RFR: 8290496: riscv: Fix build warnings-as-errors with GCC 11

[Fei Yang]

On Tue, 19 Jul 2022 09:10:37 GMT, Yadong Wang <yadongwang at openjdk.org> wrote:

>> Like AArch64 port, RISC-V port defines DEOPTIMIZE_WHEN_PATCHING and does not make use of C1 runtime patching.
>> Then there is no need to implement class NativeMovRegMem in the port-specific code. But that will make GCC 11 unhappy.
>> 
>> One way would be guarding the C1 shared code like class PatchingStub which uses class NativeMovRegMem under macro DEOPTIMIZE_WHEN_PATCHING. But turns out class PatchingStub are still partially used (mainly the PatchID enum) even under DEOPTIMIZE_WHEN_PATCHING.
>> 
>> So PR takes another way fixing this warning by implementing the NativeMovRegMem class for RISC-V like Like AArch64 port.
>> 
>> Testing: release & fastdebug build OK without --disable-warnings-as-errors
>
> Try GCC 12 if possible?

@yadongw @feilongjiang : Thanks. Could we have a Reviewer please? @shipilev ?

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PR: https://git.openjdk.org/jdk/pull/9550