1 //===- FunctionImport.cpp - ThinLTO Summary-based Function Import ---------===//
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 file implements Function import based on summaries.
12 //===----------------------------------------------------------------------===//
14 #include "llvm/Transforms/IPO/FunctionImport.h"
16 #include "llvm/ADT/SmallVector.h"
17 #include "llvm/ADT/Statistic.h"
18 #include "llvm/ADT/StringSet.h"
19 #include "llvm/ADT/Triple.h"
20 #include "llvm/Bitcode/BitcodeReader.h"
21 #include "llvm/IR/AutoUpgrade.h"
22 #include "llvm/IR/DiagnosticPrinter.h"
23 #include "llvm/IR/IntrinsicInst.h"
24 #include "llvm/IR/Module.h"
25 #include "llvm/IR/Verifier.h"
26 #include "llvm/IRReader/IRReader.h"
27 #include "llvm/Linker/Linker.h"
28 #include "llvm/Object/IRObjectFile.h"
29 #include "llvm/Support/CommandLine.h"
30 #include "llvm/Support/Debug.h"
31 #include "llvm/Support/SourceMgr.h"
32 #include "llvm/Transforms/IPO/Internalize.h"
33 #include "llvm/Transforms/Utils/FunctionImportUtils.h"
35 #define DEBUG_TYPE "function-import"
39 STATISTIC(NumImportedFunctions, "Number of functions imported");
40 STATISTIC(NumImportedModules, "Number of modules imported from");
41 STATISTIC(NumDeadSymbols, "Number of dead stripped symbols in index");
42 STATISTIC(NumLiveSymbols, "Number of live symbols in index");
44 /// Limit on instruction count of imported functions.
45 static cl::opt<unsigned> ImportInstrLimit(
46 "import-instr-limit", cl::init(100), cl::Hidden, cl::value_desc("N"),
47 cl::desc("Only import functions with less than N instructions"));
50 ImportInstrFactor("import-instr-evolution-factor", cl::init(0.7),
51 cl::Hidden, cl::value_desc("x"),
52 cl::desc("As we import functions, multiply the "
53 "`import-instr-limit` threshold by this factor "
54 "before processing newly imported functions"));
56 static cl::opt<float> ImportHotInstrFactor(
57 "import-hot-evolution-factor", cl::init(1.0), cl::Hidden,
59 cl::desc("As we import functions called from hot callsite, multiply the "
60 "`import-instr-limit` threshold by this factor "
61 "before processing newly imported functions"));
63 static cl::opt<float> ImportHotMultiplier(
64 "import-hot-multiplier", cl::init(3.0), cl::Hidden, cl::value_desc("x"),
65 cl::desc("Multiply the `import-instr-limit` threshold for hot callsites"));
67 static cl::opt<float> ImportCriticalMultiplier(
68 "import-critical-multiplier", cl::init(100.0), cl::Hidden,
71 "Multiply the `import-instr-limit` threshold for critical callsites"));
73 // FIXME: This multiplier was not really tuned up.
74 static cl::opt<float> ImportColdMultiplier(
75 "import-cold-multiplier", cl::init(0), cl::Hidden, cl::value_desc("N"),
76 cl::desc("Multiply the `import-instr-limit` threshold for cold callsites"));
78 static cl::opt<bool> PrintImports("print-imports", cl::init(false), cl::Hidden,
79 cl::desc("Print imported functions"));
81 static cl::opt<bool> ComputeDead("compute-dead", cl::init(true), cl::Hidden,
82 cl::desc("Compute dead symbols"));
84 static cl::opt<bool> EnableImportMetadata(
85 "enable-import-metadata", cl::init(
87 true /*Enabled with asserts.*/
92 cl::Hidden, cl::desc("Enable import metadata like 'thinlto_src_module'"));
94 // Load lazily a module from \p FileName in \p Context.
95 static std::unique_ptr<Module> loadFile(const std::string &FileName,
96 LLVMContext &Context) {
98 DEBUG(dbgs() << "Loading '" << FileName << "'\n");
99 // Metadata isn't loaded until functions are imported, to minimize
100 // the memory overhead.
101 std::unique_ptr<Module> Result =
102 getLazyIRFileModule(FileName, Err, Context,
103 /* ShouldLazyLoadMetadata = */ true);
105 Err.print("function-import", errs());
106 report_fatal_error("Abort");
114 /// Given a list of possible callee implementation for a call site, select one
115 /// that fits the \p Threshold.
