open-mpi/ompi — pull request #297 by hjelmn (2014-12-02 17:29:56+00:00)
Title: Add support for 128-bit compare and swap on x86_64 when available.

A 128-bit compare-and-swap will enable a better atomic lifo implementation
that uses the pointer + counter method to avoid ABA issues. This commit
adds configury to check for the instruction (cmpxchg16b) and adds an
implementation that uses the __int128 type available in C99.