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 }
77