1 //===- llvm-link.cpp - Low-level LLVM linker ------------------------------===//
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 may be invoked in the following manner:
11 //  llvm-link a.bc b.bc c.bc -o x.bc
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "llvm/Linker/Linker.h"
16 #include "llvm/Bitcode/ReaderWriter.h"
17 #include "llvm/IR/LLVMContext.h"
18 #include "llvm/IR/Module.h"
19 #include "llvm/IR/Verifier.h"
20 #include "llvm/IRReader/IRReader.h"
21 #include "llvm/Support/CommandLine.h"
22 #include "llvm/Support/FileSystem.h"
23 #include "llvm/Support/ManagedStatic.h"
24 #include "llvm/Support/Path.h"
25 #include "llvm/Support/PrettyStackTrace.h"
26 #include "llvm/Support/Signals.h"
27 #include "llvm/Support/SourceMgr.h"
28 #include "llvm/Support/SystemUtils.h"
29 #include "llvm/Support/ToolOutputFile.h"
30 #include <memory>
31 using namespace llvm;
32 
33 static cl::list<std::string>
34 InputFilenames(cl::Positional, cl::OneOrMore,
35                cl::desc("<input bitcode files>"));
36 
37 static cl::opt<std::string>
38 OutputFilename("o", cl::desc("Override output filename"), cl::init("-"),
39                cl::value_desc("filename"));
40 
41 static cl::opt<bool>
42 Force("f", cl::desc("Enable binary output on terminals"));
43 
44 static cl::opt<bool>
45 OutputAssembly("S",
46          cl::desc("Write output as LLVM assembly"), cl::Hidden);
47 
48 static cl::opt<bool>
49 Verbose("v", cl::desc("Print information about actions taken"));
50 
51 static cl::opt<bool>
52 DumpAsm("d", cl::desc("Print assembly as linked"), cl::Hidden);
53 
54 static cl::opt<bool>
55 SuppressWarnings("suppress-warnings", cl::desc("Suppress all linking warnings"),
56                  cl::init(false));
57 
58 // LoadFile - Read the specified bitcode file in and return it.  This routine
59 // searches the link path for the specified file to try to find it...
60 //
61 static inline Module *LoadFile(const char *argv0, const std::string &FN,
62                                LLVMContext& Context) {
63   SMDiagnostic Err;
64   if (Verbose) errs() << "Loading '" << FN << "'\n";
65   Module* Result = nullptr;
66 
67   Result = ParseIRFile(FN, Err, Context);
68   if (Result) return Result;   // Load successful!
69 
70   Err.print(argv0, errs());
71   return nullptr;
72 }
73 
74 int main(int argc, char **argv) {
75   // Print a stack trace if we signal out.
76   sys::PrintStackTraceOnErrorSignal();
77   PrettyStackTraceProgram X(argc, argv);
78 
79   LLVMContext &Context = getGlobalContext();
80   llvm_shutdown_obj Y;  // Call llvm_shutdown() on exit.
81   cl::ParseCommandLineOptions(argc, argv, "llvm linker\n");
82 
83   unsigned BaseArg = 0;
84   std::string ErrorMessage;
85 
86   std::unique_ptr<Module> Composite(
87       LoadFile(argv[0], InputFilenames[BaseArg], Context));
88   if (!Composite.get()) {
89     errs() << argv[0] << ": error loading file '"
90            << InputFilenames[BaseArg] << "'\n";
91     return 1;
92   }
93 
94   Linker L(Composite.get(), SuppressWarnings);
95   for (unsigned i = BaseArg+1; i < InputFilenames.size(); ++i) {
96     std::unique_ptr<Module> M(LoadFile(argv[0], InputFilenames[i], Context));
97     if (!M.get()) {
98       errs() << argv[0] << ": error loading file '" <<InputFilenames[i]<< "'\n";
99       return 1;
100     }
101 
102     if (Verbose) errs() << "Linking in '" << InputFilenames[i] << "'\n";
103 
104     if (L.linkInModule(M.get(), &ErrorMessage)) {
105       errs() << argv[0] << ": link error in '" << InputFilenames[i]
106              << "': " << ErrorMessage << "\n";
107       return 1;
108     }
109   }
110 
111   if (DumpAsm) errs() << "Here's the assembly:\n" << *Composite;
112 
113   std::string ErrorInfo;
114   tool_output_file Out(OutputFilename.c_str(), ErrorInfo, sys::fs::F_None);
115   if (!ErrorInfo.empty()) {
116     errs() << ErrorInfo << '\n';
117     return 1;
118   }
119 
120   if (verifyModule(*Composite)) {
121     errs() << argv[0] << ": linked module is broken!\n";
122     return 1;
123   }
124 
125   if (Verbose) errs() << "Writing bitcode...\n";
126   if (OutputAssembly) {
127     Out.os() << *Composite;
128   } else if (Force || !CheckBitcodeOutputToConsole(Out.os(), true))
129     WriteBitcodeToFile(Composite.get(), Out.os());
130 
131   // Declare success.
132   Out.keep();
133 
134   return 0;
135 }
136