RFR: 8277573: VmObjectAlloc is not generated by intrinsics methods which allocate objects

[Leonid Mesnik]

On Mon, 10 Apr 2023 18:46:42 GMT, Serguei Spitsyn <sspitsyn at openjdk.org> wrote:

>> Updated VM internal object allocation C2 intrinsic to post jvmti events when needed.
>
> src/hotspot/share/opto/library_call.cpp line 2856:
> 
>> 2854:   set_result(ideal.value(result));
>> 2855:   return true;
>> 2856: #else
> 
> Nit: It is better to replace #else at 2856 with #endif. Then #endif at 2859 is not needed.

In this case the code is:
 ```
 set_result(ideal.value(result));
  return true;
  set_result(obj);
  return true;


Which might cause compiler warnings and complains from static analyzers.

> src/hotspot/share/prims/jvmtiEventController.cpp line 727:
> 
>> 725:     JvmtiExport::set_should_post_on_exceptions((any_env_thread_enabled & SHOULD_POST_ON_EXCEPTIONS_BITS) != 0);
>> 726: 
>> 727:     JvmtiExport::_should_post_allocation_notifications = JvmtiExport::should_post_vm_object_alloc();
> 
> I'm not sure why this flag is needed. It looks like a dup of `JvmtiExport::should_post_vm_object_alloc()`.
> Can we just replace it with `JvmtiExport::should_post_vm_object_alloc()`?

I don't think we could replace it by function. Also, I think that it is needed later to add SampledObjectAlloc event here. It should consider VM internal object allocations along with all allocations.

> test/hotspot/jtreg/ProblemList-Xcomp.txt line 41:
> 
>> 39: serviceability/sa/TestJhsdbJstackMixed.java 8248675 linux-aarch64
>> 40: 
>> 41: serviceability/jvmti/VMObjectAlloc/VMObjectAllocTest.java 8288430 generic-all
> 
> If the 8288430 is a dup of 8277573 then should we close it as such?

Done.

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

PR Review Comment: https://git.openjdk.org/jdk/pull/13312#discussion_r1162123421
PR Review Comment: https://git.openjdk.org/jdk/pull/13312#discussion_r1162124409
PR Review Comment: https://git.openjdk.org/jdk/pull/13312#discussion_r1162124580