117 /// FIXME: select "best" instead of first that fits. But what is "best"?
118 /// - The smallest: more likely to be inlined.
119 /// - The one with the least outgoing edges (already well optimized).
120 /// - One from a module already being imported from in order to reduce the
121 /// number of source modules parsed/linked.
122 /// - One that has PGO data attached.
123 /// - [insert you fancy metric here]
124 static const GlobalValueSummary *
125 selectCallee(const ModuleSummaryIndex &Index,
126 ArrayRef<std::unique_ptr<GlobalValueSummary>> CalleeSummaryList,
127 unsigned Threshold, StringRef CallerModulePath) {
128 auto It = llvm::find_if(
130 [&](const std::unique_ptr<GlobalValueSummary> &SummaryPtr) {
131 auto *GVSummary = SummaryPtr.get();
132 if (GlobalValue::isInterposableLinkage(GVSummary->linkage()))
133 // There is no point in importing these, we can't inline them
135 if (auto *AS = dyn_cast<AliasSummary>(GVSummary)) {
136 GVSummary = &AS->getAliasee();
137 // Alias can't point to "available_externally". However when we import
138 // linkOnceODR the linkage does not change. So we import the alias
139 // and aliasee only in this case.
140 // FIXME: we should import alias as available_externally *function*,
141 // the destination module does need to know it is an alias.
142 if (!GlobalValue::isLinkOnceODRLinkage(GVSummary->linkage()))
146 auto *Summary = cast<FunctionSummary>(GVSummary);
148 // If this is a local function, make sure we import the copy
149 // in the caller's module. The only time a local function can
150 // share an entry in the index is if there is a local with the same name
151 // in another module that had the same source file name (in a different
152 // directory), where each was compiled in their own directory so there
153 // was not distinguishing path.
154 // However, do the import from another module if there is only one
155 // entry in the list - in that case this must be a reference due
156 // to indirect call profile data, since a function pointer can point to
157 // a local in another module.
158 if (GlobalValue::isLocalLinkage(Summary->linkage()) &&
159 CalleeSummaryList.size() > 1 &&
160 Summary->modulePath() != CallerModulePath)
163 if (Summary->instCount() > Threshold)
166 if (Summary->notEligibleToImport())
171 if (It == CalleeSummaryList.end())
174 return cast<GlobalValueSummary>(It->get());
177 using EdgeInfo = std::tuple<const FunctionSummary *, unsigned /* Threshold */,
180 /// Compute the list of functions to import for a given caller. Mark these
181 /// imported functions and the symbols they reference in their source module as
182 /// exported from their source module.
183 static void computeImportForFunction(
184 const FunctionSummary &Summary, const ModuleSummaryIndex &Index,
185 const unsigned Threshold, const GVSummaryMapTy &DefinedGVSummaries,
186 SmallVectorImpl<EdgeInfo> &Worklist,
187 FunctionImporter::ImportMapTy &ImportList,
188 StringMap<FunctionImporter::ExportSetTy> *ExportLists = nullptr) {
189 for (auto &Edge : Summary.calls()) {
190 ValueInfo VI = Edge.first;
191 DEBUG(dbgs() << " edge -> " << VI.getGUID() << " Threshold:" << Threshold
194 if (VI.getSummaryList().empty()) {
195 // For SamplePGO, the indirect call targets for local functions will
196 // have its original name annotated in profile. We try to find the
197 // corresponding PGOFuncName as the GUID.
