Ralf W. Grosse-Kunstleve:

Thanks for the reply! Unfortunately, it doesn't help in my case, because I have a x86_64 platform. I blindly tried all includes I could find in the Intel C++ directory, but none helped. A look at the docs also didn't lead to any insights... Is there something else I could try?

Well... you could ask Intel via Beman or John Maddock who are our points of contact at the moment. :-) In the meantime we'll probably need to add && ( !defined(__INTEL_COMPILER) || defined(__ia64) ) to the line in detail/spinlock.hpp that chooses the _sync path. But it would be nice to have an official word from Intel as to whether the __sync intrinsics are (going to be?) supported on x86-64.