Handle a peculiar comdat case: Creating a section with an undefined
signature symbol causes a local symbol to be created unless there is
some other use of the symbol.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@119026 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/MC/MCELFStreamer.cpp b/lib/MC/MCELFStreamer.cpp
index 830bd4f..1f4f146 100644
--- a/lib/MC/MCELFStreamer.cpp
+++ b/lib/MC/MCELFStreamer.cpp
@@ -84,6 +84,7 @@
   virtual void EmitThumbFunc(MCSymbol *Func);
   virtual void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value);
   virtual void EmitWeakReference(MCSymbol *Alias, const MCSymbol *Symbol);
+  virtual void SwitchSection(const MCSection *Section);
   virtual void EmitSymbolAttribute(MCSymbol *Symbol, MCSymbolAttr Attribute);
   virtual void EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
     assert(0 && "ELF doesn't support this directive");
@@ -282,6 +283,13 @@
 };
 } // end anonymous namespace
 
+void MCELFStreamer::SwitchSection(const MCSection *Section) {
+  const MCSymbol *Grp = static_cast<const MCSectionELF *>(Section)->getGroup();
+  if (Grp)
+    getAssembler().getOrCreateSymbolData(*Grp);
+  this->MCObjectStreamer::SwitchSection(Section);
+}
+
 void MCELFStreamer::EmitWeakReference(MCSymbol *Alias, const MCSymbol *Symbol) {
   getAssembler().getOrCreateSymbolData(*Symbol);
   MCSymbolData &AliasSD = getAssembler().getOrCreateSymbolData(*Alias);