Store whether a symbol is a comdat signature in MCSymbolELF.

With this getBinging can now return the correct answer for all cases not
involving a .symver and the elf writer doesn't need to patch it last minute.

llvm-svn: 238980

llvm/include/llvm/MC/MCSectionELF.h

@@ -58,7 +58,10 @@ private:
                MCSymbol *Begin, const MCSectionELF *Associated)
       : MCSection(SV_ELF, K, Begin), SectionName(Section), Type(type),
         Flags(flags), UniqueID(UniqueID), EntrySize(entrySize), Group(group),
-        Associated(Associated) {}
+        Associated(Associated) {
+    if (Group)
+      Group->setIsSignature();
+  }
   ~MCSectionELF() override;
 
   void setSectionName(StringRef Name) { SectionName = Name; }

llvm/include/llvm/MC/MCSymbolELF.h

@@ -19,6 +19,7 @@ class MCSymbolELF : public MCSymbol {
 
   mutable unsigned BindingSet : 1;
   mutable unsigned UsedInReloc : 1;
+  mutable unsigned IsSignature : 1;
 
 public:
   MCSymbolELF(const StringMapEntry<bool> *Name, bool isTemporary)
@@ -44,6 +45,9 @@ public:
   void setUsedInReloc() const;
   bool isUsedInReloc() const;
 
+  void setIsSignature() const;
+  bool isSignature() const;
+
   static bool classof(const MCSymbol *S) { return S->isELF(); }
 };
 }

llvm/lib/MC/ELFObjectWriter.cpp

@@ -74,7 +74,6 @@ class ELFObjectWriter : public MCObjectWriter {
     static uint64_t SymbolValue(const MCSymbol &Sym, const MCAsmLayout &Layout);
     static bool isInSymtab(const MCAsmLayout &Layout, const MCSymbolELF &Symbol,
                            bool Used, bool Renamed);
-    static bool isLocal(const MCSymbolELF &Symbol, bool IsSignature);
 
     /// Helper struct for containing some precomputed information on symbols.
     struct ELFSymbolData {
@@ -755,19 +754,6 @@ bool ELFObjectWriter::isInSymtab(const MCAsmLayout &Layout,
   return true;
 }
 
-bool ELFObjectWriter::isLocal(const MCSymbolELF &Symbol, bool IsSignature) {
-  if (Symbol.isExternal())
-    return false;
-
-  if (Symbol.isDefined())
-    return true;
-
-  if (Symbol.isUsedInReloc())
-    return false;
-
-  return IsSignature;
-}
-
 void ELFObjectWriter::computeSymbolTable(
     MCAssembler &Asm, const MCAsmLayout &Layout,
     const SectionIndexMapTy &SectionIndexMap, const RevGroupMapTy &RevGroupMap,
@@ -800,7 +786,7 @@ void ELFObjectWriter::computeSymbolTable(
     const auto &Symbol = cast<MCSymbolELF>(S);
     bool Used = Symbol.isUsedInReloc();
     bool WeakrefUsed = WeakrefUsedInReloc.count(&Symbol);
-    bool isSignature = RevGroupMap.count(&Symbol);
+    bool isSignature = Symbol.isSignature();
 
     if (!isInSymtab(Layout, Symbol, Used || WeakrefUsed || isSignature,
                     Renames.count(&Symbol)))
@@ -809,12 +795,7 @@ void ELFObjectWriter::computeSymbolTable(
     ELFSymbolData MSD;
     MSD.Symbol = cast<MCSymbolELF>(&Symbol);
 
-    // Undefined symbols are global, but this is the first place we
-    // are able to set it.
-    bool Local = isLocal(Symbol, isSignature);
-    if (!Local && Symbol.getBinding() == ELF::STB_LOCAL)
-      Symbol.setBinding(ELF::STB_GLOBAL);
-
+    bool Local = Symbol.getBinding() == ELF::STB_LOCAL;
     if (Symbol.isAbsolute()) {
       MSD.SectionIndex = ELF::SHN_ABS;
     } else if (Symbol.isCommon()) {

llvm/lib/MC/MCSymbolELF.cpp

@@ -24,10 +24,20 @@ void MCSymbolELF::setBinding(unsigned Binding) const {
 }
 
 unsigned MCSymbolELF::getBinding() const {
-  uint32_t Binding = (getFlags() & (0xf << ELF_STB_Shift)) >> ELF_STB_Shift;
-  assert(Binding == ELF::STB_LOCAL || Binding == ELF::STB_GLOBAL ||
-         Binding == ELF::STB_WEAK || Binding == ELF::STB_GNU_UNIQUE);
-  return Binding;
+  if (isBindingSet()) {
+    uint32_t Binding = (getFlags() & (0xf << ELF_STB_Shift)) >> ELF_STB_Shift;
+    assert(Binding == ELF::STB_LOCAL || Binding == ELF::STB_GLOBAL ||
+           Binding == ELF::STB_WEAK || Binding == ELF::STB_GNU_UNIQUE);
+    return Binding;
+  }
+
+  if (isDefined())
+    return ELF::STB_LOCAL;
+  if (isUsedInReloc())
+    return ELF::STB_GLOBAL;
+  if (isSignature())
+    return ELF::STB_LOCAL;
+  return ELF::STB_GLOBAL;
 }
 
 void MCSymbolELF::setType(unsigned Type) const {
@@ -86,4 +96,7 @@ bool MCSymbolELF::isUsedInReloc() const {
   return UsedInReloc;
 }
 
+void MCSymbolELF::setIsSignature() const { IsSignature = true; }
+
+bool MCSymbolELF::isSignature() const { return IsSignature; }
 }