198 auto GUID = Index.getGUIDFromOriginalID(VI.getGUID());
201 VI = Index.getValueInfo(GUID);
206 if (DefinedGVSummaries.count(VI.getGUID())) {
207 DEBUG(dbgs() << "ignored! Target already in destination module.\n");
211 auto GetBonusMultiplier = [](CalleeInfo::HotnessType Hotness) -> float {
212 if (Hotness == CalleeInfo::HotnessType::Hot)
213 return ImportHotMultiplier;
214 if (Hotness == CalleeInfo::HotnessType::Cold)
215 return ImportColdMultiplier;
216 if (Hotness == CalleeInfo::HotnessType::Critical)
217 return ImportCriticalMultiplier;
221 const auto NewThreshold =
222 Threshold * GetBonusMultiplier(Edge.second.Hotness);
224 auto *CalleeSummary = selectCallee(Index, VI.getSummaryList(), NewThreshold,
225 Summary.modulePath());
226 if (!CalleeSummary) {
227 DEBUG(dbgs() << "ignored! No qualifying callee with summary found.\n");
230 // "Resolve" the summary, traversing alias,
231 const FunctionSummary *ResolvedCalleeSummary;
232 if (isa<AliasSummary>(CalleeSummary)) {
233 ResolvedCalleeSummary = cast<FunctionSummary>(
234 &cast<AliasSummary>(CalleeSummary)->getAliasee());
236 GlobalValue::isLinkOnceODRLinkage(ResolvedCalleeSummary->linkage()) &&
237 "Unexpected alias to a non-linkonceODR in import list");
239 ResolvedCalleeSummary = cast<FunctionSummary>(CalleeSummary);
241 assert(ResolvedCalleeSummary->instCount() <= NewThreshold &&
242 "selectCallee() didn't honor the threshold");
244 auto GetAdjustedThreshold = [](unsigned Threshold, bool IsHotCallsite) {
245 // Adjust the threshold for next level of imported functions.
246 // The threshold is different for hot callsites because we can then
247 // inline chains of hot calls.
249 return Threshold * ImportHotInstrFactor;
250 return Threshold * ImportInstrFactor;
253 bool IsHotCallsite = Edge.second.Hotness == CalleeInfo::HotnessType::Hot;
254 const auto AdjThreshold = GetAdjustedThreshold(Threshold, IsHotCallsite);
256 auto ExportModulePath = ResolvedCalleeSummary->modulePath();
257 auto &ProcessedThreshold = ImportList[ExportModulePath][VI.getGUID()];
258 /// Since the traversal of the call graph is DFS, we can revisit a function
259 /// a second time with a higher threshold. In this case, it is added back to
260 /// the worklist with the new threshold.
261 if (ProcessedThreshold && ProcessedThreshold >= AdjThreshold) {
262 DEBUG(dbgs() << "ignored! Target was already seen with Threshold "
263 << ProcessedThreshold << "\n");
266 bool PreviouslyImported = ProcessedThreshold != 0;
267 // Mark this function as imported in this module, with the current Threshold
268 ProcessedThreshold = AdjThreshold;
270 // Make exports in the source module.
272 auto &ExportList = (*ExportLists)[ExportModulePath];
273 ExportList.insert(VI.getGUID());
274 if (!PreviouslyImported) {
275 // This is the first time this function was exported from its source
276 // module, so mark all functions and globals it references as exported
277 // to the outside if they are defined in the same source module.
278 // For efficiency, we unconditionally add all the referenced GUIDs
279 // to the ExportList for this module, and will prune out any not
280 // defined in the module later in a single pass.
281 for (auto &Edge : ResolvedCalleeSummary->calls()) {
282 auto CalleeGUID = Edge.first.getGUID();
283 ExportList.insert(CalleeGUID);
285 for (auto &Ref : ResolvedCalleeSummary->refs()) {
286 auto GUID = Ref.getGUID();
287 ExportList.insert(GUID);
292 // Insert the newly imported function to the worklist.
293 Worklist.emplace_back(ResolvedCalleeSummary, AdjThreshold, VI.getGUID());
297 /// Given the list of globals defined in a module, compute the list of imports
298 /// as well as the list of "exports", i.e. the list of symbols referenced from
299 /// another module (that may require promotion).
300 static void ComputeImportForModule(
301 const GVSummaryMapTy &DefinedGVSummaries, const ModuleSummaryIndex &Index,
302 FunctionImporter::ImportMapTy &ImportList,
303 StringMap<FunctionImporter::ExportSetTy> *ExportLists = nullptr) {
304 // Worklist contains the list of function imported in this module, for which
305 // we will analyse the callees and may import further down the callgraph.
306 SmallVector<EdgeInfo, 128> Worklist;
308 // Populate the worklist with the import for the functions in the current
310 for (auto &GVSummary : DefinedGVSummaries) {
311 if (!Index.isGlobalValueLive(GVSummary.second)) {
312 DEBUG(dbgs() << "Ignores Dead GUID: " << GVSummary.first << "\n");
315 auto *Summary = GVSummary.second;
316 if (auto *AS = dyn_cast<AliasSummary>(Summary))
317 Summary = &AS->getAliasee();
318 auto *FuncSummary = dyn_cast<FunctionSummary>(Summary);
320 // Skip import for global variables
322 DEBUG(dbgs() << "Initalize import for " << GVSummary.first << "\n");
323 computeImportForFunction(*FuncSummary, Index, ImportInstrLimit,
324 DefinedGVSummaries, Worklist, ImportList,
328 // Process the newly imported functions and add callees to the worklist.
