We now match the `IfCheckNode` trees created by the dispatchers
insertion as an unique switch.
To this we introduced a new `SwitchCheckNode` AST type, which cannot
inherith from the `SwitchNode` since the underlying container for the
`case`s is different (the index is saved as an `unsigned`, while instead
in the `SwitchNode` we use a `ConstantInt *`.
The condition inside the `IfNode`s are now represented using a custom
`ExprNode` object, which has a new hierarchy of possible nodes present
in an expression (`not`, `and` and `or`).
Moved the `flipEmptyThen` post-processing inside the beautify pass.
The ownership of the `ExprNode` is kept inside the `ASTTree` object.
This means that during the flattening we also need to transfer these
objects and to adjust the pointers inside the `IfNode`s.
Remove the pointer to the corresponding `BasicBlockNode` inside each
`ASTNode`.
We now keep directly a pointer to the original `llvm::BasicBlock`.
To do this we need to explicitly mantain some information, like the
emptyness of the node (dummy node in the `RegionCFG`).
Some little changes (like the way we retrieve the CFGNode corresponding
to an ASTNode) in the flattening have been necessary too.
Add the `IfCheckNode` AST node type, which represents the `Check` nodes
in the RegionCFG. We need an explicit type in the AST since, with the
enforce pass drop before decompilation, we need to handle the code
emission for these type of nodes.
The type has been implemented as a derived type from the `IfNode`, since
they share a lot of similarities, in order to avoid modifications to the
AST simplification functions.
The methods that should not be invoked have been (as the ones that
modify the conditions of the nodes) override and implemented with an
`revng_abort` function
Add a new AST node type for representing the nodes which set the value
for the state variable before an entry or exit dispatcher.
In this way, when printing the decompiled code we do not need to inspect
the node further.
Removed the `Switch` BBNode, which was used to create the intermediates
nodes for making an original `switch` node a nested tree of `if` checks.
Also removed the `IfEqual` AST node, which was used to represent the
intermediate check nodes in the AST, for later reconstructing the
original `Switch` node in the AST, when possible.
Remove from the `IfEqualNode` the reference to the BBNode corresponding
to the original `switch`, since we cannot have the guarantee that this
node will remain allocated in the same place (the pointer could be
invalidated).
Also insert other fixes.
Add a new AST node type for representing the nodes created starting from
the dummy nodes built in place of a `switch` statement.
These nodes contain also the information needed for emitting the code
relative to the checks performed by the node (the condition and the case
value).
This node type inherits from the `IfNode` node type, to avoid
reimplementing all the methods for its handling and transformation.
Now considering the fact that the body of a loop may become empty if
some simplification take place (e.g. we match a `while` whose body is
composed only by a check with `break` and `continue` branches).
When a `while` loop is matched and promoted, add to every `continue`
node in the current scope the instructions needed for the computation of
the loop condition.
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.
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.
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.
Pietro Fezzardi