This commit does various things oriented at reducing the number of local
variables emitted in C:
- MarkAssignments now know that @Copy and @Assign involving
@LocalVariable only have side effects that affect the local variable
itself; this enables to reduce the number of times we're forced to
emit a local variable due to interfering side effects
- Drop the @AssignmentMarker FunctionTag; AddAssignmentMarkerPass now
doesn't emit @AssignmentMarker anymore; instead it emits groups of
@LocalVariable, @Copy, and @Assign, which benefit from the previous
point
- Drop 2 MarkAssignments::Reasons: HasManyUses and HasUsesOutsideOfBB;
both these have now been aggregated into the AlwaysAssign reason for
simplicity, representing all reasons non involving side effects
- Update BeautifyGHAST and how it reasons about side effects when
beautifying; before this commit it used @AssignmentMarker, now it
looks at @Assign
- Simplify ExitSSA; before this commit it was trying hard to be smart on
where it emitted the store instructions representing the incoming
values of the PHI that was being destroyed; this seemed smart when we
originally did it but it generated C code that was not really better
to read, so this useless complexity is finally gone
This commit adds a new pass, PrettyIntFormatting, that injects calls to
decorator functions print_hex, print_char, and print_bool around
llvm::ConstantInt in various situations.
It also updates the rest of passes of the decompilation pipelin to
understand these new decorator functions and to properly emit decorated
integer literals in the decompiled C code.
Add an engine for running VMA in different modes. User can:
- Decide how to initialize the colors (e.g. from the Model or from
the LLVM IR)
- Decide what to do with the final TFG obtained by VMA
- Decide whether or not the Mincut algorithm should run
Candidate colors, accepted colors and content are now accessible
only with setters and getters. In this way, we can check that
the Candidates are always a subset of the Accepted colors.
If we find values to be used outside their scope, we need to always
mark them for assignment, so that they have a dedicated variable that
is declared in the right scope. To do this we:
1. Export the logic that decides if a value needs a top-scope variable
in a public header, to be used by both `VariableScopeAnalysis` and
`MarkAssignments`.
2. Add the `HasUsesOutsideBB` reason for assignment markers
Add `ReadsMemory` and `WritesMemory` Tags and restructure the
logic that decides whether two instructions are interfering
as follows:
1. Consider `Store`s and anything with a `WritesMemory` tag as
having side effects
2. Consider all the `TaintSet` of an instruction when deciding
if two instructions interfere
3. Consider both `ReadsMemory` and `WritesMemory` Tags when
deciding interference
A simple pass that maps LLVM IR instructions to C operators,
taking into account their precedence and associativity to
emit nice-looking parenthesized expressions.
Before this commit, the dla::Step depended on InterferingInfo, but this
was superfluous.
This commit drops the dependency and enables the Step to run before
ComputeNonInterferingComponents.
This also avoids the need to run ComputeNonInterferingComponents twice
(one before and one after DeduplicateUnionFields), so it can only run
once.
The step now collapse parents with their single child if they are
indistinguishable, i.e. if the parent has only that single child, at
offset zero, and their size is the same.
Now that the late stage of the decompilation pipeline is managed with
revng-pipeline, and we have a standalone tool for decompilation, we
have no need to use LLVM passes anymore for those stages.
This commit also renames the directories to avoid the confusing Pass
suffix, not what LLVM passes are gone.
This library replaces the old AddIRSerializationMarkers, cleaning up a
lot of historcal baggage, merging Liveness and MarkAnalysis, and
adopting a more accurate naming across all the codebase.
Over time, SerializationReason had accumlated a bunch of values that
were designed to work around the limitation of the clang-based C
decompiler backend.
Now that the clang-based C decompiler backend is gone, these workarounds
can be removed.
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
* RemoveExtractValues transforms every `extractvalue` instruction
into an opaque call. This prevents the optimization pipeline from
moving around and optimizing `extractvalue`s, since they have a
particular meaning in our IR
* RestoreExtractValues transforms such opaque calls back to regular
`extractvalue`s at the end of the pipeline
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.
Alessandro Di Federico