For PR1258:

For PR1258:
Radically simplify the SlotMachine. There is no need to keep Value planes
around any more. This change causes slot numbering to number all un-named,
non-void values starting at 0 and incrementing monotonically through the
function, regardless of type (including BasicBlocks). Getting slot numbers
is now a single lookup operation instead of a double lookup.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@35171 91177308-0d34-0410-b5e6-96231b3b80d8