[llvm-objcopy] Add support for visibility

[jakehehrlich]

Summary

I have no clue how this was missed when symbol table support was added. This change ensures that the visibility of symbols is preserved by default.

[phosek]

LGTM

[jakehehrlich]

Committed this in r321681

test/tools/llvm-objcopy/symbol-copy.test

- Name:            .data
     Content:         "0000000000000000"
 Symbols:
   Global:
     - Name:     _start
       Type:     STT_FUNC
       Section:  .text
       Value:    0x1000
       Size:     4
-    - Name:     foo
+    - Name:     bam
       Type:     STT_FUNC
       Section:  .text
+      Value:    0x1001
+      Size:     4
+      Visibility: STV_HIDDEN
+    - Name:     foo
+      Type:     STT_FUNC
       Section:  .text
       Value:    0x1004
+    - Name:     faz
+      Type:     STT_OBJECT
+      Section:  .data
+      Value:    0x2002
+      Size:     2
+      Visibility: STV_INTERNAL
     - Name:     bar
       Type:     STT_OBJECT
       Section:  .data
       Value:    0x2000
       Size:     4
     - Name:     baz
       Type:     STT_OBJECT
       Section:  .data

 #CHECK-NEXT:    Value: 0x1000
 #CHECK-NEXT:    Size: 4
 #CHECK-NEXT:    Binding: Global
 #CHECK-NEXT:    Type: Function
 #CHECK-NEXT:    Other: 0
 #CHECK-NEXT:    Section: .text
 #CHECK-NEXT:  }
 #CHECK-NEXT:  Symbol {
+#CHECK-NEXT:    Name: bam
+#CHECK-NEXT:    Value: 0x1001
+#CHECK-NEXT:    Size: 4
+#CHECK-NEXT:    Binding: Global
+#CHECK-NEXT:    Type: Function
+#CHECK-NEXT:    Other [
+#CHECK-NEXT:      STV_HIDDEN
+#CHECK-NEXT:    ]
+#CHECK-NEXT:    Section: .text
+#CHECK-NEXT:  }
+#CHECK-NEXT:  Symbol {
 #CHECK-NEXT:    Name: foo
 #CHECK-NEXT:    Value: 0x1004
 #CHECK-NEXT:    Size: 0
 #CHECK-NEXT:    Binding: Global
 #CHECK-NEXT:    Type: Function
 #CHECK-NEXT:    Other: 0
 #CHECK-NEXT:    Section: .text
 #CHECK-NEXT:  }
 #CHECK-NEXT:  Symbol {
+#CHECK-NEXT:    Name: faz
+#CHECK-NEXT:    Value: 0x2002
+#CHECK-NEXT:    Size: 2
+#CHECK-NEXT:    Binding: Global
+#CHECK-NEXT:    Type: Object
+#CHECK-NEXT:    Other [
+#CHECK-NEXT:      STV_INTERNAL
+#CHECK-NEXT:    ]
+#CHECK-NEXT:    Section: .data
+#CHECK-NEXT:  }
+#CHECK-NEXT:  Symbol {
 #CHECK-NEXT:    Name: bar
 #CHECK-NEXT:    Value: 0x2000
 #CHECK-NEXT:    Size: 4
 #CHECK-NEXT:    Binding: Global
 #CHECK-NEXT:    Type: Object
 #CHECK-NEXT:    Other: 0
 #CHECK-NEXT:    Section: .data
 #CHECK-NEXT:  }

tools/llvm-objcopy/Object.h

struct Symbol {
   SectionBase *DefinedIn = nullptr;
   SymbolShndxType ShndxType;
   uint32_t Index;
   StringRef Name;
   uint32_t NameIndex;
   uint64_t Size;
   uint8_t Type;
   uint64_t Value;
+  uint8_t Visibility;
 
   uint16_t getShndx() const;
 };
 
 class SymbolTableSection : public SectionBase {
 protected:
   std::vector<std::unique_ptr<Symbol>> Symbols;
   StringTableSection *SymbolNames = nullptr;
 
