+ /// ELFSym - This struct contains information about each symbol that is
+ /// added to logical symbol table for the module. This is eventually
+ /// turned into a real symbol table in the file.
+ struct ELFSym {
+
+ // ELF symbols are related to llvm ones by being one of the two llvm
+ // types, for the other ones (section, file, func) a null pointer is
+ // assumed by default.
+ union {
+ const GlobalValue *GV; // If this is a pointer to a GV
+ const char *Ext; // If this is a pointer to a named symbol
+ } Source;
+
+ // Describes from which source type this ELF symbol comes from,
+ // they can be GlobalValue, ExternalSymbol or neither.
+ enum {
+ isGV, // The Source.GV field is valid.
+ isExtSym, // The Source.ExtSym field is valid.
+ isOther // Not a GlobalValue or External Symbol
+ };
+ unsigned SourceType;
+
+ bool isGlobalValue() { return SourceType == isGV; }
+ bool isExternalSym() { return SourceType == isExtSym; }
+
+ // getGlobalValue - If this is a global value which originated the
+ // elf symbol, return a reference to it.
+ const GlobalValue *getGlobalValue() {
+ assert(SourceType == isGV && "This is not a global value");
+ return Source.GV;
+ };
+
+ // getExternalSym - If this is an external symbol which originated the
+ // elf symbol, return a reference to it.
+ const char *getExternalSymbol() {
+ assert(SourceType == isExtSym && "This is not an external symbol");
+ return Source.Ext;
+ };
+
+ // getGV - From a global value return a elf symbol to represent it
+ static ELFSym *getGV(const GlobalValue *GV, unsigned Bind,
+ unsigned Type, unsigned Visibility) {
+ ELFSym *Sym = new ELFSym();
+ Sym->Source.GV = GV;
+ Sym->setBind(Bind);
+ Sym->setType(Type);
+ Sym->setVisibility(Visibility);
+ Sym->SourceType = isGV;
+ return Sym;
+ }
+
+ // getExtSym - Create and return an elf symbol to represent an
+ // external symbol
+ static ELFSym *getExtSym(const char *Ext) {
+ ELFSym *Sym = new ELFSym();
+ Sym->Source.Ext = Ext;
+ Sym->setBind(STB_GLOBAL);
+ Sym->setType(STT_NOTYPE);
+ Sym->setVisibility(STV_DEFAULT);
+ Sym->SourceType = isExtSym;
+ return Sym;
+ }
+
+ // getSectionSym - Returns a elf symbol to represent an elf section
+ static ELFSym *getSectionSym() {
+ ELFSym *Sym = new ELFSym();
+ Sym->setBind(STB_LOCAL);
+ Sym->setType(STT_SECTION);
+ Sym->setVisibility(STV_DEFAULT);
+ Sym->SourceType = isOther;
+ return Sym;
+ }
+
+ // getFileSym - Returns a elf symbol to represent the module identifier
+ static ELFSym *getFileSym() {
+ ELFSym *Sym = new ELFSym();
+ Sym->setBind(STB_LOCAL);
+ Sym->setType(STT_FILE);
+ Sym->setVisibility(STV_DEFAULT);
+ Sym->SectionIdx = 0xfff1; // ELFSection::SHN_ABS;
+ Sym->SourceType = isOther;
+ return Sym;
+ }
+
+ // ELF specific fields
+ unsigned NameIdx; // Index in .strtab of name, once emitted.
+ uint64_t Value;
+ unsigned Size;
+ uint8_t Info;
+ uint8_t Other;
+ unsigned short SectionIdx;
+
+ // Symbol index into the Symbol table
+ unsigned SymTabIdx;
+
+ enum {
+ STB_LOCAL = 0, // Local sym, not visible outside obj file containing def
+ STB_GLOBAL = 1, // Global sym, visible to all object files being combined
+ STB_WEAK = 2 // Weak symbol, like global but lower-precedence
+ };
+
+ enum {
+ STT_NOTYPE = 0, // Symbol's type is not specified
+ STT_OBJECT = 1, // Symbol is a data object (variable, array, etc.)
+ STT_FUNC = 2, // Symbol is executable code (function, etc.)
+ STT_SECTION = 3, // Symbol refers to a section
+ STT_FILE = 4 // Local, absolute symbol that refers to a file
+ };
+
+ enum {
+ STV_DEFAULT = 0, // Visibility is specified by binding type
+ STV_INTERNAL = 1, // Defined by processor supplements
+ STV_HIDDEN = 2, // Not visible to other components
+ STV_PROTECTED = 3 // Visible in other components but not preemptable
+ };
+
+ ELFSym() : SourceType(isOther), NameIdx(0), Value(0),
+ Size(0), Info(0), Other(STV_DEFAULT), SectionIdx(0),
+ SymTabIdx(0) {}
+
+ unsigned getBind() const { return (Info >> 4) & 0xf; }
+ unsigned getType() const { return Info & 0xf; }
+ bool isLocalBind() const { return getBind() == STB_LOCAL; }
+ bool isFileType() const { return getType() == STT_FILE; }
+
+ void setBind(unsigned X) {
+ assert(X == (X & 0xF) && "Bind value out of range!");
+ Info = (Info & 0x0F) | (X << 4);
+ }
+
+ void setType(unsigned X) {
+ assert(X == (X & 0xF) && "Type value out of range!");
+ Info = (Info & 0xF0) | X;
+ }
+
+ void setVisibility(unsigned V) {
+ assert(V == (V & 0x3) && "Visibility value out of range!");
+ Other = V;
+ }
+ };
+