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Moved to lib/Linker (common with gccld)

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llvm-svn: 17791
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Reid Spencer 2004-11-14 22:22:45 +00:00
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commit 78e48422d0
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tools/llvm-ld/Linker.cpp
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//===- Linker.cpp - Link together 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-ld.h"
#include "llvm/Module.h"
#include "llvm/PassManager.h"
#include "llvm/Bytecode/Reader.h"
#include "llvm/Bytecode/WriteBytecodePass.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Transforms/IPO.h"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Support/Linker.h"
#include "llvm/Config/config.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/FileUtilities.h"
#include "llvm/System/Signals.h"
#include "llvm/System/Path.h"
#include "llvm/Support/SystemUtils.h"
#include <algorithm>
#include <fstream>
#include <memory>
#include <set>
using namespace llvm;
/// FindLib - Try to convert Filename into the name of a file that we can open,
/// if it does not already name a file we can open, by first trying to open
/// Filename, then libFilename.[suffix] for each of a set of several common
/// library suffixes, in each of the directories in Paths and the directory
/// named by the value of the environment variable LLVM_LIB_SEARCH_PATH. Returns
/// an empty string if no matching file can be found.
///
std::string llvm::FindLib(const std::string &Filename,
const std::vector<std::string> &Paths,
bool SharedObjectOnly) {
// Determine if the pathname can be found as it stands.
sys::Path FilePath;
if (FilePath.setFile(Filename) && FilePath.readable())
return Filename;
// Ask the System Path object to locate the library. This ensures that
// the library search is done correctly for a given platform.
sys::Path LibPath = sys::Path::GetLibraryPath(Filename,Paths);
return LibPath.get();
}
/// GetAllDefinedSymbols - Modifies its parameter DefinedSymbols to contain the
/// name of each externally-visible symbol defined in M.
///
void llvm::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.
///
void
llvm::GetAllUndefinedSymbols(Module *M,
std::set<std::string> &UndefinedSymbols) {
std::set<std::string> DefinedSymbols;
UndefinedSymbols.clear(); // Start out empty
// Add in all the external functions
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());
}
// Add in all the external globals
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
}
/// LoadObject - Read in and parse the bytecode file named by FN and return the
/// module it contains (wrapped in an auto_ptr), or 0 and set ErrorMessage if an
/// error occurs.
///
std::auto_ptr<Module> llvm::LoadObject(const std::string &FN,
std::string &ErrorMessage) {
std::string ParserErrorMessage;
Module *Result = ParseBytecodeFile(FN, &ParserErrorMessage);
if (Result) return std::auto_ptr<Module>(Result);
ErrorMessage = "Bytecode file '" + FN + "' could not be loaded";
if (ParserErrorMessage.size()) ErrorMessage += ": " + ParserErrorMessage;
return std::auto_ptr<Module>();
}
/// LinkInArchive - opens an archive library and link in all objects which
/// provide symbols that are currently undefined.
///
/// Inputs:
/// M - The module in which to link the archives.
/// Filename - The pathname of the archive.
/// Verbose - Flags whether verbose messages should be printed.
///
/// Outputs:
/// ErrorMessage - A C++ string detailing what error occurred, if any.
///
/// Return Value:
/// TRUE - An error occurred.
/// FALSE - No errors.
///
static bool LinkInArchive(Module *M,
const std::string &Filename,
std::string &ErrorMessage,
bool Verbose)
{
// 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(M, UndefinedSymbols);
if (UndefinedSymbols.empty()) {
if (Verbose) std::cerr << " No symbols undefined, don't link library!\n";
return false; // No need to link anything in!
