[caf]

This isn't the kind of instruction a compiler would emit for regular code.

[_RPM]

What would this be used for?

[loeg]

Kernel direct access to Xpoint and similar DIMMs. Potentially applications via mmap. You'd probably write a simple assembly function for it and invoke that from a language that can call assembly routines.

Obvious applications are filesystems and databases.

[amluto]

Hand-written stuff. You'd do asm volatile ("pcommit"); or similar.