1 //===-- llvm-lto2: test harness for the resolution-based LTO interface ----===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This program takes in a list of bitcode files, links them and performs
10 // link-time optimization according to the provided symbol resolutions using the
11 // resolution-based LTO interface, and outputs one or more object files.
12 //
13 // This program is intended to eventually replace llvm-lto which uses the legacy
14 // LTO interface.
15 //
16 //===----------------------------------------------------------------------===//
17 
18 #include "llvm/Bitcode/BitcodeReader.h"
19 #include "llvm/CodeGen/CommandFlags.h"
20 #include "llvm/IR/DiagnosticPrinter.h"
21 #include "llvm/LTO/LTO.h"
22 #include "llvm/Passes/PassPlugin.h"
23 #include "llvm/Remarks/HotnessThresholdParser.h"
24 #include "llvm/Support/Caching.h"
25 #include "llvm/Support/CommandLine.h"
26 #include "llvm/Support/FileSystem.h"
27 #include "llvm/Support/InitLLVM.h"
28 #include "llvm/Support/PluginLoader.h"
29 #include "llvm/Support/TargetSelect.h"
30 #include "llvm/Support/Threading.h"
31 #include <atomic>
32 
33 using namespace llvm;
34 using namespace lto;
35 
36 static codegen::RegisterCodeGenFlags CGF;
37 
38 static cl::opt<char>
39     OptLevel("O",
40              cl::desc("Optimization level. [-O0, -O1, -O2, or -O3] "
41                       "(default = '-O2')"),
42              cl::Prefix, cl::init('2'));
43 
44 static cl::opt<char> CGOptLevel(
45     "cg-opt-level",
46     cl::desc("Codegen optimization level (0, 1, 2 or 3, default = '2')"),
47     cl::init('2'));
48 
49 static cl::list<std::string> InputFilenames(cl::Positional, cl::OneOrMore,
50                                             cl::desc("<input bitcode files>"));
51 
52 static cl::opt<std::string> OutputFilename("o", cl::Required,
53                                            cl::desc("Output filename"),
54                                            cl::value_desc("filename"));
55 
56 static cl::opt<std::string> CacheDir("cache-dir", cl::desc("Cache Directory"),
57                                      cl::value_desc("directory"));
58 
59 static cl::opt<std::string> OptPipeline("opt-pipeline",
60                                         cl::desc("Optimizer Pipeline"),
61                                         cl::value_desc("pipeline"));
62 
63 static cl::opt<std::string> AAPipeline("aa-pipeline",
64                                        cl::desc("Alias Analysis Pipeline"),
65                                        cl::value_desc("aapipeline"));
66 
67 static cl::opt<bool> SaveTemps("save-temps", cl::desc("Save temporary files"));
68 
69 static cl::list<std::string> SelectSaveTemps(
70     "select-save-temps",
71     cl::value_desc("One, or multiple of: "
72                    "resolution,preopt,promote,internalize,import,opt,precodegen"
73                    ",combinedindex"),
74     cl::desc("Save selected temporary files. Cannot be specified together with "
75              "-save-temps"),
76     cl::CommaSeparated);
77 
78 constexpr const char *SaveTempsValues[] = {
79     "resolution", "preopt", "promote",    "internalize",
80     "import",     "opt",    "precodegen", "combinedindex"};
81 
82 static cl::opt<bool>
83     ThinLTODistributedIndexes("thinlto-distributed-indexes",
84                               cl::desc("Write out individual index and "
85                                        "import files for the "
86                                        "distributed backend case"));
87 
88 static cl::opt<bool>
89     ThinLTOEmitIndexes("thinlto-emit-indexes",
90                        cl::desc("Write out individual index files via "
91                                 "InProcessThinLTO"));
92 
93 static cl::opt<bool>
94     ThinLTOEmitImports("thinlto-emit-imports",
95                        cl::desc("Write out individual imports files via "
96                                 "InProcessThinLTO. Has no effect unless "
97                                 "specified with -thinlto-emit-indexes or "
98                                 "-thinlto-distributed-indexes"));
99 
100 // Default to using all available threads in the system, but using only one
101 // thread per core (no SMT).