   using SymPtr = std::unique_ptr<Symbol>;
 
 public:
   void setStrTab(StringTableSection *StrTab) { SymbolNames = StrTab; }
   void addSymbol(StringRef Name, uint8_t Bind, uint8_t Type,
-                 SectionBase *DefinedIn, uint64_t Value, uint16_t Shndx,
-                 uint64_t Sz);
+                 SectionBase *DefinedIn, uint64_t Value, uint8_t Visibility,
+                 uint16_t Shndx, uint64_t Sz);
   void addSymbolNames();
   const SectionBase *getStrTab() const { return SymbolNames; }
   const Symbol *getSymbolByIndex(uint32_t Index) const;
   void removeSectionReferences(const SectionBase *Sec) override;
   void initialize(SectionTableRef SecTable) override;
   void finalize() override;
 
   static bool classof(const SectionBase *S) {

tools/llvm-objcopy/Object.cpp

uint16_t Symbol::getShndx() const {
   case SYMBOL_HEXAGON_SCOMMON_8:
     return static_cast<uint16_t>(ShndxType);
   }
   llvm_unreachable("Symbol with invalid ShndxType encountered");
 }
 
 void SymbolTableSection::addSymbol(StringRef Name, uint8_t Bind, uint8_t Type,
                                    SectionBase *DefinedIn, uint64_t Value,
-                                   uint16_t Shndx, uint64_t Sz) {
+                                   uint8_t Visibility, uint16_t Shndx,
+                                   uint64_t Sz) {
   Symbol Sym;
   Sym.Name = Name;
   Sym.Binding = Bind;
   Sym.Type = Type;
   Sym.DefinedIn = DefinedIn;
   if (DefinedIn == nullptr) {
     if (Shndx >= SHN_LORESERVE)
       Sym.ShndxType = static_cast<SymbolShndxType>(Shndx);
     else
       Sym.ShndxType = SYMBOL_SIMPLE_INDEX;
   }
   Sym.Value = Value;
+  Sym.Visibility = Visibility;
   Sym.Size = Sz;
   Sym.Index = Symbols.size();
   Symbols.emplace_back(llvm::make_unique<Symbol>(Sym));
   Size += this->EntrySize;
 }
 
 void SymbolTableSection::removeSectionReferences(const SectionBase *Sec) {
   if (SymbolNames == Sec) {
void SymbolTableSectionImpl<ELFT>::writeSection(FileOutputBuffer &Out) const {
   uint8_t *Buf = Out.getBufferStart();
   Buf += Offset;
   typename ELFT::Sym *Sym = reinterpret_cast<typename ELFT::Sym *>(Buf);
   // Loop though symbols setting each entry of the symbol table.
   for (auto &Symbol : Symbols) {
     Sym->st_name = Symbol->NameIndex;
     Sym->st_value = Symbol->Value;
     Sym->st_size = Symbol->Size;
+    Sym->st_other = Symbol->Visibility;
     Sym->setBinding(Symbol->Binding);
     Sym->setType(Symbol->Type);
     Sym->st_shndx = Symbol->getShndx();
     ++Sym;
   }
 }
 
 template <class SymTabType>
for (const auto &Sym : unwrapOrError(ElfFile.symbols(&Shdr))) {
     } else if (Sym.st_shndx != SHN_UNDEF) {
       DefSection = SecTable.getSection(
           Sym.st_shndx,
           "Symbol '" + Name + "' is defined in invalid section with index " +
               Twine(Sym.st_shndx));
     }
 
     SymTab->addSymbol(Name, Sym.getBinding(), Sym.getType(), DefSection,
-                      Sym.getValue(), Sym.st_shndx, Sym.st_size);
+                      Sym.getValue(), Sym.st_other, Sym.st_shndx, Sym.st_size);
   }
 }
 
 template <class ELFT>
 static void getAddend(uint64_t &ToSet, const Elf_Rel_Impl<ELFT, false> &Rel) {}
 
 template <class ELFT>
 static void getAddend(uint64_t &ToSet, const Elf_Rel_Impl<ELFT, true> &Rela) {