A C compiler is not a single executable. If you take gcc, compiling C code involves a preprocessor, a compiler, an assembler and a linker (and that's a.simplified view). To make matters worse, the assembler and the linker are not even part of the GCC source code, they're a separate project. That would likely make the process of DDC significantly more difficult than if the compiler was actually a single executable. Also, there are other things involved in the whole process, like the CRT static objects, dynamic libraries and the dynamic loader. That's many more items to trust. You could even add the kernel to the list.