llvm-6502/lib/Linker/LinkArchives.cpp

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//===- lib/Linker/LinkArchives.cpp - Link LLVM objects and libraries ------===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains routines to handle linking together LLVM bytecode files,
// and to handle annoying things like static libraries.
//
//===----------------------------------------------------------------------===//
#include "llvm/Linker.h"
#include "llvm/Module.h"
#include "llvm/ModuleProvider.h"
#include "llvm/ADT/SetOperations.h"
#include "llvm/Bytecode/Reader.h"
#include "llvm/Bytecode/Archive.h"
#include "llvm/Config/config.h"
#include <memory>
#include <set>
#include <iostream>
using namespace llvm;
/// GetAllDefinedSymbols - Modifies its parameter DefinedSymbols to contain the
/// name of each externally-visible symbol defined in M.
///
static void
GetAllDefinedSymbols(Module *M, std::set<std::string> &DefinedSymbols) {
for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I)
if (I->hasName() && !I->isExternal() && !I->hasInternalLinkage())
DefinedSymbols.insert(I->getName());
for (Module::giterator I = M->gbegin(), E = M->gend(); I != E; ++I)
if (I->hasName() && !I->isExternal() && !I->hasInternalLinkage())
DefinedSymbols.insert(I->getName());
}
/// GetAllUndefinedSymbols - calculates the set of undefined symbols that still
/// exist in an LLVM module. This is a bit tricky because there may be two
/// symbols with the same name but different LLVM types that will be resolved to
/// each other but aren't currently (thus we need to treat it as resolved).
///
/// Inputs:
/// M - The module in which to find undefined symbols.
///
/// Outputs:
/// UndefinedSymbols - A set of C++ strings containing the name of all
/// undefined symbols.
///
static void
GetAllUndefinedSymbols(Module *M, std::set<std::string> &UndefinedSymbols) {
std::set<std::string> DefinedSymbols;
UndefinedSymbols.clear();
for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I)
if (I->hasName()) {
if (I->isExternal())
UndefinedSymbols.insert(I->getName());
else if (!I->hasInternalLinkage())
DefinedSymbols.insert(I->getName());
}
for (Module::giterator I = M->gbegin(), E = M->gend(); I != E; ++I)
if (I->hasName()) {
if (I->isExternal())
UndefinedSymbols.insert(I->getName());
else if (!I->hasInternalLinkage())
DefinedSymbols.insert(I->getName());
}
// Prune out any defined symbols from the undefined symbols set...
for (std::set<std::string>::iterator I = UndefinedSymbols.begin();
I != UndefinedSymbols.end(); )
if (DefinedSymbols.count(*I))
UndefinedSymbols.erase(I++); // This symbol really is defined!
else
++I; // Keep this symbol in the undefined symbols list
}
/// LinkInArchive - opens an archive library and link in all objects which
/// provide symbols that are currently undefined.
///
/// Inputs:
/// Filename - The pathname of the archive.
///
/// Return Value:
/// TRUE - An error occurred.
/// FALSE - No errors.
bool
Linker::LinkInArchive(const sys::Path &Filename) {
// Make sure this is an archive file we're dealing with
if (!Filename.isArchive())
return error("File '" + Filename.toString() + "' is not an archive.");
// Open the archive file
verbose("Linking archive file '" + Filename.toString() + "'");
// Find all of the symbols currently undefined in the bytecode program.
// If all the symbols are defined, the program is complete, and there is
// no reason to link in any archive files.
std::set<std::string> UndefinedSymbols;
GetAllUndefinedSymbols(Composite, UndefinedSymbols);
if (UndefinedSymbols.empty()) {
verbose("No symbols undefined, skipping library '" +
Filename.toString() + "'");
return false; // No need to link anything in!
}
std::string ErrMsg;
std::auto_ptr<Archive> AutoArch (
Archive::OpenAndLoadSymbols(Filename,&ErrMsg));
Archive* arch = AutoArch.get();
if (!arch)
return error("Cannot read archive '" + Filename.toString() +
"': " + ErrMsg);
// Save a set of symbols that are not defined by the archive. Since we're
// entering a loop, there's no point searching for these multiple times. This
// variable is used to "set_subtract" from the set of undefined symbols.
std::set<std::string> NotDefinedByArchive;
// While we are linking in object files, loop.
while (true) {
// Find the modules we need to link into the target module
std::set<ModuleProvider*> Modules;
arch->findModulesDefiningSymbols(UndefinedSymbols, Modules);
// If we didn't find any more modules to link this time, we are done
// searching this archive.
if (Modules.empty())
break;
// Any symbols remaining in UndefinedSymbols after
// findModulesDefiningSymbols are ones that the archive does not define. So
// we add them to the NotDefinedByArchive variable now.
NotDefinedByArchive.insert(UndefinedSymbols.begin(),
UndefinedSymbols.end());
// Loop over all the ModuleProviders that we got back from the archive
for (std::set<ModuleProvider*>::iterator I=Modules.begin(), E=Modules.end();
I != E; ++I) {
// Get the module we must link in.
std::auto_ptr<Module> AutoModule( (*I)->releaseModule() );
Module* aModule = AutoModule.get();
// Link it in
if (this->LinkInModule(aModule))
return error("Cannot link in module '" +
aModule->getModuleIdentifier() + "': " + Error);
}
// Get the undefined symbols from the aggregate module. This recomputes the
// symbols we still need after the new modules have been linked in.
GetAllUndefinedSymbols(Composite, UndefinedSymbols);
// At this point we have two sets of undefined symbols: UndefinedSymbols
// which holds the undefined symbols from all the modules, and
// NotDefinedByArchive which holds symbols we know the archive doesn't
// define. There's no point searching for symbols that we won't find in the
// archive so we subtract these sets.
set_subtract<std::set<std::string>,std::set<std::string> >(
UndefinedSymbols,NotDefinedByArchive);
// If there's no symbols left, no point in continuing to search the
// archive.
if (UndefinedSymbols.empty())
break;
}
return false;
}