Isolated functions return structs. These structs used to be constructed
using `IRBuilder::CreateAggregateRet`, which is implemented using
`insertvalue` instructions. However, this approach led to ugly
decompiled code.
This commit introduces "constructor" functions that can be easily
pattern matched down the pipeline.
This commit ensures that FunctionIsolation and EnforceABI do only
thing. This means that they no longer modify `root`.
Instead, we have a new pass, `invoke-isolated-functions` that needs to
be run after them and replaces the entry point of the functions with
invokes to the isolated functions, possibly with the appropriate
arguments.
When we compare StackAnalysis test results, the order in which things
appear in the JSON is relevant. However, the output was
non-deterministic due to a `std::map` using a pointer as key.
This commit improves the situation by sorting the elements by name
before dumping them in JSON.
This commit drops support for running StackAnalysis without ABI
analysis. This has been broken for quite some time and a source of slow
downs in (badly) crafted optimization pipelines.
We used to mark call to noreturn functions as killers, but this is not
correct.
Note that this is a temporary solution, we need to explicitly handle
such situations.
Generated code now either jumps to `anypc` or `unexpectedpc`. The latter
one is to be considered a safety measure and will be populated with an
unreachable instruction on the decompilation pipeline.
This commit makes `PCH::getUniqueJumpTarget` more robust:
1. We bail out only if we find a non-constant write to a field of
`MetaAddress` for which we already have a value. Before, any
non-constant write would lead to bailing out.
2. In case we meet an helper, we now bail out only if we didn't saw any
write to a portion of the `MetaAddress`.
This commit extracts a plain `struct` from the `MetaAddress` class. This
enables us to use `MetaAddress` from C and therefore, runtime.
The definition of such `struct`, `PlainMetaAddress`, is in
`PlainMetaAddress.h`, which is included by `early-linked.c`.
A function to print the content of a `PlainMetaAddress` has also been
introduced.
Also, anticipating the linkage of `early-linked.c` triggered a
superflous assertion in `CPUStateAccessAnalysis`. This commit removes
it.
* Introduce GCBI::buildDispatcher
* Introduce GCBI::getJumpTarget{,Block} and GCBI::getBlocksGeneratedByPC
to easily map `BasicBlock *` to jump targets and viceversa.
* PCH::buildDispatcher now returns a list of the newly created basic
blocks.
* Other minor changes
Changes include:
- `getFunctionCall` has been moved in IRHelpers.h
- `getFallthrough` and `getFunctionCallCallee`
have been simplified and added in IRHelpers.h (their old versions
have been removed respectively from FCI.h and revng.h)
- `FCI::getCall` and `FCI::isCall` have been removed
due to redundancy with `getFunctionCall`.
This commit fixes a bug that lead to be unable to instantiate from a
`Module` `ProgramCounterHandler`. The reason for this was that
`ProgramCounterHandler` was using `Module::getGlobalVariable` which, by
default, ignores variables with internal linkage.
This assertion was executed in the `runOnModule` method of the GCBI
pass, but it is too strict.
Asserting that Dispatcher != nullptr during the execution of the pass
prevents the pass from successfully running on a Module without a
Dispatcher.
This is unfortunate, because some passes that depend on GCBI in revng-c
actually do that. They do so because they are not really interested in
the Dispatcher at all. They only use GCBI to access information on the
Stack Pointer.
In fact, the check for Dispatcher being != from nullptr is already
performed also in the `dispatcher()` method which is the sane thing to
do. This commit removes the assertion from the `runOnModule` method and
leaves it in the `dispatcher` method.
This allows to run the pass successfully even on a Module without the
Dispatcher, while not changing the contract of this pass (i.e. that when
you call the `dispatcher` method you get a nonnull pointer).
This commit introduces the PruneRetSuccessors pass, whose role is to
identify all the indirect jumps whose devirtualized destinations
correspond to return addresses. In fact, they are most likely to be
return instructions and devirtualizing them is always detrimental.
Alessandro Di Federico