1 //===-- llvm-lto: a simple command-line program to link modules with LTO --===//
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 program takes in a list of bitcode files, links them, performs link-time
11 // optimization, and outputs an object file.
13 //===----------------------------------------------------------------------===//
15 #include "llvm/ADT/StringSet.h"
16 #include "llvm/Bitcode/ReaderWriter.h"
17 #include "llvm/CodeGen/CommandFlags.h"
18 #include "llvm/IR/DiagnosticPrinter.h"
19 #include "llvm/IR/LLVMContext.h"
20 #include "llvm/LTO/LTOCodeGenerator.h"
21 #include "llvm/LTO/LTOModule.h"
22 #include "llvm/Object/FunctionIndexObjectFile.h"
23 #include "llvm/Support/CommandLine.h"
24 #include "llvm/Support/FileSystem.h"
25 #include "llvm/Support/ManagedStatic.h"
26 #include "llvm/Support/PrettyStackTrace.h"
27 #include "llvm/Support/Signals.h"
28 #include "llvm/Support/TargetSelect.h"
29 #include "llvm/Support/ToolOutputFile.h"
30 #include "llvm/Support/raw_ostream.h"
37 cl::desc("Optimization level. [-O0, -O1, -O2, or -O3] "
43 static cl::opt<bool> DisableVerify(
44 "disable-verify", cl::init(false),
45 cl::desc("Do not run the verifier during the optimization pipeline"));
48 DisableInline("disable-inlining", cl::init(false),
49 cl::desc("Do not run the inliner pass"));
52 DisableGVNLoadPRE("disable-gvn-loadpre", cl::init(false),
53 cl::desc("Do not run the GVN load PRE pass"));
56 DisableLTOVectorization("disable-lto-vectorization", cl::init(false),
57 cl::desc("Do not run loop or slp vectorization during LTO"));
60 UseDiagnosticHandler("use-diagnostic-handler", cl::init(false),
61 cl::desc("Use a diagnostic handler to test the handler interface"));
64 ThinLTO("thinlto", cl::init(false),
65 cl::desc("Only write combined global index for ThinLTO backends"));
68 SaveModuleFile("save-merged-module", cl::init(false),
69 cl::desc("Write merged LTO module to file before CodeGen"));
71 static cl::list<std::string>
72 InputFilenames(cl::Positional, cl::OneOrMore,
73 cl::desc("<input bitcode files>"));
75 static cl::opt<std::string>
76 OutputFilename("o", cl::init(""),
77 cl::desc("Override output filename"),
78 cl::value_desc("filename"));
80 static cl::list<std::string>
81 ExportedSymbols("exported-symbol",
82 cl::desc("Symbol to export from the resulting object file"),
85 static cl::list<std::string>
86 DSOSymbols("dso-symbol",
87 cl::desc("Symbol to put in the symtab in the resulting dso"),
90 static cl::opt<bool> ListSymbolsOnly(
91 "list-symbols-only", cl::init(false),
92 cl::desc("Instead of running LTO, list the symbols in each IR file"));
94 static cl::opt<bool> SetMergedModule(
95 "set-merged-module", cl::init(false),
96 cl::desc("Use the first input module as the merged module"));
98 static cl::opt<unsigned> Parallelism("j", cl::Prefix, cl::init(1),
99 cl::desc("Number of backend threads"));
103 std::vector<bool> CanBeHidden;
107 static void handleDiagnostics(lto_codegen_diagnostic_severity_t Severity,
108 const char *Msg, void *) {
109 errs() << "llvm-lto: ";
115 errs() << "remark: ";
121 errs() << "warning: ";
124 errs() << Msg << "\n";
127 static void diagnosticHandler(const DiagnosticInfo &DI) {
128 raw_ostream &OS = errs();
130 switch (DI.getSeverity()) {
145 DiagnosticPrinterRawOStream DP(OS);
149 if (DI.getSeverity() == DS_Error)
153 static void error(const Twine &Msg) {
154 errs() << "llvm-lto: " << Msg << '\n';
158 static void error(std::error_code EC, const Twine &Prefix) {
160 error(Prefix + ": " + EC.message());
163 template <typename T>
164 static void error(const ErrorOr<T> &V, const Twine &Prefix) {
165 error(V.getError(), Prefix);
168 static std::unique_ptr<LTOModule>
169 getLocalLTOModule(StringRef Path, std::unique_ptr<MemoryBuffer> &Buffer,
170 const TargetOptions &Options) {
171 ErrorOr<std::unique_ptr<MemoryBuffer>> BufferOrErr =
172 MemoryBuffer::getFile(Path);
173 error(BufferOrErr, "error loading file '" + Path + "'");
174 Buffer = std::move(BufferOrErr.get());
176 std::unique_ptr<LTOModule> Ret(LTOModule::createInLocalContext(
177 Buffer->getBufferStart(), Buffer->getBufferSize(), Options, Error, Path));
179 error("error loading file '" + Path + "' " + Error);
183 /// \brief List symbols in each IR file.
