private void forEachNonSubBlockDepthFirst(int firstLabel, BasicBlock.Visitor v) {
    forEachNonSubBlockDepthFirst0(labelToBlock(firstLabel), v, new BitSet(maxLabel));
  }
Visits each non-subroutine block once in depth-first successor order.

@param firstLabel label of start block
@param v callback interface
android/android_framework/dex-maker/src/main/java/com/android/dx/cf/code/Ropper.java