Added some comments and reformatted others. No functionality change.

Added two "FIXMEs" for code that looks dubious to me (but I could be
wrong).


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@47366 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed