RFR: 8252219: C2: Randomize IGVN worklist for stress testing

[Roberto Castañeda Lozano]

On Tue, 22 Sep 2020 13:02:26 GMT, Roberto Castañeda Lozano <github.com+8792647+robcasloz at openjdk.org> wrote:

>> Add 'StressIGVN' option to let C2 randomize IGVN worklist order. When enabled,
>> the worklist is shuffled before each main run of the IGVN loop. Also add
>> 'GenerateStressSeed' and 'StressSeed=N' options to randomly generate or specify
>> the seed. In either case, the seed is logged if 'LogCompilation' is enabled.
>> The new options are declared as production+diagnostic for consistency with the
>> existing 'StressLCM' and 'StressGCM' options.
>
> This pull request is ready for review again.

Thanks for reviewing, Vladimir! I just addressed your two comments.

-------------

PR: https://git.openjdk.java.net/jdk/pull/242