RFR: 8294314: Minimize disabled warnings in hotspot [v9]

[Aleksey Shipilev]

On Tue, 27 Sep 2022 17:27:30 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> Magnus Ihse Bursie has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Don't need empty-body for ad_ppc.cpp now that it is globally disabled
>
> Related: hopefully eliminating `char-subscripts` warning with #10455.

> @shipilev I had hoped this PR would trigger warning hunting in Hotspot, but I did not anticipate that it would happen even before it was pushed! ;-) Let me know when you are done fixing individual warnings; there seem to be little point in integrating this until these fixes has started to slow down.

Well, as I dig deeper into this mess, my PRs that fix the warnings stray away from being trivial, and build changes are a small parts of them. The actual "meat" of the patches requires review. So, I am actually thinking we should integrate this PR first, wait a little, collate possible build failures due to missing disabled warnings, adding more affected files in these declarations. It would make the actual warning fix PRs more to the point: they would have to only touch the files where warnings were specifically disabled. (The same goes for JDK-side PRs, I think)

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PR: https://git.openjdk.org/jdk/pull/10414