[riscv-port-jdk11u:riscv-port] RFR: 8316645: RISC-V: Remove dependency on libatomic by adding cmpxchg 1b

[Robbin Ehn]

On Mon, 11 Mar 2024 07:25:25 GMT, Robbin Ehn <rehn at openjdk.org> wrote:

>> src/hotspot/os_cpu/linux_riscv/atomic_linux_riscv.hpp line 75:
>> 
>>> 73:                                                 T compare_value,
>>> 74:                                                 T exchange_value,
>>> 75:                                                 atomic_memory_order order) const {
>> 
>> I see the parameter order is not consistent with the one in jdk11u:
>> `T Atomic::PlatformCmpxchg<byte_size>::operator()`.
>> So this might need more adaptations, otherwise I guess it won't build.
>> Also the original commit adds one `#undef FULL_COMPILER_ATOMIC_SUPPORT` at the end of the file, which is missing for this backport.
>
> It did build and run... I'll fix thanks.

I probably used to new compiler...

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PR Review Comment: https://git.openjdk.org/riscv-port-jdk11u/pull/10#discussion_r1519263698