329 while (!Worklist.empty()) {
330 auto FuncInfo = Worklist.pop_back_val();
331 auto *Summary = std::get<0>(FuncInfo);
332 auto Threshold = std::get<1>(FuncInfo);
333 auto GUID = std::get<2>(FuncInfo);
335 // Check if we later added this summary with a higher threshold.
336 // If so, skip this entry.
337 auto ExportModulePath = Summary->modulePath();
338 auto &LatestProcessedThreshold = ImportList[ExportModulePath][GUID];
339 if (LatestProcessedThreshold > Threshold)
342 computeImportForFunction(*Summary, Index, Threshold, DefinedGVSummaries,
343 Worklist, ImportList, ExportLists);
347 } // anonymous namespace
349 /// Compute all the import and export for every module using the Index.
350 void llvm::ComputeCrossModuleImport(
351 const ModuleSummaryIndex &Index,
352 const StringMap<GVSummaryMapTy> &ModuleToDefinedGVSummaries,
353 StringMap<FunctionImporter::ImportMapTy> &ImportLists,
354 StringMap<FunctionImporter::ExportSetTy> &ExportLists) {
355 // For each module that has function defined, compute the import/export lists.
356 for (auto &DefinedGVSummaries : ModuleToDefinedGVSummaries) {
357 auto &ImportList = ImportLists[DefinedGVSummaries.first()];
358 DEBUG(dbgs() << "Computing import for Module '"
359 << DefinedGVSummaries.first() << "'\n");
360 ComputeImportForModule(DefinedGVSummaries.second, Index, ImportList,
364 // When computing imports we added all GUIDs referenced by anything
365 // imported from the module to its ExportList. Now we prune each ExportList
366 // of any not defined in that module. This is more efficient than checking
367 // while computing imports because some of the summary lists may be long
368 // due to linkonce (comdat) copies.
369 for (auto &ELI : ExportLists) {
370 const auto &DefinedGVSummaries =
371 ModuleToDefinedGVSummaries.lookup(ELI.first());
372 for (auto EI = ELI.second.begin(); EI != ELI.second.end();) {
373 if (!DefinedGVSummaries.count(*EI))
374 EI = ELI.second.erase(EI);
381 DEBUG(dbgs() << "Import/Export lists for " << ImportLists.size()
383 for (auto &ModuleImports : ImportLists) {
384 auto ModName = ModuleImports.first();
385 auto &Exports = ExportLists[ModName];
386 DEBUG(dbgs() << "* Module " << ModName << " exports " << Exports.size()
387 << " functions. Imports from " << ModuleImports.second.size()
389 for (auto &Src : ModuleImports.second) {
390 auto SrcModName = Src.first();
391 DEBUG(dbgs() << " - " << Src.second.size() << " functions imported from "
392 << SrcModName << "\n");
398 /// Compute all the imports for the given module in the Index.
399 void llvm::ComputeCrossModuleImportForModule(
400 StringRef ModulePath, const ModuleSummaryIndex &Index,
401 FunctionImporter::ImportMapTy &ImportList) {
403 // Collect the list of functions this module defines.
405 GVSummaryMapTy FunctionSummaryMap;
406 Index.collectDefinedFunctionsForModule(ModulePath, FunctionSummaryMap);
408 // Compute the import list for this module.
409 DEBUG(dbgs() << "Computing import for Module '" << ModulePath << "'\n");
410 ComputeImportForModule(FunctionSummaryMap, Index, ImportList);
413 DEBUG(dbgs() << "* Module " << ModulePath << " imports from "
414 << ImportList.size() << " modules.\n");
415 for (auto &Src : ImportList) {
416 auto SrcModName = Src.first();
417 DEBUG(dbgs() << " - " << Src.second.size() << " functions imported from "
418 << SrcModName << "\n");
423 void llvm::computeDeadSymbols(
424 ModuleSummaryIndex &Index,
425 const DenseSet<GlobalValue::GUID> &GUIDPreservedSymbols) {
426 assert(!Index.withGlobalValueDeadStripping());
429 if (GUIDPreservedSymbols.empty())
430 // Don't do anything when nothing is live, this is friendly with tests.
