RFR: 8307462: [REDO] VmObjectAlloc is not generated by intrinsics methods which allocate objects [v3]

[Tobias Hartmann]

On Fri, 4 Aug 2023 19:45:56 GMT, Leonid Mesnik <lmesnik at openjdk.org> wrote:

>> The fix adds posting VmObjectAlloc events by Unsafe.allocateInstance(Class<?> cls). The previous attempt to post event directly from 'LibraryCallKit::inline_unsafe_allocate()' cause performance regression even if jvmti event is not enabled.  Some optimizations have been disabled just because possible usage and escaping of newly allocated  object.
>> So event posting is doing by returning to interpreter if events are enabled.
>> 
>> I verified that that performance (run locally only) of
>> org.renaissance.jdk.streams.JmhScrabble.runOperation
>> doesn't change if events are not enabled.
>> 
>> There might be other intrinsics like 'LibraryCallKit::inline_unsafe_newArray()' where VM allocate memory. I'm going to file separate issue to find and fix them.
>> 
>> Many thanks to Tobias H. for proposed solution.
>> 
>> Testing with all tiers.
>
> Leonid Mesnik has updated the pull request incrementally with one additional commit since the last revision:
> 
>   The too many deopts check should be first.

Looks good to me.

src/hotspot/share/opto/library_call.cpp line 2845:

> 2843:     }
> 2844:     if (stopped())
> 2845:       return true;

Suggestion:

    if (stopped()) {
      return true;
    }

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

Marked as reviewed by thartmann (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/15110#pullrequestreview-1568773710
PR Review Comment: https://git.openjdk.org/jdk/pull/15110#discussion_r1287968367