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/BitcodeReader.h"
17 #include "llvm/Bitcode/BitcodeWriter.h"
18 #include "llvm/IR/AutoUpgrade.h"
19 #include "llvm/IR/DiagnosticInfo.h"
20 #include "llvm/IR/DiagnosticPrinter.h"
21 #include "llvm/IR/LLVMContext.h"
22 #include "llvm/IR/Module.h"
23 #include "llvm/IR/ModuleSummaryIndex.h"
24 #include "llvm/IR/Verifier.h"
25 #include "llvm/IRReader/IRReader.h"
26 #include "llvm/Linker/Linker.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/IPO/Internalize.h"
38 #include "llvm/Transforms/Utils/FunctionImportUtils.h"
44 static cl::list<std::string>
45 InputFilenames(cl::Positional, cl::OneOrMore,
46 cl::desc("<input bitcode files>"));
48 static cl::list<std::string> OverridingInputs(
49 "override", cl::ZeroOrMore, cl::value_desc("filename"),
51 "input bitcode file which can override previously defined symbol(s)"));
53 // Option to simulate function importing for testing. This enables using
54 // llvm-link to simulate ThinLTO backend processes.
55 static cl::list<std::string> Imports(
56 "import", cl::ZeroOrMore, cl::value_desc("function:filename"),
57 cl::desc("Pair of function name and filename, where function should be "
58 "imported from bitcode in filename"));
60 // Option to support testing of function importing. The module summary
61 // must be specified in the case were we request imports via the -import
62 // option, as well as when compiling any module with functions that may be
63 // exported (imported by a different llvm-link -import invocation), to ensure
64 // consistent promotion and renaming of locals.
65 static cl::opt<std::string>
66 SummaryIndex("summary-index", cl::desc("Module summary index filename"),
67 cl::init(""), cl::value_desc("filename"));
69 static cl::opt<std::string>
70 OutputFilename("o", cl::desc("Override output filename"), cl::init("-"),
71 cl::value_desc("filename"));
74 Internalize("internalize", cl::desc("Internalize linked symbols"));
77 DisableDITypeMap("disable-debug-info-type-map",
78 cl::desc("Don't use a uniquing type map for debug info"));
81 OnlyNeeded("only-needed", cl::desc("Link only needed symbols"));
84 Force("f", cl::desc("Enable binary output on terminals"));
87 DisableLazyLoad("disable-lazy-loading",
88 cl::desc("Disable lazy module loading"));
91 OutputAssembly("S", cl::desc("Write output as LLVM assembly"), cl::Hidden);
94 Verbose("v", cl::desc("Print information about actions taken"));
97 DumpAsm("d", cl::desc("Print assembly as linked"), cl::Hidden);
100 SuppressWarnings("suppress-warnings", cl::desc("Suppress all linking warnings"),
103 static cl::opt<bool> PreserveBitcodeUseListOrder(
104 "preserve-bc-uselistorder",
105 cl::desc("Preserve use-list order when writing LLVM bitcode."),
106 cl::init(true), cl::Hidden);
108 static cl::opt<bool> PreserveAssemblyUseListOrder(
109 "preserve-ll-uselistorder",
110 cl::desc("Preserve use-list order when writing LLVM assembly."),
111 cl::init(false), cl::Hidden);
113 static ExitOnError ExitOnErr;
115 // Read the specified bitcode file in and return it. This routine searches the
116 // link path for the specified file to try to find it...
118 static std::unique_ptr<Module> loadFile(const char *argv0,
119 const std::string &FN,
120 LLVMContext &Context,
121 bool MaterializeMetadata = true) {
123 if (Verbose) errs() << "Loading '" << FN << "'\n";
124 std::unique_ptr<Module> Result;
126 Result = parseIRFile(FN, Err, Context);
128 Result = getLazyIRFileModule(FN, Err, Context, !MaterializeMetadata);
131 Err.print(argv0, errs());
135 if (MaterializeMetadata) {
136 ExitOnErr(Result->materializeMetadata());
137 UpgradeDebugInfo(*Result);
145 /// Helper to load on demand a Module from file and cache it for subsequent
146 /// queries during function importing.
