| Issue |
178270
|
| Summary |
[BOLT] Explicitly check for unreachable basic blocks in gadget scanner
|
| Labels |
BOLT
|
| Assignees |
hvdijk
|
| Reporter |
atrosinenko
|
In an optimized code, unreachable basic block is likely to indicate an error in CFG reconstruction performed by BOLT's core. As this can degrade analysis quality, PtrAuth analyses implemented in `llvm-bolt-binary-analysis` warn the user about such conditions in `FunctionAnalysisContext::findUnsafeUses()` along other preparations to running gadget detectors.
As soon as #170973 is resolved (either by #176135 or by any other patch), it seems natural to skip `findUnsafeUses` altogether if only authentication oracles are searched for. In that case it would be reasonable to implement this check for unreachable basic blocks as a yet another option for `--scanners=...` argument - instead of a full-blown dataflow analysis, a simple BFS should be enough to identify exactly the same set of basic blocks (those having no predecessors at all, as well as those belonging to an unreachable loop).
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