319 lines
		
	
	
		
			10 KiB
		
	
	
	
		
			C++
		
	
	
	
			
		
		
	
	
			319 lines
		
	
	
		
			10 KiB
		
	
	
	
		
			C++
		
	
	
	
//===- gccld.cpp - LLVM 'ld' compatible linker ----------------------------===//
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// 
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//                     The LLVM Compiler Infrastructure
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//
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// This file was developed by the LLVM research group and is distributed under
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// the University of Illinois Open Source License. See LICENSE.TXT for details.
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// 
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//===----------------------------------------------------------------------===//
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//
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// This utility is intended to be compatible with GCC, and follows standard
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// system 'ld' conventions.  As such, the default output file is ./a.out.
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// Additionally, this program outputs a shell script that is used to invoke LLI
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// to execute the program.  In this manner, the generated executable (a.out for
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// example), is directly executable, whereas the bytecode file actually lives in
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// the a.out.bc file generated by this program.  Also, Force is on by default.
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//
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// Note that if someone (or a script) deletes the executable program generated,
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// the .bc file will be left around.  Considering that this is a temporary hack,
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// I'm not too worried about this.
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//
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//===----------------------------------------------------------------------===//
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#include "gccld.h"
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#include "llvm/Module.h"
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#include "llvm/PassManager.h"
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#include "llvm/Bytecode/Reader.h"
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#include "llvm/Bytecode/WriteBytecodePass.h"
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#include "llvm/Target/TargetData.h"
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#include "llvm/Transforms/IPO.h"
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#include "llvm/Transforms/Scalar.h"
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#include "llvm/Transforms/Utils/Linker.h"
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#include "Support/CommandLine.h"
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#include "Support/FileUtilities.h"
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#include "Support/Signals.h"
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#include "Support/SystemUtils.h"
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#include <fstream>
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#include <memory>
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namespace {
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  cl::list<std::string> 
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  InputFilenames(cl::Positional, cl::desc("<input bytecode files>"),
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                 cl::OneOrMore);
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  cl::opt<std::string> 
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  OutputFilename("o", cl::desc("Override output filename"), cl::init("a.out"),
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                 cl::value_desc("filename"));
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  cl::opt<bool>    
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  Verbose("v", cl::desc("Print information about actions taken"));
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  cl::list<std::string> 
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  LibPaths("L", cl::desc("Specify a library search path"), cl::Prefix,
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           cl::value_desc("directory"));
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  cl::list<std::string> 
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  Libraries("l", cl::desc("Specify libraries to link to"), cl::Prefix,
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            cl::value_desc("library prefix"));
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  cl::opt<bool>
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  Strip("s", cl::desc("Strip symbol info from executable"));
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  cl::opt<bool>
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  NoInternalize("disable-internalize",
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                cl::desc("Do not mark all symbols as internal"));
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  cl::alias
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  ExportDynamic("export-dynamic", cl::desc("Alias for -disable-internalize"),
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                cl::aliasopt(NoInternalize));
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  cl::opt<bool>
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  LinkAsLibrary("link-as-library", cl::desc("Link the .bc files together as a"
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                                            " library, not an executable"));
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  cl::alias
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  Relink("r", cl::desc("Alias for -link-as-library"),
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         cl::aliasopt(LinkAsLibrary));
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  cl::opt<bool>    
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  Native("native",
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         cl::desc("Generate a native binary instead of a shell script"));
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  // Compatibility options that are ignored but supported by LD
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  cl::opt<std::string>
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  CO3("soname", cl::Hidden, cl::desc("Compatibility option: ignored"));
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  cl::opt<std::string>
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  CO4("version-script", cl::Hidden, cl::desc("Compatibility option: ignored"));
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  cl::opt<bool>
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  CO5("eh-frame-hdr", cl::Hidden, cl::desc("Compatibility option: ignored"));
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}
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//
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// Function: PrintAndReturn ()
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//
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// Description:
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//  Prints a message (usually error message) to standard error (stderr) and
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//  returns a value usable for an exit status.
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//
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// Inputs:
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//  progname - The name of the program (i.e. argv[0]).
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//  Message  - The message to print to standard error.
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//  Extra    - Extra information to print between the program name and thei
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//             message.  It is optional.
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//
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// Outputs:
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//  None.
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//
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// Return value:
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//  Returns a value that can be used as the exit status (i.e. for exit()).
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//
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int
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PrintAndReturn (const char *progname,
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                const std::string &Message,
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                const std::string &Extra)
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{
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  std::cerr << progname << Extra << ": " << Message << "\n";
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  return 1;
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}
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//
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//
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// Function: CopyEnv()
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//
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// Description:
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//	This function takes an array of environment variables and makes a
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//	copy of it.  This copy can then be manipulated any way the caller likes
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//  without affecting the process's real environment.
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//
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// Inputs:
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//  envp - An array of C strings containing an environment.
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//
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// Outputs:
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//  None.
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//
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// Return value:
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//  NULL - An error occurred.
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//
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//  Otherwise, a pointer to a new array of C strings is returned.  Every string
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//  in the array is a duplicate of the one in the original array (i.e. we do
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//  not copy the char *'s from one array to another).
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//
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char ** CopyEnv(char ** const envp) {
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  // Count the number of entries in the old list;
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  unsigned entries;   // The number of entries in the old environment list
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  for (entries = 0; envp[entries] != NULL; entries++)
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  {
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    ;
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  }
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  // Add one more entry for the NULL pointer that ends the list.
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  ++entries;
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  // If there are no entries at all, just return NULL.
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  if (entries == 0)
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    return NULL;
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  // Allocate a new environment list.
