10b57cec5SDimitry Andric //===- LTO.cpp ------------------------------------------------------------===// 20b57cec5SDimitry Andric // 30b57cec5SDimitry Andric // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 40b57cec5SDimitry Andric // See https://llvm.org/LICENSE.txt for license information. 50b57cec5SDimitry Andric // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 60b57cec5SDimitry Andric // 70b57cec5SDimitry Andric //===----------------------------------------------------------------------===// 80b57cec5SDimitry Andric 90b57cec5SDimitry Andric #include "LTO.h" 10bdd1243dSDimitry Andric #include "COFFLinkerContext.h" 110b57cec5SDimitry Andric #include "Config.h" 120b57cec5SDimitry Andric #include "InputFiles.h" 130b57cec5SDimitry Andric #include "Symbols.h" 140b57cec5SDimitry Andric #include "lld/Common/Args.h" 1504eeddc0SDimitry Andric #include "lld/Common/CommonLinkerContext.h" 160b57cec5SDimitry Andric #include "lld/Common/Strings.h" 170b57cec5SDimitry Andric #include "lld/Common/TargetOptionsCommandFlags.h" 180b57cec5SDimitry Andric #include "llvm/ADT/STLExtras.h" 190b57cec5SDimitry Andric #include "llvm/ADT/SmallString.h" 200b57cec5SDimitry Andric #include "llvm/ADT/StringRef.h" 210b57cec5SDimitry Andric #include "llvm/ADT/Twine.h" 220b57cec5SDimitry Andric #include "llvm/Bitcode/BitcodeWriter.h" 230b57cec5SDimitry Andric #include "llvm/IR/DiagnosticPrinter.h" 240b57cec5SDimitry Andric #include "llvm/LTO/Config.h" 250b57cec5SDimitry Andric #include "llvm/LTO/LTO.h" 260b57cec5SDimitry Andric #include "llvm/Object/SymbolicFile.h" 27349cc55cSDimitry Andric #include "llvm/Support/Caching.h" 280b57cec5SDimitry Andric #include "llvm/Support/CodeGen.h" 290b57cec5SDimitry Andric #include "llvm/Support/Error.h" 300b57cec5SDimitry Andric #include "llvm/Support/FileSystem.h" 310b57cec5SDimitry Andric #include "llvm/Support/MemoryBuffer.h" 320b57cec5SDimitry Andric #include "llvm/Support/raw_ostream.h" 330b57cec5SDimitry Andric #include <algorithm> 340b57cec5SDimitry Andric #include <cstddef> 350b57cec5SDimitry Andric #include <memory> 360b57cec5SDimitry Andric #include <string> 370b57cec5SDimitry Andric #include <system_error> 380b57cec5SDimitry Andric #include <vector> 390b57cec5SDimitry Andric 400b57cec5SDimitry Andric using namespace llvm; 410b57cec5SDimitry Andric using namespace llvm::object; 425ffd83dbSDimitry Andric using namespace lld; 435ffd83dbSDimitry Andric using namespace lld::coff; 440b57cec5SDimitry Andric 450b57cec5SDimitry Andric // Creates an empty file to and returns a raw_fd_ostream to write to it. 460b57cec5SDimitry Andric static std::unique_ptr<raw_fd_ostream> openFile(StringRef file) { 470b57cec5SDimitry Andric std::error_code ec; 480b57cec5SDimitry Andric auto ret = 4985868e8aSDimitry Andric std::make_unique<raw_fd_ostream>(file, ec, sys::fs::OpenFlags::OF_None); 500b57cec5SDimitry Andric if (ec) { 510b57cec5SDimitry Andric error("cannot open " + file + ": " + ec.message()); 520b57cec5SDimitry Andric return nullptr; 