<html><head><meta http-equiv="Content-Type" content="text/html; charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><br class=""><div><br class=""><blockquote type="cite" class=""><div class="">On Apr 12, 2019, at 10:30 AM, <a href="mailto:paul.robinson@sony.com" class="">paul.robinson@sony.com</a> wrote:</div><br class="Apple-interchange-newline"><div class=""><br style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><br style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><blockquote type="cite" style="font-family: Menlo-Regular; 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-size-adjust: auto; -webkit-text-stroke-width: 0px; text-decoration: none;" class="">-----Original Message-----<br class="">From: David Blaikie [<a href="mailto:dblaikie@gmail.com" class="">mailto:dblaikie@gmail.com</a>]<br class="">Sent: Friday, April 12, 2019 12:43 PM<br class="">To: Robinson, Paul<br class="">Cc: Adrian Prantl; Clang Dev; Douglas Katzman<br class="">Subject: Re: Make standalone-debug default based on glldb tuning<br class=""><br class="">On Fri, Apr 12, 2019 at 9:38 AM <<a href="mailto:paul.robinson@sony.com" class="">paul.robinson@sony.com</a>> wrote:<br class=""><blockquote type="cite" class=""><br class=""><br class=""><br class=""><blockquote type="cite" class="">-----Original Message-----<br class="">From: David Blaikie [<a href="mailto:dblaikie@gmail.com" class="">mailto:dblaikie@gmail.com</a>]<br class="">Sent: Friday, April 12, 2019 12:06 PM<br class="">To: Robinson, Paul<br class="">Cc: Adrian Prantl; Clang Dev; Douglas Katzman<br class="">Subject: Re: Make standalone-debug default based on glldb tuning<br class=""><br class="">On Fri, Apr 12, 2019 at 8:45 AM <<a href="mailto:paul.robinson@sony.com" class="">paul.robinson@sony.com</a>> wrote:<br class=""><blockquote type="cite" class=""><br class=""><br class=""><br class=""><blockquote type="cite" class="">-----Original Message-----<br class="">From: <a href="mailto:aprantl@apple.com" class="">aprantl@apple.com</a> [<a href="mailto:aprantl@apple.com" class="">mailto:aprantl@apple.com</a>]<br class="">Sent: Friday, April 12, 2019 11:21 AM<br class="">To: David Blaikie<br class="">Cc: Clang Dev; Robinson, Paul; Douglas Katzman<br class="">Subject: Re: Make standalone-debug default based on glldb tuning<br class=""><br class=""><br class=""><br class=""><blockquote type="cite" class="">On Apr 12, 2019, at 8:18 AM, David Blaikie <<a href="mailto:dblaikie@gmail.com" class="">dblaikie@gmail.com</a>><br class=""></blockquote></blockquote></blockquote>wrote:<br class=""><blockquote type="cite" class=""><blockquote type="cite" class=""><blockquote type="cite" class=""><br class="">I realized recently (as folks at Google have started<br class=""></blockquote></blockquote></blockquote></blockquote></blockquote>experimenting<br class=""><blockquote type="cite" class=""><blockquote type="cite" class=""><blockquote type="cite" class=""><blockquote type="cite" class=""><blockquote type="cite" class="">with LLDB) that the platform default for debugger tuning and the<br class="">default for -fstandalone-debug are both independent. This seems<br class=""></blockquote></blockquote></blockquote></blockquote></blockquote>a<br class=""><blockquote type="cite" class=""><blockquote type="cite" class="">bit<br class=""><blockquote type="cite" class=""><blockquote type="cite" class=""><blockquote type="cite" class="">wrong to me because enabling -glldb doesn't enable -fstandalone-<br class=""></blockquote></blockquote></blockquote>debug.<br class=""><blockquote type="cite" class=""><blockquote type="cite" class=""><blockquote type="cite" class=""><br class="">I'm wondering if everyone's on board with removing<br class="">ToolChain::GetDefaultStandaloneDebug, and using<br class="">ToolChain::getDefaultDebuggerTuning() to select the default<br class=""></blockquote></blockquote></blockquote>standalone<br class=""><blockquote type="cite" class=""><blockquote type="cite" class=""><blockquote type="cite" class="">debug state?<br class=""><br class="">Then on the command line, I'd kind of expect one to override the<br class="">other, so things like "-glldb -fno-standalone-debug" is<br class=""></blockquote></blockquote></blockquote></blockquote></blockquote>respected<br class=""><blockquote type="cite" class=""><blockquote type="cite" class=""><blockquote type="cite" class=""><blockquote type="cite" class=""><blockquote type="cite" class="">(when it comes to hopefully fixing LLDB to cope with standalone<br class=""></blockquote></blockquote></blockquote>debug<br class=""><blockquote type="cite" class=""><blockquote type="cite" class=""><blockquote type="cite" class="">input).<br class=""><br class="">Sound good to everyone? If so I'll make a patch & send it for<br class=""></blockquote></blockquote></blockquote>review.<br class=""><blockquote type="cite" class=""><blockquote type="cite" class=""><blockquote type="cite" class="">(well, I'll probably work on the patch now anyway)<br class=""></blockquote><br class="">Since this doesn't change anything for platforms that default to -<br class=""></blockquote></blockquote>glldb,<br class=""><blockquote type="cite" class=""><blockquote type="cite" class="">I'm fine with this change.<br class=""><br class="">-- adrian<br class=""></blockquote><br class="">I'm somewhat surprised LLDB would want -fstandalone-debug,<br class=""></blockquote></blockquote></blockquote>independent<br class=""><blockquote type="cite" class=""><blockquote type="cite" class=""><blockquote type="cite" class="">of the target. It would be a source of unnecessary bloat on ELF-<br class=""></blockquote></blockquote></blockquote>using<br class=""><blockquote type="cite" class=""><blockquote type="cite" class=""><blockquote type="cite" class="">targets, no?<br class=""></blockquote><br class="">LLDB fundamentally (at the moment) doesn't support -fstandalone-debug,<br class="">no matter the file format.