102 // Use -thinlto-threads=all to use hardware_concurrency() instead, which means
103 // to use all hardware threads or cores in the system.
104 static cl::opt<std::string> Threads("thinlto-threads");
105 
106 static cl::list<std::string> SymbolResolutions(
107     "r",
108     cl::desc("Specify a symbol resolution: filename,symbolname,resolution\n"
109              "where \"resolution\" is a sequence (which may be empty) of the\n"
110              "following characters:\n"
111              " p - prevailing: the linker has chosen this definition of the\n"
112              "     symbol\n"
113              " l - local: the definition of this symbol is unpreemptable at\n"
114              "     runtime and is known to be in this linkage unit\n"
115              " x - externally visible: the definition of this symbol is\n"
116              "     visible outside of the LTO unit\n"
117              "A resolution for each symbol must be specified"));
118 
119 static cl::opt<std::string> OverrideTriple(
120     "override-triple",
121     cl::desc("Replace target triples in input files with this triple"));
122 
123 static cl::opt<std::string> DefaultTriple(
124     "default-triple",
125     cl::desc(
126         "Replace unspecified target triples in input files with this triple"));
127 
128 static cl::opt<bool> RemarksWithHotness(
129     "pass-remarks-with-hotness",
130     cl::desc("With PGO, include profile count in optimization remarks"),
131     cl::Hidden);
132 
133 cl::opt<std::optional<uint64_t>, false, remarks::HotnessThresholdParser>
134     RemarksHotnessThreshold(
135         "pass-remarks-hotness-threshold",
136         cl::desc("Minimum profile count required for an "
137                  "optimization remark to be output."
138                  " Use 'auto' to apply the threshold from profile summary."),
139         cl::value_desc("uint or 'auto'"), cl::init(0), cl::Hidden);
140 
141 static cl::opt<std::string>
142     RemarksFilename("pass-remarks-output",
143                     cl::desc("Output filename for pass remarks"),
144                     cl::value_desc("filename"));
145 
146 static cl::opt<std::string>
147     RemarksPasses("pass-remarks-filter",
148                   cl::desc("Only record optimization remarks from passes whose "
149                            "names match the given regular expression"),
150                   cl::value_desc("regex"));
151 
152 static cl::opt<std::string> RemarksFormat(
153     "pass-remarks-format",
154     cl::desc("The format used for serializing remarks (default: YAML)"),
155     cl::value_desc("format"), cl::init("yaml"));
156 
157 static cl::opt<std::string>
158     SamplePGOFile("lto-sample-profile-file",
159                   cl::desc("Specify a SamplePGO profile file"));
160 
161 static cl::opt<std::string>
162     CSPGOFile("lto-cspgo-profile-file",
163               cl::desc("Specify a context sensitive PGO profile file"));
164 
165 static cl::opt<bool>
166     RunCSIRInstr("lto-cspgo-gen",
167                  cl::desc("Run PGO context sensitive IR instrumentation"),
168                  cl::Hidden);
169 
170 static cl::opt<bool>
171     DebugPassManager("debug-pass-manager", cl::Hidden,
172                      cl::desc("Print pass management debugging information"));
173 
174 static cl::opt<std::string>
175     StatsFile("stats-file", cl::desc("Filename to write statistics to"));
176 
177 static cl::list<std::string>
178     PassPlugins("load-pass-plugin",
179                 cl::desc("Load passes from plugin library"));
180 
181 static cl::opt<std::string> UnifiedLTOMode("unified-lto", cl::Optional,
182                                            cl::desc("Set LTO mode"),
