[llvm-dev] dfsan options at the IR level

[Archa . via llvm-dev]

Hi,

I am new to LLVM and am trying out the dfsan option to perform dynamic
dataflow analysis. My understanding is that we have to insert the APIs
within the source code to create, set and get labels to achieve this. I am
attempting to do it at the IR level as an IR transformation pass.

My query is if I should first -emit-llvm it into bitcode format with the
dfsan option or is it possible to provide the dfsan option after converting
to bitcode. When I compare the IR of a simple program with and without the
dfsan option, I see for the dfsan enabled bitcode, there are calls to
__dfsan_union even when I have no instrumentation in place. I am unclear of
when dfsan features are imposed on like at conversion to bitcode or compile
time or link time.

Also there is a dfsan option available with opt, will this help in the
dataflow analysis at the IR level. Is there any documentation on how this
feature works.

Thanks
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