> How did you call a function if you didn’t have a stack for the return address or local variables? Here’s how it worked. First, the compiler defined a secret global variable for each inbound function parameter, plus another secret global variable for each function to hold the return address. It also defined a secret global variable for each of the function’s local variables.
I always assumed that functions did something like this behind the scenes. At the lowest level, all of memory is just a very large, globally-accessible array of numbers. Functions are just JMPs with fancy syntax sugar.
...is that completely wrong? Do modern computers actually have some type of hardware support for functions?
Yes they do. Depending on the architecture, there's either a stack pointer register and CALL/PUSH/POP instructions, or a general purpose auto-increment/decrement addressing mode.
Local variables are placed on the stack as well, this is necessary if you want recursion, and it also typically results in faster/shorter code, because the instruction set and microarchitecture are optimized for this type of memory access.
I always assumed that functions did something like this behind the scenes. At the lowest level, all of memory is just a very large, globally-accessible array of numbers. Functions are just JMPs with fancy syntax sugar.
...is that completely wrong? Do modern computers actually have some type of hardware support for functions?