183                                            cl::value_desc("mode"));
184 
185 static cl::opt<bool> EnableFreestanding(
186     "lto-freestanding",
187     cl::desc("Enable Freestanding (disable builtins / TLI) during LTO"),
188     cl::Hidden);
189 
190 static void check(Error E, std::string Msg) {
191   if (!E)
192     return;
193   handleAllErrors(std::move(E), [&](ErrorInfoBase &EIB) {
194     errs() << "llvm-lto2: " << Msg << ": " << EIB.message().c_str() << '\n';
195   });
196   exit(1);
197 }
198 
199 template <typename T> static T check(Expected<T> E, std::string Msg) {
200   if (E)
201     return std::move(*E);
202   check(E.takeError(), Msg);
203   return T();
204 }
205 
206 static void check(std::error_code EC, std::string Msg) {
207   check(errorCodeToError(EC), Msg);
208 }
209 
210 template <typename T> static T check(ErrorOr<T> E, std::string Msg) {
211   if (E)
212     return std::move(*E);
213   check(E.getError(), Msg);
214   return T();
215 }
216 
217 static int usage() {
218   errs() << "Available subcommands: dump-symtab run\n";
219   return 1;
220 }
221 
222 static int run(int argc, char **argv) {
223   cl::ParseCommandLineOptions(argc, argv, "Resolution-based LTO test harness");
224 
225   // FIXME: Workaround PR30396 which means that a symbol can appear
226   // more than once if it is defined in module-level assembly and
227   // has a GV declaration. We allow (file, symbol) pairs to have multiple
228   // resolutions and apply them in the order observed.
229   std::map<std::pair<std::string, std::string>, std::list<SymbolResolution>>
230       CommandLineResolutions;
231   for (std::string R : SymbolResolutions) {
232     StringRef Rest = R;
233     StringRef FileName, SymbolName;
234     std::tie(FileName, Rest) = Rest.split(',');
235     if (Rest.empty()) {
236       llvm::errs() << "invalid resolution: " << R << '\n';
237       return 1;
238     }
239     std::tie(SymbolName, Rest) = Rest.split(',');
240     SymbolResolution Res;
241     for (char C : Rest) {
242       if (C == 'p')
243         Res.Prevailing = true;
244       else if (C == 'l')
245         Res.FinalDefinitionInLinkageUnit = true;
246       else if (C == 'x')
247         Res.VisibleToRegularObj = true;
248       else if (C == 'r')
249         Res.LinkerRedefined = true;
250       else {
251         llvm::errs() << "invalid character " << C << " in resolution: " << R
252                      << '\n';
253         return 1;
254       }
255     }
256     CommandLineResolutions[{std::string(FileName), std::string(SymbolName)}]
257         .push_back(Res);
258   }
259 
260   std::vector<std::unique_ptr<MemoryBuffer>> MBs;
261 
262   Config Conf;
263 
264   Conf.CPU = codegen::getMCPU();
265   Conf.Options = codegen::InitTargetOptionsFromCodeGenFlags(Triple());
266   Conf.MAttrs = codegen::getMAttrs();
267   if (auto RM = codegen::getExplicitRelocModel())
268     Conf.RelocModel = *RM;
269   Conf.CodeModel = codegen::getExplicitCodeModel();
270 
271   Conf.DebugPassManager = DebugPassManager;
272 
273   if (SaveTemps && !SelectSaveTemps.empty()) {
274     llvm::errs() << "-save-temps cannot be specified with -select-save-temps\n";
275     return 1;
276   }
277   if (SaveTemps || !SelectSaveTemps.empty()) {
278     DenseSet<StringRef> SaveTempsArgs;
279     for (auto &S : SelectSaveTemps)
280       if (is_contained(SaveTempsValues, S))
281         SaveTempsArgs.insert(S);
282       else {
283         llvm::errs() << ("invalid -select-save-temps argument: " + S) << '\n';
284         return 1;
285       }
286     check(Conf.addSaveTemps(OutputFilename + ".", false, SaveTempsArgs),
287           "Config::addSaveTemps failed");
288   }
289 
290   // Optimization remarks.
