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/System/Signals.h"
  27 #include <memory>
  28 using namespace llvm;
  29
  30 // InputFilename - The filename to read from.
  31 static cl::opt<std::string>
  32 InputFilename(cl::Positional, cl::desc("<input bitcode file>"),
  33               cl::init("-"), cl::value_desc("filename"));
  34
  35 static cl::opt<std::string>
  36 OutputFilename("o", cl::desc("Specify output filename"),
  37                cl::value_desc("filename"), cl::init("-"));
  38
  39 static cl::opt<bool>
  40 Force("f", cl::desc("Overwrite output files"));
  41
  42 static cl::opt<bool>
  43 DeleteFn("delete", cl::desc("Delete specified Globals from Module"));
  44
  45 static cl::opt<bool>
  46 Relink("relink",
  47        cl::desc("Turn external linkage for callees of function to delete"));
  48
  49 // ExtractFunc - The function to extract from the module...
  50 static cl::opt<std::string>
  51 ExtractFunc("func", cl::desc("Specify function to extract"), cl::init(""),
  52             cl::value_desc("function"));
  53
  54 // ExtractGlobal - The global to extract from the module...
  55 static cl::opt<std::string>
  56 ExtractGlobal("glob", cl::desc("Specify global to extract"), cl::init(""),
  57               cl::value_desc("global"));
  58
  59 int main(int argc, char **argv) {
  60   // Print a stack trace if we signal out.
  61   sys::PrintStackTraceOnErrorSignal();
  62   PrettyStackTraceProgram X(argc, argv);
  63
  64   LLVMContext &Context = getGlobalContext();
  65   llvm_shutdown_obj Y;  // Call llvm_shutdown() on exit.
  66   cl::ParseCommandLineOptions(argc, argv, "llvm extractor\n");
  67
  68   std::auto_ptr<Module> M;
  69
  70   MemoryBuffer *Buffer = MemoryBuffer::getFileOrSTDIN(InputFilename);
  71   if (Buffer == 0) {
  72     cerr << argv[0] << ": Error reading file '" + InputFilename + "'\n";
  73     return 1;
  74   } else {
  75     M.reset(ParseBitcodeFile(Buffer, Context));
  76   }
  77   delete Buffer;
  78
  79   if (M.get() == 0) {
  80     cerr << argv[0] << ": bitcode didn't read correctly.\n";
  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     cerr << 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   raw_ostream *Out = 0;
 114
 115   if (OutputFilename != "-") {  // Not stdout?
 116     std::string ErrorInfo;
 117     Out = new raw_fd_ostream(OutputFilename.c_str(), /*Binary=*/true,
 118                              Force, ErrorInfo);
 119     if (!ErrorInfo.empty()) {
 120       errs() << ErrorInfo << '\n';
 121       if (!Force)
 122         errs() << "Use -f command line argument to force output\n";
 123       delete Out;
 124       return 1;
 125     }
 126   } else {                      // Specified stdout
 127     // FIXME: errs() is not binary!
 128     Out = &errs();
 129   }
 130
 131   Passes.add(createBitcodeWriterPass(*Out));
 132   Passes.run(*M.get());
 133
 134   if (Out != &errs())
 135     delete Out;
 136   return 0;
 137 }