Let’s say a compiler is doing something in a multi-threaded manner - isn’t it possible that ASLR would affect the ordering of certain events which could change the compiled output? Sure you could just set threads to 1 but there’s probably some more edge cases in there I haven’t thought of.
I think you'd need the compiler to guarantee serialization order of such operations regardless if you used ASLR or not. Otherwise you're just hoping thread scheduling, core clocking, thread memory access, and many other things are the same between every system trying to do a reproducible build. Even setting threads to 1 may not solve that problem class if asynchronous functions/syscalls come into play.
