1 //===-- llvm-lto: a simple command-line program to link modules with LTO --===//
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 program takes in a list of bitcode files, links them, performs link-time
11 // optimization, and outputs an object file.
12 //
13 //===----------------------------------------------------------------------===//
14
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"
31 #include <list>
32
33 using namespace llvm;
34
35 static cl::opt<char>
36 OptLevel("O",
37 cl::desc("Optimization level. [-O0, -O1, -O2, or -O3] "
38 "(default = '-O2')"),
39 cl::Prefix,
40 cl::ZeroOrMore,
41 cl::init('2'));
42
43 static cl::opt<bool> DisableVerify(
44 "disable-verify", cl::init(false),
45 cl::desc("Do not run the verifier during the optimization pipeline"));
46
47 static cl::opt<bool>
48 DisableInline("disable-inlining", cl::init(false),
49 cl::desc("Do not run the inliner pass"));
50
51 static cl::opt<bool>
52 DisableGVNLoadPRE("disable-gvn-loadpre", cl::init(false),
53 cl::desc("Do not run the GVN load PRE pass"));
54
55 static cl::opt<bool>
56 DisableLTOVectorization("disable-lto-vectorization", cl::init(false),
57 cl::desc("Do not run loop or slp vectorization during LTO"));
58
59 static cl::opt<bool>
60 UseDiagnosticHandler("use-diagnostic-handler", cl::init(false),
61 cl::desc("Use a diagnostic handler to test the handler interface"));
62
63 static cl::opt<bool>
64 ThinLTO("thinlto", cl::init(false),
65 cl::desc("Only write combined global index for ThinLTO backends"));
66
67 static cl::opt<bool>
68 SaveModuleFile("save-merged-module", cl::init(false),
69 cl::desc("Write merged LTO module to file before CodeGen"));
70
71 static cl::list<std::string>
72 InputFilenames(cl::Positional, cl::OneOrMore,
73 cl::desc("<input bitcode files>"));
74
75 static cl::opt<std::string>
76 OutputFilename("o", cl::init(""),
77 cl::desc("Override output filename"),
78 cl::value_desc("filename"));
79
80 static cl::list<std::string>
81 ExportedSymbols("exported-symbol",
82 cl::desc("Symbol to export from the resulting object file"),
83 cl::ZeroOrMore);
84
85 static cl::list<std::string>
86 DSOSymbols("dso-symbol",
87 cl::desc("Symbol to put in the symtab in the resulting dso"),
88 cl::ZeroOrMore);
89
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"));
93
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"));
97
98 static cl::opt<unsigned> Parallelism("j", cl::Prefix, cl::init(1),
99 cl::desc("Number of backend threads"));
100
101 namespace {
102 struct ModuleInfo {
103 std::vector<bool> CanBeHidden;
104 };
105 }
106
handleDiagnostics(lto_codegen_diagnostic_severity_t Severity,const char * Msg,void *)107 static void handleDiagnostics(lto_codegen_diagnostic_severity_t Severity,
108 const char *Msg, void *) {
109 errs() << "llvm-lto: ";
110 switch (Severity) {
111 case LTO_DS_NOTE:
112 errs() << "note: ";
113 break;
114 case LTO_DS_REMARK:
115 errs() << "remark: ";
116 break;
117 case LTO_DS_ERROR:
118 errs() << "error: ";
119 break;
120 case LTO_DS_WARNING:
121 errs() << "warning: ";
122 break;
123 }
124 errs() << Msg << "\n";
125 }
126
127 static std::string CurrentActivity;
diagnosticHandler(const DiagnosticInfo & DI)128 static void diagnosticHandler(const DiagnosticInfo &DI) {
129 raw_ostream &OS = errs();
130 OS << "llvm-lto: ";
131 switch (DI.getSeverity()) {
132 case DS_Error:
133 OS << "error";
134 break;
135 case DS_Warning:
136 OS << "warning";
137 break;
138 case DS_Remark:
139 OS << "remark";
140 break;
141 case DS_Note:
142 OS << "note";
143 break;
144 }
145 if (!CurrentActivity.empty())
146 OS << ' ' << CurrentActivity;
147 OS << ": ";
148
149 DiagnosticPrinterRawOStream DP(OS);
150 DI.print(DP);
151 OS << '\n';
152
153 if (DI.getSeverity() == DS_Error)
154 exit(1);
155 }
156
diagnosticHandlerWithContenxt(const DiagnosticInfo & DI,void * Context)157 static void diagnosticHandlerWithContenxt(const DiagnosticInfo &DI,
158 void *Context) {
159 diagnosticHandler(DI);
160 }
161
error(const Twine & Msg)162 static void error(const Twine &Msg) {
163 errs() << "llvm-lto: " << Msg << '\n';
164 exit(1);
165 }
166
error(std::error_code EC,const Twine & Prefix)167 static void error(std::error_code EC, const Twine &Prefix) {
168 if (EC)
169 error(Prefix + ": " + EC.message());
170 }
171
172 template <typename T>
error(const ErrorOr<T> & V,const Twine & Prefix)173 static void error(const ErrorOr<T> &V, const Twine &Prefix) {
174 error(V.getError(), Prefix);
175 }
176
177 static std::unique_ptr<LTOModule>
getLocalLTOModule(StringRef Path,std::unique_ptr<MemoryBuffer> & Buffer,const TargetOptions & Options)178 getLocalLTOModule(StringRef Path, std::unique_ptr<MemoryBuffer> &Buffer,
179 const TargetOptions &Options) {
180 ErrorOr<std::unique_ptr<MemoryBuffer>> BufferOrErr =
181 MemoryBuffer::getFile(Path);
182 error(BufferOrErr, "error loading file '" + Path + "'");
183 Buffer = std::move(BufferOrErr.get());
184 CurrentActivity = ("loading file '" + Path + "'").str();
185 ErrorOr<std::unique_ptr<LTOModule>> Ret = LTOModule::createInLocalContext(
186 Buffer->getBufferStart(), Buffer->getBufferSize(), Options, Path);
187 CurrentActivity = "";
188 return std::move(*Ret);
189 }
190
191 /// \brief List symbols in each IR file.
192 ///
193 /// The main point here is to provide lit-testable coverage for the LTOModule
194 /// functionality that's exposed by the C API to list symbols. Moreover, this
195 /// provides testing coverage for modules that have been created in their own
196 /// contexts.
listSymbols(const TargetOptions & Options)197 static void listSymbols(const TargetOptions &Options) {
198 for (auto &Filename : InputFilenames) {
199 std::unique_ptr<MemoryBuffer> Buffer;
200 std::unique_ptr<LTOModule> Module =
201 getLocalLTOModule(Filename, Buffer, Options);
202
203 // List the symbols.
204 outs() << Filename << ":\n";
205 for (int I = 0, E = Module->getSymbolCount(); I != E; ++I)
206 outs() << Module->getSymbolName(I) << "\n";
207 }
208 }
209
210 /// Create a combined index file from the input IR files and write it.
211 ///
212 /// This is meant to enable testing of ThinLTO combined index generation,
213 /// currently available via the gold plugin via -thinlto.
createCombinedFunctionIndex()214 static void createCombinedFunctionIndex() {
215 FunctionInfoIndex CombinedIndex;
216 uint64_t NextModuleId = 0;
217 for (auto &Filename : InputFilenames) {
218 CurrentActivity = "loading file '" + Filename + "'";
219 ErrorOr<std::unique_ptr<FunctionInfoIndex>> IndexOrErr =
220 llvm::getFunctionIndexForFile(Filename, diagnosticHandler);
221 std::unique_ptr<FunctionInfoIndex> Index = std::move(IndexOrErr.get());
222 CurrentActivity = "";
223 // Skip files without a function summary.
224 if (!Index)
225 continue;
226 CombinedIndex.mergeFrom(std::move(Index), ++NextModuleId);
227 }
228 std::error_code EC;
229 assert(!OutputFilename.empty());
230 raw_fd_ostream OS(OutputFilename + ".thinlto.bc", EC,
231 sys::fs::OpenFlags::F_None);
232 error(EC, "error opening the file '" + OutputFilename + ".thinlto.bc'");
233 WriteFunctionSummaryToFile(CombinedIndex, OS);
234 OS.close();
235 }
236
main(int argc,char ** argv)237 int main(int argc, char **argv) {
238 // Print a stack trace if we signal out.
239 sys::PrintStackTraceOnErrorSignal();
240 PrettyStackTraceProgram X(argc, argv);
241
242 llvm_shutdown_obj Y; // Call llvm_shutdown() on exit.
243 cl::ParseCommandLineOptions(argc, argv, "llvm LTO linker\n");
244
245 if (OptLevel < '0' || OptLevel > '3')
246 error("optimization level must be between 0 and 3");
247
248 // Initialize the configured targets.
249 InitializeAllTargets();
250 InitializeAllTargetMCs();
251 InitializeAllAsmPrinters();
252 InitializeAllAsmParsers();
253
254 // set up the TargetOptions for the machine
255 TargetOptions Options = InitTargetOptionsFromCodeGenFlags();
256
257 if (ListSymbolsOnly) {
258 listSymbols(Options);
259 return 0;
260 }
261
262 if (ThinLTO) {
263 createCombinedFunctionIndex();
264 return 0;
265 }
266
267 unsigned BaseArg = 0;
268
269 LLVMContext Context;
270 Context.setDiagnosticHandler(diagnosticHandlerWithContenxt, nullptr, true);
271
272 LTOCodeGenerator CodeGen(Context);
273
274 if (UseDiagnosticHandler)
275 CodeGen.setDiagnosticHandler(handleDiagnostics, nullptr);
276
277 CodeGen.setCodePICModel(RelocModel);
278
279 CodeGen.setDebugInfo(LTO_DEBUG_MODEL_DWARF);
280 CodeGen.setTargetOptions(Options);
281
282 llvm::StringSet<llvm::MallocAllocator> DSOSymbolsSet;
283 for (unsigned i = 0; i < DSOSymbols.size(); ++i)
284 DSOSymbolsSet.insert(DSOSymbols[i]);
285
286 std::vector<std::string> KeptDSOSyms;
287
288 for (unsigned i = BaseArg; i < InputFilenames.size(); ++i) {
289 CurrentActivity = "loading file '" + InputFilenames[i] + "'";
290 ErrorOr<std::unique_ptr<LTOModule>> ModuleOrErr =
291 LTOModule::createFromFile(Context, InputFilenames[i].c_str(), Options);
292 std::unique_ptr<LTOModule> &Module = *ModuleOrErr;
293 CurrentActivity = "";
294
295 unsigned NumSyms = Module->getSymbolCount();
296 for (unsigned I = 0; I < NumSyms; ++I) {
297 StringRef Name = Module->getSymbolName(I);
298 if (!DSOSymbolsSet.count(Name))
299 continue;
300 lto_symbol_attributes Attrs = Module->getSymbolAttributes(I);
301 unsigned Scope = Attrs & LTO_SYMBOL_SCOPE_MASK;
302 if (Scope != LTO_SYMBOL_SCOPE_DEFAULT_CAN_BE_HIDDEN)
303 KeptDSOSyms.push_back(Name);
304 }
305
306 // We use the first input module as the destination module when
307 // SetMergedModule is true.
