tools/llvm-extract/llvm-extract.cpp

   1 //===- llvm-extract.cpp - LLVM function extraction utility ----------------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This utility changes the input module to only contain a single function,
  11 // which is primarily used for debugging transformations.
  12 //
  13 //===----------------------------------------------------------------------===//
  14
  15 #include "llvm/LLVMContext.h"
  16 #include "llvm/Module.h"
  17 #include "llvm/PassManager.h"
  18 #include "llvm/Assembly/PrintModulePass.h"
  19 #include "llvm/Bitcode/ReaderWriter.h"
  20 #include "llvm/Transforms/IPO.h"
  21 #include "llvm/Target/TargetData.h"
  22 #include "llvm/Support/CommandLine.h"
  23 #include "llvm/Support/IRReader.h"
  24 #include "llvm/Support/ManagedStatic.h"
  25 #include "llvm/Support/MemoryBuffer.h"
  26 #include "llvm/Support/PrettyStackTrace.h"
  27 #include "llvm/Support/raw_ostream.h"
  28 #include "llvm/Support/SystemUtils.h"
  29 #include "llvm/System/Signals.h"
  30 #include <memory>
  31 using namespace llvm;
  32
  33 // InputFilename - The filename to read from.
  34 static cl::opt<std::string>
  35 InputFilename(cl::Positional, cl::desc("<input bitcode file>"),
  36               cl::init("-"), cl::value_desc("filename"));
  37
  38 static cl::opt<std::string>
  39 OutputFilename("o", cl::desc("Specify output filename"),
  40                cl::value_desc("filename"), cl::init("-"));
  41
  42 static cl::opt<bool>
  43 Force("f", cl::desc("Enable binary output on terminals"));
  44
  45 static cl::opt<bool>
  46 DeleteFn("delete", cl::desc("Delete specified Globals from Module"));
  47
  48 static cl::opt<bool>
  49 Relink("relink",
  50        cl::desc("Turn external linkage for callees of function to delete"));
  51
  52 // ExtractFunc - The function to extract from the module...
  53 static cl::opt<std::string>
  54 ExtractFunc("func", cl::desc("Specify function to extract"), cl::init(""),
  55             cl::value_desc("function"));
  56
  57 // ExtractGlobal - The global to extract from the module...
  58 static cl::opt<std::string>
  59 ExtractGlobal("glob", cl::desc("Specify global to extract"), cl::init(""),
  60               cl::value_desc("global"));
  61
  62 static cl::opt<bool>
  63 OutputAssembly("S",
  64                cl::desc("Write output as LLVM assembly"), cl::Hidden);
  65
  66 int main(int argc, char **argv) {
  67   // Print a stack trace if we signal out.
  68   sys::PrintStackTraceOnErrorSignal();
  69   PrettyStackTraceProgram X(argc, argv);
  70
  71   LLVMContext &Context = getGlobalContext();
  72   llvm_shutdown_obj Y;  // Call llvm_shutdown() on exit.
  73   cl::ParseCommandLineOptions(argc, argv, "llvm extractor\n");
  74
  75   SMDiagnostic Err;
  76   std::auto_ptr<Module> M;
  77   M.reset(ParseIRFile(InputFilename, Err, Context));
  78
  79   if (M.get() == 0) {
  80     Err.Print(argv[0], errs());
  81     return 1;
  82   }
  83
  84   // Figure out which function we should extract
  85   GlobalVariable *G = !ExtractGlobal.empty() ?
  86     M.get()->getNamedGlobal(ExtractGlobal) : 0;
  87
  88   // Figure out which function we should extract
  89   if (ExtractFunc.empty() && ExtractGlobal.empty()) ExtractFunc = "main";
  90   Function *F = M.get()->getFunction(ExtractFunc);
  91
  92   if (F == 0 && G == 0) {
  93     errs() << argv[0] << ": program doesn't contain function named '"
  94            << ExtractFunc << "' or a global named '" << ExtractGlobal << "'!\n";
  95     return 1;
  96   }
  97
  98   // In addition to deleting all other functions, we also want to spiff it
  99   // up a little bit.  Do this now.
 100   PassManager Passes;
 101   Passes.add(new TargetData(M.get())); // Use correct TargetData
 102   // Either isolate the function or delete it from the Module
 103   std::vector<GlobalValue*> GVs;
 104   if (F) GVs.push_back(F);
 105   if (G) GVs.push_back(G);
 106
 107   Passes.add(createGVExtractionPass(GVs, DeleteFn, Relink));
 108   if (!DeleteFn)
 109     Passes.add(createGlobalDCEPass());           // Delete unreachable globals
 110   Passes.add(createDeadTypeEliminationPass());   // Remove dead types...
 111   Passes.add(createStripDeadPrototypesPass());   // Remove dead func decls
 112
 113   // Make sure that the Output file gets unlinked from the disk if we get a
 114   // SIGINT
 115   sys::RemoveFileOnSignal(sys::Path(OutputFilename));
 116
 117   std::string ErrorInfo;
 118   raw_fd_ostream Out(OutputFilename.c_str(), ErrorInfo,
 119                      raw_fd_ostream::F_Binary);
 120   if (!ErrorInfo.empty()) {
 121     errs() << ErrorInfo << '\n';
 122     return 1;
 123   }
 124
 125   if (OutputAssembly)
 126     Passes.add(createPrintModulePass(&Out));
 127   else if (Force || !CheckBitcodeOutputToConsole(Out, true))
 128     Passes.add(createBitcodeWriterPass(Out));
 129
 130   Passes.run(*M.get());
 131
 132   return 0;
 133 }