[13] RFR(S): 8219807: C2 crash in IfNode::up_one_dom(Node*, bool)

[Tobias Hartmann]

Thanks Vladimir, I'll add a comment before pushing.

Best regards,
Tobias

On 29.04.19 17:47, Vladimir Kozlov wrote:
> Please, add comment. Otherwise it is good.
> 
> Thanks,
> Vladimir
> 
> On 4/29/19 6:24 AM, Tobias Hartmann wrote:
>> Hi,
>>
>> please review the following patch:
>> https://bugs.openjdk.java.net/browse/JDK-8219807
>> http://cr.openjdk.java.net/~thartmann/8219807/webrev.00/
>>
>> We crash in IfNode::up_one_dom() while walking up the dominator tree because two regions (din3 and
>> din4) are degraded to copies (for details see the bug comments). The control inputs of these regions
>> were set to NULL in RegionNode::Ideal() but the nodes were not removed because we were still parsing.
>>
>> Both regions are on the igvn worklist and will be replaced but the IfNode is processed first and
>> therefore encounters the NULL control inputs. I think the code should guard against that. The bug is
>> very old and reproduces since JDK 8 with the regression test.
>>
>> I will run extended testing as soon as Mach5 is up again.
>>
>> Thanks,
>> Tobias
>>