text: //===- llvm-extract.cpp - LLVM function extraction utility ----------------===//
  //
  //                     The LLVM Compiler Infrastructure
  //
  // This file is distributed under the University of Illinois Open Source
  // License. See LICENSE.TXT for details.
  //
  //===----------------------------------------------------------------------===//
  //
  // This utility changes the input module to only contain a single function,
  // which is primarily used for debugging transformations.
  //
  //===----------------------------------------------------------------------===//
  
  #include "llvm/ADT/SetVector.h"
  #include "llvm/ADT/SmallPtrSet.h"
  #include "llvm/Bitcode/BitcodeWriterPass.h"
  #include "llvm/IR/DataLayout.h"
  #include "llvm/IR/IRPrintingPasses.h"
  #include "llvm/IR/LLVMContext.h"
  #include "llvm/IR/Module.h"
  #include "llvm/IRReader/IRReader.h"
  #include "llvm/IR/LegacyPassManager.h"
  #include "llvm/Support/CommandLine.h"
  #include "llvm/Support/FileSystem.h"
  #include "llvm/Support/ManagedStatic.h"
  #include "llvm/Support/PrettyStackTrace.h"
  #include "llvm/Support/Regex.h"
  #include "llvm/Support/Signals.h"
  #include "llvm/Support/SourceMgr.h"
  #include "llvm/Support/SystemUtils.h"
  #include "llvm/Support/ToolOutputFile.h"
  #include "llvm/Transforms/IPO.h"
  #include <memory>
  using namespace llvm;
  
  // InputFilename - The filename to read from.
  static cl::opt<std::string>
  InputFilename(cl::Positional, cl::desc("<input bitcode file>"),
                cl::init("-"), cl::value_desc("filename"));
  
  static cl::opt<std::string>
  OutputFilename("o", cl::desc("Specify output filename"),
                 cl::value_desc("filename"), cl::init("-"));
  
  static cl::opt<bool>
  Force("f", cl::desc("Enable binary output on terminals"));
  
  static cl::opt<bool>
  DeleteFn("delete", cl::desc("Delete specified Globals from Module"));
  
  // ExtractFuncs - The functions to extract from the module.
  static cl::list<std::string>
  ExtractFuncs("func", cl::desc("Specify function to extract"),
               cl::ZeroOrMore, cl::value_desc("function"));
  
  // ExtractRegExpFuncs - The functions, matched via regular expression, to
  // extract from the module.
  static cl::list<std::string>
  ExtractRegExpFuncs("rfunc", cl::desc("Specify function(s) to extract using a "
                                       "regular expression"),
                     cl::ZeroOrMore, cl::value_desc("rfunction"));
  
  // ExtractAlias - The alias to extract from the module.
  static cl::list<std::string>
  ExtractAliases("alias", cl::desc("Specify alias to extract"),
                 cl::ZeroOrMore, cl::value_desc("alias"));
  
  
  // ExtractRegExpAliases - The aliases, matched via regular expression, to
  // extract from the module.
  static cl::list<std::string>
  ExtractRegExpAliases("ralias", cl::desc("Specify alias(es) to extract using a "
                                          "regular expression"),
                       cl::ZeroOrMore, cl::value_desc("ralias"));
  
  // ExtractGlobals - The globals to extract from the module.
  static cl::list<std::string>
  ExtractGlobals("glob", cl::desc("Specify global to extract"),
                 cl::ZeroOrMore, cl::value_desc("global"));
  
  // ExtractRegExpGlobals - The globals, matched via regular expression, to
  // extract from the module...
  static cl::list<std::string>
  ExtractRegExpGlobals("rglob", cl::desc("Specify global(s) to extract using a "
                                         "regular expression"),
                       cl::ZeroOrMore, cl::value_desc("rglobal"));
  
  static cl::opt<bool>
  OutputAssembly("S",
                 cl::desc("Write output as LLVM assembly"), cl::Hidden);
  
  static cl::opt<bool> PreserveBitcodeUseListOrder(
      "preserve-bc-uselistorder",
      cl::desc("Preserve use-list order when writing LLVM bitcode."),
      cl::init(true), cl::Hidden);
  
  static cl::opt<bool> PreserveAssemblyUseListOrder(
      "preserve-ll-uselistorder",
      cl::desc("Preserve use-list order when writing LLVM assembly."),
      cl::init(false), cl::Hidden);
  
  int main(int argc, char **argv) {
    // Print a stack trace if we signal out.
    sys::PrintStackTraceOnErrorSignal();
    PrettyStackTraceProgram X(argc, argv);
  
    LLVMContext &Context = getGlobalContext();
    llvm_shutdown_obj Y;  // Call llvm_shutdown() on exit.
    cl::ParseCommandLineOptions(argc, argv, "llvm extractor\n");
  
    // Use lazy loading, since we only care about selected global values.
    SMDiagnostic Err;
    std::unique_ptr<Module> M = getLazyIRFileModule(InputFilename, Err, Context);
  
    if (!M.get()) {
      Err.print(argv[0], errs());
      return 1;
    }
  
    // Use SetVector to avoid duplicates.
    SetVector<GlobalValue *> GVs;
  
    // Figure out which aliases we should extract.
    for (size_t i = 0, e = ExtractAliases.size(); i != e; ++i) {
      GlobalAlias *GA = M->getNamedAlias(ExtractAliases[i]);
      if (!GA) {
        errs() << argv[0] << ": program doesn't contain alias named '"
               << ExtractAliases[i] << "'!\n";
        return 1;
      }
      GVs.insert(GA);
    }
  
