RFR(XS) 8057758: Tests run TypeProfileLevel=222 crash with guarantee(0) failed: must find derived/base pair

Igor Veresov igor.veresov at oracle.com
Tue Sep 9 22:06:40 UTC 2014

Looks good.


On Sep 9, 2014, at 11:50 AM, Vladimir Kozlov <vladimir.kozlov at oracle.com> wrote:

> http://cr.openjdk.java.net/~kvn/8057758/webrev/
> https://bugs.openjdk.java.net/browse/JDK-8057758
> The problem evaluation and fix were done by Roland:
> "Crash goes away when run with -XX:-UseMultiplyToLenIntrinsic.
> After intrinsification of MultiplyToLen, type speculation registers the fact that profiling reported non null objects being returned. It adds a CheckCastPP node for that. The MultiplyToLen sets its return type to TypeAryPtr::INTS. The CheckCastPP that is created by type speculation casts the non speculative type to TypeAryPtr::INTS which has an offset of Type::OffsetBot. Even after the speculative part of the CheckCastPP is removed, the CheckCastPP is not optimized out and the buildOopMap code wrongly assumes the result of the CheckCastPP to be a derived pointer."
> Use TypeAryPtr::INT type with offset 0.
> Thanks,
> Vladimir

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