<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40"><head><meta http-equiv=Content-Type content="text/html; charset=us-ascii"><meta name=Generator content="Microsoft Word 15 (filtered medium)"><style><!--
/* Font Definitions */
@font-face
{font-family:Helvetica;
panose-1:2 11 6 4 2 2 2 2 2 4;}
@font-face
{font-family:SimSun;
panose-1:2 1 6 0 3 1 1 1 1 1;}
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
@font-face
{font-family:"\@SimSun";
panose-1:2 1 6 0 3 1 1 1 1 1;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
margin-bottom:.0001pt;
font-size:12.0pt;
font-family:"Times New Roman",serif;}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:purple;
text-decoration:underline;}
span.apple-converted-space
{mso-style-name:apple-converted-space;}
span.EmailStyle18
{mso-style-type:personal-reply;
font-family:"Calibri",sans-serif;
color:#1F497D;}
.MsoChpDefault
{mso-style-type:export-only;
font-size:10.0pt;}
@page WordSection1
{size:8.5in 11.0in;
margin:1.0in 1.0in 1.0in 1.0in;}
div.WordSection1
{page:WordSection1;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>HI Mehdi,<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'>Currently not. I am trying to reduce my large LTO case into a simple one right now.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>The problem shows when SGV is a function definition (like foo) and it has <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>Externallinkage and DGV is declaration of foo. Foo of SGV will be renamed to <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>foo.xxx. This will make unreferenced error because foo is not there anymore.<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'>Thanks,<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'>Yin <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'><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><div><div style='border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>From:</span></b><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'> mehdi.amini@apple.com [mailto:mehdi.amini@apple.com] <br><b>Sent:</b> Thursday, January 07, 2016 1:34 PM<br><b>To:</b> Yin Ma<br><b>Cc:</b> llvm-commits<br><b>Subject:</b> Re: Fix LTO unreferenced symbol bug due to alias renaming<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Hi Yin,<o:p></o:p></p><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Do you have a test-case for that?<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Thanks,<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Mehdi<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p><div><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'><div><p class=MsoNormal>On Jan 7, 2016, at 12:28 PM, Yin Ma via llvm-commits <<a href="mailto:llvm-commits@lists.llvm.org">llvm-commits@lists.llvm.org</a>> wrote:<o:p></o:p></p></div><p class=MsoNormal><o:p> </o:p></p><div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>Hi,<span class=apple-converted-space> </span><o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'> <o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>After 18f201b4db339145af8f340196943ef57b9c8d9f from Rafael was merged in, we are experiencing<span class=apple-converted-space> </span><o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>unreferenced symbol in several LTO programs. I analyzed the problem and find because 18f201 patch<span class=apple-converted-space> </span><o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>tries to discard the aliasee by renaming it. However, it will create a problem<o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>If the renaming happens for external functions, where non byte code may reference to the original<o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>name and cause unreferenced symbol at the end.<o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'> <o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>So, we have to perform forceRenaming like before without 18f201 for those symbols in ShouldLink.<o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>Like this to force those global symbols which may expose to other module to be the original name.<o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'> <o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>diff --git a/lib/Linker/IRMover.cpp b/lib/Linker/IRMover.cpp<o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>index 16de0ec..68c3346 100644<o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>--- a/lib/Linker/IRMover.cpp<o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>+++ b/lib/Linker/IRMover.cpp<o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>@@ -1077,7 +1077,7 @@ Constant *IRLinker::linkGlobalValueProto(GlobalValue *SGV, bool ForAlias) {<o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'> return nullptr;<o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'> NewGV = copyGlobalValueProto(SGV, ShouldLink);<o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>- if (!ForAlias)<o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>+ if (ShouldLink || !ForAlias)<o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'> forceRenaming(NewGV, SGV->getName());<o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'> }<o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'> if (ShouldLink || ForAlias) {<o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'> <o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>Please review.<o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'> <o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>Thanks,<o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'> <o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>Yin<span class=apple-converted-space> </span><o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'> <o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'> <o:p></o:p></span></p></div><p class=MsoNormal><i.diff><span style='font-size:9.0pt;font-family:"Helvetica",sans-serif'>_______________________________________________<br>llvm-commits mailing list<br></span><a href="mailto:llvm-commits@lists.llvm.org"><span style='font-size:9.0pt;font-family:"Helvetica",sans-serif;color:#954F72'>llvm-commits@lists.llvm.org</span></a><span style='font-size:9.0pt;font-family:"Helvetica",sans-serif'><br></span><a href="http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits"><span style='font-size:9.0pt;font-family:"Helvetica",sans-serif;color:#954F72'>http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits</span></a><o:p></o:p></p></div></blockquote></div><p class=MsoNormal><o:p> </o:p></p></div></div></body></html>