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/MemoryBuffer.h"
21 #include "llvm/Support/ToolOutputFile.h"
22 #include "llvm/Support/WithColor.h"
23 
24 using namespace llvm;
25 
26 static cl::OptionCategory ModextractCategory("Modextract Options");
27 
28 static cl::opt<bool>
29     BinaryExtract("b", cl::desc("Whether to perform binary extraction"),
30                   cl::cat(ModextractCategory));
31 
32 static cl::opt<std::string> OutputFilename("o", cl::Required,
33                                            cl::desc("Output filename"),
34                                            cl::value_desc("filename"),
35                                            cl::cat(ModextractCategory));
36 
37 static cl::opt<std::string> InputFilename(cl::Positional,
38                                           cl::desc("<input bitcode>"),
39                                           cl::init("-"),
40                                           cl::cat(ModextractCategory));
41 
42 static cl::opt<unsigned> ModuleIndex("n", cl::Required,
43                                      cl::desc("Index of module to extract"),
44                                      cl::value_desc("index"),
45                                      cl::cat(ModextractCategory));
46 
47 int main(int argc, char **argv) {
48   cl::HideUnrelatedOptions({&ModextractCategory, &getColorCategory()});
49   cl::ParseCommandLineOptions(argc, argv, "Module extractor");
50 
51   ExitOnError ExitOnErr("llvm-modextract: error: ");
52 
53   std::unique_ptr<MemoryBuffer> MB =
54       ExitOnErr(errorOrToExpected(MemoryBuffer::getFileOrSTDIN(InputFilename)));
55   std::vector<BitcodeModule> Ms = ExitOnErr(getBitcodeModuleList(*MB));
56 
57   LLVMContext Context;
58   if (ModuleIndex >= Ms.size()) {
59     errs() << "llvm-modextract: error: module index out of range; bitcode file "
60               "contains "
61            << Ms.size() << " module(s)\n";
62     return 1;
63   }
64 
65   std::error_code EC;
66   std::unique_ptr<ToolOutputFile> Out(
67       new ToolOutputFile(OutputFilename, EC, sys::fs::OF_None));
68   ExitOnErr(errorCodeToError(EC));
69 
70   if (BinaryExtract) {
71     SmallVector<char, 0> Result;
72     BitcodeWriter Writer(Result);
73     Result.append(Ms[ModuleIndex].getBuffer().begin(),
74                   Ms[ModuleIndex].getBuffer().end());
75     Writer.copyStrtab(Ms[ModuleIndex].getStrtab());
76     Out->os() << Result;
77     Out->keep();
78     return 0;
79   }
80 
81   std::unique_ptr<Module> M = ExitOnErr(Ms[ModuleIndex].parseModule(Context));
82   WriteBitcodeToFile(*M, Out->os());
83 
84   Out->keep();
85   return 0;
86 }
87