Hi @dtcxzyw,
My group at Trail of Bits is working on a spiritually similar implementation that may be a bit more fine-grained than what you are proposing here. We evaluated different approaches of supporting constant time programming in LLVM and discussed use cases with several cryptographic code developers. As we started working on the problem, we found it seemed better to implement a new intrinsic and a corresponding Clang builtin, and to also eventually provide a source-level library building on top of our approach to ease adoption in source code. We have just put up an RFC for our approach, [RFC] Constant-Time Coding Support. Would you be open to providing your thoughts on our work, reviewing as we post PRs, or even contributing?