I haven't been able to reproduce a crash that looks like either of the issues
you reported, the ShouldNotReachHere in frame.cpp and the crash in
FastScanClosure. Do you have a test that can reproduce it and are you running
against the latest version of the code?
tom
On May 23, 2011, at 7:33 PM, Ola Bini wrote:
> Hi,
>
> I'm happy to see that the performance degradation is getting addressed.
> I would like to point out that there is still a serious crash in the
> machinery too... Have you seen any reason why that happens?
>
> Cheers
>
>
> On 2011-05-24 06.11, John Rose wrote:
>> On May 23, 2011, at 3:44 PM, Tom Rodriguez wrote:
>>
>>>> I'd *love* for intermediate static Java snippits like this to
>>>> inline straight through, even if invokeExact would be megamorphic
>>>> under normal circumstances...but I don't think that's the case
>>>> right now, right?
>>>
>>> I haven't been following 292 that closely but it used to be a piece
>>> of code that did precisely that.
>>>
>>> + private Object invoke_L0() throws Throwable { +
>>> if ((boolean) test.invokeExact()) + return
>>> target.invokeExact(); + return fallback.invokeExact(); +
>>> }
>>>
>>> It looks like it was reworked at some point to use
>>> selectAlternative but the optimizer was never updated to deal with
>>> it properly. It's not particularly hard, we just need to generate
>>> code like we would for a bimorphic call site. The current code
>>> expects to either get a constant or something else and doesn't
>>> inline if it's something else. In this case we have a Phi of two
>>> constants which we just need to split.
>>
>> Yes, it would be a quasi-bimorphic call site keyed from a phi of two
>> constants, instead of a profile of two receiver classes.
>>
>>> I'm still unclear why you couldn't write your own variant of
>>> guardWithTest and have it work but my knowledge of what's really
>>> allowed is somewhat limited.
>>
>> Those snippets will inline (I think), but at some point Charlie will
>> want to fetch a bit of constant stuff out of an instance variable.
>> That will look non-constant to the optimizer, even if the instance
>> variable is final and the enclosing object is a constant reference.
>> We made sure this happens for java.lang.invoke classes, but we
>> haven't extended it yet to user code, in part because it would have
>> its own bug tail to work through.
>>
>> -- John _______________________________________________ mlvm-dev
>> mailing list mlvm-dev@openjdk.java.net
>> http://mail.openjdk.java.net/mailman/listinfo/mlvm-dev
>>
>
>
> --
> Ola Bini (http://olabini.com)
> Ioke - JRuby - ThoughtWorks
>
> "Yields falsehood when quined" yields falsehood when quined.
>
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