martong added inline comments.
================ Comment at: clang/lib/StaticAnalyzer/Core/RegionStore.cpp:1696 + const llvm::APSInt &Idx = CI->getValue(); + const uint64_t I = static_cast<uint64_t>(Idx.getExtValue()); + // Use `getZExtValue` because array extent can not be negative. ---------------- ASDenysPetrov wrote: > ASDenysPetrov wrote: > > martong wrote: > > > aaron.ballman wrote: > > > > > > > This `static_cast` seems to be dangerous to me, it might overflow. Can't > > > we compare `Idx` directly to `Extent`? I see that `Idx` is an `APSint` > > > and `Extent` is an `APInt`, but I think we should be able to handle the > > > comparison on the APInt level b/c that takes care of the signedness. And > > > the overflow situation should be handled as well properly with `APInt`, > > > given from it's name "arbitrary precision int". In this sense I don't see > > > why do we need `I` at all. > > We can't get rid of `I` because we use it below anyway in `I >= > > InitList->getNumInits()` and `InitList->getInit(I)`. > > I couldn't find any appropriate function to compare without additional > > checking for signedness or bit-width adjusting. > > I'll try to improve this snippet. > This is not dangerous because we check for negatives separately in `Idx < 0`, > so we can be sure that `I` is positive while `I >= Extent`. Unfortunately, I > didn't find any suitable way to compare `APSint` //of unknown sign and > bitwidth// with //signless// `APInt` without adding another checks for sign > and bitwidth conversions. In this way I prefer the currect condition `I >= > Extent`. I think it would be possible to use `bool llvm::APInt::uge` that does an Unsigned greater or equal comparison. Or you could use `sge` for the signed comparison. Also, both have overload that take another APInt as parameter. CHANGES SINCE LAST ACTION https://reviews.llvm.org/D104285/new/ https://reviews.llvm.org/D104285 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
