Hi Peter, > Last I checked I couldn't build a x86_64 kernel with llvm. So no, not > something I've ever ran into. > > Also, I would argue that this is broken in llvm, the kernel very much > relies on things like this all over the place. Sure, we're way outside > of what the C language spec says, but who bloody cares ;-)
True, but is there anything preventing gcc from implementing this optimisation in the future? If we are relying on undefined behaviour we should have a -fno-strict-* option to cover it. > If llvm wants to compile the kernel, it needs to learn the C dialect > the kernel uses. LLVM has done that before (eg adding -fno-strict-overflow). I don't think that option covers this case however. Anton