}
// Load in the archive objects.
if (Verbose) std::cerr << " Loading archive file '" << Filename << "'\n";
std::vector<Module*> Objects;
if (ReadArchiveFile(Filename, Objects, &ErrorMessage))
return true;
// Figure out which symbols are defined by all of the modules in the archive.
std::vector<std::set<std::string> > DefinedSymbols;
DefinedSymbols.resize(Objects.size());
for (unsigned i = 0; i != Objects.size(); ++i) {
GetAllDefinedSymbols(Objects[i], DefinedSymbols[i]);
}
// While we are linking in object files, loop.
bool Linked = true;
while (Linked) {
Linked = false;
for (unsigned i = 0; i != Objects.size(); ++i) {
// Consider whether we need to link in this module... we only need to
// link it in if it defines some symbol which is so far undefined.
//
const std::set<std::string> &DefSymbols = DefinedSymbols[i];
bool ObjectRequired = false;
//
// If the object defines main() and the program currently has main()
// undefined, then automatically link in the module. Otherwise, look to
// see if it defines a symbol that is currently undefined.
//
if ((M->getMainFunction() == NULL) &&
((DefSymbols.find ("main")) != DefSymbols.end())) {
ObjectRequired = true;
} else {
for (std::set<std::string>::iterator I = UndefinedSymbols.begin(),
E = UndefinedSymbols.end(); I != E; ++I)
if (DefSymbols.count(*I)) {
if (Verbose)
std::cerr << " Found object '"
<< Objects[i]->getModuleIdentifier ()
<< "' providing symbol '" << *I << "'...\n";
ObjectRequired = true;
break;
}
}
// We DO need to link this object into the program...
if (ObjectRequired) {
if (LinkModules(M, Objects[i], &ErrorMessage))
return true; // Couldn't link in the right object file...
// Since we have linked in this object, delete it from the list of
// objects to consider in this archive file.
std::swap(Objects[i], Objects.back());
std::swap(DefinedSymbols[i], DefinedSymbols.back());
Objects.pop_back();
DefinedSymbols.pop_back();
--i; // Do not skip an entry
// The undefined symbols set should have shrunk.
GetAllUndefinedSymbols(M, UndefinedSymbols);
Linked = true; // We have linked something in!
}
}
}
return false;
}
/// LinkInFile - opens a bytecode file and links in all objects which
/// provide symbols that are currently undefined.
///
/// Inputs:
/// HeadModule - The module in which to link the bytecode file.
/// Filename - The pathname of the bytecode file.
/// Verbose - Flags whether verbose messages should be printed.
///
/// Outputs:
/// ErrorMessage - A C++ string detailing what error occurred, if any.
///
/// Return Value:
/// TRUE - An error occurred.
/// FALSE - No errors.
///
static bool LinkInFile(Module *HeadModule,
const std::string &Filename,
std::string &ErrorMessage,
bool Verbose)
{
std::auto_ptr<Module> M(LoadObject(Filename, ErrorMessage));
if (M.get() == 0) return true;
bool Result = LinkModules(HeadModule, M.get(), &ErrorMessage);
if (Verbose) std::cerr << "Linked in bytecode file '" << Filename << "'\n";
return Result;
}
/// LinkFiles - takes a module and a list of files and links them all together.
/// It locates the file either in the current directory, as its absolute
/// or relative pathname, or as a file somewhere in LLVM_LIB_SEARCH_PATH.
///
/// Inputs:
/// progname - The name of the program (infamous argv[0]).
/// HeadModule - The module under which all files will be linked.
/// Files - A vector of C++ strings indicating the LLVM bytecode filenames
/// to be linked. The names can refer to a mixture of pure LLVM
/// bytecode files and archive (ar) formatted files.
/// Verbose - Flags whether verbose output should be printed while linking.
///
/// Outputs:
/// HeadModule - The module will have the specified LLVM bytecode files linked
/// in.
///
/// Return value:
/// FALSE - No errors.
/// TRUE - Some error occurred.
