[riscv-port] RFR: 8278337: riscv: remove unnecessary ld/sd zr around calls [v2]

[kuaiwei]

On Tue, 7 Dec 2021 12:43:08 GMT, Feilong Jiang <fjiang at openjdk.org> wrote:

>> kuaiwei has refreshed the contents of this pull request, and previous commits have been removed. The incremental views will show differences compared to the previous content of the PR. The pull request contains one new commit since the last revision:
>>
>>   8278337: riscv: remove unnecessary ld/sd zr around call
>
> src/hotspot/cpu/riscv/riscv.ad line 1188:
>
>> 1186:     return 12 * NativeInstruction::instruction_size;
>> 1187:   }
>> 1188: }
>
> `// for real runtime callouts it will be six instructions` should be five instructions now

Fixed

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PR: https://git.openjdk.java.net/riscv-port/pull/25