compiler people: how likely is it that timing-safe C code is future-proof? as in, how likely is it that future compilers will e.g. take "uint8_t diff = 0; for (size_t i=0; i<len; i++) diff |= a[i]^b[i]; return diff != 0" and put a conditional bailout jump in the loop?
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and footnote 114 says "Actions on objects so declared shall not be ‘‘optimized out’’ by an implementation or reordered except as permitted by the rules for evaluating expressions."
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I think the intuition for this rule is that a "volatile variable" might actually be something like an IO port where reads cause the IO port to sequentially give you input bytes? so reading from it and ignoring the result is for dropping an input byte from the port's buffer?
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