private void handlePhiInsns() {
    for (PhiInsn insn : phiInsns) {
      processPhiInsn(insn);
    }
  }
Handles all phi instructions, trying to map them to a common register.
android/android_framework/dex-maker/src/main/java/com/android/dx/ssa/back/FirstFitLocalCombiningAllocator.java