1 //===- llvm-link.cpp - Low-level LLVM linker ------------------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This utility may be invoked in the following manner:
11 // llvm-link a.bc b.bc c.bc -o x.bc
13 //===----------------------------------------------------------------------===//
15 #include "llvm/ADT/STLExtras.h"
16 #include "llvm/Bitcode/BitcodeWriter.h"
17 #include "llvm/IR/AutoUpgrade.h"
18 #include "llvm/IR/DiagnosticInfo.h"
19 #include "llvm/IR/DiagnosticPrinter.h"
20 #include "llvm/IR/LLVMContext.h"
21 #include "llvm/IR/Module.h"
22 #include "llvm/IR/ModuleSummaryIndex.h"
23 #include "llvm/IR/Verifier.h"
24 #include "llvm/IRReader/IRReader.h"
25 #include "llvm/Linker/Linker.h"
26 #include "llvm/Object/ModuleSummaryIndexObjectFile.h"
27 #include "llvm/Support/CommandLine.h"
28 #include "llvm/Support/FileSystem.h"
29 #include "llvm/Support/ManagedStatic.h"
30 #include "llvm/Support/Path.h"
31 #include "llvm/Support/PrettyStackTrace.h"
32 #include "llvm/Support/Signals.h"
33 #include "llvm/Support/SourceMgr.h"
34 #include "llvm/Support/SystemUtils.h"
35 #include "llvm/Support/ToolOutputFile.h"
36 #include "llvm/Transforms/IPO/FunctionImport.h"
37 #include "llvm/Transforms/Utils/FunctionImportUtils.h"
43 static cl::list<std::string>
44 InputFilenames(cl::Positional, cl::OneOrMore,
45 cl::desc("<input bitcode files>"));
47 static cl::list<std::string> OverridingInputs(
48 "override", cl::ZeroOrMore, cl::value_desc("filename"),
50 "input bitcode file which can override previously defined symbol(s)"));
52 // Option to simulate function importing for testing. This enables using
53 // llvm-link to simulate ThinLTO backend processes.
54 static cl::list<std::string> Imports(
55 "import", cl::ZeroOrMore, cl::value_desc("function:filename"),
56 cl::desc("Pair of function name and filename, where function should be "
57 "imported from bitcode in filename"));
59 // Option to support testing of function importing. The module summary
60 // must be specified in the case were we request imports via the -import
61 // option, as well as when compiling any module with functions that may be
62 // exported (imported by a different llvm-link -import invocation), to ensure
63 // consistent promotion and renaming of locals.
64 static cl::opt<std::string>
65 SummaryIndex("summary-index", cl::desc("Module summary index filename"),
66 cl::init(""), cl::value_desc("filename"));
68 static cl::opt<std::string>
69 OutputFilename("o", cl::desc("Override output filename"), cl::init("-"),
70 cl::value_desc("filename"));
73 Internalize("internalize", cl::desc("Internalize linked symbols"));
76 DisableDITypeMap("disable-debug-info-type-map",
77 cl::desc("Don't use a uniquing type map for debug info"));
80 OnlyNeeded("only-needed", cl::desc("Link only needed symbols"));
83 Force("f", cl::desc("Enable binary output on terminals"));
86 DisableLazyLoad("disable-lazy-loading",
87 cl::desc("Disable lazy module loading"));
90 OutputAssembly("S", cl::desc("Write output as LLVM assembly"), cl::Hidden);
93 Verbose("v", cl::desc("Print information about actions taken"));
96 DumpAsm("d", cl::desc("Print assembly as linked"), cl::Hidden);
99 SuppressWarnings("suppress-warnings", cl::desc("Suppress all linking warnings"),
102 static cl::opt<bool> PreserveBitcodeUseListOrder(
103 "preserve-bc-uselistorder",
104 cl::desc("Preserve use-list order when writing LLVM bitcode."),
105 cl::init(true), cl::Hidden);
107 static cl::opt<bool> PreserveAssemblyUseListOrder(
108 "preserve-ll-uselistorder",
109 cl::desc("Preserve use-list order when writing LLVM assembly."),
110 cl::init(false), cl::Hidden);
112 static ExitOnError ExitOnErr;
114 // Read the specified bitcode file in and return it. This routine searches the
115 // link path for the specified file to try to find it...
