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BinaryAnalysisPlatform / bap

Binary Analysis Platform
MIT License
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Move intrinsic calls outside of the BIL plugin #1362

Open fortunac opened 2 years ago

fortunac commented 2 years ago

Right now, it is the BIL plugin's job to turn unsupported instructions into intrinsic calls, but this will break when working on targets that don't fully rely on the BIL lifter. When the --bil-enable-intrinsic option is set, the BIL plugin will provide it's own semantics even though the instruction is properly handled by other lifters. This leads to a conflict. (e.g. the BIL will provide call llvm-thumb:ADDrr while the other lifters would provide R0 := R1 + R2.

This feature should be handled on the BIR side where it drops empty instructions. Rather than dropping these instructions, the right approach would be to represent these empty instructions as a separate blk in the BIR. See: https://github.com/BinaryAnalysisPlatform/bap/blob/6c97e430901ed680c666f87f849d0b7fa2ae8d4a/lib/bap_sema/bap_sema_lift.ml#L73

ivg commented 2 years ago

The plan is to implement missing instructions using the intrinsic primitives introduced in #1452 and deprecate the BIL intrinsics at all. It will require some work, but in the end, will give us well-defined intrinsic functions with clear argument passing semantics.