185 /// The main point here is to provide lit-testable coverage for the LTOModule
186 /// functionality that's exposed by the C API to list symbols. Moreover, this
187 /// provides testing coverage for modules that have been created in their own
189 static void listSymbols(const TargetOptions &Options) {
190 for (auto &Filename : InputFilenames) {
191 std::unique_ptr<MemoryBuffer> Buffer;
192 std::unique_ptr<LTOModule> Module =
193 getLocalLTOModule(Filename, Buffer, Options);
196 outs() << Filename << ":\n";
197 for (int I = 0, E = Module->getSymbolCount(); I != E; ++I)
198 outs() << Module->getSymbolName(I) << "\n";
202 /// Create a combined index file from the input IR files and write it.
204 /// This is meant to enable testing of ThinLTO combined index generation,
205 /// currently available via the gold plugin via -thinlto.
206 static void createCombinedFunctionIndex() {
207 FunctionInfoIndex CombinedIndex;
208 uint64_t NextModuleId = 0;
209 for (auto &Filename : InputFilenames) {
210 ErrorOr<std::unique_ptr<FunctionInfoIndex>> IndexOrErr =
211 llvm::getFunctionIndexForFile(Filename, diagnosticHandler);
212 error(IndexOrErr, "error loading file '" + Filename + "'");
213 std::unique_ptr<FunctionInfoIndex> Index = std::move(IndexOrErr.get());
214 // Skip files without a function summary.
217 CombinedIndex.mergeFrom(std::move(Index), ++NextModuleId);
220 assert(!OutputFilename.empty());
221 raw_fd_ostream OS(OutputFilename + ".thinlto.bc", EC,
222 sys::fs::OpenFlags::F_None);
223 error(EC, "error opening the file '" + OutputFilename + ".thinlto.bc'");
224 WriteFunctionSummaryToFile(CombinedIndex, OS);
228 int main(int argc, char **argv) {
229 // Print a stack trace if we signal out.
230 sys::PrintStackTraceOnErrorSignal();
231 PrettyStackTraceProgram X(argc, argv);
233 llvm_shutdown_obj Y; // Call llvm_shutdown() on exit.
234 cl::ParseCommandLineOptions(argc, argv, "llvm LTO linker\n");
236 if (OptLevel < '0' || OptLevel > '3')
237 error("optimization level must be between 0 and 3");
239 // Initialize the configured targets.
240 InitializeAllTargets();
241 InitializeAllTargetMCs();
242 InitializeAllAsmPrinters();
243 InitializeAllAsmParsers();
245 // set up the TargetOptions for the machine
246 TargetOptions Options = InitTargetOptionsFromCodeGenFlags();
248 if (ListSymbolsOnly) {
249 listSymbols(Options);
254 createCombinedFunctionIndex();
258 unsigned BaseArg = 0;
260 LTOCodeGenerator CodeGen;
262 if (UseDiagnosticHandler)
263 CodeGen.setDiagnosticHandler(handleDiagnostics, nullptr);
265 CodeGen.setCodePICModel(RelocModel);
267 CodeGen.setDebugInfo(LTO_DEBUG_MODEL_DWARF);
268 CodeGen.setTargetOptions(Options);
270 llvm::StringSet<llvm::MallocAllocator> DSOSymbolsSet;
271 for (unsigned i = 0; i < DSOSymbols.size(); ++i)
272 DSOSymbolsSet.insert(DSOSymbols[i]);
274 std::vector<std::string> KeptDSOSyms;
276 for (unsigned i = BaseArg; i < InputFilenames.size(); ++i) {
278 std::unique_ptr<LTOModule> Module(
279 LTOModule::createFromFile(InputFilenames[i].c_str(), Options, error));
280 if (!error.empty()) {
281 errs() << argv[0] << ": error loading file '" << InputFilenames[i]
282 << "': " << error << "\n";
286 unsigned NumSyms = Module->getSymbolCount();
287 for (unsigned I = 0; I < NumSyms; ++I) {
288 StringRef Name = Module->getSymbolName(I);
289 if (!DSOSymbolsSet.count(Name))
291 lto_symbol_attributes Attrs = Module->getSymbolAttributes(I);
292 unsigned Scope = Attrs & LTO_SYMBOL_SCOPE_MASK;
293 if (Scope != LTO_SYMBOL_SCOPE_DEFAULT_CAN_BE_HIDDEN)
294 KeptDSOSyms.push_back(Name);
297 // We use the first input module as the destination module when
298 // SetMergedModule is true.
