| //===- FunctionImport.cpp - ThinLTO Summary-based Function Import ---------===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file implements Function import based on summaries. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "llvm/Transforms/IPO/FunctionImport.h" |
| |
| #include "llvm/ADT/StringSet.h" |
| #include "llvm/IR/AutoUpgrade.h" |
| #include "llvm/IR/DiagnosticPrinter.h" |
| #include "llvm/IR/IntrinsicInst.h" |
| #include "llvm/IR/Module.h" |
| #include "llvm/IRReader/IRReader.h" |
| #include "llvm/Linker/Linker.h" |
| #include "llvm/Object/FunctionIndexObjectFile.h" |
| #include "llvm/Support/CommandLine.h" |
| #include "llvm/Support/Debug.h" |
| #include "llvm/Support/SourceMgr.h" |
| |
| #include <map> |
| |
| using namespace llvm; |
| |
| #define DEBUG_TYPE "function-import" |
| |
| /// Limit on instruction count of imported functions. |
| static cl::opt<unsigned> ImportInstrLimit( |
| "import-instr-limit", cl::init(100), cl::Hidden, cl::value_desc("N"), |
| cl::desc("Only import functions with less than N instructions")); |
| |
| // Load lazily a module from \p FileName in \p Context. |
| static std::unique_ptr<Module> loadFile(const std::string &FileName, |
| LLVMContext &Context) { |
| SMDiagnostic Err; |
| DEBUG(dbgs() << "Loading '" << FileName << "'\n"); |
| // Metadata isn't loaded or linked until after all functions are |
| // imported, after which it will be materialized and linked. |
| std::unique_ptr<Module> Result = |
| getLazyIRFileModule(FileName, Err, Context, |
| /* ShouldLazyLoadMetadata = */ true); |
| if (!Result) { |
| Err.print("function-import", errs()); |
| return nullptr; |
| } |
| |
| return Result; |
| } |
| |
| namespace { |
| /// Helper to load on demand a Module from file and cache it for subsequent |
| /// queries. It can be used with the FunctionImporter. |
| class ModuleLazyLoaderCache { |
| /// Cache of lazily loaded module for import. |
| StringMap<std::unique_ptr<Module>> ModuleMap; |
| |
| /// Retrieve a Module from the cache or lazily load it on demand. |
| std::function<std::unique_ptr<Module>(StringRef FileName)> createLazyModule; |
| |
| public: |
| /// Create the loader, Module will be initialized in \p Context. |
| ModuleLazyLoaderCache(std::function< |
| std::unique_ptr<Module>(StringRef FileName)> createLazyModule) |
| : createLazyModule(createLazyModule) {} |
| |
| /// Retrieve a Module from the cache or lazily load it on demand. |
| Module &operator()(StringRef FileName); |
| |
| std::unique_ptr<Module> takeModule(StringRef FileName) { |
| auto I = ModuleMap.find(FileName); |
| assert(I != ModuleMap.end()); |
| std::unique_ptr<Module> Ret = std::move(I->second); |
| ModuleMap.erase(I); |
| return Ret; |
| } |
| }; |
| |
| // Get a Module for \p FileName from the cache, or load it lazily. |
| Module &ModuleLazyLoaderCache::operator()(StringRef Identifier) { |
| auto &Module = ModuleMap[Identifier]; |
| if (!Module) |
| Module = createLazyModule(Identifier); |
| return *Module; |
| } |
| } // anonymous namespace |
| |
| /// Walk through the instructions in \p F looking for external |
| /// calls not already in the \p CalledFunctions set. If any are |
| /// found they are added to the \p Worklist for importing. |
| static void findExternalCalls(const Module &DestModule, Function &F, |
| const FunctionInfoIndex &Index, |
| StringSet<> &CalledFunctions, |
| SmallVector<StringRef, 64> &Worklist) { |
| // We need to suffix internal function calls imported from other modules, |
| // prepare the suffix ahead of time. |
| std::string Suffix; |
| if (F.getParent() != &DestModule) |
| Suffix = |
| (Twine(".llvm.") + |
| Twine(Index.getModuleId(F.getParent()->getModuleIdentifier()))).str(); |
| |
| for (auto &BB : F) { |
| for (auto &I : BB) { |
| if (isa<CallInst>(I)) { |
| auto CalledFunction = cast<CallInst>(I).getCalledFunction(); |
| // Insert any new external calls that have not already been |
| // added to set/worklist. |
| if (!CalledFunction || !CalledFunction->hasName()) |
| continue; |
| // Ignore intrinsics early |
| if (CalledFunction->isIntrinsic()) { |
| assert(CalledFunction->getIntrinsicID() != 0); |
