The ECLiPSe compiler is actually contained in the eclipse library lib(ecl_compiler) which relies on a number of auxiliary modules. It uses lib(source_processor) to read programs, and produces abstract machine code that is assembled using lib(asm).
The built-in predicate als/1 or asm:wam/1 lists the abstract code of the given predicate and it can thus be used by experts to check if the predicate was compiled as expected.