This analysis will be used for the following features:
1) Edit Type in the Model
2) Edit Function Prototype in the Model
3) Add Type to the Model
It takes C code as an input, parses it and produces a Model
type that represents the C type.
Now extractvalue instruction are replaced by dedicated
OpaqueExtractValue custom opcode, that prevents LLVM from doing strange
things with extractvalues during optimizations (such as e.g. sinking).
This is important since extractvalue instructions and struct-typed
values in general in our LLVM IR are not real first-class citizens, but
only a byproduct of the binary lifting process, and they actually
represent bundles of registers that are returned from isolated
functions.
Introduce the hybrid beautifier aiming to simplify double `not`s (one on
the IR side (e.g., a `icmp ne`), and one on the `ExprNode` side on the
`GHAST` in the form of a `NotNode`.
To do this hybrid beautifier, we basically need to do the following:
- Implement a preliminary collection phase which computes which
`ExprNode`s are affected by which `BasicBlock`.
- Compute the so-called consesus, i.e., verify that for all the
`ExprNode`s affected by a certain `BasicBlock`, the transformation
would be beneficial in terms of output. Basically:
1) That the number of `!(!=)` transformed into `(==)` outscores the
number of correlated `(!=)` which are transformed into `!(==)`.
2) That the number of `!(==)` transformed into `(!=)` outscores the
number of correlated `(==)` which are transformed into `!(!=)`.
- Actually perform the transformation for those situations where the
consensus agrees.
This commit enables to emit accesses with the square bracket array
access operator on pointers.
This is accomplished by adding an additional mandatory argument to
ModelGEP (AND NOT to ModelGEPRef) to represent this case.
MakeModelGEPPass is updated to take this into account, together with all
the other passes that handle ModelGEPs.
In ModelToHeader generate Inline Types in PTML by handling
Structs, Unions and Enums.
In addition, during the ModelToHeader we avoid producing
Structs that describe stacks, and in the DecompileFunction we
produce the definition of it inline if it is safe (referenced
only once).
This pass splits calls `*.with.overflow*` intrinsics into the a pair of
instructions: the underlying operation and a call to an `Helper`-tagged
function that computes whether such operation overflowed.
For instance, we go from:
%2 = call { i32, i1 } @llvm.umul.with.overflow.i32(i32 %0, i32 %1)
%3 = extractvalue { i32, i1 } %2, 1
br i1 %3, label %..., label %...
To:
%2 = mul i32 %0, %1
%3 = call i1 @mul_overflow_u32(i32 %0, i32 %1)
br i1 %3, label %..., label %...
This saves from handling `struct` in the backend.
This commit introduces modelType, which supersedes `llvmIntToModelType`
in order to better handle translation of LLVM types into model types
after introduction of opaque pointer types. The main differences is
that `modelType` accepts the `Value` (instead of just the `Type`), so it
can better handle `AllocaInst` and `GlobalVariable`, which provide
information about the pointee.
This commit changes MakeSegmentRefPass so that it's now a ModulePass and
it uses the binary to detect integer constants that represent the
address of strings.
When it detects address of constant strings, instead of injecting calls
to SegmentRef, we now inject calls to cstringLiteral, so that we can
later emit them as inline string literals in C.
In segmentRef we use integer type meaning address in memory, so we
generate segmentRef function with non-pointer type. For cstringLiteral
function we need real pointer type of operand.
Save MetaAddress, size, offset and original type for every
cstringLiteral call in metadata as we do for segmentRef calls.
For cstringLiteral "revng.cstring_literal" metadata name is used.
StringLiteralPool needs tuple of address, size, offset and type to
keep distinct string decorator functions for each string. This tuple is
represented by StringLiteralPoolKey struct.
Pipe for MakeSegmentRefPass needs to be defined explicitly, because
additional wrapper passes are required in MakeSegmentRef:
1. LoadModelWrapperPass
2. LoadBinaryWrapperPass
MakeSegmentRefPass requires access to RawBinaryView to detect cstring
literals in binary.
Fix printed command in MakeSegmentRefPipe
This printed command might not work. @ale commented it will be replaced
with `revng pipe run-pipe` once we will have it.
Update IRHelpers to new revng API
Switch String and Namespace arguments in getUniqueString
SegregateStackAccesses and PromoteStackPointer were not handling
functions declarated (but not defined) properly.
This commit fixes this, in part by adopting `TaggedFunctionPass`.
Using a named metadata is simply wrong, because we need to have many of
these metadata alive at the same time with different values.
Using a named metadata has the unpleasant side effect of making all the
`SegmentRef` functions to refer to the same segment.
Compute the weight of collpased regions the first time it is requested
and cache it, and use the cached value for all successive queries.
This also prevents a bug which occurs when we query the weight two
times for the same collapsed node, whose related collapsed region object
has been in the meantime destroyed by the tiling process.
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
Djordje Todorovic