Not a reviewer, but Re: https://reviews.llvm.org/D15075#940711 the changes in this review are identical to the ones I made locally yesterday and they resolved my problem with bad code generation. TYVM

In the process of upgrading from clang 3.6.1 to a newer version, I ran into this new error and thus imported the new intrinsics from intrin.h for rep movsb and friends. I see several discussions in this thread about how having the registers solely in the inputs list is not sufficient for something like "rep movsb" because the modified registers will not be clobbered, however none of these suggested changes made it into the eventual intrin.h.