tools/llvm-modextract/llvm-modextract.cpp

   1 //===-- llvm-modextract.cpp - LLVM module extractor utility ---------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This program is for testing features that rely on multi-module bitcode files.
  10 // It takes a multi-module bitcode file, extracts one of the modules and writes
  11 // it to the output file.
  12 //
  13 //===----------------------------------------------------------------------===//
  14
  15 #include "llvm/Bitcode/BitcodeReader.h"
  16 #include "llvm/Bitcode/BitcodeWriter.h"
  17 #include "llvm/Support/CommandLine.h"
  18 #include "llvm/Support/Error.h"
  19 #include "llvm/Support/FileSystem.h"
  20 #include "llvm/Support/ToolOutputFile.h"
  21
  22 using namespace llvm;
  23
  24 static cl::opt<bool>
  25     BinaryExtract("b", cl::desc("Whether to perform binary extraction"));
  26
  27 static cl::opt<std::string> OutputFilename("o", cl::Required,
  28                                            cl::desc("Output filename"),
  29                                            cl::value_desc("filename"));
  30
  31 static cl::opt<std::string>
  32     InputFilename(cl::Positional, cl::desc("<input bitcode>"), cl::init("-"));
  33
  34 static cl::opt<unsigned> ModuleIndex("n", cl::Required,
  35                                      cl::desc("Index of module to extract"),
  36                                      cl::value_desc("index"));
  37
  38 int main(int argc, char **argv) {
  39   cl::ParseCommandLineOptions(argc, argv, "Module extractor");
  40
  41   ExitOnError ExitOnErr("llvm-modextract: error: ");
  42
  43   std::unique_ptr<MemoryBuffer> MB =
  44       ExitOnErr(errorOrToExpected(MemoryBuffer::getFileOrSTDIN(InputFilename)));
  45   std::vector<BitcodeModule> Ms = ExitOnErr(getBitcodeModuleList(*MB));
  46
  47   LLVMContext Context;
  48   if (ModuleIndex >= Ms.size()) {
  49     errs() << "llvm-modextract: error: module index out of range; bitcode file "
  50               "contains "
  51            << Ms.size() << " module(s)\n";
  52     return 1;
  53   }
  54
  55   std::error_code EC;
  56   std::unique_ptr<ToolOutputFile> Out(
  57       new ToolOutputFile(OutputFilename, EC, sys::fs::OF_None));
  58   ExitOnErr(errorCodeToError(EC));
  59
  60   if (BinaryExtract) {
  61     SmallVector<char, 0> Result;
  62     BitcodeWriter Writer(Result);
  63     Result.append(Ms[ModuleIndex].getBuffer().begin(),
  64                   Ms[ModuleIndex].getBuffer().end());
  65     Writer.copyStrtab(Ms[ModuleIndex].getStrtab());
  66     Out->os() << Result;
  67     Out->keep();
  68     return 0;
  69   }
  70
  71   std::unique_ptr<Module> M = ExitOnErr(Ms[ModuleIndex].parseModule(Context));
  72   WriteBitcodeToFile(*M, Out->os());
  73
  74   Out->keep();
  75   return 0;
  76 }