Comment by PaulHoule

The techniques in the Dragon Book are scientific and let the run-of-the-mill systems programmers build compilers consistently. Before that the field was fragmented, formal grammar not well understood, and compilers faced difficult hardware constraints. So each compiler was hand built, often by exceptional developers, and techniques used were all over the place.

This one is legendary

https://ibm-1401.info/1401-IBM-Systems-Journal-FORTRAN.html

which is sliced into a huge number of passes so the compiler could fit inside a tiny memory footprint (e.g. a "mainframe" with the memory capacity of an Altair)

Another interesting if not so high performance compiler was the first FORTRAN IV compiler for the PDP-11 which used a stack machine instead of register allocation . DEC wasn't interested in making the best possible FORTRAN but instead in making a product that was competitive on the market so they started out with that, then developed a floating point processor designed specifically for that compiler, and then evolved from there.

Although machines from the IBM 360 were broadly competitive they varied from 4k of 16M of RAM and core and had very different implementations which varied in performance by orders of magnitude. Back then it was common for a hardware vendor to publish several compilers for a machine aimed at different balances of compile time and run time. It's not like we don't have some of that now, but anybody who was developing compilers in 1970 was flying on a wing and a prayer.