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

[Igor Veresov]

I’ll fix that. Thanks for the review, Chris!

igor

On Dec 23, 2013, at 7:22 PM, Christian Thalinger <christian.thalinger at oracle.com> wrote:

> +         // assume that the result of the LoadP is the the argument of the StoreP.
> Typo: “the the”
> 
> The fix is good.
> 
> On Dec 21, 2013, at 12:53 AM, Igor Veresov <igor.veresov at oracle.com> 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
> 

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