> Sure, but you still generate the machine code, right? You still have to master the instructions and their specifics of the target CPUs.
replyYou do, but self-hosted compilers tend to have two huge benefits:
1) they tend to be easier to reason about, being written in a high-level language
2) they exercise the code, and usually even seldom-used parts of the code, to make problems more noticeable
But once you have written in assembly, you could start to write the next version in the higher level language. The first version (written in assembly) doesn't necessarily have to produce the most optimal code, just good enough and correct. Most of the improvements can be done in the self hosted compiler (in a higher level language). So this period did not have to last many years.
replyI am sure writing a self-hosted Fortran compiler is possible, but it wouldn’t be my first choice for writing a Fortran compiler, even given the Fortran of today.
replyIn the 1970s, it would have been really low on my list, likely below using a macro assembler.