RFR (S) 8131782: C1 Class.cast optimization breaks when Class is loaded from static final

Aleksey Shipilev aleksey.shipilev at oracle.com
Fri Jul 24 09:50:26 UTC 2015

On 21.07.2015 13:05, Aleksey Shipilev wrote:
> On 21.07.2015 00:14, John Rose wrote:
>> On Jul 20, 2015, at 6:52 AM, Aleksey Shipilev <aleksey.shipilev at oracle.com> wrote:
>>> On the road from Unsafe to VarHandles lies a small deficiency in C1
>>> Class.cast/isInstance optimization: the canonicalizer folds constant
>>> class perfectly when it is coming from "inlined" constant, but not from
>>> static final, because the constant "shapes" are different:
>>>  https://bugs.openjdk.java.net/browse/JDK-8131782
>> I suggest a deeper fix, to the factory that produces the oddly formatted constant.
>> That may help with other, similar constant folding problems.
> All right, let's do that!
>   http://cr.openjdk.java.net/~shade/8131782/webrev.02/
> I respinned it through JRPT and my targeted benchmarks, and it performs
> the same as previous patch.

Any other reviews pending? If not, please sponsor!


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