RFR: 8372685: C2 SuperWord: wrong requires in test after JDK-8371146

[Christian Hagedorn]

On Thu, 27 Nov 2025 13:53:12 GMT, Emanuel Peter <epeter at openjdk.org> wrote:

> @MBaesken Reported this issue on windows:
> 
> TestAliasingCheckPreLimitNotAvailable_all-flags-fixed-stress-seed.jtr and TestAliasingCheckPreLimitNotAvailable_all-flags-no-stress-seed.jtr show failures on WIndows :
> 
> [0.095s][error][gc] Failed to lookup symbol: VirtualAlloc2
> Error occurred during initialization of VM
> ZGC requires Windows version 1803 or later
> 
> AIX fails too :
> Error occurred during initialization of VM
> Option -XX:+UseZGC not supported
> 
> 
> I learned a small lesson here: `@requires vm.gc.Z` is much smarter than checking that no other GC is set, or ZGC is set. It also checks if ZGC is available, which is not always the case, e.g. on the reported Windows machne.
> 
> @MBaesken Can you please confirm that this fixes the test for you?

That was hard to spot, looks good and trivial but let's wait for @MBaesken to confirm.

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Marked as reviewed by chagedorn (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/28537#pullrequestreview-3515692306