IR: Don't allow operands to become unresolved

Operands shouldn't change from being resolved to unresolved during graph
construction.  Simplify the logic based on that assumption.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225649 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed