<instructions>Your goal is to analyze the following comment and estimate how highly it will be upvoted by the Hacker News community.</instructions><comment><author>jvanderbot</author><text>&amp;gt; Removing all uses of undefined behaviour is probably a fool&amp;#x27;s errand, as it would require significant changes throughout the code that would take time and come with a performance impact, all for no immediate practical benefit. So I just hunted down the undefined behaviour cases that actually broke determinism. This was easy enough, as we have plenty of tools we use to test determinism. By comparing the game state CRC for every tick of every test (we have 2,417 tests) between x86 and ARM, I believe I got a pretty good coverage of potential issues.&lt;p&gt;Holy hell.</text><parent_chain></parent_chain></comment><story><title>The journey to Nintendo Switch</title><url>https://factorio.com/blog/post/fff-370</url></story>
<instructions>Your goal is to analyze the following comment and estimate how highly it will be upvoted by the Hacker News community.</instructions><comment><author>Arrath</author><text>&amp;gt; &amp;quot;This is the first time we had to make sure the game is deterministic between ARM and x86. We should be fine, C++ is portable, right? Just don&amp;#x27;t use undefined behavior. Turns out we use quite a lot of undefined behavior...&amp;quot;&lt;p&gt;Hah</text><parent_chain></parent_chain></comment><story><title>The journey to Nintendo Switch</title><url>https://factorio.com/blog/post/fff-370</url></story>