I am also asking how stables are llvm and llvm-gcc under cygwin (since
our engine is windows based)? Do you think that we can compile such
thing without really big problems (and hacks)?
I haven't tried Cygwin for ages, but, as it seems to me, it's not a
solution you're looking for (due to some license restrictions, etc).
LLVM (and llvm-gcc4) compiles and runs fine on Mingw32 platform, so,
maybe it will be much better for you.