C99 did not introduce the “strict” aliasing rules, C89 says more or less the same thing about that. It’s just that the inexorable (relative) slowing down of RAM

C99 did not introduce the “strict” aliasing rules, C89 says more or less the same thing about that. It’s just that the inexorable (relative) slowing down of RAM and the gradual extinction of low-hanging optimization fruit led compiler authors to seriously consider aliasing-based optimizations at around the same time.