Integrated: 8356159: RISC-V: Add Zabha

[Robbin Ehn]

On Thu, 15 May 2025 14:08:48 GMT, Robbin Ehn <rehn at openjdk.org> wrote:

> Hi, please consider.
> 
> This adds the byte and halfword atomic memory operations (Zabha) - https://github.com/riscv/riscv-zabha.
> All amo-instructions, except load-reserve and store-conditional, can also be performed on natural aligned half-words and bytes. (i.e. the extension do not add lr.h/b or sc.h/b) This includes amocas if zacas extension is present.
> 
> The majority of this patch is to support amocas.h/b. We are now starting to really feel the pain of all these extensions, as CAS:ing 16/8-bits can now be done in three different ways:
> - lr.w/sc.w 'narrow' CAS (no extension)
> - amocas.w 'narrow' CAS (Zacas)
> - amocas.h/b (Zacas + Zabha)
> 
> There is no hwprobe support yet.
> 
> Ran t1-3 with Zacas+Zabha and t1 without Zabha in qemu.
> 
> Thanks, Robbin

This pull request has now been integrated.

Changeset: dc961609
Author:    Robbin Ehn <rehn at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/dc961609f84a38164d10852cb92c005c3eb077e4
Stats:     824 lines in 6 files changed: 563 ins; 64 del; 197 mod

8356159: RISC-V: Add Zabha

Reviewed-by: fyang, fjiang

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PR: https://git.openjdk.org/jdk/pull/25252