530b57cec5SDimitry Andric } 540b57cec5SDimitry Andric return ret; 550b57cec5SDimitry Andric } 560b57cec5SDimitry Andric 57bdd1243dSDimitry Andric std::string BitcodeCompiler::getThinLTOOutputFile(StringRef path) { 585ffd83dbSDimitry Andric return lto::getThinLTOOutputFile( 59bdd1243dSDimitry Andric std::string(path), std::string(ctx.config.thinLTOPrefixReplace.first), 60bdd1243dSDimitry Andric std::string(ctx.config.thinLTOPrefixReplace.second)); 610b57cec5SDimitry Andric } 620b57cec5SDimitry Andric 63bdd1243dSDimitry Andric lto::Config BitcodeCompiler::createConfig() { 640b57cec5SDimitry Andric lto::Config c; 650b57cec5SDimitry Andric c.Options = initTargetOptionsFromCodeGenFlags(); 66fe6060f1SDimitry Andric c.Options.EmitAddrsig = true; 67bdd1243dSDimitry Andric for (StringRef C : ctx.config.mllvmOpts) 68bdd1243dSDimitry Andric c.MllvmArgs.emplace_back(C.str()); 690b57cec5SDimitry Andric 700b57cec5SDimitry Andric // Always emit a section per function/datum with LTO. LLVM LTO should get most 710b57cec5SDimitry Andric // of the benefit of linker GC, but there are still opportunities for ICF. 720b57cec5SDimitry Andric c.Options.FunctionSections = true; 730b57cec5SDimitry Andric c.Options.DataSections = true; 740b57cec5SDimitry Andric 750b57cec5SDimitry Andric // Use static reloc model on 32-bit x86 because it usually results in more 760b57cec5SDimitry Andric // compact code, and because there are also known code generation bugs when 770b57cec5SDimitry Andric // using the PIC model (see PR34306). 78bdd1243dSDimitry Andric if (ctx.config.machine == COFF::IMAGE_FILE_MACHINE_I386) 790b57cec5SDimitry Andric c.RelocModel = Reloc::Static; 800b57cec5SDimitry Andric else 810b57cec5SDimitry Andric c.RelocModel = Reloc::PIC_; 82bdd1243dSDimitry Andric #ifndef NDEBUG 83bdd1243dSDimitry Andric c.DisableVerify = false; 84bdd1243dSDimitry Andric #else 850b57cec5SDimitry Andric c.DisableVerify = true; 86bdd1243dSDimitry Andric #endif 870b57cec5SDimitry Andric c.DiagHandler = diagnosticHandler; 88bdd1243dSDimitry Andric c.OptLevel = ctx.config.ltoo; 890b57cec5SDimitry Andric c.CPU = getCPUStr(); 900b57cec5SDimitry Andric c.MAttrs = getMAttrs(); 91bdd1243dSDimitry Andric c.CGOptLevel = args::getCGOptLevel(ctx.config.ltoo); 92bdd1243dSDimitry Andric c.AlwaysEmitRegularLTOObj = !ctx.config.ltoObjPath.empty(); 93bdd1243dSDimitry Andric c.DebugPassManager = ctx.config.ltoDebugPassManager; 94bdd1243dSDimitry Andric c.CSIRProfile = std::string(ctx.config.ltoCSProfileFile); 95bdd1243dSDimitry Andric c.RunCSIRInstr = ctx.config.ltoCSProfileGenerate; 96bdd1243dSDimitry Andric c.PGOWarnMismatch = ctx.config.ltoPGOWarnMismatch; 970b57cec5SDimitry Andric 98bdd1243dSDimitry Andric if (ctx.config.saveTemps) 99bdd1243dSDimitry Andric checkError(c.addSaveTemps(std::string(ctx.config.outputFile) + ".", 1000b57cec5SDimitry Andric /*UseInputModulePath*/ true)); 1010b57cec5SDimitry Andric return c; 1020b57cec5SDimitry Andric } 1030b57cec5SDimitry Andric 104bdd1243dSDimitry Andric BitcodeCompiler::BitcodeCompiler(COFFLinkerContext &c) : ctx(c) { 1050b57cec5SDimitry Andric // Initialize indexFile. 