public void removeAllPhiInsns() {
    /*
     * Presently we assume PhiInsn's are in a continuous
     * block at the top of the list.
     */

    insns.subList(0, getCountPhiInsns()).clear();
  }
Deletes all phi insns. Do this after adding appropriate move insns.
android/android_framework/dex-maker/src/main/java/com/android/dx/ssa/SsaBasicBlock.java