RFR: 8255367: C2: Deoptimization during vector box construction is broken [v2]

[Vladimir Ivanov]

Thanks for the review, Vladimir.

> The only concern with such approach is that array could be allocated twice if deoptimization happens during Vector object allocation (after compiled code allocated array). We saw some JVMTI issues with Graal which too does reallocation in some cases during deoptimization.

I assume itcaused some test failures where tests verify that exact 
number of allocations performed. Considering vectors are aggressively 
scalarized and reboxed, it's already hard to predict exact boxing 
behavior. In other words, the number of allocations already drastically 
differ between execution modes (C2 vs C1/interpreter).

Best regards,
Vladimir Ivanov