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Diffstat (limited to 'contrib/llvm/lib/Transforms/IPO/FunctionImport.cpp')
| -rw-r--r-- | contrib/llvm/lib/Transforms/IPO/FunctionImport.cpp | 433 |
1 files changed, 433 insertions, 0 deletions
diff --git a/contrib/llvm/lib/Transforms/IPO/FunctionImport.cpp b/contrib/llvm/lib/Transforms/IPO/FunctionImport.cpp new file mode 100644 index 000000000000..d8b677b966f2 --- /dev/null +++ b/contrib/llvm/lib/Transforms/IPO/FunctionImport.cpp @@ -0,0 +1,433 @@ +//===- 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"); + std::unique_ptr<Module> Result = getLazyIRFileModule(FileName, Err, Context); + if (!Result) { + Err.print("function-import", errs()); + return nullptr; + } + + Result->materializeMetadata(); + UpgradeDebugInfo(*Result); + + 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) { + 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()); + + // 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(); + } + + // Perform the import now. + auto ModuleLoader = [&M](StringRef Identifier) { + return loadFile(Identifier, M.getContext()); + }; + FunctionImporter Importer(*Index, ModuleLoader); + return Importer.importFunctions(M); + + return false; + } +}; +} // 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); +} +} |