* Clean up how PHI nodes are handled

* Correct global variable references
* Fix loads & stores with zero indices
* Do not emit an else part of a branch if there is no code (no phi node
  and a fallthrough branch), makes code more readable to get:
  if (l2_cond240) {
    goto l13_bb10;
  }

with no else{} branch

llvm-svn: 2583