432 unsigned LiveSymbols = 0;
433 SmallVector<ValueInfo, 128> Worklist;
434 Worklist.reserve(GUIDPreservedSymbols.size() * 2);
435 for (auto GUID : GUIDPreservedSymbols) {
436 ValueInfo VI = Index.getValueInfo(GUID);
439 for (auto &S : VI.getSummaryList())
443 // Add values flagged in the index as live roots to the worklist.
444 for (const auto &Entry : Index)
445 for (auto &S : Entry.second.SummaryList)
447 DEBUG(dbgs() << "Live root: " << Entry.first << "\n");
448 Worklist.push_back(ValueInfo(&Entry));
453 // Make value live and add it to the worklist if it was not live before.
454 // FIXME: we should only make the prevailing copy live here
455 auto visit = [&](ValueInfo VI) {
456 for (auto &S : VI.getSummaryList())
459 for (auto &S : VI.getSummaryList())
462 Worklist.push_back(VI);
465 while (!Worklist.empty()) {
466 auto VI = Worklist.pop_back_val();
467 for (auto &Summary : VI.getSummaryList()) {
468 for (auto Ref : Summary->refs())
470 if (auto *FS = dyn_cast<FunctionSummary>(Summary.get()))
471 for (auto Call : FS->calls())
473 if (auto *AS = dyn_cast<AliasSummary>(Summary.get())) {
474 auto AliaseeGUID = AS->getAliasee().getOriginalName();
475 ValueInfo AliaseeVI = Index.getValueInfo(AliaseeGUID);
481 Index.setWithGlobalValueDeadStripping();
483 unsigned DeadSymbols = Index.size() - LiveSymbols;
484 DEBUG(dbgs() << LiveSymbols << " symbols Live, and " << DeadSymbols
485 << " symbols Dead \n");
486 NumDeadSymbols += DeadSymbols;
487 NumLiveSymbols += LiveSymbols;
490 /// Compute the set of summaries needed for a ThinLTO backend compilation of
492 void llvm::gatherImportedSummariesForModule(
493 StringRef ModulePath,
494 const StringMap<GVSummaryMapTy> &ModuleToDefinedGVSummaries,
495 const FunctionImporter::ImportMapTy &ImportList,
496 std::map<std::string, GVSummaryMapTy> &ModuleToSummariesForIndex) {
497 // Include all summaries from the importing module.
498 ModuleToSummariesForIndex[ModulePath] =
499 ModuleToDefinedGVSummaries.lookup(ModulePath);
500 // Include summaries for imports.
501 for (auto &ILI : ImportList) {
502 auto &SummariesForIndex = ModuleToSummariesForIndex[ILI.first()];
503 const auto &DefinedGVSummaries =
504 ModuleToDefinedGVSummaries.lookup(ILI.first());
505 for (auto &GI : ILI.second) {
506 const auto &DS = DefinedGVSummaries.find(GI.first);
507 assert(DS != DefinedGVSummaries.end() &&
508 "Expected a defined summary for imported global value");
509 SummariesForIndex[GI.first] = DS->second;
514 /// Emit the files \p ModulePath will import from into \p OutputFilename.
516 llvm::EmitImportsFiles(StringRef ModulePath, StringRef OutputFilename,
517 const FunctionImporter::ImportMapTy &ModuleImports) {
519 raw_fd_ostream ImportsOS(OutputFilename, EC, sys::fs::OpenFlags::F_None);
522 for (auto &ILI : ModuleImports)
523 ImportsOS << ILI.first() << "\n";
524 return std::error_code();
527 /// Fixup WeakForLinker linkages in \p TheModule based on summary analysis.
528 void llvm::thinLTOResolveWeakForLinkerModule(
529 Module &TheModule, const GVSummaryMapTy &DefinedGlobals) {
530 auto ConvertToDeclaration = [](GlobalValue &GV) {
531 DEBUG(dbgs() << "Converting to a declaration: `" << GV.getName() << "\n");
532 if (Function *F = dyn_cast<Function>(&GV)) {
535 } else if (GlobalVariable *V = dyn_cast<GlobalVariable>(&GV)) {
536 V->setInitializer(nullptr);
537 V->setLinkage(GlobalValue::ExternalLinkage);
540 // For now we don't resolve or drop aliases. Once we do we'll
541 // need to add support here for creating either a function or
542 // variable declaration, and return the new GlobalValue* for
543 // the caller to use.
