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

[eme64]

@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?

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Issue

• JDK-8372685: C2 SuperWord: wrong requires in test after JDK-8371146 (Bug - P4)

Reviewers

• Christian Hagedorn (@chhagedorn - Reviewer)
• Matthias Baesken (@MBaesken - Reviewer)

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

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[chhagedorn]

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

[MBaesken]

ZGC requires Windows version 1803 or later

Maybe this can be improved to something like 'ZGC requires Windows 10 version 1803, Windows 11 or Windows server 2019 or later' .
In fact, not all Windows server 2016 have VirtualAlloc2 (see also this discussion microsoft/ebpf-for-windows#704 ) .
Our test machine with Windows server 2016 generated the error above .

Unfortunately MS claims here
https://learn.microsoft.com/en-us/windows/win32/api/memoryapi/nf-memoryapi-virtualalloc2
Windows 10 [desktop apps only] / Windows Server 2016 [desktop apps only]
without stating any OS versions.

[eme64]

@MBaesken Thanks for the additional information!

I leave it up to you if you want to file an RFE for the error message. I don't have the expertise on Windows nor on GC.

Can you confirm that this change fixes your issue though? Because I could not reproduce the issue on my machine, so I'm relying on you here ;)

[MBaesken]

Can you confirm that this change fixes your issue though? Because I could not reproduce the issue on my machine, so I'm relying on you here ;)

This fixes the issue on all our machines where the problem showed up yesterday!

[MBaesken]

LGTM

[MBaesken]

I leave it up to you if you want to file an RFE for the error message. I don't have the expertise on Windows nor on GC.

@xmas92 , @jsikstro what do you think ?
Is this about the 'ZGC requires Windows version 1803 or later' message that surprised us a little bit because we see it on Windows server 2016 , but the 1803 looks like it refers to some update of good old Win 10 .

[jsikstro]

@MBaesken 1803 seems to refer to both a Windows 10 and Windows Server 2016 (internal) release number/version. Here's a version list of the old semi-annual releases of Windows Server 2016: https://en.wikipedia.org/wiki/Windows_Server#Semi-Annual_releases_(discontinued)

[MBaesken]

@MBaesken 1803 seems to refer to both a Windows 10 and Windows Server 2016 (internal) release number/version. Here's a version list of the old semi-annual releases of Windows Server 2016: https://en.wikipedia.org/wiki/Windows_Server#Semi-Annual_releases_(discontinued)

Thanks !
The wikipedia says 'semi-annual releases do not include any desktop environments. Instead, they are restricted to the Nano Server configuration installed in a Docker container,[17][29] and the Server Core configuration, licensed only to serve as a container host' so this sounds like it is a rather special 'flavor' of Win Server 2016 .
So maybe it is no wonder what we get the warning and have no VirtualAlloc2 on our Win Server 2016 test machine.