RFR: 8252219: C2: Randomize IGVN worklist for stress testing [v6]

[Vladimir Kozlov]

On Thu, 24 Sep 2020 07:38:06 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 incrementally with one additional commit since the last revision:
> 
>   Empty commit to trigger jcheck after updating GitHub user name

test/hotspot/jtreg/compiler/arguments/TestStressIGVNOptions.java line 32:

> 30:  *      compiler.arguments.TestStressIGVNOptions
> 31:  * @run main/othervm -XX:+StressIGVN -XX:StressSeed=42
> 32:  *      compiler.arguments.TestStressIGVNOptions

Please, add next to run test when C2 is enabled as you did for other 2 tests:
@requires vm.compiler2.enabled

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

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