106bdd1243dSDimitry Andric if (!ctx.config.thinLTOIndexOnlyArg.empty()) 107bdd1243dSDimitry Andric indexFile = openFile(ctx.config.thinLTOIndexOnlyArg); 1080b57cec5SDimitry Andric 1090b57cec5SDimitry Andric // Initialize ltoObj. 1100b57cec5SDimitry Andric lto::ThinBackend backend; 111bdd1243dSDimitry Andric if (ctx.config.thinLTOIndexOnly) { 1120b57cec5SDimitry Andric auto OnIndexWrite = [&](StringRef S) { thinIndices.erase(S); }; 1130b57cec5SDimitry Andric backend = lto::createWriteIndexesThinBackend( 114bdd1243dSDimitry Andric std::string(ctx.config.thinLTOPrefixReplace.first), 115bdd1243dSDimitry Andric std::string(ctx.config.thinLTOPrefixReplace.second), 116bdd1243dSDimitry Andric ctx.config.thinLTOEmitImportsFiles, indexFile.get(), OnIndexWrite); 1175ffd83dbSDimitry Andric } else { 1185ffd83dbSDimitry Andric backend = lto::createInProcessThinBackend( 119bdd1243dSDimitry Andric llvm::heavyweight_hardware_concurrency(ctx.config.thinLTOJobs)); 1200b57cec5SDimitry Andric } 1210b57cec5SDimitry Andric 12285868e8aSDimitry Andric ltoObj = std::make_unique<lto::LTO>(createConfig(), backend, 123bdd1243dSDimitry Andric ctx.config.ltoPartitions); 1240b57cec5SDimitry Andric } 1250b57cec5SDimitry Andric 1260b57cec5SDimitry Andric BitcodeCompiler::~BitcodeCompiler() = default; 1270b57cec5SDimitry Andric 1280b57cec5SDimitry Andric static void undefine(Symbol *s) { replaceSymbol<Undefined>(s, s->getName()); } 1290b57cec5SDimitry Andric 1300b57cec5SDimitry Andric void BitcodeCompiler::add(BitcodeFile &f) { 1310b57cec5SDimitry Andric lto::InputFile &obj = *f.obj; 1320b57cec5SDimitry Andric unsigned symNum = 0; 1330b57cec5SDimitry Andric std::vector<Symbol *> symBodies = f.getSymbols(); 1340b57cec5SDimitry Andric std::vector<lto::SymbolResolution> resols(symBodies.size()); 1350b57cec5SDimitry Andric 136bdd1243dSDimitry Andric if (ctx.config.thinLTOIndexOnly) 1370b57cec5SDimitry Andric thinIndices.insert(obj.getName()); 1380b57cec5SDimitry Andric 1390b57cec5SDimitry Andric // Provide a resolution to the LTO API for each symbol. 1400b57cec5SDimitry Andric for (const lto::InputFile::Symbol &objSym : obj.symbols()) { 1410b57cec5SDimitry Andric Symbol *sym = symBodies[symNum]; 1420b57cec5SDimitry Andric lto::SymbolResolution &r = resols[symNum]; 1430b57cec5SDimitry Andric ++symNum; 1440b57cec5SDimitry Andric 1450b57cec5SDimitry Andric // Ideally we shouldn't check for SF_Undefined but currently IRObjectFile 1460b57cec5SDimitry Andric // reports two symbols for module ASM defined. Without this check, lld 1470b57cec5SDimitry Andric // flags an undefined in IR with a definition in ASM as prevailing. 1480b57cec5SDimitry Andric // Once IRObjectFile is fixed to report only one symbol this hack can 1490b57cec5SDimitry Andric // be removed. 