544 llvm_unreachable("Expected function or variable");
547 auto updateLinkage = [&](GlobalValue &GV) {
548 // See if the global summary analysis computed a new resolved linkage.
549 const auto &GS = DefinedGlobals.find(GV.getGUID());
550 if (GS == DefinedGlobals.end())
552 auto NewLinkage = GS->second->linkage();
553 if (NewLinkage == GV.getLinkage())
556 // Switch the linkage to weakany if asked for, e.g. we do this for
557 // linker redefined symbols (via --wrap or --defsym).
558 // We record that the visibility should be changed here in `addThinLTO`
559 // as we need access to the resolution vectors for each input file in
560 // order to find which symbols have been redefined.
561 // We may consider reorganizing this code and moving the linkage recording
562 // somewhere else, e.g. in thinLTOResolveWeakForLinkerInIndex.
563 if (NewLinkage == GlobalValue::WeakAnyLinkage) {
564 GV.setLinkage(NewLinkage);
568 if (!GlobalValue::isWeakForLinker(GV.getLinkage()))
570 // Check for a non-prevailing def that has interposable linkage
571 // (e.g. non-odr weak or linkonce). In that case we can't simply
572 // convert to available_externally, since it would lose the
573 // interposable property and possibly get inlined. Simply drop
574 // the definition in that case.
575 if (GlobalValue::isAvailableExternallyLinkage(NewLinkage) &&
576 GlobalValue::isInterposableLinkage(GV.getLinkage()))
577 ConvertToDeclaration(GV);
579 DEBUG(dbgs() << "ODR fixing up linkage for `" << GV.getName() << "` from "
580 << GV.getLinkage() << " to " << NewLinkage << "\n");
581 GV.setLinkage(NewLinkage);
583 // Remove declarations from comdats, including available_externally
584 // as this is a declaration for the linker, and will be dropped eventually.
585 // It is illegal for comdats to contain declarations.
586 auto *GO = dyn_cast_or_null<GlobalObject>(&GV);
587 if (GO && GO->isDeclarationForLinker() && GO->hasComdat())
588 GO->setComdat(nullptr);
591 // Process functions and global now
592 for (auto &GV : TheModule)
594 for (auto &GV : TheModule.globals())
596 for (auto &GV : TheModule.aliases())
600 /// Run internalization on \p TheModule based on symmary analysis.
601 void llvm::thinLTOInternalizeModule(Module &TheModule,
602 const GVSummaryMapTy &DefinedGlobals) {
603 // Parse inline ASM and collect the list of symbols that are not defined in
604 // the current module.
605 StringSet<> AsmUndefinedRefs;
606 ModuleSymbolTable::CollectAsmSymbols(
608 [&AsmUndefinedRefs](StringRef Name, object::BasicSymbolRef::Flags Flags) {
609 if (Flags & object::BasicSymbolRef::SF_Undefined)
610 AsmUndefinedRefs.insert(Name);
613 // Declare a callback for the internalize pass that will ask for every
614 // candidate GlobalValue if it can be internalized or not.
615 auto MustPreserveGV = [&](const GlobalValue &GV) -> bool {
616 // Can't be internalized if referenced in inline asm.
617 if (AsmUndefinedRefs.count(GV.getName()))
620 // Lookup the linkage recorded in the summaries during global analysis.
621 auto GS = DefinedGlobals.find(GV.getGUID());
622 if (GS == DefinedGlobals.end()) {
623 // Must have been promoted (possibly conservatively). Find original
624 // name so that we can access the correct summary and see if it can
625 // be internalized again.
626 // FIXME: Eventually we should control promotion instead of promoting
627 // and internalizing again.
629 ModuleSummaryIndex::getOriginalNameBeforePromote(GV.getName());
630 std::string OrigId = GlobalValue::getGlobalIdentifier(
631 OrigName, GlobalValue::InternalLinkage,
632 TheModule.getSourceFileName());
633 GS = DefinedGlobals.find(GlobalValue::getGUID(OrigId));
634 if (GS == DefinedGlobals.end()) {
635 // Also check the original non-promoted non-globalized name. In some
636 // cases a preempted weak value is linked in as a local copy because
637 // it is referenced by an alias (IRLinker::linkGlobalValueProto).
638 // In that case, since it was originally not a local value, it was
639 // recorded in the index using the original name.
640 // FIXME: This may not be needed once PR27866 is fixed.