117 static std::unique_ptr<Module> loadFile(const char *argv0,
118 const std::string &FN,
119 LLVMContext &Context,
120 bool MaterializeMetadata = true) {
122 if (Verbose) errs() << "Loading '" << FN << "'\n";
123 std::unique_ptr<Module> Result;
125 Result = parseIRFile(FN, Err, Context);
127 Result = getLazyIRFileModule(FN, Err, Context, !MaterializeMetadata);
130 Err.print(argv0, errs());
134 if (MaterializeMetadata) {
135 ExitOnErr(Result->materializeMetadata());
136 UpgradeDebugInfo(*Result);
144 /// Helper to load on demand a Module from file and cache it for subsequent
145 /// queries during function importing.
146 class ModuleLazyLoaderCache {
147 /// Cache of lazily loaded module for import.
148 StringMap<std::unique_ptr<Module>> ModuleMap;
150 /// Retrieve a Module from the cache or lazily load it on demand.
151 std::function<std::unique_ptr<Module>(const char *argv0,
152 const std::string &FileName)>
156 /// Create the loader, Module will be initialized in \p Context.
157 ModuleLazyLoaderCache(std::function<std::unique_ptr<Module>(
158 const char *argv0, const std::string &FileName)>
160 : createLazyModule(std::move(createLazyModule)) {}
162 /// Retrieve a Module from the cache or lazily load it on demand.
163 Module &operator()(const char *argv0, const std::string &FileName);
165 std::unique_ptr<Module> takeModule(const std::string &FileName) {
166 auto I = ModuleMap.find(FileName);
167 assert(I != ModuleMap.end());
168 std::unique_ptr<Module> Ret = std::move(I->second);
174 // Get a Module for \p FileName from the cache, or load it lazily.
175 Module &ModuleLazyLoaderCache::operator()(const char *argv0,
176 const std::string &Identifier) {
177 auto &Module = ModuleMap[Identifier];
179 Module = createLazyModule(argv0, Identifier);
182 } // anonymous namespace
184 static void diagnosticHandler(const DiagnosticInfo &DI, void *C) {
185 unsigned Severity = DI.getSeverity();
191 if (SuppressWarnings)
193 errs() << "WARNING: ";
197 llvm_unreachable("Only expecting warnings and errors");
200 DiagnosticPrinterRawOStream DP(errs());
205 /// Import any functions requested via the -import option.
206 static bool importFunctions(const char *argv0, Module &DestModule) {
207 if (SummaryIndex.empty())
209 std::unique_ptr<ModuleSummaryIndex> Index =
210 ExitOnErr(llvm::getModuleSummaryIndexForFile(SummaryIndex));
212 // Map of Module -> List of globals to import from the Module
213 FunctionImporter::ImportMapTy ImportList;
215 auto ModuleLoader = [&DestModule](const char *argv0,
216 const std::string &Identifier) {
217 return loadFile(argv0, Identifier, DestModule.getContext(), false);
220 ModuleLazyLoaderCache ModuleLoaderCache(ModuleLoader);
221 for (const auto &Import : Imports) {
222 // Identify the requested function and its bitcode source file.
223 size_t Idx = Import.find(':');
224 if (Idx == std::string::npos) {
225 errs() << "Import parameter bad format: " << Import << "\n";
228 std::string FunctionName = Import.substr(0, Idx);
229 std::string FileName = Import.substr(Idx + 1, std::string::npos);
231 // Load the specified source module.
232 auto &SrcModule = ModuleLoaderCache(argv0, FileName);
234 if (verifyModule(SrcModule, &errs())) {
235 errs() << argv0 << ": " << FileName
236 << ": error: input module is broken!\n";
240 Function *F = SrcModule.getFunction(FunctionName);
242 errs() << "Ignoring import request for non-existent function "
243 << FunctionName << " from " << FileName << "\n";
246 // We cannot import weak_any functions without possibly affecting the
247 // order they are seen and selected by the linker, changing program
249 if (F->hasWeakAnyLinkage()) {
250 errs() << "Ignoring import request for weak-any function " << FunctionName
251 << " from " << FileName << "\n";
256 errs() << "Importing " << FunctionName << " from " << FileName << "\n";
258 auto &Entry = ImportList[FileName];
259 Entry.insert(std::make_pair(F->getGUID(), /* (Unused) threshold */ 1.0));
261 auto CachedModuleLoader = [&](StringRef Identifier) {
262 return ModuleLoaderCache.takeModule(Identifier);
264 FunctionImporter Importer(*Index, CachedModuleLoader);
265 ExitOnErr(Importer.importFunctions(DestModule, ImportList));
270 static bool linkFiles(const char *argv0, LLVMContext &Context, Linker &L,
271 const cl::list<std::string> &Files,
273 // Filter out flags that don't apply to the first file we load.
