<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><br class=""><div><blockquote type="cite" class=""><div class="">On Mar 14, 2017, at 2:16 PM, John McCall <<a href="mailto:rjmccall@apple.com" class="">rjmccall@apple.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><meta http-equiv="Content-Type" content="text/html charset=utf-8" class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div class=""><blockquote type="cite" class=""><div class="">On Mar 14, 2017, at 5:08 PM, Jordan Rose via swift-dev <<a href="mailto:swift-dev@swift.org" class="">swift-dev@swift.org</a>> wrote:</div></blockquote></div></div></div></blockquote><blockquote type="cite" class=""><blockquote type="cite" class=""><br class=""></blockquote></blockquote><blockquote type="cite" class=""><div class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div class=""><blockquote type="cite" class=""><div class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div class=""><blockquote type="cite" class=""><div class="">On Mar 14, 2017, at 13:52, Greg Parker via swift-dev <<a href="mailto:swift-dev@swift.org" class="">swift-dev@swift.org</a>> wrote:</div><div class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><br class=""><div class=""><blockquote type="cite" class=""><div class="">On Mar 14, 2017, at 1:34 PM, Greg Parker via swift-dev <<a href="mailto:swift-dev@swift.org" class="">swift-dev@swift.org</a>> wrote:</div><div class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><br class=""><div class=""><blockquote type="cite" class=""><div class="">On Mar 14, 2017, at 12:43 PM, Joe Groff <<a href="mailto:jgroff@apple.com" class="">jgroff@apple.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div class="">Hey Greg, what are the correct refcounting bits now to set in a global statically-emitted heap object that shouldn't ever be released?</div></div></blockquote><br class=""></div><div class="">For now use the same thing that stack-allocated objects use. I forget what the bit pattern is exactly. (I assume you are not in strictly read-only memory and can tolerate writes to the refcount word. We don't yet have an implementation for immortal read-only objects.)</div></div></div></blockquote><br class=""></div><div class="">Oh wait, you *don't* want to use what stack-allocated objects use. They get deinited without being deallocated, and I assume you want neither deinit nor dealloc. Let me work this out.</div></div></div></blockquote><br class=""></div><div class="">Wouldn’t it be okay to just emit it with an unbalanced retain?</div></div></div></blockquote><div class=""><br class=""></div>It's better if there's some way to make an object completely ref-count inert. Often, the compiler only sees one side of a retain/release pair, like when you return a constant NSString — you know locally that you're retaining a constant string, but you're returning it to some context that has no idea what it's getting. If the object is just unbalanced-retained, you have to preserve the retain or else the caller might release it. (That's true even if the imbalance is quite large — no fair crashing the program but only after a function's been called 2^19 times! Imagine reproducing that...) Making the object completely inert means you can just unconditionally say "hey, I know R/R are no-ops on this value" and delete them as a peephole.</div></div></div></blockquote><br class=""></div><div>That's right. Unbalanced retain is the solution today. I expect a truly inert solution soon.</div><div><br class=""></div><div><br class=""></div><div>-- </div><div>Greg Parker <a href="mailto:gparker@apple.com" class="">gparker@apple.com</a> Runtime Wrangler</div><div><br class=""></div><br class=""></body></html>