[lworld] RFR: 8264414: [lworld] [AArch64] TestBufferTearing.java fails with C1 [v3]

[Frederic Parain]

On Mon, 12 Apr 2021 09:51:42 GMT, Nick Gasson <ngasson at openjdk.org> wrote:

>> We see failures like this on AArch64 when MyValue.incrementAndCheck() is
>> compiled with C1:
>> 
>>   java.lang.RuntimeException: Inconsistent field values: expected 0 to equal 675128
>>         at jdk.test.lib.Asserts.fail(Asserts.java:594)
>>         at jdk.test.lib.Asserts.assertEquals(Asserts.java:205)
>>         at jdk.test.lib.Asserts.assertEQ(Asserts.java:178)
>>         at compiler.valhalla.inlinetypes.MyValue.incrementAndCheck(TestBufferTearing.java:81)
>>         at compiler.valhalla.inlinetypes.TestBufferTearing$Runner.run(TestBufferTearing.java:124)
>> 
>> The barrier that is usually inserted on return from a method that wrote
>> final fields should be sufficient to prevent another thread seeing the
>> zero-initialised intermediate state.  However this barrier isn't
>> inserted at the moment because method()->is_object_constructor() is
>> false for primitive class constructors.
>> 
>> C2 has a similar guard around the memory barrier in Parse::do_exits().
>> I'm not sure if that needs amending as well but I've not seen any
>> failures due to it.
>
> Nick Gasson has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Add extra missing membar and simplify test

Looks good to me.
Thank you for finding and fixing it!

Fred

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Marked as reviewed by fparain (Committer).

PR: https://git.openjdk.java.net/valhalla/pull/376