1500b57cec5SDimitry Andric r.Prevailing = !objSym.isUndefined() && sym->getFile() == &f; 1510b57cec5SDimitry Andric r.VisibleToRegularObj = sym->isUsedInRegularObj; 1520b57cec5SDimitry Andric if (r.Prevailing) 1530b57cec5SDimitry Andric undefine(sym); 154e8d8bef9SDimitry Andric 155e8d8bef9SDimitry Andric // We tell LTO to not apply interprocedural optimization for wrapped 156e8d8bef9SDimitry Andric // (with -wrap) symbols because otherwise LTO would inline them while 157e8d8bef9SDimitry Andric // their values are still not final. 158e8d8bef9SDimitry Andric r.LinkerRedefined = !sym->canInline; 1590b57cec5SDimitry Andric } 1600b57cec5SDimitry Andric checkError(ltoObj->add(std::move(f.obj), resols)); 1610b57cec5SDimitry Andric } 1620b57cec5SDimitry Andric 1630b57cec5SDimitry Andric // Merge all the bitcode files we have seen, codegen the result 1640b57cec5SDimitry Andric // and return the resulting objects. 165bdd1243dSDimitry Andric std::vector<InputFile *> BitcodeCompiler::compile() { 1660b57cec5SDimitry Andric unsigned maxTasks = ltoObj->getMaxTasks(); 1670b57cec5SDimitry Andric buf.resize(maxTasks); 1680b57cec5SDimitry Andric files.resize(maxTasks); 169bdd1243dSDimitry Andric file_names.resize(maxTasks); 1700b57cec5SDimitry Andric 1710b57cec5SDimitry Andric // The /lldltocache option specifies the path to a directory in which to cache 1720b57cec5SDimitry Andric // native object files for ThinLTO incremental builds. If a path was 1730b57cec5SDimitry Andric // specified, configure LTO to use it as the cache directory. 174349cc55cSDimitry Andric FileCache cache; 175bdd1243dSDimitry Andric if (!ctx.config.ltoCache.empty()) 176bdd1243dSDimitry Andric cache = check(localCache("ThinLTO", "Thin", ctx.config.ltoCache, 177bdd1243dSDimitry Andric [&](size_t task, const Twine &moduleName, 178bdd1243dSDimitry Andric std::unique_ptr<MemoryBuffer> mb) { 1790b57cec5SDimitry Andric files[task] = std::move(mb); 180bdd1243dSDimitry Andric file_names[task] = moduleName.str(); 1810b57cec5SDimitry Andric })); 1820b57cec5SDimitry Andric 1830b57cec5SDimitry Andric checkError(ltoObj->run( 184bdd1243dSDimitry Andric [&](size_t task, const Twine &moduleName) { 185bdd1243dSDimitry Andric buf[task].first = moduleName.str(); 186349cc55cSDimitry Andric return std::make_unique<CachedFileStream>( 187bdd1243dSDimitry Andric std::make_unique<raw_svector_ostream>(buf[task].second)); 1880b57cec5SDimitry Andric }, 1890b57cec5SDimitry Andric cache)); 1900b57cec5SDimitry Andric 1910b57cec5SDimitry Andric // Emit empty index files for non-indexed files 1920b57cec5SDimitry Andric for (StringRef s : thinIndices) { 1930b57cec5SDimitry Andric std::string path = getThinLTOOutputFile(s); 1940b57cec5SDimitry Andric openFile(path + ".thinlto.bc"); 195bdd1243dSDimitry Andric if (ctx.config.thinLTOEmitImportsFiles) 1960b57cec5SDimitry Andric openFile(path + ".imports"); 1970b57cec5SDimitry Andric } 1980b57cec5SDimitry Andric 1990b57cec5SDimitry Andric // ThinLTO with index only option is required to generate only the index 2000b57cec5SDimitry Andric // files. After that, we exit from linker and ThinLTO backend runs in a 2010b57cec5SDimitry Andric // distributed environment. 