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//===- Core/SymbolTable.cpp - Main Symbol Table ---------------------------===//
//
// The LLVM Linker
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "lld/Core/SymbolTable.h"
#include "lld/Core/Atom.h"
#include "lld/Core/File.h"
#include "lld/Core/InputFiles.h"
#include "lld/Core/Resolver.h"
#include "lld/Core/UndefinedAtom.h"
#include "lld/Platform/Platform.h"
#include "llvm/Support/ErrorHandling.h"
#include <algorithm>
#include <cassert>
#include <stdlib.h>
#include <vector>
namespace lld {
SymbolTable::SymbolTable(Platform& plat)
: _platform(plat) {
}
void SymbolTable::add(const Atom &atom) {
assert(atom.scope() != Atom::scopeTranslationUnit);
if ( !atom.internalName() ) {
this->addByName(atom);
}
else if ( atom.mergeDuplicates() ) {
// TO DO: support constants merging
}
}
enum NameCollisionResolution {
NCR_First,
NCR_Second,
NCR_Weak,
NCR_Larger,
NCR_Dup,
NCR_Error
};
static NameCollisionResolution cases[6][6] = {
//regular weak tentative absolute undef sharedLib
{
// first is regular
NCR_Dup, NCR_First, NCR_First, NCR_Error, NCR_First, NCR_First
},
{
// first is weak
NCR_Second, NCR_Weak, NCR_Larger, NCR_Error, NCR_First, NCR_First
},
{
// first is tentative
NCR_Second, NCR_Second, NCR_Larger, NCR_Error, NCR_First, NCR_First
},
{
// first is absolute
NCR_Error, NCR_Error, NCR_Error, NCR_Error, NCR_First, NCR_First
},
{
// first is undef
NCR_Second, NCR_Second, NCR_Second, NCR_Second, NCR_First, NCR_Second
},
{
// first is sharedLib
NCR_Second, NCR_Second, NCR_Second, NCR_Second, NCR_First, NCR_First
}
};
static NameCollisionResolution collide(Atom::Definition first,
Atom::Definition second) {
return cases[first][second];
}
void SymbolTable::addByName(const Atom & newAtom) {
llvm::StringRef name = newAtom.name();
const Atom *existing = this->findByName(name);
if (existing == NULL) {
// name is not in symbol table yet, add it associate with this atom
_nameTable[name] = &newAtom;
} else {
// name is already in symbol table and associated with another atom
switch (collide(existing->definition(), newAtom.definition())) {
case NCR_First:
// using first, just add new to _replacedAtoms
_replacedAtoms[&newAtom] = existing;
break;
case NCR_Second:
// using second, update tables
_nameTable[name] = &newAtom;
_replacedAtoms[existing] = &newAtom;
break;
case NCR_Dup:
if ( existing->mergeDuplicates() && newAtom.mergeDuplicates() ) {
// using existing atom, add new atom to _replacedAtoms
_replacedAtoms[&newAtom] = existing;
}
else {
const Atom& use = _platform.handleMultipleDefinitions(*existing, newAtom);
if ( &use == existing ) {
// using existing atom, add new atom to _replacedAtoms
_replacedAtoms[&newAtom] = existing;
}
else {
// using new atom, update tables
_nameTable[name] = &newAtom;
_replacedAtoms[existing] = &newAtom;
}
}
break;
default:
llvm::report_fatal_error("SymbolTable::addByName(): unhandled switch clause");
}
}
}
const Atom *SymbolTable::findByName(llvm::StringRef sym) {
NameToAtom::iterator pos = _nameTable.find(sym);
if (pos == _nameTable.end())
return NULL;
return pos->second;
}
bool SymbolTable::isDefined(llvm::StringRef sym) {
const Atom *atom = this->findByName(sym);
if (atom == NULL)
return false;
if (atom->definition() == Atom::definitionUndefined)
return false;
return true;
}
const Atom *SymbolTable::replacement(const Atom *atom) {
AtomToAtom::iterator pos = _replacedAtoms.find(atom);
if (pos == _replacedAtoms.end())
return atom;
// might be chain, recurse to end
return this->replacement(pos->second);
}
unsigned int SymbolTable::size() {
return _nameTable.size();
}
void SymbolTable::undefines(std::vector<const Atom *> &undefs) {
for (NameToAtom::iterator it = _nameTable.begin(),
end = _nameTable.end(); it != end; ++it) {
const Atom *atom = it->second;
assert(atom != NULL);
if (atom->definition() == Atom::definitionUndefined)
undefs.push_back(atom);
}
}
} // namespace lld
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