Fix base must-writing all invalidated variables #1562
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set_many writes one after another, so they all end up in protection privatization's P set for example (although it cannot be observed by precision). Nevertheless, this is the morally correct thing to do: an unknown function may or may not write each argument.
michael-schwarz
approved these changes
Sep 9, 2024
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set_manywrites one after another, so they all end up in protection privatization'sPset for example (although it cannot be observed by precision).Nevertheless, this is the morally correct thing to do: an unknown function may or may not write each argument.
This issue was revealed by #1531, because deep reachability returns all reachable variables as singleton points-to sets. So when
NULLis reachable, it's must-written and it becomes dead code whenNULLpointer writes are assumed to not happen. This is unsound because the unknown function only may-writes.It will be possible to test this difference with #1531.
I checked other analyses and they don't seem to have the same problem. For example, relation/var_eq also invalidate sequentially but they don't invalidate by writing, rather by removing known information.