When running some benchmarks with a fastdebug build an assertion is triggered in most cases:

```
# A fatal error has been detected by the Java Runtime Environment:
#
# Internal Error (/**********/jdk/src/hotspot/share/opto/parse1.cpp:521), pid=3049929, tid=3050028
# assert(false) failed: type flow analysis failed during parsing
```

It seems that https://bugs.openjdk.org/browse/JDK-8303951 is the origin of that assertion.

I cannot share the code for the benchmark but I have attached the hs_err file.