Added a pass that removes the `bad_return_pc` check, which is useful
only when we want to preserve semantics, but it is useless and harmful
for decompilation.
Instead of rebuilding the dominator and postdominator at each iteration
of the inflate procedure, use the utilities introduced in LLVM 7.0 to
keep the data structures updated after each change to the RegionCFG.
Now, during the simplification of short-circuits the so called
`de-optimization` is also applied to the corresponding `RegionCFGTree`.
This allows us to avoid loss of information during the iterative
refinement phase, which basically divides for ever the existencies of
two nodes that have been cloned starting from a single original one.
We now perform the AST serialization directly on file, without using
stderr. In this way we can follow the evolution of simplifications and
changes to the AST tree.
After short-circuit simplification, we can have that a conditional node
corresponds to more than one `BasicBlockNode`.
This change reflects this fact, and takes care of merging blocks during
short-circuit simplification, and of representing this change in the
serialization.
Improved the `dumpOnDotFile` function to take as a parameter also a
sub-folder name.
Modified the `inflate` function to dump on file the graphs after each
modification.
Now the `isEqual` operator does what we call a `deep` comparison,
meaning for every type of `ASTNode` it recursively check if the
structures of the AST tree originating in that node can be considered
equivalent (e.g., two sequence nodes are considered equal if every node
they contain is in turn equal).
This operator gives more space to the short-circuit simplification,
which relies heavily on the `isEqual` operator.
First concept of short-circuit simplification.
The `isEqual` operator between ASTNodes is very limited (it does only
check if two nodes originate from the same `BasicBlock` in the original
IR.
Added a new pass that simply purge all the functions in a module from
the useless basic blocks that simply do the `pc` serialization.
Without this until we have available the optimization/comb iterative
refinement, we would not be able to test the short-circuit
simplification.
Pietro Fezzardi