<br class=""><br class="">As far as I understand it: LLDB constructs ASTs from DWARF on a<br class="">per-binary level (so, .so or executable). -fstandalone-debug creates<br class="">"impossible" DWARF (eg: if one base class's vtable (& thus DWARF<br class="">definition) is in one .so, but a derived class is in another .so -<br class="">then the DWARF in the second .so contains a definition that derives<br class="">from a declaration (& the DWARF consumer would have to go look in the<br class="">other .so to stitch it up to a definition).<br class=""></blockquote><br class="">Uh. Am I misunderstanding? Somehow I thought -fstandalone-debug meant<br class="">"full" which means the base class ought not to be a declaration in<br class="">the second .so? Or is that pruning not based on the full/limited<br class="">distinction?<br class=""></blockquote><br class="">Sorry, I misspoke - the default ("no standalone debug") creates the<br class="">DWARF that doesn't correspond to source in that you can see classes<br class="">derived from declarations and the like. LLDB won't go searching for a<br class="">definition that matches the declaration outside the scope of a single<br class="">blob of DWARF (either a single object or single dsym, I guess).<br class="">Turning on standalone debug avoids LLDB encountering these<br class="">"impossible" situations.<br class=""></blockquote><br style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><span style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;" class="">Okay then! So the story is, LLDB doesn't want to chase after things</span><br style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><span style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;" class="">in other objects, which on Darwin is either expensive (in a .o case)</span><br style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><span style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;" class="">or moot (when dsymutil has done it all ahead of time). Which leaves</span><br style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><span style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;" class="">me wondering about the ELF case; LLDB also doesn't want to troll<span class="Apple-converted-space"> </span></span><br style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><span style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;" class="">through other CUs even when they are in the same executable? That<span class="Apple-converted-space"> </span></span><br style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><span style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;" class="">strikes me as a real inadequacy in LLDB, not something that the</span><br style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><span style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;" class="">compiler should compensate for. Especially once you upgrade to v5</span><br style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><span style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;" class="">and get the spiffy new index (thanks to Pavel).</span><br style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""></div></blockquote><div><br class=""></div><div>The relevant unit of granularity here is an lldb::Module, which is one shared library (or executable). Even using ELF, LLDB doesn't want to cross this boundary. My best guess is that LLDB will run into this issue if, e.g., a base class is defined in a different .so file.</div><div><br class=""></div><div>-- adrian</div><br class=""><blockquote type="cite" class=""><div class=""><br style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><span style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;" class="">So I'm unconvinced that the basis of the -fstandalone-debug default</span><br style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><span style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;" class="">should be changed.</span><br style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><br style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><span style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;" class="">FTR, I completely get the scenario Adrian describes where some</span><br style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><span style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;" class="">library has no debug info and the normal (limited) case fails to</span><br style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><span style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;" class="">provide a full definition. We've had complaints about not being</span><br style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><span style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;" class="">able to debug some STL-derived classes. Licensees are not too</span><br style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><span style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;" class="">happy about the extra size with the full-info workaround.</span><br style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><span style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;" class="">--paulr</span><br style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><br style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><blockquote type="cite" style="font-family: Menlo-Regular; 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-size-adjust: auto; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><br class=""><blockquote type="cite" class=""><br class=""><blockquote type="cite" class=""><br class="">(FreeBSD defaults to -fstandalone-debug because it defaults to LLDB as<br class="">the debugger - Adrian's reply makes me wonder if that's clear, so<br class="">figured I'd mention that)<br class=""><br class=""><blockquote type="cite" class="">--paulr</blockquote></blockquote></blockquote></blockquote></div></blockquote></div><br class=""></body></html>