RFR: 8276799: Implementation of JEP 422: Linux/RISC-V Port [v5]

[SUN Guoyun]

On Thu, 24 Mar 2022 07:01:43 GMT, Fei Yang <fyang at openjdk.org> wrote:

>> This PR implements JEP 422: Linux/RISC-V Port [1].
>> The PR starts as a squashed merge of the https://openjdk.java.net/projects/riscv-port branch.
>> 
>> This has been tested with jtreg tier{1,2,3,4} and jcstress on HiFive Unmatched board. Dacapo, SPECjbb2015 and SPECjvm2008 benchmark tests are also carried out regularly. So it should be good enough to run most Java programs.
>> 
>> [1] https://openjdk.java.net/jeps/422
>
> Fei Yang 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 five additional commits since the last revision:
> 
>  - Merge remote-tracking branch 'upstream/master' into JDK-8276799
>  - Fix copyright header
>  - Address review comments
>  - Merge remote-tracking branch 'upstream/master' into JDK-8276799
>  - 8276799: Implementation of JEP 422: Linux/RISC-V Port

src/hotspot/cpu/riscv/riscv.ad line 8758:

> 8756: %{
> 8757:   // Same match rule as `far_cmpU_loop'.
> 8758:   match(CountedLoopEnd cmp (CmpU op1 op2));

Which testcases can test this instruct and the following instructs?
match(CountedLoopEnd cmp (CmpP op1 op2));
match(CountedLoopEnd cmp (CmpN op1 op2));
match(CountedLoopEnd cmp (CmpF op1 op2));
match(CountedLoopEnd cmp (CmpD op1 op2));

 I suspect this instruction is useless.

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PR: https://git.openjdk.org/jdk/pull/6294