llvm-project/lld/ELF/SymbolTable.cpp

70 lines
2.0 KiB
C++

//===- SymbolTable.cpp ----------------------------------------------------===//
//
// The LLVM Linker
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "SymbolTable.h"
#include "Error.h"
#include "Symbols.h"
using namespace llvm;
using namespace lld;
using namespace lld::elf2;
SymbolTable::SymbolTable() { resolve(new (Alloc) Undefined("_start")); }
void SymbolTable::addFile(std::unique_ptr<InputFile> File) {
File->parse();
InputFile *FileP = File.release();
auto *P = cast<ObjectFileBase>(FileP);
addObject(P);
}
void SymbolTable::addObject(ObjectFileBase *File) {
if (!ObjectFiles.empty()) {
ObjectFileBase &Old = *ObjectFiles[0];
if (!Old.isCompatibleWith(*File))
error(Twine(Old.getName() + " is incompatible with " + File->getName()));
}
ObjectFiles.emplace_back(File);
for (SymbolBody *Body : File->getSymbols())
resolve(Body);
}
void SymbolTable::reportRemainingUndefines() {
for (auto &I : Symtab) {
Symbol *Sym = I.second;
if (auto *Undef = dyn_cast<Undefined>(Sym->Body))
error(Twine("undefined symbol: ") + Undef->getName());
}
}
// This function resolves conflicts if there's an existing symbol with
// the same name. Decisions are made based on symbol type.
void SymbolTable::resolve(SymbolBody *New) {
// Find an existing Symbol or create and insert a new one.
StringRef Name = New->getName();
Symbol *&Sym = Symtab[Name];
if (!Sym) {
Sym = new (Alloc) Symbol(New);
New->setBackref(Sym);
return;
}
New->setBackref(Sym);
// compare() returns -1, 0, or 1 if the lhs symbol is less preferable,
// equivalent (conflicting), or more preferable, respectively.
SymbolBody *Existing = Sym->Body;
int comp = Existing->compare(New);
if (comp < 0)
Sym->Body = New;
if (comp == 0)
error(Twine("duplicate symbol: ") + Name);
}