RFR(XS) 8027388: JVM crashes with SIGSEGV (0xb) at pc=0x00000001077cbbf6

[Vladimir Kozlov]

Looks good.

Thanks,
Vladimir

On 12/21/13 12:53 AM, Igor Veresov wrote:
> Given the following graph, escape analysis currently fails to track the fact that we can load from null.
>
>   Allocate A <-- ...---------- StoreP
>   Allocate B <-- ... - AddP <--/
>            \
>             Phi <--- ... -- AddP <--- LoadP
>   null <-- /
>
> The AddPs may refer to the same field of B, however, B could be null so we cannot assume that the result of the LoadP is
> the the argument of the StoreP.
> We don't want to add edges to null_obj for performance reasons, so we handle this case by faking the effect of storing a
> null to this field, which will force a potential non-escaping object (that is also stored to this field) to be marked as
> not scalarizable. The end result is the same -- we cannot predict that value of the field. Notice that if B is
> non-escaping it will be made non-scalarizable as well because the field has two bases.
>
> Webrev: http://cr.openjdk.java.net/~iveresov/8027388/webrev.00/
> Testing: jtreg, ctw
>
> Huge thanks to Vladimir for discussions and helping me out with this problem!
>
> igor