Assembler
As we explained before, a platform has to have an assembler in order to produce object files that contain correct machine-level instructions. In a Unix-like operating system, the assembler can be invoked by using the as utility program. In the rest of this section, we are going to discuss what can be put in an object file by the assembler.
If you install two different Unix-like operating systems on the same architecture, the installed assemblers might not be the same, which is very important. What this means is that, despite the fact that the machine-level instructions are the same, because of being on the same hardware, the produced object files can be different!
If you compile a program and produce the corresponding object file on Linux for an AMD64 architecture, it could be different from if you had tried to compile the same program in a different operating system such as FreeBSD or macOS, and on the same hardware. This implies that while the object files cannot...