| continue; |
| } |
| auto ImportedName = CalledFunction->getName(); |
| auto Renamed = (ImportedName + Suffix).str(); |
| // Rename internal functions |
| if (CalledFunction->hasInternalLinkage()) { |
| ImportedName = Renamed; |
| } |
| auto It = CalledFunctions.insert(ImportedName); |
| if (!It.second) { |
| // This is a call to a function we already considered, skip. |
| continue; |
| } |
| // Ignore functions already present in the destination module |
| auto *SrcGV = DestModule.getNamedValue(ImportedName); |
| if (SrcGV) { |
| if (GlobalAlias *SGA = dyn_cast<GlobalAlias>(SrcGV)) |
| SrcGV = SGA->getBaseObject(); |
| assert(isa<Function>(SrcGV) && "Name collision during import"); |
| if (!cast<Function>(SrcGV)->isDeclaration()) { |
| DEBUG(dbgs() << DestModule.getModuleIdentifier() << ": Ignoring " |
| << ImportedName << " already in DestinationModule\n"); |
| continue; |
| } |
| } |
| |
| Worklist.push_back(It.first->getKey()); |
| DEBUG(dbgs() << DestModule.getModuleIdentifier() |
| << ": Adding callee for : " << ImportedName << " : " |
| << F.getName() << "\n"); |
| } |
| } |
| } |
| } |
| |
| // Helper function: given a worklist and an index, will process all the worklist |
| // and decide what to import based on the summary information. |
| // |
| // Nothing is actually imported, functions are materialized in their source |
| // module and analyzed there. |
| // |
| // \p ModuleToFunctionsToImportMap is filled with the set of Function to import |
| // per Module. |
| static void GetImportList(Module &DestModule, |
| SmallVector<StringRef, 64> &Worklist, |
| StringSet<> &CalledFunctions, |
| std::map<StringRef, DenseSet<const GlobalValue *>> |
| &ModuleToFunctionsToImportMap, |
| const FunctionInfoIndex &Index, |
| ModuleLazyLoaderCache &ModuleLoaderCache) { |
| while (!Worklist.empty()) { |
| auto CalledFunctionName = Worklist.pop_back_val(); |
| DEBUG(dbgs() << DestModule.getModuleIdentifier() << ": Process import for " |
| << CalledFunctionName << "\n"); |
| |
| // Try to get a summary for this function call. |
| auto InfoList = Index.findFunctionInfoList(CalledFunctionName); |
| if (InfoList == Index.end()) { |
| DEBUG(dbgs() << DestModule.getModuleIdentifier() << ": No summary for " |
| << CalledFunctionName << " Ignoring.\n"); |
| continue; |
| } |
| assert(!InfoList->second.empty() && "No summary, error at import?"); |
| |
| // Comdat can have multiple entries, FIXME: what do we do with them? |
| auto &Info = InfoList->second[0]; |
| assert(Info && "Nullptr in list, error importing summaries?\n"); |
| |
| auto *Summary = Info->functionSummary(); |
| if (!Summary) { |
| // FIXME: in case we are lazyloading summaries, we can do it now. |
| DEBUG(dbgs() << DestModule.getModuleIdentifier() |
| << ": Missing summary for " << CalledFunctionName |
| << ", error at import?\n"); |
| llvm_unreachable("Missing summary"); |
| } |
| |
| if (Summary->instCount() > ImportInstrLimit) { |
| DEBUG(dbgs() << DestModule.getModuleIdentifier() << ": Skip import of " |
| << CalledFunctionName << " with " << Summary->instCount() |
| << " instructions (limit " << ImportInstrLimit << ")\n"); |
| continue; |
| } |
| |
| // Get the module path from the summary. |
| auto ModuleIdentifier = Summary->modulePath(); |
| DEBUG(dbgs() << DestModule.getModuleIdentifier() << ": Importing " |
| << CalledFunctionName << " from " << ModuleIdentifier << "\n"); |
| |
| auto &SrcModule = ModuleLoaderCache(ModuleIdentifier); |
| |
| // The function that we will import! |
| GlobalValue *SGV = SrcModule.getNamedValue(CalledFunctionName); |
| |
| if (!SGV) { |
| // The destination module is referencing function using their renamed name |
| // when importing a function that was originally local in the source |
| // module. The source module we have might not have been renamed so we try |
| // to remove the suffix added during the renaming to recover the original |
| // name in the source module. |
| std::pair<StringRef, StringRef> Split = |
| CalledFunctionName.split(".llvm."); |
| SGV = SrcModule.getNamedValue(Split.first); |
| assert(SGV && "Can't find function to import in source module"); |
| } |
