Split the `InlineHelpers` pass into the three phases:
- `link-helpers-to-inline` links the missing `revng_inline` helper
bodies from the `libtcg-helpers-to-inline-arch` module.
- `inline-helpers` inlines, in every function except those tagged
`Root` or `Helper`, the calls to `revng_inline` helpers whose
critical arguments on the call site are constant.
- `delete-helper-bodies` drops from the module the body of every
`revng_inline` function, leaving only the declaration.
The three passes live in a dedicated `revngInlineHelpers` library
(`lib/InlineHelpers/` + `include/revng/InlineHelpers/`), so that
libraries which do not depend on `revngFunctionIsolation` can use them
without creating cyclic dependencies.
Several components in both pipeline YAMLs are slated for removal.
Prepend a legacy prefix to their names, and to the matching c++ code, so
they are clearly distinguished from the new Clift-based pipeline until
they are dropped.
Move all per-function state and logic into a new SegregateFunctionStack
worker, so the pass class itself only holds module-wide state and the
runOnFunction body is just upgrade() + segregate(). The discovery loop
now uses the MFP ExtraState surface to capture the analysis value
before each interesting program point, replacing the splitBasicBlock
trick that introduced fake nodes only to read the lattice value at
them.
Other changes that ride along:
- StackOffsetCache memoizes getStackOffset per function.
- findAllWriters does a single sorted sweep instead of a quadratic
scan over Ranges.
- The pipeline gains a stack-accesses-segregated artifact entry.
- Test fixtures (filecheck.ll, override.yml, segregate-stack-accesses
configuration) are updated to match the new IR shape.
Replace the hoist-struct-phis pass with a split-struct-phis pass that
breaks struct PHI nodes into per-field PHIs instead of moving them
out, and update both pipelines to use the new name.
Introduce a new canonicalisation pass that forces a small set of
exponential-dataflow-prone instructions (SelectInst plus the FShl
and FShr intrinsic patterns) to be stored into a dedicated local
variable. Without this, expanding their value into C expressions
during decompilation can blow up into exponential path enumeration
on real binaries.
This is a temporary workaround. A more principled split of
pathological dataflows is planned and will replace this pass.
Run -strip-dead-prototypes as part of the LLVM-pass list invoked
just before the Clifter, so that all unused helpers are stripped
away. In particular, this prevents some LLVM intrinsics that
return structs containing i1 (e.g. the overflow intrinsics) from
ending up in the C output and tripping later passes.
Add a canonicalisation pass that rewrites extractvalue from a
pointer-returning struct as an i8 GEP plus a load. Together with
ArithmeticToGEP this lets later passes consume the result through
the same GEP-based interface they use for ordinary memory accesses.
Introduce the ArithmeticToGEP canonicalisation pass. It detects
pointers (LLVM-typed pointer values, model pointers flagged by the
"revng.pointers" metadata, and pointer-tagged extract values) and
rewrites integer arithmetic computed on top of them as i8 GEPs,
followed by a ptrtoint when the original use needs an integer.
For each obvious pointer the pass also walks backwards through Add
chains and disambiguates the pointer operand of each Add when the
other operand cannot be a pointer, so the rewrite extends to integer
arithmetic that only later flows into a pointer use.
This commit introduces an analysis to import prototypes from a SQLite
database of well-known prototypes, typically built from debug info of
operating systems.
This analysis supersedes import-well-known-models.
Drop the `MaterializeLoopScopes` pass after the re-design the loop
matching stage to work entirely on `clift`, without the need to insert a
`scope_closer` edge to guide the emission.
Simultaneously, drop the DAGify `Head` metadata insertion, since it will
not be checked anymore during the `MaterializeLoopScopes` pass.
Because of misplaced `From` value, comment we not adopted by
the recompilable archive, leading to desyncronization between it
and the usual decompilation branch of the pipeline.
This pass wraps LLVM's vanilla InstCombine, to hijack one of its
options. The goal of this hijack is to prevent InstCombine from
splitting and replacing accesses to arrays with GEPs and smaller
accesses.
This pass wraps LLVM's vanilla SROA, to hijack one of its options.
The goal of this hijack is to prevent SROA from splitting and replacing
memory accesses to arrays with GEPs and smaller accesses.
This commit further centralizes the creation of allocas + ptrtoint. The
creation of these pair of instructions is problematic when the size of a
pointer in the input and target architecture differ.
In fact, in such cases, LLVM turns trunc into masking the integer to
suppresse the high bits. This results in problematic code.
This commit introduces an assumption that ensures LLVM does not do that.
Passes without an artifact and a single successor are pointless anyway.
You can't get their output with revng artifact but you need to save
them on disk.
At the moment this pipe is broken, because it claims to be producing
artifacts with function rank, while it only produces types.
This pipe should be extended and turned into a pipe that generates
the whole Clift module including functions from LLVM IR, and not just
types.
We should add an input LLVMContainer, and the run() method should first
import types, and then create the functions and their bodies.
For the time being the Pipe is removed from the pipeline.
The previous conversion from LLVM to MLIR was translating plain LLVM IR
to LLVM MLIR Dialect, as a preliminary step for further conversion from
LLVM MLIR Dialect to Clift.
This is not how things are expected to work anymore, so the old code is
now dead and can be removed.
Introduce LegacySegregateStackAccessesPipe
This commit restructures the SegregateStackAccesses pass and
SegregateStackAccessesPipe so that they can have 2 modes of operations:
1. Legacy, with the same behavior as the old version, injecting local
variables as custom llvm::Functions representing opcodes, such as
LocalVariable, AddressOf, StackFrameAllocator, and CallStackArguments
allocator.
2. Non-legacy, that is meant to operate with the new LocalVariableHelper
to inject local variables as regular alloca instructions, with
additional metadata to discriminate among them.
This commit renames the old SegregateStackAccessesPipe to
LegacySegregateStackAccessesPipe.
It then re-uses the old SegregateStackAccessesPipe name for a new pipe,
meant to work in non-legacy mode.
The pipeline definition YAML file is updated to keep using the legacy
version for now.
For now the implementation is still the same.
Andrea Gussoni