dblaikie added a comment. In D146466#4218011 <https://reviews.llvm.org/D146466#4218011>, @efriedma wrote:
> I think the reason "recoverable" ubsan causes trouble is that it introduces > branches that subsequent optimizations can abuse. So without ubsan, we just > have an udiv instruction. With ubsan, we conveniently have a branch on > exactly the condition that would make the udiv undefined, so we can easily > prove control flow doesn't continue after the ubsan handler. Subsequent > optimizations take advantage of that, so ubsan "breaks" code. (So the code > was never actually correct according to the semantic model, but it was broken > in a way the compiler is less likely optimize.) Ah, interesting - thanks for the explanation! (but, yeah, not sure we can/should provide any further guarantees beyond "does /something/ after the sanitizer failure... " don't get stronger guarantees than without the sanitizer & while worth documenting that the sanitizer could make the problems after "recovery" worse than without the sanitizer enabled) Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D146466/new/ https://reviews.llvm.org/D146466 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
