RFR: 8292329: Enable CDS shared heap for zero builds [v2]

[Ioi Lam]

On Wed, 24 Aug 2022 06:04:52 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> Ioi Lam has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   @shipilev review comments
>
> Zero can default to G1 after #9994. Together with this patch, it should also be able to use the shared heap from CDS, I think. It also tells me that it is good to force G1 at CDS dump time, even without Zero, because the ergonomics might select Serial on some machines. (Like, as I remember from the `compilerDefinitions.cpp` code, might happen on Windows x86_32 that drops to "client emulation" mode.).

Thanks @shipilev @erikj79 @magicus for the review.

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PR: https://git.openjdk.org/jdk/pull/9984