PHI nodes which were matched, rather than climbing up the
original PHI node's operands to rediscover PHI nodes for
recording, since the PHI nodes found that are not
necessarily part of the matched set.
This fixes rdar://10589171.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@149654 91177308-0d34-0410-b5e6-96231b3b80d8
