RFR: aaload/aastore profiling

[Roland Westrelin]

>> A non null free value array has a subtype, the null free value array,
>> right?
>> Without that change, the c1 code assumes that if it sees any value
>> array, it knows the exact type.
>
> Okay, I was just wondering why we didn't need that code before.

Could be it's only used by profiling and so incorrect profiling doesn't
cause any failure.

>> The problem is that I replaced the existing aastore profiling. So with
>> -EnableValhalla we would go back to the previous aastore profiling and
>> previous MonomorphicArrayCheck?
>
> Right if that's getting too complex, we can just have it always enabled.

Also for -EnableValhalla/+EnableValhalla performance comparisons, I
think it makes sense that -EnableValhalla runs with the improved
MonomorphicArrayCheck or type speculation that leverages the new
aaload/aastore profile data.

Roland.