Through Reddit I've just found something nice, "Finding Integer Undefined Behaviors in C/C++": http://embed.cs.utah.edu/ubc/
>We modified Clang to dynamically detect most of C/C++'s integer undefined >behaviors. Using it, we have found undefined behaviors in nearly every piece >of open source software that we have checked.< >Slowdown due to checking is highly variable, but is in the 0%-30% range for >most codes. A few math-intensive codes (codecs, crypto) slow down by more than >100%. It seems likely that by tuning LLVM and our patch a bit, these overheads >could be substantially reduced.< In real programs in Delphi I used to see about 10-15% slowdown caused by such runtime tests. This is not that different from the slowdown caused by array bound tests. And you are able to disable them globally or in a part of the code. Bye, bearophile
