"C is a genereal purpose language, not tied to a particular system" The C programming Language, BRIAN W KERNIGHAN & DENNIS M. RITCHIE
Yet with the right compiler we can make a .exe which runs on every Windows machine, which in turn means on every CPU Windows runs on.
So my question is: does every x86-64 CPU (Intel or AMD) use the same instruction set ? (yes, I could make a comparison...) if not, then I'll have to assume that the compiler detects what CPU we're running and uses the right instruction set during compile time.
Am I totally mistaken ?
I barely know what I'm talking about so please bear with me. Just a dude trying to look under the hood.
Thank you
Intel makes many different processor models that share a core instruction set of the “x86-64” family (and additional processor models that do not). Even among the processors with the shared core instructions, there are variations. Newer models may have instructions that older models did not, and some parts of the instruction set may be on certain models and not others.
Some instructions even behave differently on different processors.
When you compile a program, the compiler “targets” a particular combination of instruction subsets. This means the instructions in those subsets are available for the compiler to use when it is generating code. The compiler might or might not use any particular instruction or subset depending on its needs or choices when compiling a particular program. The resulting program is then suitable for processor models with the targeted instructions and not for other models (unless the compiler happened not to use any of the instructions not on those models, even though it could have).
Often, the default setting for the compiler‘s target is either a processor model like the one you are running on or some typical selection of instruction subsets that is common for modern processor models. The target may also be selected based on other settings you give the compiler, such as asking it to target a particular version of an operating system. However, you can pass the compiler switches to tell it to compile for entirely different targets, even for entirely different architectures, such as compiling for an ARM processor while running on an Intel processor.
Software is also part of a computer system, so the executable file the compiler produces may also depend on certain software libraries being available at run-time or certain operating system features being available.