Revert "use range loop, try to make comments more meaningful; NFCI"

This reverts commit r266541 since it introduces a use-after-free:
  http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux-bootstrap/builds/11471

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@266550 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed