// LoadObject - Read in and parse the bitcode file named by FN and return the
// module it contains (wrapped in an auto_ptr), or auto_ptr<Module>() and set
// Error if an error occurs.
std::auto_ptr<Module>
Linker::LoadObject(const sys::Path &FN) {
std::string ParseErrorMessage;
Module *Result = 0;
const std::string &FNS = FN.toString();
std::auto_ptr<MemoryBuffer> Buffer(MemoryBuffer::getFileOrSTDIN(FNS.c_str()));
if (Buffer.get())
Result = ParseBitcodeFile(Buffer.get(), &ParseErrorMessage);
else
ParseErrorMessage = "Error reading file '" + FNS + "'";
if (Result)
return std::auto_ptr<Module>(Result);
Error = "Bitcode file '" + FN.toString() + "' could not be loaded";
if (ParseErrorMessage.size())
Error += ": " + ParseErrorMessage;
return std::auto_ptr<Module>();
}
/// LinkInFile - opens a bitcode file and links in all objects which
/// provide symbols that are currently undefined.
///
/// Inputs:
/// File - The pathname of the bitcode file.
///
/// Outputs:
/// ErrorMessage - A C++ string detailing what error occurred, if any.
///
/// Return Value:
/// TRUE - An error occurred.
/// FALSE - No errors.
///
bool Linker::LinkInFile(const sys::Path &File, bool &is_native) {
is_native = false;
// Check for a file of name "-", which means "read standard input"
if (File.toString() == "-") {
std::auto_ptr<Module> M;
if (MemoryBuffer *Buffer = MemoryBuffer::getSTDIN()) {
M.reset(ParseBitcodeFile(Buffer, Context, &Error));
delete Buffer;
if (M.get())
if (!LinkInModule(M.get(), &Error))
return false;
} else
Error = "standard input is empty";
return error("Cannot link stdin: " + Error);
}
// Make sure we can at least read the file
if (!File.canRead())
return error("Cannot find linker input '" + File.toString() + "'");
// If its an archive, try to link it in
std::string Magic;
File.getMagicNumber(Magic, 64);
switch (sys::IdentifyFileType(Magic.c_str(), 64)) {
default: llvm_unreachable("Bad file type identification");
case sys::Unknown_FileType:
return warning("Ignoring file '" + File.toString() +
"' because does not contain bitcode.");
case sys::Archive_FileType:
// A user may specify an ar archive without -l, perhaps because it
// is not installed as a library. Detect that and link the archive.
verbose("Linking archive file '" + File.toString() + "'");
if (LinkInArchive(File, is_native))
return true;
break;
case sys::Bitcode_FileType: {
verbose("Linking bitcode file '" + File.toString() + "'");
std::auto_ptr<Module> M(LoadObject(File));
if (M.get() == 0)
return error("Cannot load file '" + File.toString() + "': " + Error);
if (LinkInModule(M.get(), &Error))
return error("Cannot link file '" + File.toString() + "': " + Error);
verbose("Linked in file '" + File.toString() + "'");
break;
}
case sys::ELF_Relocatable_FileType:
case sys::ELF_SharedObject_FileType:
case sys::Mach_O_Object_FileType:
case sys::Mach_O_FixedVirtualMemorySharedLib_FileType:
case sys::Mach_O_DynamicallyLinkedSharedLib_FileType:
case sys::Mach_O_DynamicallyLinkedSharedLibStub_FileType:
case sys::COFF_FileType:
is_native = true;
break;
}
return false;
}
/// 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, bool &is_native) {
// 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 bitcode 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, Context, &ErrMsg));
Archive* arch = AutoArch.get();
if (!arch)
return error("Cannot read archive '" + Filename.toString() +
"': " + ErrMsg);
if (!arch->isBitcodeArchive()) {
is_native = true;
return false;
}
is_native = false;
// 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;
// Save the current set of undefined symbols, because we may have to make
// multiple passes over the archive:
std::set<std::string> CurrentlyUndefinedSymbols;
do {
CurrentlyUndefinedSymbols = UndefinedSymbols;
// Find the modules we need to link into the target module
std::set<ModuleProvider*> Modules;
if (!arch->findModulesDefiningSymbols(UndefinedSymbols, Modules, &ErrMsg))
return error("Cannot find symbols in '" + Filename.toString() +
"': " + ErrMsg);
// 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::string moduleErrorMsg;
std::auto_ptr<Module> AutoModule((*I)->releaseModule( &moduleErrorMsg ));
if (!moduleErrorMsg.empty())
return error("Could not load a module: " + moduleErrorMsg);
Module* aModule = AutoModule.get();
if (aModule != NULL) {
verbose(" Linking in module: " + aModule->getModuleIdentifier());
// Link it in
if (LinkInModule(aModule, &moduleErrorMsg)) {
return error("Cannot link in module '" +
aModule->getModuleIdentifier() + "': " + moduleErrorMsg);
}
}
}
// 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(UndefinedSymbols, NotDefinedByArchive);
// If there's no symbols left, no point in continuing to search the
// archive.
if (UndefinedSymbols.empty())
break;
} while (CurrentlyUndefinedSymbols != UndefinedSymbols);
return false;
}