RFR: 8274379: Allow process of unsafe access errors in check_special_condition_for_native_trans [v2]

[David Holmes]

On Tue, 5 Oct 2021 19:57:32 GMT, Patricio Chilano Mateo <pchilanomate at openjdk.org> wrote:

>> Hi,
>> 
>> 
>> Please review the following patch to allow processing of unsafe access errors in check_special_condition_for_native_trans().
>> 
>> Today we special case unsafe access errors from other async exceptions in that we don't process them when transitioning from native back to Java. Code comments in check_special_condition_for_native_trans() mention that unsafe access errors should not be handled because that may block while creating the exception. But that should not be an issue since we can always make sure we call process_if_requested_with_exit_check() after the call to throw_unsafe_access_internal_error() to process any pending operations not already handled in a ThreadBlockInVM wrapper (today that only means suspend requests and object reallocation operations).
>> 
>> By removing this special treatment for unsafe access errors we can also simplify the async exception support API. For instance we can remove _async_exception_condition and simplify some of the supporting methods. I also removed the _thread_in_native case from the switch statement in check_and_handle_async_exceptions() since we never call that method in that state.
>> 
>> Testing by running tiers1-6 in mach5. 
>> 
>> Thanks,
>> Patricio
>
> Patricio Chilano Mateo has updated the pull request incrementally with four additional commits since the last revision:
> 
>  - async API cleanup
>  - general cleanup
>  - allow process of unsafe access errors in check_special_condition_for_native_trans
>  - revert to separate commits

The final commit for API changes was a bit harder to follow, but overall seems okay.

One comment/suggestion below but otherwise I'll use this to approve the overal change.

Thanks,
David

src/hotspot/share/runtime/thread.cpp line 1722:

> 1720:       // Set async. pending exception in thread.
> 1721:       _pending_async_exception = java_throwable;
> 1722:       set_suspend_flag(_has_async_exception);

Not clear why we didn't just simplify set_pending_async_exception.

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Marked as reviewed by dholmes (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/5741