llvm-project

a590b831 - [BOLT] Gadget scanner: prevent false positives due to jump tables

[BOLT] Gadget scanner: prevent false positives due to jump tables As part of PAuth hardening, AArch64 LLVM backend can use a special BR_JumpTable pseudo (enabled by -faarch64-jump-table-hardening Clang option) which is expanded in the AsmPrinter into a contiguous sequence without unsafe instructions in the middle. This commit adds another target-specific callback to MCPlusBuilder to make it possible to inhibit false positives for known-safe jump table dispatch sequences. Without special handling, the branch instruction is likely to be reported as a non-protected call (as its destination is not produced by an auth instruction, PC-relative address materialization, etc.) and possibly as a tail call being performed with unsafe link register (as the detection whether the branch instruction is a tail call is an heuristic). For now, only the specific instruction sequence used by the AArch64 LLVM backend is matched.