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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">(remembering to cc: cfe-dev this time)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">On PS4 we put those kinds of smarts into the linker. We invented a custom ELF section for passing things like extra library names (a-la pragma comment lib)
plus the linker will auto-detect BC files and run them through LTO.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">I've also seen a platform (not sure which) that invented really elaborate mechanisms that they then stuck into the .comment section.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">--paulr<o:p></o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> cfe-dev [mailto:cfe-dev-bounces@lists.llvm.org]
<b>On Behalf Of </b>Beren Minor via cfe-dev<br>
<b>Sent:</b> Tuesday, January 12, 2016 9:51 AM<br>
<b>To:</b> Reid Kleckner<br>
<b>Cc:</b> Clang Dev<br>
<b>Subject:</b> Re: [cfe-dev] [clang] Implementing autolink with LLVM bitcode objects<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt">Wouldn't it be possible to create a custom section in the ELF object for the linker flags, and have Clang parse them when it is used as a linker invocation then pass them down to the linker? Obvisouly this won't
work when invoking the linker alone, but it could be a first step.<o:p></o:p></p>
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<p class="MsoNormal">I believe Swift compiler does this kind of thing: <a href="https://github.com/apple/swift/blob/master/tools/driver/autolink_extract_main.cpp" target="_blank">
https://github.com/apple/swift/blob/master/tools/driver/autolink_extract_main.cpp</a><br clear="all">
<o:p></o:p></p>
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<p class="MsoNormal">--<br>
Beren Minor<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">On Tue, Jan 12, 2016 at 6:44 PM, Reid Kleckner <<a href="mailto:rnk@google.com" target="_blank">rnk@google.com</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal">On Thu, Jan 7, 2016 at 8:07 AM, David Blaikie via cfe-dev <<a href="mailto:cfe-dev@lists.llvm.org" target="_blank">cfe-dev@lists.llvm.org</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal">Sounds plausible - as for which direction to go, I don't know (it's hardly my area of expertise) though the bitcode/module-agnostic version does seem preferable. Is there any prior art in the area? One or more linkers that already support
the sort of feature you've described (so the linker looks for the special object file section with the info, rather than the compile driver?)<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">We already implement autolinking on Mac and Windows, but not Linux. So far as I know there is no way for an ELF object file to tell the linker to pull in more libraries, but MachO and COFF can do this.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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