Fix value-set-based pointer test resolution for non-deterministic pointer values #4686
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tautschnig
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peterschrammel and
smowton
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May 22, 2019
src/goto-symex/symex_goto.cpp
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| if(value_set_elements.empty()) | ||
| { | ||
| return {}; | ||
| } |
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The fact that the function is not correct when the value set is empty is suspicious.
Maybe we should check that the value set has size at least one just after the call to get_value_set, and can you say in which case it can be empty?
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That is a very good point. It seems value sets are missing an ID_nondet_symbol case. I'll fix this. Marking do-not-merge in the meantime.
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The value-set based filtering (rightfully) expects a value-set to be non-empty. As we previously ignored some right-hand sides, notably non-det symbols, this wasn't guaranteed. This entails changes to the tests of let-expression use in dereferencing as some of those tests have non-deterministically initialised arrays. Changes as discussed with @smowton.
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When we do not have any entry in the value set we shouldn't rely on it
being a trustworthy source of information.