| //===- LTO.cpp ------------------------------------------------------------===// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "LTO.h" |
| #include "COFFLinkerContext.h" |
| #include "Config.h" |
| #include "InputFiles.h" |
| #include "Symbols.h" |
| #include "lld/Common/Args.h" |
| #include "lld/Common/CommonLinkerContext.h" |
| #include "lld/Common/Filesystem.h" |
| #include "lld/Common/Strings.h" |
| #include "lld/Common/TargetOptionsCommandFlags.h" |
| #include "llvm/ADT/STLExtras.h" |
| #include "llvm/ADT/SmallString.h" |
| #include "llvm/ADT/StringRef.h" |
| #include "llvm/ADT/Twine.h" |
| #include "llvm/Bitcode/BitcodeWriter.h" |
| #include "llvm/IR/DiagnosticPrinter.h" |
| #include "llvm/LTO/Config.h" |
| #include "llvm/LTO/LTO.h" |
| #include "llvm/Object/SymbolicFile.h" |
| #include "llvm/Support/Caching.h" |
| #include "llvm/Support/CodeGen.h" |
| #include "llvm/Support/Error.h" |
| #include "llvm/Support/FileSystem.h" |
| #include "llvm/Support/MemoryBuffer.h" |
| #include "llvm/Support/raw_ostream.h" |
| #include <algorithm> |
| #include <cstddef> |
| #include <memory> |
| #include <string> |
| #include <system_error> |
| #include <vector> |
| |
| using namespace llvm; |
| using namespace llvm::object; |
| using namespace lld; |
| using namespace lld::coff; |
| |
| std::string BitcodeCompiler::getThinLTOOutputFile(StringRef path) { |
| return lto::getThinLTOOutputFile(path, ctx.config.thinLTOPrefixReplaceOld, |
| ctx.config.thinLTOPrefixReplaceNew); |
| } |
| |
| lto::Config BitcodeCompiler::createConfig() { |
| lto::Config c; |
| c.Options = initTargetOptionsFromCodeGenFlags(); |
| c.Options.EmitAddrsig = true; |
| for (StringRef C : ctx.config.mllvmOpts) |
| c.MllvmArgs.emplace_back(C.str()); |
| |
| // Always emit a section per function/datum with LTO. LLVM LTO should get most |
| // of the benefit of linker GC, but there are still opportunities for ICF. |
| c.Options.FunctionSections = true; |
| c.Options.DataSections = true; |
| |
| // Use static reloc model on 32-bit x86 because it usually results in more |
| // compact code, and because there are also known code generation bugs when |
| // using the PIC model (see PR34306). |
| if (ctx.config.machine == COFF::IMAGE_FILE_MACHINE_I386) |
| c.RelocModel = Reloc::Static; |
| else |
| c.RelocModel = Reloc::PIC_; |
| #ifndef NDEBUG |
| c.DisableVerify = false; |
| #else |
| c.DisableVerify = true; |
| #endif |
| c.DiagHandler = diagnosticHandler; |
| c.DwoDir = ctx.config.dwoDir.str(); |
| c.OptLevel = ctx.config.ltoo; |
| c.CPU = getCPUStr(); |
| c.MAttrs = getMAttrs(); |
| std::optional<CodeGenOptLevel> optLevelOrNone = CodeGenOpt::getLevel( |
| ctx.config.ltoCgo.value_or(args::getCGOptLevel(ctx.config.ltoo))); |
| assert(optLevelOrNone && "Invalid optimization level!"); |
| c.CGOptLevel = *optLevelOrNone; |
| c.AlwaysEmitRegularLTOObj = !ctx.config.ltoObjPath.empty(); |
| c.DebugPassManager = ctx.config.ltoDebugPassManager; |
| c.CSIRProfile = std::string(ctx.config.ltoCSProfileFile); |
| c.RunCSIRInstr = ctx.config.ltoCSProfileGenerate; |
| c.PGOWarnMismatch = ctx.config.ltoPGOWarnMismatch; |
| c.TimeTraceEnabled = ctx.config.timeTraceEnabled; |
| c.TimeTraceGranularity = ctx.config.timeTraceGranularity; |
