Add simplification to mcd-structured verification module#2828
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| // #buf simplification comparing to null-bytes: compare as Int | ||
| rule #buf(N, X:Int) ==K NULLBYTES => X ==Int 0 | ||
| requires 0 <=Int X | ||
| andBool X <=Int 2 ^Int ( 8 *Int N) | ||
| andBool #asInteger(NULLBYTES) ==Int 0 | ||
| [simplification, concrete(NULLBYTES)] |
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@jberthold shouldn't this be X <Int 2 ^Int (8 *Int N), not <=Int?
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That's right, should be <Int, sorry for that. I'll make a PR to correct it.
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Thinking about it, we would also want length(NULLBYTES) ==Int N (and 0 <=Int N but that's implied by the former), as well as preserves-definedness.
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The added simplification lowers a comparison between a
#buf(..)expression and null-bytes to anIntcomparison when the magnitude of the#bufargument allows.This simplification is necessary to pass
mcd-structuredproofs once the HS backend change runtimeverification/haskell-backend#4133 arrives downstream.