While simplifying branches in the MachineInstr representation, the
routine BuildCondBr must preserve flags on register MachineOperands. In
particular, it must preserve the <undef> flag.
This fixes a bug that is unlikely to occur in any real scenario, but
which bugpoint is likely to introduce.
Patch By Nick Johnson!
Reviewers: ahatanak, sdardis
Differential Revision: https://reviews.llvm.org/D34041
llvm-svn: 305290
Simon Dardis