| |
| if (ctx.config.emit == EmitKind::LLVM) { |
| c.PostInternalizeModuleHook = [this](size_t task, const Module &m) { |
| if (std::unique_ptr<raw_fd_ostream> os = |
| openLTOOutputFile(ctx.config.outputFile)) |
| WriteBitcodeToFile(m, *os, false); |
| return false; |
| }; |
| } else if (ctx.config.emit == EmitKind::ASM) { |
| c.CGFileType = CodeGenFileType::AssemblyFile; |
| c.Options.MCOptions.AsmVerbose = true; |
| } |
| |
| if (ctx.config.saveTemps) |
| checkError(c.addSaveTemps(std::string(ctx.config.outputFile) + ".", |
| /*UseInputModulePath*/ true)); |
| return c; |
| } |
| |
| BitcodeCompiler::BitcodeCompiler(COFFLinkerContext &c) : ctx(c) { |
| // Initialize indexFile. |
| if (!ctx.config.thinLTOIndexOnlyArg.empty()) |
| indexFile = openFile(ctx.config.thinLTOIndexOnlyArg); |
| |
| // Initialize ltoObj. |
| lto::ThinBackend backend; |
| if (ctx.config.thinLTOIndexOnly) { |
| auto OnIndexWrite = [&](StringRef S) { thinIndices.erase(S); }; |
| backend = lto::createWriteIndexesThinBackend( |
| std::string(ctx.config.thinLTOPrefixReplaceOld), |
| std::string(ctx.config.thinLTOPrefixReplaceNew), |
| std::string(ctx.config.thinLTOPrefixReplaceNativeObject), |
| ctx.config.thinLTOEmitImportsFiles, indexFile.get(), OnIndexWrite); |
| } else { |
| backend = lto::createInProcessThinBackend( |
| llvm::heavyweight_hardware_concurrency(ctx.config.thinLTOJobs)); |
| } |
| |
| ltoObj = std::make_unique<lto::LTO>(createConfig(), backend, |
| ctx.config.ltoPartitions); |
| } |
| |
| BitcodeCompiler::~BitcodeCompiler() = default; |
| |
| static void undefine(Symbol *s) { replaceSymbol<Undefined>(s, s->getName()); } |
| |
| void BitcodeCompiler::add(BitcodeFile &f) { |
| lto::InputFile &obj = *f.obj; |
| unsigned symNum = 0; |
| std::vector<Symbol *> symBodies = f.getSymbols(); |
| std::vector<lto::SymbolResolution> resols(symBodies.size()); |
| |
| if (ctx.config.thinLTOIndexOnly) |
| thinIndices.insert(obj.getName()); |
| |
| // Provide a resolution to the LTO API for each symbol. |
| for (const lto::InputFile::Symbol &objSym : obj.symbols()) { |
| Symbol *sym = symBodies[symNum]; |
| lto::SymbolResolution &r = resols[symNum]; |
| ++symNum; |
| |
| // Ideally we shouldn't check for SF_Undefined but currently IRObjectFile |
| // reports two symbols for module ASM defined. Without this check, lld |
| // flags an undefined in IR with a definition in ASM as prevailing. |
| // Once IRObjectFile is fixed to report only one symbol this hack can |
| // be removed. |
| r.Prevailing = !objSym.isUndefined() && sym->getFile() == &f; |
| r.VisibleToRegularObj = sym->isUsedInRegularObj; |
| if (r.Prevailing) |
| undefine(sym); |
| |
| // We tell LTO to not apply interprocedural optimization for wrapped |
| // (with -wrap) symbols because otherwise LTO would inline them while |
| // their values are still not final. |
| r.LinkerRedefined = !sym->canInline; |
| } |
| checkError(ltoObj->add(std::move(f.obj), resols)); |
| } |
| |
| // Merge all the bitcode files we have seen, codegen the result |
| // and return the resulting objects. |
| std::vector<InputFile *> BitcodeCompiler::compile() { |
| unsigned maxTasks = ltoObj->getMaxTasks(); |
| buf.resize(maxTasks); |
