I'm looking for gcc and clang compiler options that effectively tell the compiler to emit constant-time object code. Ideally there'd be a compiler option equivalent to -Os that instead of optimizing for size, optimizes for constant-timeness of the emitted code. Current compilers to my knowledge do not provide such an option, so what I'm asking for really is a set of compiler options that would have a similar effect.
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nebel
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2I think you have answered your own question: gcc and clang do not support this. It would necessarily limit you to a subset of C with no loops except maybe obviously constant ones. – Nate Eldredge Jul 31 '21 at 18:59
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Basically a duplicate of https://stackoverflow.com/questions/68327985/require-compiler-to-emit-branchless-constant-time-code, which is unanswered but has comments explaining that it's not feasible. – Nate Eldredge Aug 01 '21 at 17:28
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Well I was thinking of options such as `-ftree-loop-if-convert` (`gcc`) that can have such an effect on the emitted code. Unlike the linked question, I'm not looking for a perfect solution. – nebel Aug 02 '21 at 19:02