641 GS = DefinedGlobals.find(GlobalValue::getGUID(OrigName));
642 assert(GS != DefinedGlobals.end());
645 return !GlobalValue::isLocalLinkage(GS->second->linkage());
648 // FIXME: See if we can just internalize directly here via linkage changes
649 // based on the index, rather than invoking internalizeModule.
650 llvm::internalizeModule(TheModule, MustPreserveGV);
653 // Automatically import functions in Module \p DestModule based on the summaries
656 Expected<bool> FunctionImporter::importFunctions(
657 Module &DestModule, const FunctionImporter::ImportMapTy &ImportList) {
658 DEBUG(dbgs() << "Starting import for Module "
659 << DestModule.getModuleIdentifier() << "\n");
660 unsigned ImportedCount = 0;
662 IRMover Mover(DestModule);
663 // Do the actual import of functions now, one Module at a time
664 std::set<StringRef> ModuleNameOrderedList;
665 for (auto &FunctionsToImportPerModule : ImportList) {
666 ModuleNameOrderedList.insert(FunctionsToImportPerModule.first());
668 for (auto &Name : ModuleNameOrderedList) {
669 // Get the module for the import
670 const auto &FunctionsToImportPerModule = ImportList.find(Name);
671 assert(FunctionsToImportPerModule != ImportList.end());
672 Expected<std::unique_ptr<Module>> SrcModuleOrErr = ModuleLoader(Name);
674 return SrcModuleOrErr.takeError();
675 std::unique_ptr<Module> SrcModule = std::move(*SrcModuleOrErr);
676 assert(&DestModule.getContext() == &SrcModule->getContext() &&
679 // If modules were created with lazy metadata loading, materialize it
680 // now, before linking it (otherwise this will be a noop).
681 if (Error Err = SrcModule->materializeMetadata())
682 return std::move(Err);
684 auto &ImportGUIDs = FunctionsToImportPerModule->second;
685 // Find the globals to import
686 SetVector<GlobalValue *> GlobalsToImport;
687 for (Function &F : *SrcModule) {
690 auto GUID = F.getGUID();
691 auto Import = ImportGUIDs.count(GUID);
692 DEBUG(dbgs() << (Import ? "Is" : "Not") << " importing function " << GUID
693 << " " << F.getName() << " from "
694 << SrcModule->getSourceFileName() << "\n");
696 if (Error Err = F.materialize())
697 return std::move(Err);
698 if (EnableImportMetadata) {
699 // Add 'thinlto_src_module' metadata for statistics and debugging.
701 "thinlto_src_module",
703 DestModule.getContext(),
704 {llvm::MDString::get(DestModule.getContext(),
705 SrcModule->getSourceFileName())}));
707 GlobalsToImport.insert(&F);
710 for (GlobalVariable &GV : SrcModule->globals()) {
713 auto GUID = GV.getGUID();
714 auto Import = ImportGUIDs.count(GUID);
715 DEBUG(dbgs() << (Import ? "Is" : "Not") << " importing global " << GUID
716 << " " << GV.getName() << " from "
717 << SrcModule->getSourceFileName() << "\n");
719 if (Error Err = GV.materialize())
720 return std::move(Err);
721 GlobalsToImport.insert(&GV);
724 for (GlobalAlias &GA : SrcModule->aliases()) {
725 // FIXME: This should eventually be controlled entirely by the summary.
726 if (FunctionImportGlobalProcessing::doImportAsDefinition(
727 &GA, &GlobalsToImport)) {
728 GlobalsToImport.insert(&GA);
734 auto GUID = GA.getGUID();
735 auto Import = ImportGUIDs.count(GUID);
736 DEBUG(dbgs() << (Import ? "Is" : "Not") << " importing alias " << GUID
737 << " " << GA.getName() << " from "
738 << SrcModule->getSourceFileName() << "\n");
740 // Alias can't point to "available_externally". However when we import
741 // linkOnceODR the linkage does not change. So we import the alias
742 // and aliasee only in this case. This has been handled by
743 // computeImportForFunction()
744 GlobalObject *GO = GA.getBaseObject();
745 assert(GO->hasLinkOnceODRLinkage() &&
746 "Unexpected alias to a non-linkonceODR in import list");
748 if (!GlobalsToImport.count(GO))
749 DEBUG(dbgs() << " alias triggers importing aliasee " << GO->getGUID()
750 << " " << GO->getName() << " from "
751 << SrcModule->getSourceFileName() << "\n");
753 if (Error Err = GO->materialize())
754 return std::move(Err);
755 GlobalsToImport.insert(GO);
756 if (Error Err = GA.materialize())
757 return std::move(Err);
758 GlobalsToImport.insert(&GA);
762 // Upgrade debug info after we're done materializing all the globals and we
763 // have loaded all the required metadata!
