regression test coverage for sim/common ?

[Joern Rennecke]

I have a patch that speeds up simulator startup for simulators that
use code in sim/common to create a new simulator instance.

Instead of xmalloc / memset I use xcalloc to obtain zeroed memory;
on operating systems like a recent glibc/Linux system, this allows
the pages to me faultyed in as if they had been mmapped.

What would be a suitable simulator target for a regression test?