FXC, the shader compiler - emd4600/SporeModder-FX GitHub Wiki

FXC is a program included in the DirectX SDK (now Microsoft SDK) that is used to compile/decompile shaders. If you want to use shaders with SporeModder FX, you will need it (just download the Microsoft SDK).

SporeModder FX should be able to autodetect the path if you have it installed. Still, you can specify the path manually in the Program Settings: