I got some free time again to look at GCC stuff, so I'm going through the source code for Nyog Sothep looking at the problems there.
Right now I'm looking at a problem resulting in "internal compiler error: in use_regs, at expr.c:2245"
This is the result of an assert requiring that all registers be valid. This assert is within expr.c::use_regs.
The call_regs function is being called to validate the usage of a record requiring 19 registers, starting at R1. This sounds like an entire structure is being loaded into registers, and not just the element of that structure we are interested in.
This is the operation which is causing problems:
All of "investigators[i]" is being passed by value in registers instead of passed by reference using one register. Since we don't have enough registers to hold the entire structure, we get a fatal error.