> Why are they leaving out difficilty of building a compiler backend when the ISA has variable-length codes? Because compiling into the maching code and the ma

> Why are they leaving out difficilty of building a compiler backend when the ISA has variable-length codes? Because compiling into the maching code and the machine code decoding by the CPU have different time constraints. One can even argue that a compiler has an infinite time (however impractical it is) to translate a programming language into the binary code, whereas the CPU does not have the same luxury hence the haggle over the ISA's. So it makes sense to leave the compiler code generator out of the picture.