299 if (SetMergedModule && i == BaseArg) {
300 // Transfer ownership to the code generator.
301 CodeGen.setModule(std::move(Module));
302 } else if (!CodeGen.addModule(Module.get())) {
303 // Print a message here so that we know addModule() did not abort.
304 errs() << argv[0] << ": error adding file '" << InputFilenames[i] << "'\n";
309 // Add all the exported symbols to the table of symbols to preserve.
310 for (unsigned i = 0; i < ExportedSymbols.size(); ++i)
311 CodeGen.addMustPreserveSymbol(ExportedSymbols[i].c_str());
313 // Add all the dso symbols to the table of symbols to expose.
314 for (unsigned i = 0; i < KeptDSOSyms.size(); ++i)
315 CodeGen.addMustPreserveSymbol(KeptDSOSyms[i].c_str());
317 // Set cpu and attrs strings for the default target/subtarget.
318 CodeGen.setCpu(MCPU.c_str());
320 CodeGen.setOptLevel(OptLevel - '0');
323 for (unsigned i = 0; i < MAttrs.size(); ++i) {
326 attrs.append(MAttrs[i]);
330 CodeGen.setAttr(attrs.c_str());
332 if (FileType.getNumOccurrences())
333 CodeGen.setFileType(FileType);
335 if (!OutputFilename.empty()) {
336 if (!CodeGen.optimize(DisableVerify, DisableInline, DisableGVNLoadPRE,
337 DisableLTOVectorization)) {
338 // Diagnostic messages should have been printed by the handler.
339 errs() << argv[0] << ": error optimizing the code\n";
343 if (SaveModuleFile) {
344 std::string ModuleFilename = OutputFilename;
345 ModuleFilename += ".merged.bc";
348 if (!CodeGen.writeMergedModules(ModuleFilename.c_str())) {
349 errs() << argv[0] << ": writing merged module failed.\n";
354 std::list<tool_output_file> OSs;
355 std::vector<raw_pwrite_stream *> OSPtrs;
356 for (unsigned I = 0; I != Parallelism; ++I) {
357 std::string PartFilename = OutputFilename;
358 if (Parallelism != 1)
359 PartFilename += "." + utostr(I);
361 OSs.emplace_back(PartFilename, EC, sys::fs::F_None);
363 errs() << argv[0] << ": error opening the file '" << PartFilename
364 << "': " << EC.message() << "\n";
367 OSPtrs.push_back(&OSs.back().os());
370 if (!CodeGen.compileOptimized(OSPtrs)) {
371 // Diagnostic messages should have been printed by the handler.
372 errs() << argv[0] << ": error compiling the code\n";
376 for (tool_output_file &OS : OSs)
379 if (Parallelism != 1) {
380 errs() << argv[0] << ": -j must be specified together with -o\n";
384 if (SaveModuleFile) {
385 errs() << argv[0] << ": -save-merged-module must be specified with -o\n";
389 const char *OutputName = nullptr;
390 if (!CodeGen.compile_to_file(&OutputName, DisableVerify, DisableInline,
391 DisableGVNLoadPRE, DisableLTOVectorization)) {
392 // Diagnostic messages should have been printed by the handler.
393 errs() << argv[0] << ": error compiling the code\n";
397 outs() << "Wrote native object file '" << OutputName << "'\n";