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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Actually the discriminator is implicitly reset to 0 after every "copy" or special opcode (i.e. after emitting each "row" of the virtual line table) so this
change would make the line table *smaller*. I verified this for the test case.<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>
<p class="MsoNormal"><a name="_MailEndCompose"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></a></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> Thursday, August 31, 2017 7:05 PM<br>
<b>To:</b> reviews+D37364+public+afdebe9cf3065eb2@reviews.llvm.org; aprantl@apple.com<br>
<b>Cc:</b> jdevlieghere@apple.com; llvm-commits@lists.llvm.org<br>
<b>Subject:</b> Re: [PATCH] D37364: [DWARF] Line 0 should not have a discriminator<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p>Wouldn't this make line tables longer, as it would take extra bits in the line table state machine to change the discriminator back to zero?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">On Thu., 31 Aug. 2017, 5:46 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 created this revision.<br>
Herald added a subscriber: JDevlieghere.<br>
<br>
We have line 0 inherit the scope of the previous non-zero line, to limit the size cost of the line 0 records; but that scope might have a discriminator attached, and a discriminator on line 0 is pointless.<br>
<br>
<br>
<a href="https://reviews.llvm.org/D37364" target="_blank">https://reviews.llvm.org/D37364</a><br>
<br>
Files:<br>
lib/CodeGen/AsmPrinter/DwarfDebug.cpp<br>
test/CodeGen/Generic/dbg-line-0-no-discriminator.ll<o:p></o:p></p>
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