RFR: 8203923: Add @requires feature to check flag values for the running JVM

[Vladimir Kozlov]

Looks good.

When you do tests changes you need to filter out running Graal with ZGC 
because it does not support it yet.

Vladimir

On 5/29/18 7:21 AM, Stefan Karlsson wrote:
> Hi all,
> 
> Please review this patch to add @requires vm.opt.final.<vm flag name>, 
> as a way to filter jtreg tests on the final value of flags in the test VM.
> 
> http://cr.openjdk.java.net/~stefank/8203923/webrev.01/
> https://bugs.openjdk.java.net/browse/JDK-8203923
> 
> This patch is needed to allow tests to be filtered out when ZGC is run.
> 
> ZGC doesn't support UseCompressedOops (and currently doesn't support 
> ClassUnloading). Instead of adding @requires vm.gc != "Z" for tests that 
> rely on ClassUnloading, I think it's nicer to write @requires 
> vm.opt.final.ClassUnloading.
> 
> This will filter out the test if any of the following conditions are met:
> 1) The currently executing VM doesn't support ClassUnloading
> 2) -XX:-ClassUnloading is passed to the test
> 
> The second case can today be handled by @requires vm.opt.ClassUnloading 
> == NULL | vm.opt.ClassUnloading == true, or maybe simpler @requires 
> vm.opt.ClassUnloading != false, but if you need both @requires 
> vm.opt.final.ClassUnloading should be used.
> 
> The current solution requires the queried flags to be listed in 
> vmOptFinalFlags. Maybe there's a way to get this to cover all flags 
> automatically?
> 
> Thanks,
> StefanK