[WalterBright]

Java has a far, far more restricted view of exceptions than C++ and D have,[1] and hence more opportunities for optimization. I did implement exceptions in the Javascript compiler I implemented 20 years ago, and they're a cakewalk compared to C++. I also implemented a native Java compiler, including EH.

As for clang, see what Chandler said. But maybe things have changed in the last couple years.

[1] for example, Java doesn't have objects on the stack that need their destructors run. That's a massive simplification.

[titzer]

I don't know the internals of clang very well, but everything I have heard second hand (and third hand) makes me think that its approach to modeling exceptions isn't very good.