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

[Fei Yang]

On Wed, 8 Dec 2021 06:43:31 GMT, kuaiwei <duke at openjdk.java.net> wrote:

>> It seems zr(x0) is used as stack alignment when saving/restoring registers around calls. But it's unnecessary to ld/st x0 from/to stack. We just need reserve a stack slot in case alignment is required.
>
> 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

May I ask what kind of test is carried out for this change? Normally, testing result should also be added in PR description.

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