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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">GCC actually doesn’t support function multiversioning in C mode, so this fix is part of our extension to support C with multiversioning. I perhaps wonder if
this is part of the reason GCC only supports it in C++ mode... <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>
<p class="MsoNormal"><a name="_____replyseparator"></a><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"> David Blaikie [mailto:dblaikie@gmail.com]
<br>
<b>Sent:</b> Monday, October 29, 2018 11:25 AM<br>
<b>To:</b> Keane, Erich <erich.keane@intel.com>; Eric Christopher <echristo@gmail.com><br>
<b>Cc:</b> cfe-commits@lists.llvm.org<br>
<b>Subject:</b> Re: r344957 - Give Multiversion-inline functions linkonce linkage<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt">Does this match GCC's approach here?<br>
<br>
(I ask this sort of as throwaway/conversation starter - because the linkage/behavior around multiversion functions and their inlining is full of sharp corners/risks of code moving out of the areas appropriately restricted based on the cpu features)<o:p></o:p></p>
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<p class="MsoNormal">On Mon, Oct 22, 2018 at 2:22 PM Erich Keane via cfe-commits <<a href="mailto:cfe-commits@lists.llvm.org">cfe-commits@lists.llvm.org</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal">Author: erichkeane<br>
Date: Mon Oct 22 14:20:45 2018<br>
New Revision: 344957<br>
<br>
URL: <a href="http://llvm.org/viewvc/llvm-project?rev=344957&view=rev" target="_blank">
http://llvm.org/viewvc/llvm-project?rev=344957&view=rev</a><br>
Log:<br>
Give Multiversion-inline functions linkonce linkage<br>
<br>
Since multiversion variant functions can be inline, in C they become<br>
available-externally linkage. This ends up causing the variants to not<br>
be emitted, and not available to the linker.<br>
<br>
The solution is to make sure that multiversion functions are always<br>
emitted by marking them linkonce.<br>
<br>
Change-Id: I897aa37c7cbba0c1eb2c57ee881d5000a2113b75<br>
<br>
Modified:<br>
cfe/trunk/lib/CodeGen/CodeGenModule.cpp<br>
cfe/trunk/test/CodeGen/attr-target-mv.c<br>
<br>
Modified: cfe/trunk/lib/CodeGen/CodeGenModule.cpp<br>
URL: <a href="http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CodeGenModule.cpp?rev=344957&r1=344956&r2=344957&view=diff" target="_blank">
http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CodeGenModule.cpp?rev=344957&r1=344956&r2=344957&view=diff</a><br>
==============================================================================<br>
--- cfe/trunk/lib/CodeGen/CodeGenModule.cpp (original)<br>
+++ cfe/trunk/lib/CodeGen/CodeGenModule.cpp Mon Oct 22 14:20:45 2018<br>
@@ -3669,6 +3669,10 @@ llvm::GlobalValue::LinkageTypes CodeGenM<br>
return llvm::GlobalVariable::WeakAnyLinkage;<br>
}<br>
<br>
+ if (const auto *FD = D->getAsFunction())<br>
+ if (FD->isMultiVersion() && Linkage == GVA_AvailableExternally)<br>
+ return llvm::GlobalVariable::LinkOnceAnyLinkage;<br>
+<br>
// We are guaranteed to have a strong definition somewhere else,<br>
// so we can use available_externally linkage.<br>
if (Linkage == GVA_AvailableExternally)<br>
<br>
Modified: cfe/trunk/test/CodeGen/attr-target-mv.c<br>
URL: <a href="http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGen/attr-target-mv.c?rev=344957&r1=344956&r2=344957&view=diff" target="_blank">
http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGen/attr-target-mv.c?rev=344957&r1=344956&r2=344957&view=diff</a><br>
==============================================================================<br>
--- cfe/trunk/test/CodeGen/attr-target-mv.c (original)<br>
+++ cfe/trunk/test/CodeGen/attr-target-mv.c Mon Oct 22 14:20:45 2018<br>
@@ -88,19 +88,19 @@ void bar4() {<br>
<br>
// CHECK: declare i32 @foo.arch_sandybridge()<br>
<br>
-// CHECK: define available_externally i32 @foo_inline.sse4.2()<br>
+// CHECK: define linkonce i32 @foo_inline.sse4.2()<br>
// CHECK: ret i32 0<br>
<br>
// CHECK: declare i32 @foo_inline.arch_sandybridge()<br>
//<br>
-// CHECK: define available_externally i32 @foo_inline.arch_ivybridge()<br>
+// CHECK: define linkonce i32 @foo_inline.arch_ivybridge()<br>
// CHECK: ret i32 1<br>
-// CHECK: define available_externally i32 @foo_inline()<br>
+// CHECK: define linkonce i32 @foo_inline()<br>
// CHECK: ret i32 2<br>
<br>
-// CHECK: define available_externally void @foo_decls()<br>
-// CHECK: define available_externally void @foo_decls.sse4.2()<br>
+// CHECK: define linkonce void @foo_decls()<br>
+// CHECK: define linkonce void @foo_decls.sse4.2()<br>
<br>
-// CHECK: define available_externally void @foo_multi.avx_sse4.2()<br>
-// CHECK: define available_externally void @foo_multi.fma4_sse4.2()<br>
-// CHECK: define available_externally void @foo_multi.arch_ivybridge_fma4_sse4.2()<br>
+// CHECK: define linkonce void @foo_multi.avx_sse4.2()<br>
+// CHECK: define linkonce void @foo_multi.fma4_sse4.2()<br>
+// CHECK: define linkonce void @foo_multi.arch_ivybridge_fma4_sse4.2()<br>
<br>
<br>
_______________________________________________<br>
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<a href="mailto:cfe-commits@lists.llvm.org" target="_blank">cfe-commits@lists.llvm.org</a><br>
<a href="http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits" target="_blank">http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits</a><o:p></o:p></p>
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