Change company name to "rev.ng Labs Srl" in all license headers
to reflect changed company name and legal status
Add missing license headers to files that didn't have one
Before this commit there was a single pass removing equality SCC and
inheritance SCC.
This commit splits the removal of each kind of SCC in a separate
DLAStep, and adds handling of instance-at-offset-0 SCCs that were not
considered before.
DeduplicateUnionFields does not depend on CollapseSingleChild, but can
break if CollapseSingleChild has not run.
However, we don't want to introduce an explicit dependency between the
two steps, because CollapseSingleChild could soon become obsolete on
its own, superseeded by a more powerful and costly step.
This commit changes DeduplicateUnionFields with an additional
pre-processing that runs CollapseSingleChild on each node at step one,
to ensure the step does not fail if CollapseSingleChild child is not
executed.
* Changes to the `LayoutTypeSystem` graph
Pointers are identified in the TypeSystem graph as leaf nodes which
have a new type of edge (PointerEdge) that connects them to another
node of the graph. The destination of the edge represents the layout of
the pointed type.
* Changes to the Front-end
Pointer edges, and their destination nodes, are created by the DLA
front-end (`DLACreateIntraProceduralTypes`) whenever an access node has
a size that is compatible with the size of a pointer in the current
Architecture.
Successors might then be added to the newly generated node, if any,
by looking up the llvm::Value it is attached to.
* Changes to the Middle-end
Most of the DLA passes should ignore Pointer Edges, so they are modified
accordingly. Most notably, nodes that represent pointed layouts should
never be merged/pruned-off.
* Changes to the Back-end
The `TypeDeclCreationAction` of the decompiler and the `DLAMakeLayouts`
step of the DLA back-end are modified to take into account the new
information about pointers.
⚠️ There is a known issue with this version of the decompiler,
namely the fact that type loops are not detected and can cause the
emitter to enter an infinite loop.
Add a step that recognizes if two subtrees of a union node are
topologically equivalent and merges them. This corresponds to removing
duplicate fields in unions.
This deduplication was prevously done while emitting layouts.
A check is inserted into DLAMakeLayouts to assert that, after
constructing unions, no union has only one child, which could be the
case if we didn't deduplicate union fields in the graph.
Giacomo Vercesi