Vectorizing compilers have been around since at least the late 1970s; the Cray 1[0] had a vectorizing compiler in 1978.
Lamport’s Parallel Execution of DO Loops[1] was published in 1974.
[0] https://en.m.wikipedia.org/wiki/Cray-1#Software
[1] http://lamport.azurewebsites.net/pubs/do-loops.pdf