RFR: 8296158: Refactor the verification of CDS region checksum [v2]

[Ioi Lam]

On Wed, 8 Feb 2023 22:15:53 GMT, Matias Saavedra Silva <matsaave at openjdk.org> wrote:

>> Ioi Lam has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   @matias9927 suggestions
>
> src/hotspot/share/cds/filemap.cpp line 1599:
> 
>> 1597:   // loaded into memory via FileMapInfo::map_region() or FileMapInfo::read_region().
>> 1598:   // I.e., this->mapped_base() must be valid.
>> 1599:   if (!VerifySharedSpaces) {
> 
> While I think this is a nice shortcut to avoid checking VerifySharedSpaces, I think it occludes the fact it is a necessary condition in the if statements below. Just my 2 cents but I think it is more intuitive to keep `if (VerifySharesSpaces && !check_region_crc())` and keep an assert inside this method. 
> 
> Either way does work, so go with what you think makes the most sense. Other than that, LGTM!

Thanks for the comment. I fixed the code as you suggested.

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PR: https://git.openjdk.org/jdk/pull/12424