291   Conf.RemarksFilename = RemarksFilename;
292   Conf.RemarksPasses = RemarksPasses;
293   Conf.RemarksWithHotness = RemarksWithHotness;
294   Conf.RemarksHotnessThreshold = RemarksHotnessThreshold;
295   Conf.RemarksFormat = RemarksFormat;
296 
297   Conf.SampleProfile = SamplePGOFile;
298   Conf.CSIRProfile = CSPGOFile;
299   Conf.RunCSIRInstr = RunCSIRInstr;
300 
301   // Run a custom pipeline, if asked for.
302   Conf.OptPipeline = OptPipeline;
303   Conf.AAPipeline = AAPipeline;
304 
305   Conf.OptLevel = OptLevel - '0';
306   Conf.Freestanding = EnableFreestanding;
307   for (auto &PluginFN : PassPlugins)
308     Conf.PassPlugins.push_back(PluginFN);
309   if (auto Level = CodeGenOpt::parseLevel(CGOptLevel)) {
310     Conf.CGOptLevel = *Level;
311   } else {
312     llvm::errs() << "invalid cg optimization level: " << CGOptLevel << '\n';
313     return 1;
314   }
315 
316   if (auto FT = codegen::getExplicitFileType())
317     Conf.CGFileType = *FT;
318 
319   Conf.OverrideTriple = OverrideTriple;
320   Conf.DefaultTriple = DefaultTriple;
321   Conf.StatsFile = StatsFile;
322   Conf.PTO.LoopVectorization = Conf.OptLevel > 1;
323   Conf.PTO.SLPVectorization = Conf.OptLevel > 1;
324 
325   ThinBackend Backend;
326   if (ThinLTODistributedIndexes)
327     Backend = createWriteIndexesThinBackend(/*OldPrefix=*/"",
328                                             /*NewPrefix=*/"",
329                                             /*NativeObjectPrefix=*/"",
330                                             ThinLTOEmitImports,
331                                             /*LinkedObjectsFile=*/nullptr,
332                                             /*OnWrite=*/{});
333   else
334     Backend = createInProcessThinBackend(
335         llvm::heavyweight_hardware_concurrency(Threads),
336         /* OnWrite */ {}, ThinLTOEmitIndexes, ThinLTOEmitImports);
337 
338   // Track whether we hit an error; in particular, in the multi-threaded case,
339   // we can't exit() early because the rest of the threads wouldn't have had a
340   // change to be join-ed, and that would result in a "terminate called without
341   // an active exception". Altogether, this results in nondeterministic
342   // behavior. Instead, we don't exit in the multi-threaded case, but we make
343   // sure to report the error and then at the end (after joining cleanly)
344   // exit(1).
345   std::atomic<bool> HasErrors;
346   std::atomic_init(&HasErrors, false);
347   Conf.DiagHandler = [&](const DiagnosticInfo &DI) {
348     DiagnosticPrinterRawOStream DP(errs());
349     DI.print(DP);
350     errs() << '\n';
351     if (DI.getSeverity() == DS_Error)
352       HasErrors = true;
353   };
354 
355   LTO::LTOKind LTOMode = LTO::LTOK_Default;
356 
357   if (UnifiedLTOMode == "full") {
358     LTOMode = LTO::LTOK_UnifiedRegular;
359   } else if (UnifiedLTOMode == "thin") {
360     LTOMode = LTO::LTOK_UnifiedThin;
361   } else if (UnifiedLTOMode == "default") {
362     LTOMode = LTO::LTOK_Default;
363   } else if (!UnifiedLTOMode.empty()) {
364     llvm::errs() << "invalid LTO mode\n";
365     return 1;
366   }
367 
368   LTO Lto(std::move(Conf), std::move(Backend), 1, LTOMode);
369 
370   for (std::string F : InputFilenames) {
371     std::unique_ptr<MemoryBuffer> MB = check(MemoryBuffer::getFile(F), F);
372     std::unique_ptr<InputFile> Input =
373         check(InputFile::create(MB->getMemBufferRef()), F);
374 
375     std::vector<SymbolResolution> Res;
376     for (const InputFile::Symbol &Sym : Input->symbols()) {
377       auto I = CommandLineResolutions.find({F, std::string(Sym.getName())});
378       // If it isn't found, look for ".", which would have been added
379       // (followed by a hash) when the symbol was promoted during module
380       // splitting if it was defined in one part and used in the other.
