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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Yes, addFlag() does choose what to do based on version, and something like that for implicit const would work. The fallback would use a regular addSInt().<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""> llvm-commits [mailto:llvm-commits-bounces@lists.llvm.org]
<b>On Behalf Of </b>David Blaikie via llvm-commits<br>
<b>Sent:</b> Tuesday, February 28, 2017 5:05 PM<br>
<b>To:</b> reviews+D30377+public+7bf5043b5c30d2d5@reviews.llvm.org; vleschuk@accesssoftek.com; mehdi.amini@apple.com; echristo@gmail.com; aprantl@apple.com<br>
<b>Cc:</b> llvm-commits@lists.llvm.org<br>
<b>Subject:</b> Re: [PATCH] D30377: [DebugInfo] [DWARFv5] Support for DW_AT_calling_convention for types<o:p></o:p></span></p>
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<p class="MsoNormal">We'll probably want to add a generic function that can choose between implicit_const and a DWARF4 form - because we'll probably want to use implicit_const for existing attributes (like accessibility, etc). How do we handle form_present?
I think we have a high level "add Flag" operation that uses form_present or something backwards compatible depending on the target DWARF verison)<o:p></o:p></p>
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<p class="MsoNormal">On Tue, Feb 28, 2017 at 3:26 PM Paul Robinson via Phabricator <<a href="mailto:reviews@reviews.llvm.org">reviews@reviews.llvm.org</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt">probinson added inline comments.<br>
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================<br>
Comment at: lib/CodeGen/AsmPrinter/DwarfUnit.cpp:973<br>
+ // Add DW_AT_calling_convention attr.<br>
+ if (DD->getDwarfVersion() >= 5) {<br>
+ auto ArgABI = CTy->getArgABI();<br>
----------------<br>
aprantl wrote:<br>
> Technically true, but I think there is no harm in emitting this attribute also in DWARF 4 or earlier. We usually only do this if the new attribute cannot be safely ignored by an older consumer.<br>
Actually DW_FORM_implicit_const is new in DWARF 5, and new FORMs cannot be used in prior-version DIEs. So, either we have to guard the entire attribute, or we have to conditionalize the FORM.<br>
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<a href="https://reviews.llvm.org/D30377" target="_blank">https://reviews.llvm.org/D30377</a><br>
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<o:p></o:p></p>
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