* Adjust stack pointer upon returning from call.
In architecture where the return address is pushed on the stack, on
the caller side, we see the the push but not the pop. This means that,
once the stack pointer is no longer global, we need to take this into
account.
This commit fixes this increase the stack pointer of
`FinalStackOffset` right after a function call.
* Drop the size argument from the `revng_init_local_sp` function. We
will have a `revng_stack_frame` function to represent the actual stack
frame pointing to its beginning.
The PromoteStackPointerPass now trivially handles running on modules
where the global variable for the stack pointer is missing.
When the global is not found, the pass just does nothing and returns
false.
This is necessary to handle very small functions, typically from tests.
Pietro Fezzardi