381       // Try looking up the symbol name before the suffix.
382       if (I == CommandLineResolutions.end()) {
383         auto SplitName = Sym.getName().rsplit(".");
384         I = CommandLineResolutions.find({F, std::string(SplitName.first)});
385       }
386       if (I == CommandLineResolutions.end()) {
387         llvm::errs() << argv[0] << ": missing symbol resolution for " << F
388                      << ',' << Sym.getName() << '\n';
389         HasErrors = true;
390       } else {
391         Res.push_back(I->second.front());
392         I->second.pop_front();
393         if (I->second.empty())
394           CommandLineResolutions.erase(I);
395       }
396     }
397 
398     if (HasErrors)
399       continue;
400 
401     MBs.push_back(std::move(MB));
402     check(Lto.add(std::move(Input), Res), F);
403   }
404 
405   if (!CommandLineResolutions.empty()) {
406     HasErrors = true;
407     for (auto UnusedRes : CommandLineResolutions)
408       llvm::errs() << argv[0] << ": unused symbol resolution for "
409                    << UnusedRes.first.first << ',' << UnusedRes.first.second
410                    << '\n';
411   }
412   if (HasErrors)
413     return 1;
414 
415   auto AddStream =
416       [&](size_t Task,
417           const Twine &ModuleName) -> std::unique_ptr<CachedFileStream> {
418     std::string Path = OutputFilename + "." + utostr(Task);
419 
420     std::error_code EC;
421     auto S = std::make_unique<raw_fd_ostream>(Path, EC, sys::fs::OF_None);
422     check(EC, Path);
423     return std::make_unique<CachedFileStream>(std::move(S), Path);
424   };
425 
426   auto AddBuffer = [&](size_t Task, const Twine &ModuleName,
427                        std::unique_ptr<MemoryBuffer> MB) {
428     *AddStream(Task, ModuleName)->OS << MB->getBuffer();
429   };
430 
431   FileCache Cache;
432   if (!CacheDir.empty())
433     Cache = check(localCache("ThinLTO", "Thin", CacheDir, AddBuffer),
434                   "failed to create cache");
435 
436   check(Lto.run(AddStream, Cache), "LTO::run failed");
437   return static_cast<int>(HasErrors);
438 }
439 
440 static int dumpSymtab(int argc, char **argv) {
441   for (StringRef F : make_range(argv + 1, argv + argc)) {
442     std::unique_ptr<MemoryBuffer> MB =
443         check(MemoryBuffer::getFile(F), std::string(F));
444     BitcodeFileContents BFC =
445         check(getBitcodeFileContents(*MB), std::string(F));
446 
447     if (BFC.Symtab.size() >= sizeof(irsymtab::storage::Header)) {
448       auto *Hdr = reinterpret_cast<const irsymtab::storage::Header *>(
449           BFC.Symtab.data());
450       outs() << "version: " << Hdr->Version << '\n';
451       if (Hdr->Version == irsymtab::storage::Header::kCurrentVersion)
452         outs() << "producer: " << Hdr->Producer.get(BFC.StrtabForSymtab)
453                << '\n';
454     }
455 
456     std::unique_ptr<InputFile> Input =
457         check(InputFile::create(MB->getMemBufferRef()), std::string(F));
458 
459     outs() << "target triple: " << Input->getTargetTriple() << '\n';
460     Triple TT(Input->getTargetTriple());
461 
462     outs() << "source filename: " << Input->getSourceFileName() << '\n';
463 
464     if (TT.isOSBinFormatCOFF())
