<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 Nov 4, 2014, at 1:40 PM, Eric Christopher <<a href="mailto:echristo@gmail.com" class="">echristo@gmail.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: 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 style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: 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=""><div class="gmail_quote" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: 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;">On Tue Nov 04 2014 at 12:43:05 PM Peter S. Housel <<a href="mailto:housel@acm.org" class="">housel@acm.org</a>> wrote:<br class=""><blockquote class="gmail_quote" 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;">On 11/04/2014 07:04 AM, Robinson, Paul wrote:<br class="">>> From:<span class="Apple-converted-space"> </span><a href="mailto:llvmdev-bounces@cs.uiuc.edu" target="_blank" class="">llvmdev-bounces@cs.uiuc.edu</a><span class="Apple-converted-space"> </span>[mailto:<a href="mailto:llvmdev-bounces@cs.uiuc.edu" target="_blank" class="">llvmdev-bounces@cs.<u class=""></u>uiuc.edu</a>] On Behalf Of Sean Silva<br class="">>><br class="">>> You haven't established that you really need this. AFAIK Apple's linker<br class="">>> doesn't need this version information and they have shipped LTO for a<br class="">>> while now.<br class="">> Does Apple support library/middleware providers shipping bitcode instead<br class="">> of object code? That's the most nervous-making scenario for compatibility.<br class="">> LTO by itself needs bitcode only as an ephemeral stage between source and<br class="">> object; it's supporting bitcode as a long-lived on-disk format that keeps<br class="">> us awake at night.<br class="">><br class="">> I acknowledge the compatibility promise but I've been whacked upside the<br class="">> head too often by QA over the years to take an unverified promise at<br class="">> face value. I would like worked examples and industry experience reports.<br class="">> --paulr<br class=""><br class="">I've been bitten by trying to do this sort of thing recently. The<br class="">released LLVM 3.4 and 3.5, and the Xcode 5.x tools, generate debug info<br class="">marked with the module flag:<br class=""><br class=""> !49 = metadata !{i32 2, metadata !"Debug Info Version", i32 1}<br class=""><br class="">The tools included with Xcode 6.x generate debug info marked as:<br class=""><br class=""> !49 = metadata !{i32 2, metadata !"Debug Info Version", i32 600054001}<br class=""><br class=""></blockquote><div class=""><br class=""></div><div class="">This is an apple bug. You should report it.</div></div></div></blockquote><div><br class=""></div>No, it is intentional. Because our releases are not aligned with any LLVM release, we’re using debug version numbers that are completely different from trunk.</div><div><br class=""><blockquote type="cite" class=""><div class=""><div class="gmail_quote" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: 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;"><div class=""> </div><blockquote class="gmail_quote" 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;">and will discard debug info marked with any other version.<br class=""><br class=""></blockquote><div class=""><br class=""></div><div class="">This is correct behavior.</div><div class=""> </div><blockquote class="gmail_quote" 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;">I had originally hoped that our (Open Dylan) compiler could output<br class="">bitcode that people could compile and link using the standard<br class="">/usr/bin/clang installed with Xcode, but it's looking more like we may<br class="">want to provide users with a build of vanilla LLVM/Clang for this<br class="">platform instead.<br class=""><br class="">Hopefully the debug info improvements currently under way will<br class="">incorporate a compatibility guarantee that Apple-distributed tools will<br class="">stick to as well.<br class=""><br class=""></blockquote><div class=""><br class=""></div><div class="">Unlikely for now though I don't speak for Apple.</div></div></div></blockquote><br class=""></div><div>We would love to have our debug info be compatible with the open-source version. We would need a stable representation of debug info for that to be possible.</div></body></html>