Disallow assigning symbol a null section.

They are constructed without one and they can't go back, so this was
effectively dead code.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@249220 91177308-0d34-0410-b5e6-96231b3b80d8

lib/MC/MCAsmStreamer.cpp

@@ -533,9 +533,6 @@ void MCAsmStreamer::emitELFSize(MCSymbolELF *Symbol, const MCExpr *Value) {
 
 void MCAsmStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
                                      unsigned ByteAlignment) {
-  // Common symbols do not belong to any actual section.
-  AssignSection(Symbol, nullptr);
-
   OS << "\t.comm\t";
   Symbol->print(OS, MAI);
   OS << ',' << Size;
@@ -555,9 +552,6 @@ void MCAsmStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
 /// @param Size - The size of the common symbol.
 void MCAsmStreamer::EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
                                           unsigned ByteAlign) {
-  // Common symbols do not belong to any actual section.
-  AssignSection(Symbol, nullptr);
-
   OS << "\t.lcomm\t";
   Symbol->print(OS, MAI);
   OS << ',' << Size;

lib/MC/MCMachOStreamer.cpp

@@ -384,8 +384,6 @@ void MCMachOStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
   // FIXME: Darwin 'as' does appear to allow redef of a .comm by itself.
   assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
 
-  AssignSection(Symbol, nullptr);
-
   getAssembler().registerSymbol(*Symbol);
   Symbol->setExternal(true);
   Symbol->setCommon(Size, ByteAlignment);

lib/MC/MCStreamer.cpp

@@ -189,10 +189,8 @@ void MCStreamer::InitSections(bool NoExecStack) {
 }
 
 void MCStreamer::AssignSection(MCSymbol *Symbol, MCSection *Section) {
-  if (Section)
-    Symbol->setSection(*Section);
-  else
-    Symbol->setUndefined();
+  assert(Section);
+  Symbol->setSection(*Section);
 
   // As we emit symbols into a section, track the order so that they can
   // be sorted upon later. Zero is reserved to mean 'unemitted'.

lib/MC/WinCOFFStreamer.cpp

@@ -214,8 +214,6 @@ void MCWinCOFFStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
     Size = std::max(Size, static_cast<uint64_t>(ByteAlignment));
   }
 
-  AssignSection(Symbol, nullptr);
-
   getAssembler().registerSymbol(*Symbol);
   Symbol->setExternal(true);
   Symbol->setCommon(Size, ByteAlignment);