10:27:30 GMT, Martin Doerr <mdoerr at openjdk.org> wrote:

>> Other barriers do flattening for access address, this is what non-reference store shortcut avoids in them. Given the prevalence of non-reference stores, it is worthwhile to optimize for. It is not the issue for PPC64 per se. I like to have barriers in the same shape across architectures, so that we do not have to think twice (pun intended) why did not we do `BSA::store_at` twice in PPC64, like in other arches :)
>
>> I like to have barriers in the same shape across architectures
> 
> Agreed. My idea was rather changing it for all platforms. But that may be a bit out of scope, here.

Yeah, I was looking at it when implementing, and like I said: the flattening comes into picture sideways for x86 and AArch64, robbing us of real readability benefits. Plus, other barriers, e.g. `load_at`, have the same initial check for reference-ness. I think we are in good place with this shape now.

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PR Review Comment: https://git.openjdk.org/jdk/pull/29444#discussion_r2745633151