| //===- 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 "Config.h" |
| #include "InputFiles.h" |
| #include "Symbols.h" |
| #include "lld/Common/Args.h" |
| #include "lld/Common/ErrorHandler.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/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; |
| |
| namespace lld { |
| namespace wasm { |
| static std::unique_ptr<lto::LTO> createLTO() { |
| lto::Config c; |
| c.Options = initTargetOptionsFromCodeGenFlags(); |
| |
| // Always emit a section per function/data with LTO. |
| c.Options.FunctionSections = true; |
| c.Options.DataSections = true; |
| |
| c.DisableVerify = config->disableVerify; |
| c.DiagHandler = diagnosticHandler; |
| c.OptLevel = config->ltoo; |
| c.MAttrs = getMAttrs(); |
| c.CGOptLevel = args::getCGOptLevel(config->ltoo); |
| c.UseNewPM = config->ltoNewPassManager; |
| c.DebugPassManager = config->ltoDebugPassManager; |
| |
| if (config->relocatable) |
| c.RelocModel = None; |
| else if (config->isPic) |
| c.RelocModel = Reloc::PIC_; |
| else |
| c.RelocModel = Reloc::Static; |
| |
| if (config->saveTemps) |
| checkError(c.addSaveTemps(config->outputFile.str() + ".", |
| /*UseInputModulePath*/ true)); |
| lto::ThinBackend backend = lto::createInProcessThinBackend( |
| llvm::heavyweight_hardware_concurrency(config->thinLTOJobs)); |
| return std::make_unique<lto::LTO>(std::move(c), backend, |
| config->ltoPartitions); |
| } |
| |
| BitcodeCompiler::BitcodeCompiler() : ltoObj(createLTO()) {} |
| |
| BitcodeCompiler::~BitcodeCompiler() = default; |
| |
| static void undefine(Symbol *s) { |
| if (auto f = dyn_cast<DefinedFunction>(s)) |
| replaceSymbol<UndefinedFunction>(f, f->getName(), None, None, 0, |
| f->getFile(), f->signature); |
| else if (isa<DefinedData>(s)) |
| replaceSymbol<UndefinedData>(s, s->getName(), 0, s->getFile()); |
| else |
| llvm_unreachable("unexpected symbol kind"); |
| } |
| |
| void BitcodeCompiler::add(BitcodeFile &f) { |
| lto::InputFile &obj = *f.obj; |
| unsigned symNum = 0; |
| ArrayRef<Symbol *> syms = f.getSymbols(); |
| std::vector<lto::SymbolResolution> resols(syms.size()); |
| |
| // Provide a resolution to the LTO API for each symbol. |
| for (const lto::InputFile::Symbol &objSym : obj.symbols()) { |
| Symbol *sym = syms[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 = config->relocatable || sym->isUsedInRegularObj || |
| sym->isNoStrip() || |
| (r.Prevailing && sym->isExported()); |
| 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<StringRef> BitcodeCompiler::compile() { |
| unsigned maxTasks = ltoObj->getMaxTasks(); |
| buf.resize(maxTasks); |
| files.resize(maxTasks); |
| |
| // The --thinlto-cache-dir 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 (!config->thinLTOCacheDir.empty()) |
| cache = |
| check(localCache("ThinLTO", "Thin", config->thinLTOCacheDir, |
| [&](size_t task, std::unique_ptr<MemoryBuffer> mb) { |
| files[task] = std::move(mb); |
| })); |
| |
| checkError(ltoObj->run( |
| [&](size_t task) { |
| return std::make_unique<CachedFileStream>( |
| std::make_unique<raw_svector_ostream>(buf[task])); |
| }, |
| cache)); |
| |
| if (!config->thinLTOCacheDir.empty()) |
| pruneCache(config->thinLTOCacheDir, config->thinLTOCachePolicy); |
| |
| std::vector<StringRef> ret; |
| for (unsigned i = 0; i != maxTasks; ++i) { |
| if (buf[i].empty()) |
| continue; |
| if (config->saveTemps) { |
| if (i == 0) |
| saveBuffer(buf[i], config->outputFile + ".lto.o"); |
| else |
| saveBuffer(buf[i], config->outputFile + Twine(i) + ".lto.o"); |
| } |
| ret.emplace_back(buf[i].data(), buf[i].size()); |
| } |
| |
| for (std::unique_ptr<MemoryBuffer> &file : files) |
| if (file) |
| ret.push_back(file->getBuffer()); |
| |
| return ret; |
| } |
| |
| } // namespace wasm |
| } // namespace lld |