RFR: 8320069: RISC-V: Add Zcb instructions [v3]

[Robbin Ehn]

On Wed, 20 Dec 2023 09:57:10 GMT, Robbin Ehn <rehn at openjdk.org> wrote:

>> Hi, this is the instructions for zcb.
>> 
>> Due to over lack of infrastructure having multiple extension dependent instruction does not fit well.
>> Some of these compressed instructions are also missing 1 to 1 mapping, e.g. now we have a compressed not, but the corresponding instruction in uncompressed is still xor.
>> I think we need to do some rework here.
>> 
>> I also I don't like the macro expansion as it hopeless in debugger and 'IDE's (vim+rtags for me).
>> (macro stuff was originally done when templates where blacklisted in hotspot)
>> 
>> And I don't want an option for this, as zcb is coming in hwprobe, if you have compressed on you get them if they are supported (may depend on e.g. zbb).
>> 
>> I have done some modification since it passed tier1, so I'm running stuff over the weekend.
>
> Robbin Ehn has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains three additional commits since the last revision:
> 
>  - Merge branch 'master' into zcb
>  - Merge branch 'master' into zcb
>  - zcb instruction set

Passes t1+t2 fastdebug (with some expected timeouts).

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PR Comment: https://git.openjdk.org/jdk/pull/17122#issuecomment-1873667517