Even at that point, there was the PDP-11 compiler and the compiler for the Perkins-Elmer implementation, not to mention the (straight) C compiler (/usr/bin/cc)

Even at that point, there was the PDP-11 compiler and the compiler for the Perkins-Elmer implementation, not to mention the (straight) C compiler (/usr/bin/cc) vs the Portable C Compiler, both of which were available on V7. The maxim then (and now) being: Don't Write Silly Code.