RFR: 8335921: Fix HotSpot VM build without JVMTI

[Vladimir Kozlov]

On Wed, 17 Jul 2024 04:52:35 GMT, David Holmes <dholmes at openjdk.org> wrote:

>> Citing David Holmes from bug report:
>> "We provided the ability to leave out certain VM services (JVMTI, GC's other than serial, ...) as part of the design of the MinimalVM to support Java SE Embedded, along with the Compact Profiles of JDK 8. This manifested in the source code as a set of INCLUDE_XXX ifdef guards. The build system later exposed these as individual --with-jvm-features=xxx,yyy support. However, it was never intended (and certainly not tested) that you could mix-and-match arbitrary subsets of these VM features at will. Consequently if you start trying to do this you will find things that need fixing."
>> 
>> I added `INCLUDE_JVMTI` guards in two places where it was missed: JVMCI and JFR.  Affected code was added recently, in the past year. After that I was able to build VM on all supported platforms.
>> 
>> Note: building VM without JVMTI is not officially supported feature. We are not testing it and such failures (missing guards) are not unexpected.
>> 
>> A lot of tests failed with VM without JVMTI. All are expected failures. I listed failed tests in bug report.
>> I fixed (added requires `vm.jvmti`) only one which was part of [JDK-8257967](https://bugs.openjdk.org/browse/JDK-8257967) changes which introduced JFR code without `INCLUDE_JVMTI` guards.
>> 
>> I ran 2 rounds of testing:
>> 
>> First, only **tier1** with VM built without JVMTI to see if builds passed and which tests affected. I wrote comment in bug report which tests failed (all expected to fail without JVMTI).
>> 
>> Second round of testing with JVMTI in VM: tier1-4
>
> src/hotspot/share/jfr/instrumentation/jfrJvmtiAgent.hpp line 35:
> 
>> 33:   JfrJvmtiAgent();
>> 34:   ~JfrJvmtiAgent();
>> 35:   static bool create() NOT_JVMTI_RETURN_(true);
> 
> It initially seemed odd to return `true` here, but looking through the JFR code that interacts with the Agent it seems the right way to view this is that without JVMTI we have a no-op agent.

Right.

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PR Review Comment: https://git.openjdk.org/jdk/pull/20209#discussion_r1680433885