///
bool llvm::LinkFiles(const char *progname, Module *HeadModule,
const std::vector<std::string> &Files, bool Verbose) {
// String in which to receive error messages.
std::string ErrorMessage;
// Full pathname of the file
std::string Pathname;
// Get the library search path from the environment
char *SearchPath = getenv("LLVM_LIB_SEARCH_PATH");
for (unsigned i = 0; i < Files.size(); ++i) {
// Determine where this file lives.
if (FileOpenable(Files[i])) {
Pathname = Files[i];
} else {
if (SearchPath == NULL) {
std::cerr << progname << ": Cannot find linker input file '"
<< Files[i] << "'\n";
std::cerr << progname
<< ": Warning: Your LLVM_LIB_SEARCH_PATH is unset.\n";
return true;
}
Pathname = std::string(SearchPath)+"/"+Files[i];
if (!FileOpenable(Pathname)) {
std::cerr << progname << ": Cannot find linker input file '"
<< Files[i] << "'\n";
return true;
}
}
// A user may specify an ar archive without -l, perhaps because it
// is not installed as a library. Detect that and link the library.
if (IsArchive(Pathname)) {
if (Verbose)
std::cerr << "Trying to link archive '" << Pathname << "'\n";
if (LinkInArchive(HeadModule, Pathname, ErrorMessage, Verbose)) {
std::cerr << progname << ": Error linking in archive '" << Pathname
<< "': " << ErrorMessage << "\n";
return true;
}
} else if (IsBytecode(Pathname)) {
if (Verbose)
std::cerr << "Trying to link bytecode file '" << Pathname << "'\n";
if (LinkInFile(HeadModule, Pathname, ErrorMessage, Verbose)) {
std::cerr << progname << ": Error linking in bytecode file '"
<< Pathname << "': " << ErrorMessage << "\n";
return true;
}
}
}
return false;
}
/// LinkLibraries - takes the specified library files and links them into the
/// main bytecode object file.
///
/// Inputs:
/// progname - The name of the program (infamous argv[0]).
/// HeadModule - The module into which all necessary libraries will be linked.
/// Libraries - The list of libraries to link into the module.
/// LibPaths - The list of library paths in which to find libraries.
/// Verbose - Flags whether verbose messages should be printed.
/// Native - Flags whether native code is being generated.
///
/// Outputs:
/// HeadModule - The module will have all necessary libraries linked in.
///
/// Return value:
/// FALSE - No error.
/// TRUE - Error.
///
void llvm::LinkLibraries(const char *progname, Module *HeadModule,
const std::vector<std::string> &Libraries,
const std::vector<std::string> &LibPaths,
bool Verbose, bool Native) {
// String in which to receive error messages.
std::string ErrorMessage;
for (unsigned i = 0; i < Libraries.size(); ++i) {
// Determine where this library lives.
std::string Pathname = FindLib(Libraries[i], LibPaths);
if (Pathname.empty()) {
// If the pathname does not exist, then continue to the next one if
// we're doing a native link and give an error if we're doing a bytecode
// link.
if (!Native) {
std::cerr << progname << ": WARNING: Cannot find library -l"
<< Libraries[i] << "\n";
continue;
}
}
// A user may specify an ar archive without -l, perhaps because it
// is not installed as a library. Detect that and link the library.
if (IsArchive(Pathname)) {
if (Verbose)
std::cerr << "Trying to link archive '" << Pathname << "' (-l"
<< Libraries[i] << ")\n";
if (LinkInArchive(HeadModule, Pathname, ErrorMessage, Verbose)) {
std::cerr << progname << ": " << ErrorMessage
<< ": Error linking in archive '" << Pathname << "' (-l"
<< Libraries[i] << ")\n";
exit(1);
}
} else if (IsBytecode(Pathname)) {
if (Verbose)
std::cerr << "Trying to link bytecode file '" << Pathname
<< "' (-l" << Libraries[i] << ")\n";
if (LinkInFile(HeadModule, Pathname, ErrorMessage, Verbose)) {
std::cerr << progname << ": " << ErrorMessage
<< ": error linking in bytecode file '" << Pathname << "' (-l"
<< Libraries[i] << ")\n";
exit(1);
}
}
}
}