Implement suggestions from Chris:

Implement suggestions from Chris:
  - Use a more accurate heuristic for the size of the hashtable.
  - Use bitwise and instead of modulo since the size is a power of two.
  - Use new[] instead of malloc().

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@52951 91177308-0d34-0410-b5e6-96231b3b80d8