Is there a website with non-UB C code snippets for stuff that is UB if done directly (like converting uint to int assuming twos complement)?
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But anyway, x>INT_MAX ? -1-(int)(-1-x) : x
hmm.. cprover (cbmc) is not happy with that: "arithmetic overflow on signed to unsigned type conversion in (unsigned int)-1"
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Pretty sure per the C standard that's required to produce 0U-1U - or UINT_MAX
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Yes, conversion from signed to unsigned is completely defined.
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That's a bad bug in a C prover, since the behavior is fully defined.
Thanks. Twitter will use this to make your timeline better. UndoUndo
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jfyi everyone: This version passes all cbmc checks (b is an uint64_t).pic.twitter.com/DKExVdRkeS
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I prefer my version because it's algebraically obvious that the two branches collapse to the same thing, without thinking of def'n of ~.
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