RFR: 8310829: guarantee(!HAS_PENDING_EXCEPTION) failed in ExceptionTranslation::doit [v4]

[Tom Rodriguez]

On Tue, 27 Jun 2023 21:29:53 GMT, Doug Simon <dnsimon at openjdk.org> wrote:

>> The VMSupport class is required for translating an exception between the HotSpot and libgraal heaps.
>> Loading it lazily can result in a loading exception, obscuring the exception being translated.
>> To avoid this, VMSupport is loaded eagerly along with the other vmClasses.
>
> Doug Simon has updated the pull request incrementally with one additional commit since the last revision:
> 
>   revert to lazy loading of VMSupport

I don't think pushing it down that far improves things.  encode always precedes decode so why not resolve it before the encode call.

      // Resolve VMSupport class explicitly as HotSpotJVMCI::compute_offsets
      // may not have been called.
      Klass* vmSupport = SystemDictionary::resolve_or_fail(vmSymbols::jdk_internal_vm_VMSupport(), true, THREAD);
      int res = 0;
      if (!HAS_PENDING_EXCEPTION) {
        res = encode(THREAD, vmSupport, buffer, buffer_size);
      }

src/hotspot/share/jvmci/jvmciEnv.cpp line 402:

> 400:       }
> 401:       int res = encode(THREAD, buffer, buffer_size);
> 402:       if (_from_env != nullptr && !_from_env->is_hotspot() && _from_env->has_pending_exception()) {

Why is this check before the `HAS_PENDING_EXCEPTION` check?  Couldn't you end up returning with a pending exception in this path?

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PR Comment: https://git.openjdk.org/jdk/pull/14641#issuecomment-1610335668
PR Review Comment: https://git.openjdk.org/jdk/pull/14641#discussion_r1244461845