[MachineVerifier] Check if predecessor is jointly dominated by undefs

Each use of a value should be jointly dominated by the union of defs and
undefs. It can happen that it will only be jointly dominated by undefs,
and that is still legal. Make sure that the verifier is aware of that.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@339924 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed