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/LLVMContext.h"
19 #include "llvm/LTO/LTOCodeGenerator.h"
20 #include "llvm/LTO/LTOModule.h"
21 #include "llvm/Object/FunctionIndexObjectFile.h"
22 #include "llvm/Support/CommandLine.h"
23 #include "llvm/Support/FileSystem.h"
24 #include "llvm/Support/ManagedStatic.h"
25 #include "llvm/Support/PrettyStackTrace.h"
26 #include "llvm/Support/Signals.h"
27 #include "llvm/Support/TargetSelect.h"
28 #include "llvm/Support/ToolOutputFile.h"
29 #include "llvm/Support/raw_ostream.h"
36 cl::desc("Optimization level. [-O0, -O1, -O2, or -O3] "
42 static cl::opt<bool> DisableVerify(
43 "disable-verify", cl::init(false),
44 cl::desc("Do not run the verifier during the optimization pipeline"));
47 DisableInline("disable-inlining", cl::init(false),
48 cl::desc("Do not run the inliner pass"));
51 DisableGVNLoadPRE("disable-gvn-loadpre", cl::init(false),
52 cl::desc("Do not run the GVN load PRE pass"));
55 DisableLTOVectorization("disable-lto-vectorization", cl::init(false),
56 cl::desc("Do not run loop or slp vectorization during LTO"));
59 UseDiagnosticHandler("use-diagnostic-handler", cl::init(false),
60 cl::desc("Use a diagnostic handler to test the handler interface"));
62 static cl::opt<bool> ThinLTO(
63 "thinlto", cl::init(false),
64 cl::desc("Only write combined global index for ThinLTO backends"));
66 static cl::list<std::string>
67 InputFilenames(cl::Positional, cl::OneOrMore,
68 cl::desc("<input bitcode files>"));
70 static cl::opt<std::string>
71 OutputFilename("o", cl::init(""),
72 cl::desc("Override output filename"),
73 cl::value_desc("filename"));
75 static cl::list<std::string>
76 ExportedSymbols("exported-symbol",
77 cl::desc("Symbol to export from the resulting object file"),
80 static cl::list<std::string>
81 DSOSymbols("dso-symbol",
82 cl::desc("Symbol to put in the symtab in the resulting dso"),
85 static cl::opt<bool> ListSymbolsOnly(
86 "list-symbols-only", cl::init(false),
87 cl::desc("Instead of running LTO, list the symbols in each IR file"));
89 static cl::opt<bool> SetMergedModule(
90 "set-merged-module", cl::init(false),
91 cl::desc("Use the first input module as the merged module"));
93 static cl::opt<unsigned> Parallelism("j", cl::Prefix, cl::init(1),
94 cl::desc("Number of backend threads"));
98 std::vector<bool> CanBeHidden;
102 static void handleDiagnostics(lto_codegen_diagnostic_severity_t Severity,
103 const char *Msg, void *) {
109 errs() << "remark: ";
115 errs() << "warning: ";
118 errs() << Msg << "\n";
121 static std::unique_ptr<LTOModule>
122 getLocalLTOModule(StringRef Path, std::unique_ptr<MemoryBuffer> &Buffer,
123 const TargetOptions &Options, std::string &Error) {
124 ErrorOr<std::unique_ptr<MemoryBuffer>> BufferOrErr =
125 MemoryBuffer::getFile(Path);
126 if (std::error_code EC = BufferOrErr.getError()) {
127 Error = EC.message();
130 Buffer = std::move(BufferOrErr.get());
131 return std::unique_ptr<LTOModule>(LTOModule::createInLocalContext(
132 Buffer->getBufferStart(), Buffer->getBufferSize(), Options, Error, Path));
135 /// \brief List symbols in each IR file.