274 unsigned ApplicableFlags = Flags & Linker::Flags::OverrideFromSrc;
275 for (const auto &File : Files) {
276 std::unique_ptr<Module> M = loadFile(argv0, File, Context);
278 errs() << argv0 << ": error loading file '" << File << "'\n";
282 // Note that when ODR merging types cannot verify input files in here When
283 // doing that debug metadata in the src module might already be pointing to
285 if (DisableDITypeMap && verifyModule(*M, &errs())) {
286 errs() << argv0 << ": " << File << ": error: input module is broken!\n";
290 // If a module summary index is supplied, load it so linkInModule can treat
291 // local functions/variables as exported and promote if necessary.
292 if (!SummaryIndex.empty()) {
293 std::unique_ptr<ModuleSummaryIndex> Index =
294 ExitOnErr(llvm::getModuleSummaryIndexForFile(SummaryIndex));
296 // Conservatively mark all internal values as promoted, since this tool
297 // does not do the ThinLink that would normally determine what values to
299 for (auto &I : *Index) {
300 for (auto &S : I.second) {
301 if (GlobalValue::isLocalLinkage(S->linkage()))
302 S->setLinkage(GlobalValue::ExternalLinkage);
307 if (renameModuleForThinLTO(*M, *Index))
312 errs() << "Linking in '" << File << "'\n";
314 if (L.linkInModule(std::move(M), ApplicableFlags))
316 // All linker flags apply to linking of subsequent files.
317 ApplicableFlags = Flags;
323 int main(int argc, char **argv) {
324 // Print a stack trace if we signal out.
325 sys::PrintStackTraceOnErrorSignal(argv[0]);
326 PrettyStackTraceProgram X(argc, argv);
328 ExitOnErr.setBanner(std::string(argv[0]) + ": ");
331 Context.setDiagnosticHandler(diagnosticHandler, nullptr, true);
333 llvm_shutdown_obj Y; // Call llvm_shutdown() on exit.
334 cl::ParseCommandLineOptions(argc, argv, "llvm linker\n");
336 if (!DisableDITypeMap)
337 Context.enableDebugTypeODRUniquing();
339 auto Composite = make_unique<Module>("llvm-link", Context);
340 Linker L(*Composite);
342 unsigned Flags = Linker::Flags::None;
344 Flags |= Linker::Flags::InternalizeLinkedSymbols;
346 Flags |= Linker::Flags::LinkOnlyNeeded;
348 // First add all the regular input files
349 if (!linkFiles(argv[0], Context, L, InputFilenames, Flags))
352 // Next the -override ones.
353 if (!linkFiles(argv[0], Context, L, OverridingInputs,
354 Flags | Linker::Flags::OverrideFromSrc))
357 // Import any functions requested via -import
358 if (!importFunctions(argv[0], *Composite))
361 if (DumpAsm) errs() << "Here's the assembly:\n" << *Composite;
364 tool_output_file Out(OutputFilename, EC, sys::fs::F_None);
366 errs() << EC.message() << '\n';
370 if (verifyModule(*Composite, &errs())) {
371 errs() << argv[0] << ": error: linked module is broken!\n";
375 if (Verbose) errs() << "Writing bitcode...\n";
376 if (OutputAssembly) {
377 Composite->print(Out.os(), nullptr, PreserveAssemblyUseListOrder);
378 } else if (Force || !CheckBitcodeOutputToConsole(Out.os(), true))
379 WriteBitcodeToFile(Composite.get(), Out.os(), PreserveBitcodeUseListOrder);