| files.resize(maxTasks); |
| file_names.resize(maxTasks); |
| |
| // The /lldltocache option specifies the path to a directory in which to cache |
| // native object files for ThinLTO incremental builds. If a path was |
| // specified, configure LTO to use it as the cache directory. |
| FileCache cache; |
| if (!ctx.config.ltoCache.empty()) |
| cache = check(localCache("ThinLTO", "Thin", ctx.config.ltoCache, |
| [&](size_t task, const Twine &moduleName, |
| std::unique_ptr<MemoryBuffer> mb) { |
| files[task] = std::move(mb); |
| file_names[task] = moduleName.str(); |
| })); |
| |
| checkError(ltoObj->run( |
| [&](size_t task, const Twine &moduleName) { |
| buf[task].first = moduleName.str(); |
| return std::make_unique<CachedFileStream>( |
| std::make_unique<raw_svector_ostream>(buf[task].second)); |
| }, |
| cache)); |
| |
| // Emit empty index files for non-indexed files |
| for (StringRef s : thinIndices) { |
| std::string path = getThinLTOOutputFile(s); |
| openFile(path + ".thinlto.bc"); |
| if (ctx.config.thinLTOEmitImportsFiles) |
| openFile(path + ".imports"); |
| } |
| |
| // ThinLTO with index only option is required to generate only the index |
| // files. After that, we exit from linker and ThinLTO backend runs in a |
| // distributed environment. |
| if (ctx.config.thinLTOIndexOnly) { |
| if (!ctx.config.ltoObjPath.empty()) |
| saveBuffer(buf[0].second, ctx.config.ltoObjPath); |
| if (indexFile) |
| indexFile->close(); |
| return {}; |
| } |
| |
| if (!ctx.config.ltoCache.empty()) |
| pruneCache(ctx.config.ltoCache, ctx.config.ltoCachePolicy, files); |
| |
| std::vector<InputFile *> ret; |
| bool emitASM = ctx.config.emit == EmitKind::ASM; |
| const char *Ext = emitASM ? ".s" : ".obj"; |
| for (unsigned i = 0; i != maxTasks; ++i) { |
| StringRef bitcodeFilePath; |
| // Get the native object contents either from the cache or from memory. Do |
| // not use the cached MemoryBuffer directly, or the PDB will not be |
| // deterministic. |
| StringRef objBuf; |
| if (files[i]) { |
| objBuf = files[i]->getBuffer(); |
| bitcodeFilePath = file_names[i]; |
| } else { |
| objBuf = buf[i].second; |
| bitcodeFilePath = buf[i].first; |
| } |
| if (objBuf.empty()) |
| continue; |
| |
| // If the input bitcode file is path/to/a.obj, then the corresponding lto |
| // object file name will look something like: path/to/main.exe.lto.a.obj. |
| StringRef ltoObjName; |
| if (bitcodeFilePath == "ld-temp.o") { |
| ltoObjName = |
| saver().save(Twine(ctx.config.outputFile) + ".lto" + |
| (i == 0 ? Twine("") : Twine('.') + Twine(i)) + Ext); |
| } else { |
| StringRef directory = sys::path::parent_path(bitcodeFilePath); |
| StringRef baseName = sys::path::stem(bitcodeFilePath); |
| StringRef outputFileBaseName = sys::path::filename(ctx.config.outputFile); |
| SmallString<64> path; |
| sys::path::append(path, directory, |
| outputFileBaseName + ".lto." + baseName + Ext); |
| sys::path::remove_dots(path, true); |
| ltoObjName = saver().save(path.str()); |
| } |
| if (ctx.config.saveTemps || emitASM) |
| saveBuffer(buf[i].second, ltoObjName); |
| if (!emitASM) |
| ret.push_back(make<ObjFile>(ctx, MemoryBufferRef(objBuf, ltoObjName))); |
| } |
| |
| return ret; |
| } |