308 if (SetMergedModule && i == BaseArg) {
309 // Transfer ownership to the code generator.
310 CodeGen.setModule(std::move(Module));
311 } else if (!CodeGen.addModule(Module.get())) {
312 // Print a message here so that we know addModule() did not abort.
313 errs() << argv[0] << ": error adding file '" << InputFilenames[i] << "'\n";
314 return 1;
315 }
316 }
317
318 // Add all the exported symbols to the table of symbols to preserve.
319 for (unsigned i = 0; i < ExportedSymbols.size(); ++i)
320 CodeGen.addMustPreserveSymbol(ExportedSymbols[i].c_str());
321
322 // Add all the dso symbols to the table of symbols to expose.
323 for (unsigned i = 0; i < KeptDSOSyms.size(); ++i)
324 CodeGen.addMustPreserveSymbol(KeptDSOSyms[i].c_str());
325
326 // Set cpu and attrs strings for the default target/subtarget.
327 CodeGen.setCpu(MCPU.c_str());
328
329 CodeGen.setOptLevel(OptLevel - '0');
330
331 std::string attrs;
332 for (unsigned i = 0; i < MAttrs.size(); ++i) {
333 if (i > 0)
334 attrs.append(",");
335 attrs.append(MAttrs[i]);
336 }
337
338 if (!attrs.empty())
339 CodeGen.setAttr(attrs.c_str());
340
341 if (FileType.getNumOccurrences())
342 CodeGen.setFileType(FileType);
343
344 if (!OutputFilename.empty()) {
345 if (!CodeGen.optimize(DisableVerify, DisableInline, DisableGVNLoadPRE,
346 DisableLTOVectorization)) {
347 // Diagnostic messages should have been printed by the handler.
348 errs() << argv[0] << ": error optimizing the code\n";
349 return 1;
350 }
351
352 if (SaveModuleFile) {
353 std::string ModuleFilename = OutputFilename;
354 ModuleFilename += ".merged.bc";
355 std::string ErrMsg;
356
357 if (!CodeGen.writeMergedModules(ModuleFilename.c_str())) {
358 errs() << argv[0] << ": writing merged module failed.\n";
359 return 1;
360 }
361 }
362
363 std::list<tool_output_file> OSs;
364 std::vector<raw_pwrite_stream *> OSPtrs;
365 for (unsigned I = 0; I != Parallelism; ++I) {
366 std::string PartFilename = OutputFilename;
367 if (Parallelism != 1)
368 PartFilename += "." + utostr(I);
369 std::error_code EC;
370 OSs.emplace_back(PartFilename, EC, sys::fs::F_None);
371 if (EC) {
372 errs() << argv[0] << ": error opening the file '" << PartFilename
373 << "': " << EC.message() << "\n";
374 return 1;
375 }
376 OSPtrs.push_back(&OSs.back().os());
377 }
378
379 if (!CodeGen.compileOptimized(OSPtrs)) {
380 // Diagnostic messages should have been printed by the handler.
381 errs() << argv[0] << ": error compiling the code\n";
382 return 1;
383 }
384
385 for (tool_output_file &OS : OSs)
386 OS.keep();
387 } else {
388 if (Parallelism != 1) {
389 errs() << argv[0] << ": -j must be specified together with -o\n";
390 return 1;
391 }
392
393 if (SaveModuleFile) {
394 errs() << argv[0] << ": -save-merged-module must be specified with -o\n";
395 return 1;
396 }
397
398 const char *OutputName = nullptr;
399 if (!CodeGen.compile_to_file(&OutputName, DisableVerify, DisableInline,
400 DisableGVNLoadPRE, DisableLTOVectorization)) {
401 // Diagnostic messages should have been printed by the handler.
402 errs() << argv[0] << ": error compiling the code\n";
403 return 1;
404 }
405
406 outs() << "Wrote native object file '" << OutputName << "'\n";
407 }
408
409 return 0;
410 }
411