| if (!SGV) { |
| report_fatal_error(Twine("Can't load function '") + CalledFunctionName + |
| "' in Module '" + SrcModule.getModuleIdentifier() + |
| "', error in the summary?\n"); |
| } |
| |
| Function *F = dyn_cast<Function>(SGV); |
| if (!F && isa<GlobalAlias>(SGV)) { |
| auto *SGA = dyn_cast<GlobalAlias>(SGV); |
| F = dyn_cast<Function>(SGA->getBaseObject()); |
| CalledFunctionName = F->getName(); |
| } |
| assert(F && "Imported Function is ... not a Function"); |
| |
| // We cannot import weak_any functions/aliases without possibly affecting |
| // the order they are seen and selected by the linker, changing program |
| // semantics. |
| if (SGV->hasWeakAnyLinkage()) { |
| DEBUG(dbgs() << DestModule.getModuleIdentifier() |
| << ": Ignoring import request for weak-any " |
| << (isa<Function>(SGV) ? "function " : "alias ") |
| << CalledFunctionName << " from " |
| << SrcModule.getModuleIdentifier() << "\n"); |
| continue; |
| } |
| |
| // Add the function to the import list |
| auto &Entry = ModuleToFunctionsToImportMap[SrcModule.getModuleIdentifier()]; |
| Entry.insert(F); |
| |
| // Process the newly imported functions and add callees to the worklist. |
| F->materialize(); |
| findExternalCalls(DestModule, *F, Index, CalledFunctions, Worklist); |
| } |
| } |
| |
| // Automatically import functions in Module \p DestModule based on the summaries |
| // index. |
| // |
| // The current implementation imports every called functions that exists in the |
| // summaries index. |
| bool FunctionImporter::importFunctions(Module &DestModule) { |
| DEBUG(dbgs() << "Starting import for Module " |
| << DestModule.getModuleIdentifier() << "\n"); |
| unsigned ImportedCount = 0; |
| |
| /// First step is collecting the called external functions. |
| StringSet<> CalledFunctions; |
| SmallVector<StringRef, 64> Worklist; |
| for (auto &F : DestModule) { |
| if (F.isDeclaration() || F.hasFnAttribute(Attribute::OptimizeNone)) |
| continue; |
| findExternalCalls(DestModule, F, Index, CalledFunctions, Worklist); |
| } |
| if (Worklist.empty()) |
| return false; |
| |
| /// Second step: for every call to an external function, try to import it. |
| |
| // Linker that will be used for importing function |
| Linker TheLinker(DestModule); |
| |
| // Map of Module -> List of Function to import from the Module |
| std::map<StringRef, DenseSet<const GlobalValue *>> |
| ModuleToFunctionsToImportMap; |
| |
| // Analyze the summaries and get the list of functions to import by |
| // populating ModuleToFunctionsToImportMap |
| ModuleLazyLoaderCache ModuleLoaderCache(ModuleLoader); |
| GetImportList(DestModule, Worklist, CalledFunctions, |
| ModuleToFunctionsToImportMap, Index, ModuleLoaderCache); |
| assert(Worklist.empty() && "Worklist hasn't been flushed in GetImportList"); |
| |
| StringMap<std::unique_ptr<DenseMap<unsigned, MDNode *>>> |
| ModuleToTempMDValsMap; |
| |
| // Do the actual import of functions now, one Module at a time |
| for (auto &FunctionsToImportPerModule : ModuleToFunctionsToImportMap) { |
| // Get the module for the import |
| auto &FunctionsToImport = FunctionsToImportPerModule.second; |
| std::unique_ptr<Module> SrcModule = |
| ModuleLoaderCache.takeModule(FunctionsToImportPerModule.first); |
| assert(&DestModule.getContext() == &SrcModule->getContext() && |
| "Context mismatch"); |
| |
| // Save the mapping of value ids to temporary metadata created when |
| // importing this function. If we have already imported from this module, |
| // add new temporary metadata to the existing mapping. |
| auto &TempMDVals = ModuleToTempMDValsMap[SrcModule->getModuleIdentifier()]; |
| if (!TempMDVals) |
| TempMDVals = llvm::make_unique<DenseMap<unsigned, MDNode *>>(); |
| |
| // Link in the specified functions. |
| if (TheLinker.linkInModule(std::move(SrcModule), Linker::Flags::None, |
| &Index, &FunctionsToImport, TempMDVals.get())) |
| report_fatal_error("Function Import: link error"); |
| |
| ImportedCount += FunctionsToImport.size(); |
| } |
| |
| // Now link in metadata for all modules from which we imported functions. |
| for (StringMapEntry<std::unique_ptr<DenseMap<unsigned, MDNode *>>> &SME : |