764 UpgradeDebugInfo(*SrcModule);
766 // Link in the specified functions.
767 if (renameModuleForThinLTO(*SrcModule, Index, &GlobalsToImport))
771 for (const auto *GV : GlobalsToImport)
772 dbgs() << DestModule.getSourceFileName() << ": Import " << GV->getName()
773 << " from " << SrcModule->getSourceFileName() << "\n";
776 if (Mover.move(std::move(SrcModule), GlobalsToImport.getArrayRef(),
777 [](GlobalValue &, IRMover::ValueAdder) {},
778 /*IsPerformingImport=*/true))
779 report_fatal_error("Function Import: link error");
781 ImportedCount += GlobalsToImport.size();
782 NumImportedModules++;
785 NumImportedFunctions += ImportedCount;
787 DEBUG(dbgs() << "Imported " << ImportedCount << " functions for Module "
788 << DestModule.getModuleIdentifier() << "\n");
789 return ImportedCount;
792 /// Summary file to use for function importing when using -function-import from
793 /// the command line.
794 static cl::opt<std::string>
795 SummaryFile("summary-file",
796 cl::desc("The summary file to use for function importing."));
798 static bool doImportingForModule(Module &M) {
799 if (SummaryFile.empty())
800 report_fatal_error("error: -function-import requires -summary-file\n");
801 Expected<std::unique_ptr<ModuleSummaryIndex>> IndexPtrOrErr =
802 getModuleSummaryIndexForFile(SummaryFile);
803 if (!IndexPtrOrErr) {
804 logAllUnhandledErrors(IndexPtrOrErr.takeError(), errs(),
805 "Error loading file '" + SummaryFile + "': ");
808 std::unique_ptr<ModuleSummaryIndex> Index = std::move(*IndexPtrOrErr);
810 // First step is collecting the import list.
811 FunctionImporter::ImportMapTy ImportList;
812 ComputeCrossModuleImportForModule(M.getModuleIdentifier(), *Index,
815 // Conservatively mark all internal values as promoted. This interface is
816 // only used when doing importing via the function importing pass. The pass
817 // is only enabled when testing importing via the 'opt' tool, which does
818 // not do the ThinLink that would normally determine what values to promote.
819 for (auto &I : *Index) {
820 for (auto &S : I.second.SummaryList) {
821 if (GlobalValue::isLocalLinkage(S->linkage()))
822 S->setLinkage(GlobalValue::ExternalLinkage);
826 // Next we need to promote to global scope and rename any local values that
827 // are potentially exported to other modules.
828 if (renameModuleForThinLTO(M, *Index, nullptr)) {
829 errs() << "Error renaming module\n";
833 // Perform the import now.
834 auto ModuleLoader = [&M](StringRef Identifier) {
835 return loadFile(Identifier, M.getContext());
837 FunctionImporter Importer(*Index, ModuleLoader);
838 Expected<bool> Result = Importer.importFunctions(M, ImportList);
840 // FIXME: Probably need to propagate Errors through the pass manager.
842 logAllUnhandledErrors(Result.takeError(), errs(),
843 "Error importing module: ");
851 /// Pass that performs cross-module function import provided a summary file.
852 class FunctionImportLegacyPass : public ModulePass {
854 /// Pass identification, replacement for typeid
857 /// Specify pass name for debug output
858 StringRef getPassName() const override { return "Function Importing"; }
860 explicit FunctionImportLegacyPass() : ModulePass(ID) {}
862 bool runOnModule(Module &M) override {
866 return doImportingForModule(M);
869 } // anonymous namespace
871 PreservedAnalyses FunctionImportPass::run(Module &M,
872 ModuleAnalysisManager &AM) {
873 if (!doImportingForModule(M))
874 return PreservedAnalyses::all();
876 return PreservedAnalyses::none();
879 char FunctionImportLegacyPass::ID = 0;
880 INITIALIZE_PASS(FunctionImportLegacyPass, "function-import",
881 "Summary Based Function Import", false, false)
884 Pass *createFunctionImportPass() {
885 return new FunctionImportLegacyPass();