<html><head><meta http-equiv="Content-Type" content="text/html charset=us-ascii"></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 2016-Nov-18, at 16:21, David Blaikie <<a href="mailto:dblaikie@gmail.com" class="">dblaikie@gmail.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div dir="ltr" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><br class=""><br class=""><div class="gmail_quote"><div dir="ltr" class="">On Fri, Nov 18, 2016 at 3:49 PM Adrian Prantl <<a href="mailto:aprantl@apple.com" class="">aprantl@apple.com</a>> wrote:<br class=""></div><blockquote style="margin: 0px 0px 0px 0.8ex; border-left-width: 1px; border-left-color: rgb(204, 204, 204); border-left-style: solid; padding-left: 1ex;" class="gmail_quote"> </blockquote><blockquote style="margin: 0px 0px 0px 0.8ex; border-left-width: 1px; border-left-color: rgb(204, 204, 204); border-left-style: solid; padding-left: 1ex;" class="gmail_quote">Regardless of which implementation we choose we will also need to<br class="gmail_msg">introduce a new bitcode record for DIExpressions with the<br class="gmail_msg">corrected semantics in order to safely upgrade existing bitcode.<br class="gmail_msg"></blockquote><div class=""><br class=""></div><div class="">Ah, good point.</div></div></div></div></blockquote><div><br class=""></div><div>The first field in METADATA_EXPRESSION is effectively a bitfield, and we're only using the first bit (for isDistinct). We can just use the second bit for "is-new-format"; no reason for a completely new record ID. (Maybe you weren't suggesting that, and you just meant "new format, some way to distinguish, etc.", but I wanted to be sure we didn't use a new record ID unnecessarily.)</div></div></body></html>