147 class ModuleLazyLoaderCache {
148 /// Cache of lazily loaded module for import.
149 StringMap<std::unique_ptr<Module>> ModuleMap;
151 /// Retrieve a Module from the cache or lazily load it on demand.
152 std::function<std::unique_ptr<Module>(const char *argv0,
153 const std::string &FileName)>
157 /// Create the loader, Module will be initialized in \p Context.
158 ModuleLazyLoaderCache(std::function<std::unique_ptr<Module>(
159 const char *argv0, const std::string &FileName)>
161 : createLazyModule(std::move(createLazyModule)) {}
163 /// Retrieve a Module from the cache or lazily load it on demand.
164 Module &operator()(const char *argv0, const std::string &FileName);
166 std::unique_ptr<Module> takeModule(const std::string &FileName) {
167 auto I = ModuleMap.find(FileName);
168 assert(I != ModuleMap.end());
169 std::unique_ptr<Module> Ret = std::move(I->second);
175 // Get a Module for \p FileName from the cache, or load it lazily.
176 Module &ModuleLazyLoaderCache::operator()(const char *argv0,
177 const std::string &Identifier) {
178 auto &Module = ModuleMap[Identifier];
180 Module = createLazyModule(argv0, Identifier);
183 } // anonymous namespace
185 static void diagnosticHandler(const DiagnosticInfo &DI, void *C) {
186 unsigned Severity = DI.getSeverity();
192 if (SuppressWarnings)
194 errs() << "WARNING: ";
198 llvm_unreachable("Only expecting warnings and errors");
201 DiagnosticPrinterRawOStream DP(errs());
206 /// Import any functions requested via the -import option.
207 static bool importFunctions(const char *argv0, Module &DestModule) {
208 if (SummaryIndex.empty())
210 std::unique_ptr<ModuleSummaryIndex> Index =
211 ExitOnErr(llvm::getModuleSummaryIndexForFile(SummaryIndex));
213 // Map of Module -> List of globals to import from the Module
214 FunctionImporter::ImportMapTy ImportList;
216 auto ModuleLoader = [&DestModule](const char *argv0,
217 const std::string &Identifier) {
218 return loadFile(argv0, Identifier, DestModule.getContext(), false);
221 ModuleLazyLoaderCache ModuleLoaderCache(ModuleLoader);
222 for (const auto &Import : Imports) {
223 // Identify the requested function and its bitcode source file.
224 size_t Idx = Import.find(':');
225 if (Idx == std::string::npos) {
226 errs() << "Import parameter bad format: " << Import << "\n";
229 std::string FunctionName = Import.substr(0, Idx);
230 std::string FileName = Import.substr(Idx + 1, std::string::npos);
232 // Load the specified source module.
233 auto &SrcModule = ModuleLoaderCache(argv0, FileName);
235 if (verifyModule(SrcModule, &errs())) {
236 errs() << argv0 << ": " << FileName
237 << ": error: input module is broken!\n";
241 Function *F = SrcModule.getFunction(FunctionName);
243 errs() << "Ignoring import request for non-existent function "
244 << FunctionName << " from " << FileName << "\n";
247 // We cannot import weak_any functions without possibly affecting the
248 // order they are seen and selected by the linker, changing program
250 if (F->hasWeakAnyLinkage()) {
251 errs() << "Ignoring import request for weak-any function " << FunctionName
252 << " from " << FileName << "\n";
257 errs() << "Importing " << FunctionName << " from " << FileName << "\n";
259 auto &Entry = ImportList[FileName];
260 Entry.insert(std::make_pair(F->getGUID(), /* (Unused) threshold */ 1.0));
262 auto CachedModuleLoader = [&](StringRef Identifier) {
263 return ModuleLoaderCache.takeModule(Identifier);
265 FunctionImporter Importer(*Index, CachedModuleLoader);
266 ExitOnErr(Importer.importFunctions(DestModule, ImportList));
271 static bool linkFiles(const char *argv0, LLVMContext &Context, Linker &L,
272 const cl::list<std::string> &Files,
274 // Filter out flags that don't apply to the first file we load.
