Local blocks alignment

[nunoplopes]

This example shows that we need to align src/tgt's local blocks. Described in the paper but not implemented yet:

define ptr @src(i8 %arg) {
bb:
  %tmp = icmp ne i8 %arg, 0
  br i1 %tmp, label %bb1, label %bb3

bb1:
  %tmp2 = call noalias ptr @f()
  br label %bb5

bb3:
  %tmp4 = call noalias ptr @f()
  br label %bb5

bb5:
  %tmp6 = phi ptr [ null, %bb1 ], [ %tmp4, %bb3 ]
  %tmp7 = call ptr @h(ptr %tmp6)
  ret ptr %tmp7
}

define ptr @tgt(i8 %arg) {
bb:
  %tmp = icmp eq i8 %arg, 0
  br i1 %tmp, label %bb3, label %bb1

bb1:
  %tmp2 = call noalias ptr @f()
  br label %bb5

bb3:
  %tmp4 = call noalias ptr @f()
  br label %bb5

bb5:
  %tmp6 = phi ptr [ null, %bb1 ], [ %tmp4, %bb3 ]
  %tmp7 = call ptr @h(ptr %tmp6)
  ret ptr %tmp7
}

declare ptr @f()
declare ptr @h(ptr)