Szelethus added a comment. After reading @martong's comment D72705#2035844 <https://reviews.llvm.org/D72705#2035844> and @balazske's comment D72705#2086994 <https://reviews.llvm.org/D72705#2086994>, I think there is a need to argue across all paths of execution within the function, and as such this is a dataflow problem.
In D72705#2086994 <https://reviews.llvm.org/D72705#2086994>, @balazske wrote: > c = fgetc(fd); > if (c == '+' || c == '*' || c == '|' || c == '>' || c == '@' || c == EOF || > c == '\n') { ... } > > > > The first `c == '+'` is found by the checker and reported as false positive > (the later `c == EOF` is not found). Such a case can be found if the checker > can collect expressions that are separated by `||` or `&&` and the symbol to > check occurs in these and there is only a simple comparison. Our current dataflow analyses definitely have to make judgement of which block (and in that, which `CFGStmt`s) **reads** or **writes** a variable/expression. You can actually register an observer for expression writes (or in other terms, //kills//), so I don't think it'd be too challenging to do this with reads. `DeadStoresChecker` is a great example for a checker that utilizes dataflow and pathsensitive analyses. In D72705#1863381 <https://reviews.llvm.org/D72705#1863381>, @Szelethus wrote: > In D72705#1859711 <https://reviews.llvm.org/D72705#1859711>, @balazske wrote: > > > Generally, is it a problem if there are multiple checkers that may detect > > same defects but with different approach? > > > If avoidable, yes. If not, I think its an acceptable sacrifice. Mind that since D80905 <https://reviews.llvm.org/D80905> landed, the tone has shifted, if a more checker detects a specific bug (like double free) but a more general checker does as well (as passing garbage value to a function) we're okay with that. Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D72705/new/ https://reviews.llvm.org/D72705 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