275 unsigned ApplicableFlags = Flags & Linker::Flags::OverrideFromSrc;
276 // Similar to some flags, internalization doesn't apply to the first file.
277 bool InternalizeLinkedSymbols = false;
278 for (const auto &File : Files) {
279 std::unique_ptr<Module> M = loadFile(argv0, File, Context);
281 errs() << argv0 << ": error loading file '" << File << "'\n";
285 // Note that when ODR merging types cannot verify input files in here When
286 // doing that debug metadata in the src module might already be pointing to
288 if (DisableDITypeMap && verifyModule(*M, &errs())) {
289 errs() << argv0 << ": " << File << ": error: input module is broken!\n";
293 // If a module summary index is supplied, load it so linkInModule can treat
294 // local functions/variables as exported and promote if necessary.
295 if (!SummaryIndex.empty()) {
296 std::unique_ptr<ModuleSummaryIndex> Index =
297 ExitOnErr(llvm::getModuleSummaryIndexForFile(SummaryIndex));
299 // Conservatively mark all internal values as promoted, since this tool
300 // does not do the ThinLink that would normally determine what values to
302 for (auto &I : *Index) {
303 for (auto &S : I.second.SummaryList) {
304 if (GlobalValue::isLocalLinkage(S->linkage()))
305 S->setLinkage(GlobalValue::ExternalLinkage);
310 if (renameModuleForThinLTO(*M, *Index))
315 errs() << "Linking in '" << File << "'\n";
318 if (InternalizeLinkedSymbols) {
319 Err = L.linkInModule(
320 std::move(M), ApplicableFlags, [](Module &M, const StringSet<> &GVS) {
321 internalizeModule(M, [&GVS](const GlobalValue &GV) {
322 return !GV.hasName() || (GVS.count(GV.getName()) == 0);
326 Err = L.linkInModule(std::move(M), ApplicableFlags);
332 // Internalization applies to linking of subsequent files.
333 InternalizeLinkedSymbols = Internalize;
335 // All linker flags apply to linking of subsequent files.
336 ApplicableFlags = Flags;
342 int main(int argc, char **argv) {
343 // Print a stack trace if we signal out.
344 sys::PrintStackTraceOnErrorSignal(argv[0]);
345 PrettyStackTraceProgram X(argc, argv);
347 ExitOnErr.setBanner(std::string(argv[0]) + ": ");
350 Context.setDiagnosticHandler(diagnosticHandler, nullptr, true);
352 llvm_shutdown_obj Y; // Call llvm_shutdown() on exit.
353 cl::ParseCommandLineOptions(argc, argv, "llvm linker\n");
355 if (!DisableDITypeMap)
356 Context.enableDebugTypeODRUniquing();
358 auto Composite = make_unique<Module>("llvm-link", Context);
359 Linker L(*Composite);
361 unsigned Flags = Linker::Flags::None;
363 Flags |= Linker::Flags::LinkOnlyNeeded;
365 // First add all the regular input files
366 if (!linkFiles(argv[0], Context, L, InputFilenames, Flags))
369 // Next the -override ones.
370 if (!linkFiles(argv[0], Context, L, OverridingInputs,
371 Flags | Linker::Flags::OverrideFromSrc))
374 // Import any functions requested via -import
375 if (!importFunctions(argv[0], *Composite))
378 if (DumpAsm) errs() << "Here's the assembly:\n" << *Composite;
381 tool_output_file Out(OutputFilename, EC, sys::fs::F_None);
383 errs() << EC.message() << '\n';
387 if (verifyModule(*Composite, &errs())) {
388 errs() << argv[0] << ": error: linked module is broken!\n";
392 if (Verbose) errs() << "Writing bitcode...\n";
393 if (OutputAssembly) {
394 Composite->print(Out.os(), nullptr, PreserveAssemblyUseListOrder);
395 } else if (Force || !CheckBitcodeOutputToConsole(Out.os(), true))
396 WriteBitcodeToFile(Composite.get(), Out.os(), PreserveBitcodeUseListOrder);