137 /// The main point here is to provide lit-testable coverage for the LTOModule
138 /// functionality that's exposed by the C API to list symbols. Moreover, this
139 /// provides testing coverage for modules that have been created in their own
141 static int listSymbols(StringRef Command, const TargetOptions &Options) {
142 for (auto &Filename : InputFilenames) {
144 std::unique_ptr<MemoryBuffer> Buffer;
145 std::unique_ptr<LTOModule> Module =
146 getLocalLTOModule(Filename, Buffer, Options, Error);
148 errs() << Command << ": error loading file '" << Filename
149 << "': " << Error << "\n";
154 outs() << Filename << ":\n";
155 for (int I = 0, E = Module->getSymbolCount(); I != E; ++I)
156 outs() << Module->getSymbolName(I) << "\n";
161 /// Parse the function index out of an IR file and return the function
162 /// index object if found, or nullptr if not.
163 static std::unique_ptr<FunctionInfoIndex> getFunctionIndexForFile(
164 StringRef Path, std::string &Error, LLVMContext &Context) {
165 std::unique_ptr<MemoryBuffer> Buffer;
166 ErrorOr<std::unique_ptr<MemoryBuffer>> BufferOrErr =
167 MemoryBuffer::getFile(Path);
168 if (std::error_code EC = BufferOrErr.getError()) {
169 Error = EC.message();
172 Buffer = std::move(BufferOrErr.get());
173 ErrorOr<std::unique_ptr<object::FunctionIndexObjectFile>> ObjOrErr =
174 object::FunctionIndexObjectFile::create(Buffer->getMemBufferRef(),
176 if (std::error_code EC = ObjOrErr.getError()) {
177 Error = EC.message();
180 return (*ObjOrErr)->takeIndex();
183 /// Create a combined index file from the input IR files and write it.
185 /// This is meant to enable testing of ThinLTO combined index generation,
186 /// currently available via the gold plugin via -thinlto.
187 static int createCombinedFunctionIndex(StringRef Command) {
189 FunctionInfoIndex CombinedIndex;
190 uint64_t NextModuleId = 0;
191 for (auto &Filename : InputFilenames) {
193 std::unique_ptr<FunctionInfoIndex> Index =
194 getFunctionIndexForFile(Filename, Error, Context);
196 errs() << Command << ": error loading file '" << Filename
197 << "': " << Error << "\n";
200 CombinedIndex.mergeFrom(std::move(Index), ++NextModuleId);
203 assert(!OutputFilename.empty());
204 raw_fd_ostream OS(OutputFilename + ".thinlto.bc", EC,
205 sys::fs::OpenFlags::F_None);
207 errs() << Command << ": error opening the file '" << OutputFilename
208 << ".thinlto.bc': " << EC.message() << "\n";
211 WriteFunctionSummaryToFile(CombinedIndex, OS);
216 int main(int argc, char **argv) {
217 // Print a stack trace if we signal out.
218 sys::PrintStackTraceOnErrorSignal();
219 PrettyStackTraceProgram X(argc, argv);
221 llvm_shutdown_obj Y; // Call llvm_shutdown() on exit.
222 cl::ParseCommandLineOptions(argc, argv, "llvm LTO linker\n");
224 if (OptLevel < '0' || OptLevel > '3') {
225 errs() << argv[0] << ": optimization level must be between 0 and 3\n";
229 // Initialize the configured targets.
