C++: Add more sanitizers to cpp/uncontrolled-arithmetic
#5887
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rdmarsh2
reviewed
May 12, 2021
| * Holds if `fc` is a part of the left operand of a binary operation that greatly reduces the range | ||
| * of possible values. | ||
| */ | ||
| predicate bounded(Expr e) { |
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This is the kind of awkward code that the IR is supposed to avoid - would it help here, or would mapping back into the AST to use SimpleRangeAnalysis be equally awkward?
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I think mapping back to expressions will make this solution equally awkward, yeah. Since RemInstruction.getUnconvertedResultExpr() won't have a result if the original expression was a compound assignment, I think we'd need a disjunct for both % and %= anyway, unfortunately.
I like the idea, though. An easy-to-use mapping like that would certainly be helpful for predicates like this. I guess this is thematically related to https://github.com/github/codeql-c-team/issues/147.
rdmarsh2
approved these changes
May 14, 2021
This was referenced Jun 21, 2021
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(Part of https://github.com/github/codeql-c-team/issues/272.)
This PR does a couple of things to reduce the number of false positives on
cpp/uncontrolled-arithmetic:%and&as sanitizers.This reduces the number of false positives quite a bit when running our favorite projects on LGTM (compare the one from this PR with the one on main). This doesn't affect any of the results on SAMATE.