RFR: 8252219: C2: Randomize IGVN worklist for stress testing [v8]

[Vladimir Kozlov]

On Fri, 25 Sep 2020 07:54:06 GMT, Roberto Castaneda 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.
>
> Roberto Castaneda Lozano has updated the pull request with a new target base due to a merge or a rebase. The pull
> request now contains 14 commits:
>  - Merge master
>  - Add missing @requires annotation to test case
>  - Empty commit to trigger jcheck after updating GitHub user name
>  - Generate random seed if 'StressSeed' is unset
>  - Use generic swap() for shuffling
>  - Add basic sanity test for stress IGVN options
>  - Fix typo
>  - Move shuffle() to PhaseIterGVN
>  - Define 'StressSeed' option as 'uint' rather than 'uintx'
>  - Apply minor rearrangements to simplify the patch
>  - ... and 4 more: https://git.openjdk.java.net/jdk/compare/37b70282...c2c31c3e

Marked as reviewed by kvn (Reviewer).

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