Fix another assert failure very similar to PR16651's test case. This
test case came from Benjamin and found the parallel bug in the vector
promotion code.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186666 91177308-0d34-0410-b5e6-96231b3b80d8
Cleanup the stats counters for the new implementation. These actually
count the right things and have the right names.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186667 91177308-0d34-0410-b5e6-96231b3b80d8