[10] RFR(M): 8176506: C2: loop unswitching and unsafe accesses cause crash

[Vladimir Ivanov]

> http://cr.openjdk.java.net/~roland/8176506/webrev.02/

Looks good.

>> src/share/vm/opto/library_call.cpp:
>>     } else {
>> +    // We know it's an on heap access so base can't be null
>> +    base = must_be_not_null(base, true);
>>       return basic_plus_adr(base, offset);
>>     }
>>
>> Why do you unconditionally apply GK::must_be_not_null() even when base
>> is provably non-null?
>
> It would be optimized out. Anyway, I followed your suggestion and added
> a check.

Thanks. It goes away only after macro node expansion (since the test is 
hidden behind Opaque4), so my concern was that it can hinder some 
optimizations.

Best regards,
Vladimir Ivanov