The stack analysis is the foundation to obtain accurate information
about the body of a function, which registers are callee-saved,
arguments, return values and so on.
It is implemented as a pass to run in revamb-dump.
This commit also introduces analysis tests specific to what we aim to
obtain from the analysis and also some basic unit tests for data
structures related to the stack analysis.
When in `NoFunctionCallsCFG` form it's easy to identify small infinite
loops (i.e., loops without exiting basic blocks), which are often used
to implement the last chance behavior of `abort` or `exit`
functions. Therefore, we include all the involved basic blocks as killer
BBs, which will participate in the computation of the final killer set.
Alessandro Di Federico