202bdd1243dSDimitry Andric if (ctx.config.thinLTOIndexOnly) { 203bdd1243dSDimitry Andric if (!ctx.config.ltoObjPath.empty()) 204bdd1243dSDimitry Andric saveBuffer(buf[0].second, ctx.config.ltoObjPath); 2050b57cec5SDimitry Andric if (indexFile) 2060b57cec5SDimitry Andric indexFile->close(); 2070b57cec5SDimitry Andric return {}; 2080b57cec5SDimitry Andric } 2090b57cec5SDimitry Andric 210bdd1243dSDimitry Andric if (!ctx.config.ltoCache.empty()) 211bdd1243dSDimitry Andric pruneCache(ctx.config.ltoCache, ctx.config.ltoCachePolicy, files); 2120b57cec5SDimitry Andric 2135ffd83dbSDimitry Andric std::vector<InputFile *> ret; 2140b57cec5SDimitry Andric for (unsigned i = 0; i != maxTasks; ++i) { 215bdd1243dSDimitry Andric StringRef bitcodeFilePath; 2165ffd83dbSDimitry Andric // Get the native object contents either from the cache or from memory. Do 2175ffd83dbSDimitry Andric // not use the cached MemoryBuffer directly, or the PDB will not be 2185ffd83dbSDimitry Andric // deterministic. 2195ffd83dbSDimitry Andric StringRef objBuf; 220bdd1243dSDimitry Andric if (files[i]) { 2215ffd83dbSDimitry Andric objBuf = files[i]->getBuffer(); 222bdd1243dSDimitry Andric bitcodeFilePath = file_names[i]; 223bdd1243dSDimitry Andric } else { 224bdd1243dSDimitry Andric objBuf = buf[i].second; 225bdd1243dSDimitry Andric bitcodeFilePath = buf[i].first; 226bdd1243dSDimitry Andric } 2275ffd83dbSDimitry Andric if (objBuf.empty()) 2285ffd83dbSDimitry Andric continue; 2295ffd83dbSDimitry Andric 230bdd1243dSDimitry Andric // If the input bitcode file is path/to/a.obj, then the corresponding lto 231bdd1243dSDimitry Andric // object file name will look something like: path/to/main.exe.lto.a.obj. 232bdd1243dSDimitry Andric StringRef ltoObjName; 233bdd1243dSDimitry Andric if (bitcodeFilePath == "ld-temp.o") { 234bdd1243dSDimitry Andric ltoObjName = 235bdd1243dSDimitry Andric saver().save(Twine(ctx.config.outputFile) + ".lto" + 236bdd1243dSDimitry Andric (i == 0 ? Twine("") : Twine('.') + Twine(i)) + ".obj"); 237bdd1243dSDimitry Andric } else { 238bdd1243dSDimitry Andric StringRef directory = sys::path::parent_path(bitcodeFilePath); 239bdd1243dSDimitry Andric StringRef baseName = sys::path::filename(bitcodeFilePath); 240bdd1243dSDimitry Andric StringRef outputFileBaseName = sys::path::filename(ctx.config.outputFile); 241bdd1243dSDimitry Andric SmallString<64> path; 242bdd1243dSDimitry Andric sys::path::append(path, directory, 243bdd1243dSDimitry Andric outputFileBaseName + ".lto." + baseName); 244bdd1243dSDimitry Andric sys::path::remove_dots(path, true); 245bdd1243dSDimitry Andric ltoObjName = saver().save(path.str()); 246bdd1243dSDimitry Andric } 247bdd1243dSDimitry Andric if (ctx.config.saveTemps) 248bdd1243dSDimitry Andric saveBuffer(buf[i].second, ltoObjName); 249349cc55cSDimitry Andric ret.push_back(make<ObjFile>(ctx, MemoryBufferRef(objBuf, ltoObjName))); 2505ffd83dbSDimitry Andric } 2510b57cec5SDimitry Andric 2520b57cec5SDimitry Andric return ret; 2530b57cec5SDimitry Andric } 254