A TPF stack frame has up to two return addresses in it. The second one is used when the call crosses a shared object domain, where a stub is between the two functions. The stub does not change the stack, but it does eventually chain to the "correct" return address.
In the TPF unwinder, a fallback handler is provided that traps these stub addresses, updates the RA in the frame data, and returns. The next iteration of the unwinding loop sees the "right" RA. However, the CFA is used to "uniquely identify" a call frame. Since the same CFA has two RAs, it is no longer unique, and the assert in _Unwind_RaiseException_Phase2() is triggered. Removing the assert makes everything work just fine, since the next iteration of the loop finds the correct personality etc. In the past, the RA was used to uniquely identify the frame, which also worked for TPF. Any ideas on how to work around this "bug" in the tpf-specific files?
