RFR: 8308656: RISC-V: vstring_compare doesnt manifest usage of all vector registers [v2]

[Gui Cao]

On Wed, 24 May 2023 15:37:07 GMT, Vladimir Kempik <vkempik at openjdk.org> wrote:

>> Please review this fix. 
>> vstring_compare instrinsic ( from c2_MacroAssembler_riscv.cpp ) uses vector registers v6 and v7 ( https://github.com/openjdk/jdk/blob/master/src/hotspot/cpu/riscv/c2_MacroAssembler_riscv.cpp#L1482 , vstr1 == v4, lmul=4) , but doesn't manifest their usage in riscv_v.ad file.
>> This fix resolves this situation.
>> No noticable difference one might see in generated code for now.
>> 
>> Testing: build testing only.
>
> Vladimir Kempik has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Revert part of the fix

Hi, I tested tier1 and `test/jdk/jdk/incubator/vector` before and after using this PR , and the test results are consistent, no new errors are introduced.

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PR Comment: https://git.openjdk.org/jdk/pull/14102#issuecomment-1562134928