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Diffstat (limited to 'tools/gccld/Linker.cpp')
| -rw-r--r-- | tools/gccld/Linker.cpp | 601 |
1 files changed, 601 insertions, 0 deletions
diff --git a/tools/gccld/Linker.cpp b/tools/gccld/Linker.cpp new file mode 100644 index 0000000000..d72c485330 --- /dev/null +++ b/tools/gccld/Linker.cpp @@ -0,0 +1,601 @@ +//===- gccld.cpp - LLVM 'ld' compatible linker ----------------------------===// +// +// This utility is intended to be compatible with GCC, and follows standard +// system 'ld' conventions. As such, the default output file is ./a.out. +// Additionally, this program outputs a shell script that is used to invoke LLI +// to execute the program. In this manner, the generated executable (a.out for +// example), is directly executable, whereas the bytecode file actually lives in +// the a.out.bc file generated by this program. Also, Force is on by default. +// +// Note that if someone (or a script) deletes the executable program generated, +// the .bc file will be left around. Considering that this is a temporary hack, +// I'm not too worried about this. +// +//===----------------------------------------------------------------------===// + +#include "llvm/Transforms/Utils/Linker.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 "Support/FileUtilities.h" +#include "Support/SystemUtils.h" +#include "Support/CommandLine.h" +#include "Support/Signals.h" +#include "Config/stdlib.h" +#include "gccld.h" + +#include <fstream> +#include <memory> +#include <set> +#include <algorithm> + +// +// Function: FileExists () +// +// Description: +// Determine if the specified filename exists and is readable. +// +// Inputs: +// FN - The name of the file. +// +// Outputs: +// None. +// +// Return Value: +// TRUE - The file exists and is readable. +// FALSE - The file does not exist or is unreadable. +// +static inline bool +FileExists(const std::string &FN) +{ + return access(FN.c_str(), R_OK | F_OK) != -1; +} + +// +// Function: IsArchive () +// +// Description: +// Determine if the specified file is an ar archive. It determines this by +// checking the magic string at the beginning of the file. +// +// Inputs: +// filename - A C++ string containing the name of the file. +// +// Outputs: +// None. +// +// Return value: +// TRUE - The file is an archive. +// FALSE - The file is not an archive. +// +static inline bool +IsArchive (const std::string &filename) +{ + std::string ArchiveMagic("!<arch>\012"); + char buf[1 + ArchiveMagic.size()]; + + std::ifstream f(filename.c_str()); + f.read(buf, ArchiveMagic.size()); + buf[ArchiveMagic.size()] = '\0'; + return ArchiveMagic == buf; +} + +// +// Function: FindLib () +// +// Description: +// This function locates a particular library. It will prepend and append +// various directories, prefixes, and suffixes until it can find the library. +// +// Inputs: +// Filename - Name of the file to find. +// Paths - List of directories to search. +// +// Outputs: +// None. +// +// Return value: +// The name of the file is returned. +// If the file is not found, an empty string is returned. +// +static std::string +FindLib (const std::string & Filename, const std::vector<std::string> & Paths) +{ + // + // Determine if the pathname can be found as it stands. + // + if (FileExists (Filename)) + { + return Filename; + } + + // + // If that doesn't work, convert the name into a library name. + // + std::string LibName = "lib" + Filename; + + // + // Iterate over the directories in Paths to see if we can find the library + // there. + // + for (unsigned Index = 0; Index != Paths.size(); ++Index) + { + std::string Directory = Paths[Index] + "/"; + + if (FileExists (Directory + LibName + ".bc")) + { + return Directory + LibName + ".bc"; + } + + if (FileExists (Directory + LibName + ".so")) + { + return Directory + LibName + ".so"; + } + + if (FileExists (Directory + LibName + ".a")) + { + return Directory + LibName + ".a"; + } + } + + // + // One last hope: Check LLVM_LIB_SEARCH_PATH. + // + char *SearchPath = getenv("LLVM_LIB_SEARCH_PATH"); + if (SearchPath == NULL) + { + return std::string(); + } + + LibName = std::string(SearchPath) + "/" + LibName; + if (FileExists (LibName)) + { + return LibName; + } + + return std::string(); +} + +// +// Function: GetAllDefinedSymbols () +// +// Description: +// Find all of the defined symbols in the specified module. +// +// Inputs: +// M - The module in which to find defined symbols. +// +// Outputs: +// DefinedSymbols - A set of C++ strings that will contain the name of all +// defined symbols. +// +// Return value: +// None. +// +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()); +} + +// +// Function: GetAllUndefinedSymbols () +// +// Description: +// This 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. +// +// Return value: +// None. +// +void +GetAllUndefinedSymbols(Module *M, std::set<std::string> &UndefinedSymbols) +{ + std::set<std::string> DefinedSymbols; + UndefinedSymbols.clear(); // Start out empty + + 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 +} + + +// +// Function: LoadObject () +// +// Description: +// Read the specified bytecode object file. +// +// Inputs: +// FN - The name of the file to load. +// +// Outputs: +// OutErrorMessage - The error message to give back to the caller. +// +// Return Value: +// A pointer to a module represening the bytecode file is returned. +// If an error occurs, the pointer is 0. +// +std::auto_ptr<Module> +LoadObject (const std::string & FN, std::string &OutErrorMessage) +{ + std::string ErrorMessage; + Module *Result = ParseBytecodeFile(FN, &ErrorMessage); + if (Result) return std::auto_ptr<Module>(Result); + + OutErrorMessage = "Bytecode file '" + FN + "' corrupt!"; + if (ErrorMessage.size()) OutErrorMessage += ": " + ErrorMessage; + return std::auto_ptr<Module>(); +} + +// +// Function: LinkInArchive () +// +// Description: +// This function will open 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 '" << 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; + 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 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; +} + +// +// Function: LinkInFile () +// +// Description: +// This function will open an archive library and link in all objects which +// provide symbols that are currently undefined. +// +// Inputs: +// HeadModule - 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 +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; + } + + if (Verbose) std::cerr << "Linking in '" << Filename << "'\n"; + + return (LinkModules (HeadModule, M.get(), &ErrorMessage)); +} + +// +// Function: LinkFiles () +// +// Description: +// This function takes a module and a list of files and links them all +// together. It locates the file either in the current directory, as it's +// 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 +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 = 1; i < Files.size(); ++i) + { + // + // Determine where this file lives. + // + if (FileExists (Files[i])) + { + Pathname = Files[i]; + } + else + { + if (SearchPath == NULL) + { + std::cerr << "Cannot find " << Files[i]; + return true; + } + + Pathname = std::string(SearchPath)+"/"+Files[i]; + if (!FileExists (Pathname)) + { + std::cerr << "Cannot find " << Files[i]; + 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 << "Linking archive '" << Files[i] << "'\n"; + } + + if (LinkInArchive (HeadModule, Pathname, ErrorMessage, Verbose)) + { + PrintAndReturn(progname, ErrorMessage, + ": Error linking in '" + Files[i] + "'"); + return true; + } + } + else + { + if (Verbose) + { + std::cerr << "Linking file '" << Files[i] << "'\n"; + } + + if (LinkInFile (HeadModule, Pathname, ErrorMessage, Verbose)) + { + PrintAndReturn(progname, ErrorMessage, + ": error linking in '" + Files[i] + "'"); + return true; + } + } + } + + return false; +} + +// +// Function: LinkLibraries () +// +// Description: +// This function 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. +// +bool +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 = 1; 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) + { + continue; + } + else + { + PrintAndReturn (progname, "Cannot find " + Libraries[i]); + 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 << "Linking archive '" << Libraries[i] << "'\n"; + } + + if (LinkInArchive (HeadModule, Pathname, ErrorMessage, Verbose)) + { + PrintAndReturn(progname, ErrorMessage, + ": Error linking in '" + Libraries[i] + "'"); + return true; + } + } + else + { + if (Verbose) + { + std::cerr << "Linking file '" << Libraries[i] << "'\n"; + } + + if (LinkInFile (HeadModule, Pathname, ErrorMessage, Verbose)) + { + PrintAndReturn(progname, ErrorMessage, + ": error linking in '" + Libraries[i] + "'"); + return true; + } + } + } + + return false; +} |