RFR 8216327 [lworld][c1] checkcast for value type should throw NullPointerException with null operand

[Ioi Lam]

Hi Tobias,

Thanks for the review. The reason I was deoptimizing was I didn't know 
how to distinguish between the Point.box vs Point.val case, so I let the 
interpreter decide whether to throw or not.

Anyway, I've fixed it so that the C1 code can properly decide whether to 
throw NPE, so there's no need to deoptimize.

I also renamed get_never_null() to is_klass_never_null(), so it's more 
apparent what this function does.

What do you think?

http://cr.openjdk.java.net/~iklam/valhalla/8216327-c1-checkcast-null.v02/


On 1/8/19 8:29 AM, Tobias Hartmann wrote:
> Hi Ioi,
>
> what about Point.box? No null check is needed in that case.
>
> Also, why do you need to deoptimize?
>
> Best regards,
> Tobias
>
> On 08.01.19 06:29, Ioi Lam wrote:
>> https://bugs.openjdk.java.net/browse/JDK-8216327
>> http://cr.openjdk.java.net/~iklam/valhalla/8216327-c1-checkcast-null.v01/
>>
>> Please review this small fix.
>>
>> When we have something like this:
>>
>> static Point test() {
>>      Object o = null;
>>      Point p = (Point)o;
>>      return p;
>> }
>>
>> Deoptimize and let the interpreter generate the NPE.
>>
>> Thanks
>> - Ioi
>>
>>
>>
>>
>>
>>