| ModuleToTempMDValsMap) { |
| // Load the specified source module. |
| auto &SrcModule = ModuleLoaderCache(SME.getKey()); |
| // The modules were created with lazy metadata loading. Materialize it |
| // now, before linking it. |
| SrcModule.materializeMetadata(); |
| UpgradeDebugInfo(SrcModule); |
| |
| // Link in all necessary metadata from this module. |
| if (TheLinker.linkInMetadata(SrcModule, SME.getValue().get())) |
| return false; |
| } |
| |
| DEBUG(dbgs() << "Imported " << ImportedCount << " functions for Module " |
| << DestModule.getModuleIdentifier() << "\n"); |
| return ImportedCount; |
| } |
| |
| /// Summary file to use for function importing when using -function-import from |
| /// the command line. |
| static cl::opt<std::string> |
| SummaryFile("summary-file", |
| cl::desc("The summary file to use for function importing.")); |
| |
| static void diagnosticHandler(const DiagnosticInfo &DI) { |
| raw_ostream &OS = errs(); |
| DiagnosticPrinterRawOStream DP(OS); |
| DI.print(DP); |
| OS << '\n'; |
| } |
| |
| /// Parse the function index out of an IR file and return the function |
| /// index object if found, or nullptr if not. |
| static std::unique_ptr<FunctionInfoIndex> |
| getFunctionIndexForFile(StringRef Path, std::string &Error, |
| DiagnosticHandlerFunction DiagnosticHandler) { |
| std::unique_ptr<MemoryBuffer> Buffer; |
| ErrorOr<std::unique_ptr<MemoryBuffer>> BufferOrErr = |
| MemoryBuffer::getFile(Path); |
| if (std::error_code EC = BufferOrErr.getError()) { |
| Error = EC.message(); |
| return nullptr; |
| } |
| Buffer = std::move(BufferOrErr.get()); |
| ErrorOr<std::unique_ptr<object::FunctionIndexObjectFile>> ObjOrErr = |
| object::FunctionIndexObjectFile::create(Buffer->getMemBufferRef(), |
| DiagnosticHandler); |
| if (std::error_code EC = ObjOrErr.getError()) { |
| Error = EC.message(); |
| return nullptr; |
| } |
| return (*ObjOrErr)->takeIndex(); |
| } |
| |
| namespace { |
| /// Pass that performs cross-module function import provided a summary file. |
| class FunctionImportPass : public ModulePass { |
| /// Optional function summary index to use for importing, otherwise |
| /// the summary-file option must be specified. |
| const FunctionInfoIndex *Index; |
| |
| public: |
| /// Pass identification, replacement for typeid |
| static char ID; |
| |
| /// Specify pass name for debug output |
| const char *getPassName() const override { |
| return "Function Importing"; |
| } |
| |
| explicit FunctionImportPass(const FunctionInfoIndex *Index = nullptr) |
| : ModulePass(ID), Index(Index) {} |
| |
| bool runOnModule(Module &M) override { |
| if (SummaryFile.empty() && !Index) |
| report_fatal_error("error: -function-import requires -summary-file or " |
| "file from frontend\n"); |
| std::unique_ptr<FunctionInfoIndex> IndexPtr; |
| if (!SummaryFile.empty()) { |
| if (Index) |
| report_fatal_error("error: -summary-file and index from frontend\n"); |
| std::string Error; |
| IndexPtr = getFunctionIndexForFile(SummaryFile, Error, diagnosticHandler); |
| if (!IndexPtr) { |
| errs() << "Error loading file '" << SummaryFile << "': " << Error |
| << "\n"; |
| return false; |
| } |
| Index = IndexPtr.get(); |
| } |
| |
| // First we need to promote to global scope and rename any local values that |
| // are potentially exported to other modules. |
| if (renameModuleForThinLTO(M, Index)) { |
| errs() << "Error renaming module\n"; |
| return false; |
| } |
| |
| // Perform the import now. |
| auto ModuleLoader = [&M](StringRef Identifier) { |
| return loadFile(Identifier, M.getContext()); |
| }; |
| FunctionImporter Importer(*Index, ModuleLoader); |
| return Importer.importFunctions(M); |
| } |
| }; |
| } // anonymous namespace |
| |
| char FunctionImportPass::ID = 0; |
| INITIALIZE_PASS_BEGIN(FunctionImportPass, "function-import", |
| "Summary Based Function Import", false, false) |
| INITIALIZE_PASS_END(FunctionImportPass, "function-import", |
| "Summary Based Function Import", false, false) |
| |
| namespace llvm { |
| Pass *createFunctionImportPass(const FunctionInfoIndex *Index = nullptr) { |
| return new FunctionImportPass(Index); |
| } |
| } |