* Multiplications by 2^X are turned into shifts. This factors code out of the

* Multiplications by 2^X are turned into shifts.  This factors code out of the
  getelementptr code path for use by other code paths (like malloc and alloca).
* Optimize comparisons with zero
* Generate neg, not, inc, and dec instructions, when possible.

This gives some code size wins, which might translate into performance.  We'll
see tommorow in the nightly tester.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@9267 91177308-0d34-0410-b5e6-96231b3b80d8