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  char **newenv;
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  if ((newenv = new (char *) [entries]) == NULL)
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    return NULL;
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  // Make a copy of the list.  Don't forget the NULL that ends the list.
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  entries = 0;
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  while (envp[entries] != NULL) {
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    newenv[entries] = new char[strlen (envp[entries]) + 1];
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    strcpy (newenv[entries], envp[entries]);
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    ++entries;
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  }
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  newenv[entries] = NULL;
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  return newenv;
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}
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//
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// Function: RemoveEnv()
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//
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// Description:
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//	Remove the specified environment variable from the environment array.
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//
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// Inputs:
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//	name - The name of the variable to remove.  It cannot be NULL.
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//	envp - The array of environment variables.  It cannot be NULL.
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//
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// Outputs:
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//	envp - The pointer to the specified variable name is removed.
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//
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// Return value:
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//	None.
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//
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// Notes:
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//  This is mainly done because functions to remove items from the environment
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//  are not available across all platforms.  In particular, Solaris does not
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//  seem to have an unsetenv() function or a setenv() function (or they are
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//  undocumented if they do exist).
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//
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void RemoveEnv(const char * name, char ** const envp) {
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  for (unsigned index=0; envp[index] != NULL; index++) {
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    // Find the first equals sign in the array and make it an EOS character.
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    char *p = strchr (envp[index], '=');
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    if (p == NULL)
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      continue;
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    else
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      *p = '\0';
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    // Compare the two strings.  If they are equal, zap this string.
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    // Otherwise, restore it.
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    if (!strcmp(name, envp[index]))
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      *envp[index] = '\0';
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    else
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      *p = '=';
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  }
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  return;
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}
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int main(int argc, char **argv, char **envp) {
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  cl::ParseCommandLineOptions(argc, argv, " llvm linker for GCC\n");
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  std::string ErrorMessage;
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  std::auto_ptr<Module> Composite(LoadObject(InputFilenames[0], ErrorMessage));
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  if (Composite.get() == 0)
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    return PrintAndReturn(argv[0], ErrorMessage);
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  // We always look first in the current directory when searching for libraries.
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  LibPaths.insert(LibPaths.begin(), ".");
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  // If the user specified an extra search path in their environment, respect
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  // it.
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  if (char *SearchPath = getenv("LLVM_LIB_SEARCH_PATH"))
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    LibPaths.push_back(SearchPath);
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  // Remove any consecutive duplicates of the same library...
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  Libraries.erase(std::unique(Libraries.begin(), Libraries.end()),
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                  Libraries.end());
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  // Link in all of the files
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  if (LinkFiles(argv[0], Composite.get(), InputFilenames, Verbose))
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    return 1; // Error already printed
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  if (!LinkAsLibrary)
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    LinkLibraries(argv[0], Composite.get(), Libraries, LibPaths,
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                  Verbose, Native);
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  // Link in all of the libraries next...
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  // Create the output file.
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  std::string RealBytecodeOutput = OutputFilename;
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  if (!LinkAsLibrary) RealBytecodeOutput += ".bc";
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  std::ofstream Out(RealBytecodeOutput.c_str());
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  if (!Out.good())
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    return PrintAndReturn(argv[0], "error opening '" + RealBytecodeOutput +
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                                   "' for writing!");
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  // Ensure that the bytecode file gets removed from the disk if we get a
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  // SIGINT signal.
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  RemoveFileOnSignal(RealBytecodeOutput);
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  // Generate the bytecode file.
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  if (GenerateBytecode(Composite.get(), Strip, !NoInternalize, &Out)) {
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    Out.close();
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    return PrintAndReturn(argv[0], "error generating bytcode");
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  }
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  // Close the bytecode file.
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  Out.close();
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  // If we are not linking a library, generate either a native executable
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  // or a JIT shell script, depending upon what the user wants.
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  if (!LinkAsLibrary) {
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    // If the user wants to generate a native executable, compile it from the
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    // bytecode file.
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    //
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    // Otherwise, create a script that will run the bytecode through the JIT.
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    if (Native) {
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      // Name of the Assembly Language output file
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      std::string AssemblyFile = OutputFilename + ".s";
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      // Mark the output files for removal if we get an interrupt.
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      RemoveFileOnSignal(AssemblyFile);
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      RemoveFileOnSignal(OutputFilename);
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      // Determine the locations of the llc and gcc programs.
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      std::string llc = FindExecutable("llc", argv[0]);
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      std::string gcc = FindExecutable("gcc", argv[0]);
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      if (llc.empty())
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        return PrintAndReturn(argv[0], "Failed to find llc");
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      if (gcc.empty())
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        return PrintAndReturn(argv[0], "Failed to find gcc");
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      // Generate an assembly language file for the bytecode.
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      if (Verbose) std::cout << "Generating Assembly Code\n";
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      GenerateAssembly(AssemblyFile, RealBytecodeOutput, llc, envp);
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      if (Verbose) std::cout << "Generating Native Code\n";
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      GenerateNative(OutputFilename, AssemblyFile, Libraries, LibPaths,
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                     gcc, envp);
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      // Remove the assembly language file.
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      removeFile (AssemblyFile);
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    } else {
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      // Output the script to start the program...
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      std::ofstream Out2(OutputFilename.c_str());
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      if (!Out2.good())
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        return PrintAndReturn(argv[0], "error opening '" + OutputFilename +
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                                       "' for writing!");
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      Out2 << "#!/bin/sh\nlli $0.bc $*\n";
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      Out2.close();
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    }
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    // Make the script executable...
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    MakeFileExecutable(OutputFilename);
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    // Make the bytecode file readable and directly executable in LLEE as well
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    MakeFileExecutable(RealBytecodeOutput);
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    MakeFileReadable(RealBytecodeOutput);
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  }
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  return 0;
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}
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