When deduplicating unions, for each union we compare each successor
with all other successors. However, the same successor node might be
reachable by more than one edge from the parent.
This can cause problems when a node gets merged while the comparison is
still ongoing. In particular, since the comparison is done using a copy
of the successor list, to avoid iterator invalidation, the links in
the worklist are not updated when a node gets merged, causing links to
the merged node to have an invalid destination.
The fix here is to keep a list of **nodes** to visit, and a list of
**edges** that have already been visited, so that, if a node is merged
through one of its links, we are not visiting other links connected to
the same node after the merge.
Before this commit, SerializeModelPass and SerializeModelWrapperPass had
hard dependencies on the passes that load the model from LLVM-IR.
This commit makes this dependency optional. When the passes for model
serialization are executed, if they see that nobody requested to load
the model, they will not try to serialize it.
This prevents them from crashing when running in pipelines that only
contain passes that ignore the model.
This is particularly beneficial because `revng opt` automatically adds
`-serialize-model` at the end of each pipeline and, before this commit,
this meant that `revng opt` could not be used for unit-testing simple
llvm passes that do not use the model.
With this commit, `revng opt` can be used for unit-tests, even on LLVM IR
with missing model.
* Introduce some documentation for the model.
* Improve the way enums are serialized/deserialized.
* Mark certain fields of model data structures as optional.
* introduces some error messages during model validation.
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.
Since the reasoning behind single child collapsing can be reused in
other points of the DLA pipeline, move the logic that acts on a single
node in a static function out of the CollapseSingleChild step.
This commit reserves the "unnamed_" prefix for revng.
The first use of this reserved prefix is in `model::Type`s
`CustomName`s and `model::Identifier`s.
This commit also makes the `verify()` method stricter for
`model::Identifier` so that an `Identifier` whose name starts with the
reserved prefix does fails verification.
This commit changes the `TupleTree::deserialize` method to return an
`llvm::ErrorOr<TupleTree>`, enabling users to choose their policies on
error reporting.
Break node creation is now improved to avoid edge index swapping that
can cause inversion of conditions later on in the decompilation
pipeline.
To do this, the creation and connection of the break nodes is done
during the bulk insertion of nodes in a collapsed region.
* Inheritance straight lines are now collapsed by CollapseSingleChild
* Don't collapse if parent has more than one parent or if the child has
more than one parent
* Allow the possibility to construct single-member struct: if this
struct is inherited by many other structs, "flattening" the struct is not
the most sensible thing to do, since inheritance information is something
we want to preserve in these cases.
This commit introduces the type system of the model along with several
various other improvements to the model and its users.
* Introduce the type system.
* Introduce possibility to tag certain fields in the model as to be
optional during YAML serialization.
* All the `Name` fields have been replaced in favor of `CustomName` plus
a `name` method that will use `CustomName` if available, or an
automatically generated name otherwise.
* Make TupleTreeReferences behavior more robust: now you either need to
have a valid pointer to `Root` and a `Path` or be default constructed
(`nullptr` for `Root` and an empty `Path`). Any other configuration is
invalid.
* The type system introduces `RawFunctionType`: this superseds the
previous way in which we were specifying arguments and return
values. Users of such information have been updated accordingly.
These may happen in nasty functions like memchr, where you have a loop
pre-header iterating over single bytes, a loop iterating over 4 bytes,
and finally the loop exit iterating over single bytes again.
Now we stop at the first non-decreasing nested AddRec.
Alvise de Faveri