This enables us to add all local variable Definitions to the DAST so that downstream visitors don't need to compute the local variables of a function again.
The GenASM visitor only uses quad mnemonics so each manipulation to the stack is done in 8 byte chunks. This means our stack is always 8 byte aligned which is fine when only calling KLang code. libc functions like 'malloc' or 'free' require the stack to be 16 byte aligned which isn't automatically guaranteed when being 8 byte aligned. This is why we need to be careful when manipulating the stack (e.g. pushq, popq, subq x, %rsp). By assuming that we are stack aligned at the beginning of execution and by tracking the number of pushq operations we can deduce whether we misaligned the stack and align it again by adding another 8 byte to the stack.
This re-alignment of the stack is done directly before entering a function body or calling malloc. Since there are no stack manipulations involved when generating the code to calling 'free' there is reason to check for alignment there.
We generate our own main function that executes the user's specified expression at the end of his file. This auto generated function has to be called "main" in order for it to be executed on startup. If the user chooses to call one of his own functions "main" our auto generated function would collide with the user's function. That's why we quietly rewrite the user's function to "main_by_user". This way we prevent a collision.
Note for the future: We should change our Syntax to allow for no expression as the last definition of a file. This way the user can choose if a particular source file needs to contain a main function or not (just like c does it). This is also one of the requirements for modules to work.
This allows us to store the index of the enum value along the name. The index can be used to compare two enum values in assembler.
Later on this might be used to enable users of KLang to set arbitrary values as the index of an enum value.
