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/Bitcode/ReaderWriter.h"
  19 #include "llvm/Transforms/IPO.h"
  20 #include "llvm/Target/TargetData.h"
  21 #include "llvm/Support/CommandLine.h"
  22 #include "llvm/Support/ManagedStatic.h"
  23 #include "llvm/Support/MemoryBuffer.h"
  24 #include "llvm/Support/PrettyStackTrace.h"
  25 #include "llvm/Support/raw_ostream.h"
  26 #include "llvm/Support/SystemUtils.h"
  27 #include "llvm/System/Signals.h"
  28 #include <memory>
  29 using namespace llvm;
  30
  31 // InputFilename - The filename to read from.
  32 static cl::opt<std::string>
  33 InputFilename(cl::Positional, cl::desc("<input bitcode file>"),
  34               cl::init("-"), cl::value_desc("filename"));
  35
  36 static cl::opt<std::string>
  37 OutputFilename("o", cl::desc("Specify output filename"),
  38                cl::value_desc("filename"), cl::init("-"));
  39
  40 static cl::opt<bool>
  41 Force("f", cl::desc("Enable binary output on terminals"));
  42
  43 static cl::opt<bool>
  44 DeleteFn("delete", cl::desc("Delete specified Globals from Module"));
  45
  46 static cl::opt<bool>
  47 Relink("relink",
  48        cl::desc("Turn external linkage for callees of function to delete"));
  49
  50 // ExtractFunc - The function to extract from the module...
  51 static cl::opt<std::string>
  52 ExtractFunc("func", cl::desc("Specify function to extract"), cl::init(""),
  53             cl::value_desc("function"));
  54
  55 // ExtractGlobal - The global to extract from the module...
  56 static cl::opt<std::string>
  57 ExtractGlobal("glob", cl::desc("Specify global to extract"), cl::init(""),
  58               cl::value_desc("global"));
  59
  60 int main(int argc, char **argv) {
  61   // Print a stack trace if we signal out.
  62   sys::PrintStackTraceOnErrorSignal();
  63   PrettyStackTraceProgram X(argc, argv);
  64
  65   LLVMContext &Context = getGlobalContext();
  66   llvm_shutdown_obj Y;  // Call llvm_shutdown() on exit.
  67   cl::ParseCommandLineOptions(argc, argv, "llvm extractor\n");
  68
  69   std::auto_ptr<Module> M;
  70
  71   MemoryBuffer *Buffer = MemoryBuffer::getFileOrSTDIN(InputFilename);
  72   if (Buffer == 0) {
  73     errs() << argv[0] << ": Error reading file '" + InputFilename + "'\n";
  74     return 1;
  75   } else {
  76     M.reset(ParseBitcodeFile(Buffer, Context));
  77   }
  78   delete Buffer;
  79
  80   if (M.get() == 0) {
  81     errs() << argv[0] << ": bitcode didn't read correctly.\n";
  82     return 1;
  83   }
  84
  85   // Figure out which function we should extract
  86   GlobalVariable *G = !ExtractGlobal.empty() ?
  87     M.get()->getNamedGlobal(ExtractGlobal) : 0;
  88
  89   // Figure out which function we should extract
  90   if (ExtractFunc.empty() && ExtractGlobal.empty()) ExtractFunc = "main";
  91   Function *F = M.get()->getFunction(ExtractFunc);
  92
  93   if (F == 0 && G == 0) {
  94     errs() << argv[0] << ": program doesn't contain function named '"
  95            << ExtractFunc << "' or a global named '" << ExtractGlobal << "'!\n";
  96     return 1;
  97   }
  98
  99   // In addition to deleting all other functions, we also want to spiff it
 100   // up a little bit.  Do this now.
 101   PassManager Passes;
 102   Passes.add(new TargetData(M.get())); // Use correct TargetData
 103   // Either isolate the function or delete it from the Module
 104   std::vector<GlobalValue*> GVs;
 105   if (F) GVs.push_back(F);
 106   if (G) GVs.push_back(G);
 107
 108   Passes.add(createGVExtractionPass(GVs, DeleteFn, Relink));
 109   if (!DeleteFn)
 110     Passes.add(createGlobalDCEPass());           // Delete unreachable globals
 111   Passes.add(createDeadTypeEliminationPass());   // Remove dead types...
 112   Passes.add(createStripDeadPrototypesPass());   // Remove dead func decls
 113
 114   std::string ErrorInfo;
 115   std::auto_ptr<raw_fd_ostream>
 116   Out(new raw_fd_ostream(OutputFilename.c_str(), ErrorInfo,
 117                          raw_fd_ostream::F_Binary));
 118   if (!ErrorInfo.empty()) {
 119     errs() << ErrorInfo << '\n';
 120     return 1;
 121   }
 122
 123   if (Force || !CheckBitcodeOutputToConsole(*Out, true))
 124     Passes.add(createBitcodeWriterPass(*Out));
 125
 126   Passes.run(*M.get());
 127
 128   return 0;
 129 }