This commit fixes two interacting problems in the beautification of if
statements.
First, in `simplifyShortCircuit`, there were two assertion on null
pointers that were too strict. These assertions didn't take into
consideration that one among the "then" and the "else" branch of an
`IfNode` could be simplified away _during_ the beautification itself.
Second, a previous commit had moved the execution `flipEmptyThen` after
the two beautification of short-circuit, leading to assertions failed
in `simplifyTrivialShortCircuit`.
This was caused by the fact that `simplifyTrivialShortCircuit` only
never expected `IfNode`s with empty "then".
This was fixed by running `flipEmptyThen` also before
`simplifyTrivialShortCircuit`.
This commit is a hack, that removes an assertion on NDuplicates.
For now we can remove this check, because we declare all the local
variables at the beginning of the function body.
Whenever we start emitting the declarations of local variables
as-late-as-possible, we'll need to take care of this.
Before this commit, we assigned names to struct types without looking at
the function names of which they were return types.
Now we do, so that the name of the generated type for the function `f`
is `f_ret_type`.
This also fixes errors when reparsing the generated C code, where the
names of the struct types did not match.
We now craft a new decompilation pipeline. We remove the exceptions
introduced as fallbacks to preserve the semantics, and we perform passes
of `dce` and `simplifycfg` to remove all the superfluos basic block
remaining after this change. To do this, we need an additional pass that
removes also the calls to the `llvm.assume` intrinsic, and another pass
of `dce` to remove all the dead uses.
In addition, we also remove dead stores to the `cpu_loop_exiting` global
variable in order to improve the decompiled code.
As a byproduct of this, we remove also the dependency from the
`-remove-pc-stores` pass, since its jobs is included by the changes
mentioned above.
This commit fixes an issue that caused to emit duplicated statements
for BasicBlocks that terminated with a conditional branch.
This was caused by a redundant call to `buildStmtsForBasicBlocks()`
inside `createCondExpr`, that has now been removed.
With this commit `ExtractValueInst`s are handled so that they don't have
side effects.
This significantly improves the quality of the decompiled output,
preventing the forced serialization of all the extraction of struct
fields after calls to function that return structs, except for when it's
really needed.
With this commit, the declarations of local variables and function
parameters now use the name of the associated `llvm::Value` if present,
instead of always using the prefix "param_" or "var_".
Before this commit, when GlobalDeclCreationAction needed to emit
literals for initialization of global variables, it did it using
custom code.
This was not working properly, an in some cases it emitted short
literals which are not allowed in C.
Hence the generated C code that was impossible to recompile without
syntax errors.
This commit fixes this problem, using the getLiteralFromConstant method
of StmtBuilder.
In order to do this, we need to make the StmtBuilder available inside
the GlobalDeclCreationAction, which is not a very clean design.
However, we are already planning to merge the GlobalDeclCreationAction
and the StmtBuilder class, so this issue will be taken care of in the
future.
The simplifyLastContinue beautifier was too ambitious and there were
many corner cases that it handled in the wrong way, leaving the AST in a
shape that could not be emitted, or breaking the semantics.
This commit severely weakens the simplifyLastContinue, so that it does
not break things anymore.
It is now able to match only continue statements that are in the last
position of a sequence node which is the body of a ScsNode.
This obviously is not enough but allows revng-c to pass all the
decompilation tests.
In the future we will need to extend simplifyLastContinue to match more
cases in a sane way.
This commit moves the matching of short-circuited ifs before the stage
of flipping if nodes with emtpy then.
This is necessary because the if short-circuiting may produce if nodes
with empty then, which can be then flipped by the next beautify step.
Before this commit, we couldn't handle simplification of atomic
sequences in cases of switches that had a default.
The reason is that if you remove a case from a switch that has a
default, you are implicitly saying that the case that you remove will be
handled by the default, hence you're changing the semantics.
Now we handle this case by not removing the case, substituting it with a
SwitchBreak node instead.
Remove from the `RegionCFGTreeImpl.h` header the helper functions used
for the first AST simplification that are now part of the
`GenerateAst.h` header.
Count the number of duplication (needed later in the `Mark` pass) right
before the AST generation phase, where the `RegionCFG` will be destroyed
by the tiling matching.
Change the interface of the `findReachableNodes` helper function, so
that now accepts arguments passed by pointer instead of by reference.
Also, the helper function now does not accept a `nullptr` `Source`
parameter.
The `Successors` and `Predecessors` field on the `BasicBlockNode` are
now promoted from being a `std::pair` composed by the pointer to the
successor and the set representing the cases, to a pair between the
pointer to the successor and a new struct called `EdgeInfo`.
This struct is used to contain both the information about the cases, the
information representing whether and edge is inlined or not, and
possibly more information in the future.
This commit fixes the detection of the revng-c include file in build
directory, using the PathList facility provided by revng.
Before this commit, running revng-c from build directory failed to
properly identify the revng-c include if it was not already installed
but only available in the build directory itself.
Before this commit, the original llvm BasicBlock was not embedded
properly in the GHAST SwitchNodes. This caused problems and crashes in
decompilation.
This commit SwitchNode constructors so the that the BasicBlock properly
reaches the GHAST and it is printed correctly by the decompiler.
Before this commit, the C statements before an IfNode or a SwitchNode
were not guaranteed to be emitted if they were not involved in the
computation of the branch condition.
This commit fixes this problem.
Pietro Fezzardi