230 InitializeAllTargets();
231 InitializeAllTargetMCs();
232 InitializeAllAsmPrinters();
233 InitializeAllAsmParsers();
235 // set up the TargetOptions for the machine
236 TargetOptions Options = InitTargetOptionsFromCodeGenFlags();
239 return listSymbols(argv[0], Options);
241 if (ThinLTO) return createCombinedFunctionIndex(argv[0]);
243 unsigned BaseArg = 0;
245 LTOCodeGenerator CodeGen;
247 if (UseDiagnosticHandler)
248 CodeGen.setDiagnosticHandler(handleDiagnostics, nullptr);
250 CodeGen.setCodePICModel(RelocModel);
252 CodeGen.setDebugInfo(LTO_DEBUG_MODEL_DWARF);
253 CodeGen.setTargetOptions(Options);
255 llvm::StringSet<llvm::MallocAllocator> DSOSymbolsSet;
256 for (unsigned i = 0; i < DSOSymbols.size(); ++i)
257 DSOSymbolsSet.insert(DSOSymbols[i]);
259 std::vector<std::string> KeptDSOSyms;
261 for (unsigned i = BaseArg; i < InputFilenames.size(); ++i) {
263 std::unique_ptr<LTOModule> Module(
264 LTOModule::createFromFile(InputFilenames[i].c_str(), Options, error));
265 if (!error.empty()) {
266 errs() << argv[0] << ": error loading file '" << InputFilenames[i]
267 << "': " << error << "\n";
271 unsigned NumSyms = Module->getSymbolCount();
272 for (unsigned I = 0; I < NumSyms; ++I) {
273 StringRef Name = Module->getSymbolName(I);
274 if (!DSOSymbolsSet.count(Name))
276 lto_symbol_attributes Attrs = Module->getSymbolAttributes(I);
277 unsigned Scope = Attrs & LTO_SYMBOL_SCOPE_MASK;
278 if (Scope != LTO_SYMBOL_SCOPE_DEFAULT_CAN_BE_HIDDEN)
279 KeptDSOSyms.push_back(Name);
282 // We use the first input module as the destination module when
283 // SetMergedModule is true.
284 if (SetMergedModule && i == BaseArg) {
285 // Transfer ownership to the code generator.
286 CodeGen.setModule(std::move(Module));
287 } else if (!CodeGen.addModule(Module.get())) {
288 // Print a message here so that we know addModule() did not abort.
289 errs() << argv[0] << ": error adding file '" << InputFilenames[i] << "'\n";
294 // Add all the exported symbols to the table of symbols to preserve.
295 for (unsigned i = 0; i < ExportedSymbols.size(); ++i)
296 CodeGen.addMustPreserveSymbol(ExportedSymbols[i].c_str());
298 // Add all the dso symbols to the table of symbols to expose.
299 for (unsigned i = 0; i < KeptDSOSyms.size(); ++i)
300 CodeGen.addMustPreserveSymbol(KeptDSOSyms[i].c_str());
302 // Set cpu and attrs strings for the default target/subtarget.
303 CodeGen.setCpu(MCPU.c_str());
305 CodeGen.setOptLevel(OptLevel - '0');
308 for (unsigned i = 0; i < MAttrs.size(); ++i) {
311 attrs.append(MAttrs[i]);
315 CodeGen.setAttr(attrs.c_str());
317 if (!OutputFilename.empty()) {
318 std::string ErrorInfo;
319 if (!CodeGen.optimize(DisableVerify, DisableInline, DisableGVNLoadPRE,
320 DisableLTOVectorization, ErrorInfo)) {
321 errs() << argv[0] << ": error optimizing the code: " << ErrorInfo << "\n";
325 std::list<tool_output_file> OSs;
326 std::vector<raw_pwrite_stream *> OSPtrs;
327 for (unsigned I = 0; I != Parallelism; ++I) {
328 std::string PartFilename = OutputFilename;
329 if (Parallelism != 1)
330 PartFilename += "." + utostr(I);
332 OSs.emplace_back(PartFilename, EC, sys::fs::F_None);
334 errs() << argv[0] << ": error opening the file '" << PartFilename
335 << "': " << EC.message() << "\n";
338 OSPtrs.push_back(&OSs.back().os());
341 if (!CodeGen.compileOptimized(OSPtrs, ErrorInfo)) {
342 errs() << argv[0] << ": error compiling the code: " << ErrorInfo << "\n";
346 for (tool_output_file &OS : OSs)
349 if (Parallelism != 1) {
350 errs() << argv[0] << ": -j must be specified together with -o\n";
354 std::string ErrorInfo;
355 const char *OutputName = nullptr;
356 if (!CodeGen.compile_to_file(&OutputName, DisableVerify, DisableInline,
357 DisableGVNLoadPRE, DisableLTOVectorization,
360 << ": error compiling the code: " << ErrorInfo
365 outs() << "Wrote native object file '" << OutputName << "'\n";