465       outs() << "linker opts: " << Input->getCOFFLinkerOpts() << '\n';
466 
467     if (TT.isOSBinFormatELF()) {
468       outs() << "dependent libraries:";
469       for (auto L : Input->getDependentLibraries())
470         outs() << " \"" << L << "\"";
471       outs() << '\n';
472     }
473 
474     ArrayRef<std::pair<StringRef, Comdat::SelectionKind>> ComdatTable =
475         Input->getComdatTable();
476     for (const InputFile::Symbol &Sym : Input->symbols()) {
477       switch (Sym.getVisibility()) {
478       case GlobalValue::HiddenVisibility:
479         outs() << 'H';
480         break;
481       case GlobalValue::ProtectedVisibility:
482         outs() << 'P';
483         break;
484       case GlobalValue::DefaultVisibility:
485         outs() << 'D';
486         break;
487       }
488 
489       auto PrintBool = [&](char C, bool B) { outs() << (B ? C : '-'); };
490       PrintBool('U', Sym.isUndefined());
491       PrintBool('C', Sym.isCommon());
492       PrintBool('W', Sym.isWeak());
493       PrintBool('I', Sym.isIndirect());
494       PrintBool('O', Sym.canBeOmittedFromSymbolTable());
495       PrintBool('T', Sym.isTLS());
496       PrintBool('X', Sym.isExecutable());
497       outs() << ' ' << Sym.getName() << '\n';
498 
499       if (Sym.isCommon())
500         outs() << "         size " << Sym.getCommonSize() << " align "
501                << Sym.getCommonAlignment() << '\n';
502 
503       int Comdat = Sym.getComdatIndex();
504       if (Comdat != -1) {
505         outs() << "         comdat ";
506         switch (ComdatTable[Comdat].second) {
507         case Comdat::Any:
508           outs() << "any";
509           break;
510         case Comdat::ExactMatch:
511           outs() << "exactmatch";
512           break;
513         case Comdat::Largest:
514           outs() << "largest";
515           break;
516         case Comdat::NoDeduplicate:
517           outs() << "nodeduplicate";
518           break;
519         case Comdat::SameSize:
520           outs() << "samesize";
521           break;
522         }
523         outs() << ' ' << ComdatTable[Comdat].first << '\n';
524       }
525 
526       if (TT.isOSBinFormatCOFF() && Sym.isWeak() && Sym.isIndirect())
527         outs() << "         fallback " << Sym.getCOFFWeakExternalFallback() << '\n';
528 
529       if (!Sym.getSectionName().empty())
530         outs() << "         section " << Sym.getSectionName() << "\n";
531     }
532 
533     outs() << '\n';
534   }
535 
536   return 0;
537 }
538 
539 int main(int argc, char **argv) {
540   InitLLVM X(argc, argv);
541   InitializeAllTargets();
542   InitializeAllTargetMCs();
543   InitializeAllAsmPrinters();
544   InitializeAllAsmParsers();
545 
546   // FIXME: This should use llvm::cl subcommands, but it isn't currently
547   // possible to pass an argument not associated with a subcommand to a
548   // subcommand (e.g. -use-new-pm).
549   if (argc < 2)
550     return usage();
551 
552   StringRef Subcommand = argv[1];
553   // Ensure that argv[0] is correct after adjusting argv/argc.
554   argv[1] = argv[0];
555   if (Subcommand == "dump-symtab")
556     return dumpSymtab(argc - 1, argv + 1);
557   if (Subcommand == "run")
558     return run(argc - 1, argv + 1);
559   return usage();
560 }
561