private static boolean hasSideEffect(SsaInsn insn) {
    if (insn == null) {
      /* While false would seem to make more sense here, true
       * prevents us from adding this back to a worklist unnecessarally.
       */
      return true;
    }

    return insn.hasSideEffect();
  }
Returns true if this insn has a side-effect. Returns true if the insn is null for reasons
stated in the code block.

@param insn {@code null-ok;} instruction in question
@return true if it has a side-effect
android/android_framework/dex-maker/src/main/java/com/android/dx/ssa/DeadCodeRemover.java