Before this commit we were not adding nodes to DLATypeSystem for calls
with 0 uses.
This commit fixes the problem, and only avoids adding nodes for calls
that return void.
Before this commit, the creation of intra-procedural types and edges
was too liberal, possibly leading to creation of pointer edges starting
from nodes that were not pointer-sized.
This commit fixes the issue, never creating outgoing pointer edges from
non-pointer-sized nodes.
This commit adds placeholder pointer nodes to the DLA graph during
initialization, to point to nodes that represent model types whose size
should not altered during the Middleend.
These two parts of the code needed to be separated into libraries
because they were used both by the old C backend and by
IRCanonicalization.
Now that the old C backend is dead, they have been incorporated into
IRCanonicalization.
Further changes are necessary to strip away the last leftovers of the
old C backend from MarkAnalysis.
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
Nested SCEVAddRecs are not guaranteed to have strides that go from
larger to smaller. Both cases are valid and can convey interesting
information to DLA. But DLA assumes that the outermost strides are
always larger than the innermost, because this is the only scenario
allowed by well-nested types.
This commit re-orders the strides (and the associated trip counts) so
that they always go from larger to smaller sizes.
The assertGetLayoutTypePreConditions methods didn't really need to be
exposed as methods in a header. This commit moves them to static
standalone functions in the only place they're used.
Since in the model a FunctionPrototype can be shared among different
functions or indirect calls, we should take into account this fact when
initializing the DLA.
In particular, if the aforementioned case happens, we want to add
equality edges between the return value(s) and the arguments of all the
functions that have the same prototype. These will then be merged by
later steps in the middle-end, and the resulting information will be
shared among all the merged nodes.
* 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.
While doing thie, also drop `printAccessNode()` from DLA DebugPrinter.
The information about which LLVM instruction originated a given access
node is already available in the csv generated by the `dla-accesses-log`
logger.
Massimo Fioravanti