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LinkItems.cpp

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00001 //===- lib/Linker/LinkItems.cpp - Link LLVM objects and libraries ---------===//
00002 // 
00003 //                     The LLVM Compiler Infrastructure
00004 //
00005 // This file was developed by Reid Spencer and is distributed under the 
00006 // University of Illinois Open Source License. See LICENSE.TXT for details.
00007 // 
00008 //===----------------------------------------------------------------------===//
00009 //
00010 // This file contains routines to handle linking together LLVM bytecode files,
00011 // and to handle annoying things like static libraries.
00012 //
00013 //===----------------------------------------------------------------------===//
00014 
00015 #include "llvm/Linker.h"
00016 #include "llvm/Module.h"
00017 #include "llvm/ModuleProvider.h"
00018 #include "llvm/PassManager.h"
00019 #include "llvm/ADT/SetOperations.h"
00020 #include "llvm/Bytecode/Reader.h"
00021 #include "llvm/Bytecode/Archive.h"
00022 #include "llvm/Bytecode/WriteBytecodePass.h"
00023 #include "llvm/Target/TargetData.h"
00024 #include "llvm/Transforms/IPO.h"
00025 #include "llvm/Transforms/Scalar.h"
00026 #include "llvm/Config/config.h"
00027 #include "llvm/Support/CommandLine.h"
00028 #include "llvm/Support/FileUtilities.h"
00029 #include "llvm/Support/Timer.h"
00030 #include "llvm/System/Signals.h"
00031 #include "llvm/Support/SystemUtils.h"
00032 #include <algorithm>
00033 #include <fstream>
00034 #include <memory>
00035 #include <set>
00036 using namespace llvm;
00037 
00038 static bool 
00039 LinkOneLibrary(const char*progname, Module* HeadModule, 
00040                const std::string& Lib, 
00041                const std::vector<std::string>& LibPaths,
00042                bool Verbose, bool Native) {
00043 
00044   // String in which to receive error messages.
00045   std::string ErrorMessage;
00046 
00047   // Determine where this library lives.
00048   std::string Pathname = FindLib(Lib, LibPaths);
00049   if (Pathname.empty()) {
00050     // If the pathname does not exist, then simply return if we're doing a 
00051     // native link and give a warning if we're doing a bytecode link.
00052     if (!Native) {
00053       std::cerr << progname << ": warning: Cannot find library '"
00054                 << Lib << "'\n";
00055       return false;
00056     }
00057   }
00058 
00059   // A user may specify an ar archive without -l, perhaps because it
00060   // is not installed as a library. Detect that and link the library.
00061   if (IsArchive(Pathname)) {
00062     if (Verbose)
00063       std::cerr << "Trying to link archive '" << Pathname << "' (-l"
00064                 << Lib << ")\n";
00065 
00066     if (LinkInArchive(HeadModule, Pathname, &ErrorMessage, Verbose)) {
00067       std::cerr << progname << ": " << ErrorMessage
00068                 << ": Error linking in archive '" << Pathname << "' (-l"
00069                 << Lib << ")\n";
00070       return true;
00071     }
00072   } else {
00073       std::cerr << progname << ": WARNING: Supposed library -l"
00074                 << Lib << " isn't a library.\n";
00075   }
00076   return false;
00077 }
00078 
00079 // LinkItems - preserve link order for an arbitrary set of linkage items.
00080 Module* 
00081 llvm::LinkItems(const char *progname, const LinkItemList& Items,
00082                 const std::vector<std::string>& LibPaths,
00083                 bool Verbose, bool Native) {
00084 
00085   // Construct the HeadModule to contain the result of the linkage
00086   std::auto_ptr<Module> HeadModule(new Module(progname));
00087 
00088   // Construct a mutable path list we can add paths to. This list will always
00089   // have LLVM_LIB_SEARCH_PATH at the end so we place it there now.
00090   std::vector<std::string> MyLibPaths(LibPaths);
00091   MyLibPaths.insert(MyLibPaths.begin(),".");
00092   char* SearchPath = getenv("LLVM_LIB_SEARCH_PATH");
00093   if (SearchPath)
00094     MyLibPaths.push_back(SearchPath);
00095 
00096   // For each linkage item ...
00097   for (LinkItemList::const_iterator I = Items.begin(), E = Items.end(); 
00098        I != E; ++I) {
00099     if (I->second) {
00100       // Link in the library suggested.
00101       if (LinkOneLibrary(progname,HeadModule.get(),I->first,MyLibPaths,
00102                      Verbose,Native))
00103         return 0;
00104     } else {
00105       std::vector<std::string> Files;
00106       Files.push_back(I->first);
00107       if (LinkFiles(progname,HeadModule.get(),Files,Verbose))
00108         return 0;
00109     }
00110   }
00111 
00112   // At this point we have processed all the link items provided to us. Since
00113   // we have an aggregated module at this point, the dependent libraries in
00114   // that module should also be aggregated with duplicates eliminated. This is
00115   // now the time to process the dependent libraries to resolve any remaining
00116   // symbols.
00117   const Module::LibraryListType& DepLibs = HeadModule->getLibraries();
00118   for (Module::LibraryListType::const_iterator I = DepLibs.begin(), 
00119       E = DepLibs.end(); I != E; ++I) {
00120     if(LinkOneLibrary(progname,HeadModule.get(),*I,MyLibPaths,Verbose,Native))
00121       return 0;
00122   }
00123 
00124   return HeadModule.release();
00125 }
00126 
00127 // BuildLinkItems -- This function
00128 void llvm::BuildLinkItems(
00129   LinkItemList& Items,
00130   const cl::list<std::string>& Files,
00131   const cl::list<std::string>& Libraries) {
00132 
00133   // Build the list of linkage items for LinkItems. 
00134 
00135   cl::list<std::string>::const_iterator fileIt = Files.begin();
00136   cl::list<std::string>::const_iterator libIt  = Libraries.begin();
00137 
00138   int libPos = -1, filePos = -1;
00139   while ( 1 ) {
00140     if (libIt != Libraries.end())
00141       libPos = Libraries.getPosition(libIt - Libraries.begin());
00142     else
00143       libPos = -1;
00144     if (fileIt != Files.end())
00145       filePos = Files.getPosition(fileIt - Files.begin());
00146     else
00147       filePos = -1;
00148 
00149     if (filePos != -1 && (libPos == -1 || filePos < libPos)) {
00150       // Add a source file
00151       Items.push_back(std::make_pair(*fileIt++, false));
00152     } else if (libPos != -1 && (filePos == -1 || libPos < filePos)) {
00153       // Add a library
00154       Items.push_back(std::make_pair(*libIt++, true));
00155     } else {
00156         break; // we're done with the list
00157     }
00158   }
00159 }