hesis that, when passed to <code>compare_subs</code>, will generate a precondition which is provable only if (modulo soundness bugs) the registers at post-execution will have equal values given the registers at pre-execution have equal values.</p></div></div><div class="odoc-spec"><div class="spec value" id="val-compare_subs_empty" class="anchored"><a href="#val-compare_subs_empty" class="anchor"></a><code><span><span class="keyword">val</span> compare_subs_empty : <a href="#type-comparator">comparator</a> 