Improve specs of bitwise operations #1839
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jhjourdan
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Nov 26, 2025
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| #[ensures(self >> $type::BITS - result == $zero)] | ||
| #[ensures((result != $type::BITS) == (self >> ($type::BITS - result - 1u32) == $one))] | ||
| #[ensures((result == $type::BITS) == (self == $zero))] |
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| #[ensures(self >> $type::BITS - result == $zero)] | |
| #[ensures((result != $type::BITS) == (self >> ($type::BITS - result - 1u32) == $one))] | |
| #[ensures((result == $type::BITS) == (self == $zero))] | |
| #[ensures((result != $type::BITS) == (self >> ($type::BITS - result - 1u32) == $one))] | |
| #[ensures((result == $type::BITS) == (self == $zero))] |
This clause is redundant (though it's unclear whether SMT solvers will be more comfortable with suc or such clause).
jhjourdan
reviewed
Nov 26, 2025
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| #[ensures(self << $type::BITS - result == $zero)] | ||
| #[ensures((result != $type::BITS) == ((self >> $type::BITS) & $one == $one))] | ||
| #[ensures((result == $type::BITS) == (self == $zero))] |
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Suggested change
| #[ensures(self << $type::BITS - result == $zero)] | |
| #[ensures((result != $type::BITS) == ((self >> $type::BITS) & $one == $one))] | |
| #[ensures((result == $type::BITS) == (self == $zero))] | |
| #[ensures((result != $type::BITS) == (self << ($type::BITS - result - 1u32) == $one << ($type::BITS - 1u32))] | |
| #[ensures((result == $type::BITS) == (self == $zero))] |
I see no reason we would have a different spec for both functions.
jhjourdan
reviewed
Nov 26, 2025
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| #[ensures(!self >> $type::BITS - result == $zero)] | ||
| #[ensures((result != $type::BITS) == (!self >> ($type::BITS - result - 1u32) == $zero))] | ||
| #[ensures((result == $type::BITS) == (self == $type::MAX))] |
Collaborator
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Suggested change
| #[ensures(!self >> $type::BITS - result == $zero)] | |
| #[ensures((result != $type::BITS) == (!self >> ($type::BITS - result - 1u32) == $zero))] | |
| #[ensures((result == $type::BITS) == (self == $type::MAX))] | |
| #[ensures((result != $type::BITS) == (!self >> ($type::BITS - result - 1u32) == $zero))] | |
| #[ensures((result == $type::BITS) == (self == $type::MAX))] |
jhjourdan
reviewed
Nov 26, 2025
Comment on lines
+225
to
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| #[ensures(!self << $type::BITS - result == $zero)] | ||
| #[ensures((result != $type::BITS) == ((!self >> $type::BITS) & $one == $one))] | ||
| #[ensures((result == $type::BITS) == (self == $type::MAX))] |
Collaborator
There was a problem hiding this comment.
Suggested change
| #[ensures(!self << $type::BITS - result == $zero)] | |
| #[ensures((result != $type::BITS) == ((!self >> $type::BITS) & $one == $one))] | |
| #[ensures((result == $type::BITS) == (self == $type::MAX))] | |
| #[ensures((result == $type::BITS) == (!self << ($type::BITS - result - 1u32) == $one << ($type::BITS - 1u32)))] | |
| #[ensures((result == $type::BITS) == (self == $type::MAX))] |
Collaborator
|
Suggestion: have logic functions for |
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Author
|
@mcoulmance the main todo is to fix the translation of |
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