public <T> void compareZ(Comparison comparison, Label trueLabel, Local<?> a) {
    adopt(trueLabel);
    Rop rop = comparison.rop(StdTypeList.make(a.type.ropType));
    addInstruction(
        new PlainInsn(rop, sourcePosition, null, RegisterSpecList.make(a.spec())), trueLabel);
  }
Check if an int or reference equals to zero. If the comparison is true, execution jumps to
{@code trueLabel}. If it is false, execution continues to the next instruction.
android/android_framework/dex-maker/src/main/java/com/android/dx/Code.java