    // Extract aliases via regular expression matching.
    for (size_t i = 0, e = ExtractRegExpAliases.size(); i != e; ++i) {
      std::string Error;
      Regex RegEx(ExtractRegExpAliases[i]);
      if (!RegEx.isValid(Error)) {
        errs() << argv[0] << ": '" << ExtractRegExpAliases[i] << "' "
          "invalid regex: " << Error;
      }
      bool match = false;
      for (Module::alias_iterator GA = M->alias_begin(), E = M->alias_end();
           GA != E; GA++) {
        if (RegEx.match(GA->getName())) {
          GVs.insert(&*GA);
          match = true;
        }
      }
      if (!match) {
        errs() << argv[0] << ": program doesn't contain global named '"
               << ExtractRegExpAliases[i] << "'!\n";
        return 1;
      }
    }
  
    // Figure out which globals we should extract.
    for (size_t i = 0, e = ExtractGlobals.size(); i != e; ++i) {
      GlobalValue *GV = M->getNamedGlobal(ExtractGlobals[i]);
      if (!GV) {
        errs() << argv[0] << ": program doesn't contain global named '"
               << ExtractGlobals[i] << "'!\n";
        return 1;
      }
      GVs.insert(GV);
    }
  
    // Extract globals via regular expression matching.
    for (size_t i = 0, e = ExtractRegExpGlobals.size(); i != e; ++i) {
      std::string Error;
      Regex RegEx(ExtractRegExpGlobals[i]);
      if (!RegEx.isValid(Error)) {
        errs() << argv[0] << ": '" << ExtractRegExpGlobals[i] << "' "
          "invalid regex: " << Error;
      }
      bool match = false;
      for (auto &GV : M->globals()) {
        if (RegEx.match(GV.getName())) {
          GVs.insert(&GV);
          match = true;
        }
      }
      if (!match) {
        errs() << argv[0] << ": program doesn't contain global named '"
               << ExtractRegExpGlobals[i] << "'!\n";
        return 1;
      }
    }
  
    // Figure out which functions we should extract.
    for (size_t i = 0, e = ExtractFuncs.size(); i != e; ++i) {
      GlobalValue *GV = M->getFunction(ExtractFuncs[i]);
      if (!GV) {
        errs() << argv[0] << ": program doesn't contain function named '"
               << ExtractFuncs[i] << "'!\n";
        return 1;
      }
      GVs.insert(GV);
    }
    // Extract functions via regular expression matching.
    for (size_t i = 0, e = ExtractRegExpFuncs.size(); i != e; ++i) {
      std::string Error;
      StringRef RegExStr = ExtractRegExpFuncs[i];
      Regex RegEx(RegExStr);
      if (!RegEx.isValid(Error)) {
        errs() << argv[0] << ": '" << ExtractRegExpFuncs[i] << "' "
          "invalid regex: " << Error;
      }
      bool match = false;
      for (Module::iterator F = M->begin(), E = M->end(); F != E;
           F++) {
        if (RegEx.match(F->getName())) {
          GVs.insert(&*F);
          match = true;
        }
      }
      if (!match) {
        errs() << argv[0] << ": program doesn't contain global named '"
               << ExtractRegExpFuncs[i] << "'!\n";
        return 1;
      }
    }
  
    // Materialize requisite global values.
    if (!DeleteFn)
      for (size_t i = 0, e = GVs.size(); i != e; ++i) {
        GlobalValue *GV = GVs[i];
        if (std::error_code EC = GV->materialize()) {
          errs() << argv[0] << ": error reading input: " << EC.message() << "\n";
          return 1;
        }
      }
    else {
      // Deleting. Materialize every GV that's *not* in GVs.
      SmallPtrSet<GlobalValue *, 8> GVSet(GVs.begin(), GVs.end());
      for (auto &G : M->globals()) {
        if (!GVSet.count(&G)) {
          if (std::error_code EC = G.materialize()) {
            errs() << argv[0] << ": error reading input: " << EC.message()
                   << "\n";
            return 1;
          }
        }
      }
      for (auto &F : *M) {
        if (!GVSet.count(&F)) {
          if (std::error_code EC = F.materialize()) {
            errs() << argv[0] << ": error reading input: " << EC.message()
                   << "\n";
            return 1;
          }
        }
      }
    }
  
    // In addition to deleting all other functions, we also want to spiff it
    // up a little bit.  Do this now.
    legacy::PassManager Passes;
  
    std::vector<GlobalValue*> Gvs(GVs.begin(), GVs.end());
  
    Passes.add(createGVExtractionPass(Gvs, DeleteFn));
    if (!DeleteFn)
      Passes.add(createGlobalDCEPass());           // Delete unreachable globals
    Passes.add(createStripDeadDebugInfoPass());    // Remove dead debug info
    Passes.add(createStripDeadPrototypesPass());   // Remove dead func decls
  
    std::error_code EC;
    tool_output_file Out(OutputFilename, EC, sys::fs::F_None);
    if (EC) {
      errs() << EC.message() << '\n';
      return 1;
    }
  
    if (OutputAssembly)
      Passes.add(
          createPrintModulePass(Out.os(), "", PreserveAssemblyUseListOrder));
    else if (Force || !CheckBitcodeOutputToConsole(Out.os(), true))
      Passes.add(createBitcodeWriterPass(Out.os(), PreserveBitcodeUseListOrder));
  
    Passes.run(*M.get());
  
    // Declare success.
    Out.keep();
  
    return 0;
  }
  