| //===- 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/Caching.h" |
| #include "llvm/LTO/Config.h" |
| #include "llvm/LTO/LTO.h" |
| #include "llvm/Object/SymbolicFile.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 lld; |
| using namespace lld::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; |
| |
| // Wasm currently only supports ThreadModel::Single |
| C.Options.ThreadModel = ThreadModel::Single; |
| |
| C.DisableVerify = Config->DisableVerify; |
| C.DiagHandler = diagnosticHandler; |
| C.OptLevel = Config->LTOO; |
| C.MAttrs = getMAttrs(); |
| C.CGOptLevel = args::getCGOptLevel(Config->LTOO); |
| |
| if (Config->Relocatable) |
| C.RelocModel = None; |
| else if (Config->Pic) |
| C.RelocModel = Reloc::PIC_; |
| else |
| C.RelocModel = Reloc::Static; |
| |
| if (Config->SaveTemps) |
| checkError(C.addSaveTemps(Config->OutputFile.str() + ".", |
| /*UseInputModulePath*/ true)); |
| |
| lto::ThinBackend Backend; |
| if (Config->ThinLTOJobs != -1U) |
| Backend = lto::createInProcessThinBackend(Config->ThinLTOJobs); |
| return llvm::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(), F->getName(), |
| DefaultModule, 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 || |
| (R.Prevailing && Sym->isExported()); |
| if (R.Prevailing) |
| undefine(Sym); |
| } |
| 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. |
| lto::NativeObjectCache Cache; |
| if (!Config->ThinLTOCacheDir.empty()) |
| Cache = check( |
| lto::localCache(Config->ThinLTOCacheDir, |
| [&](size_t Task, std::unique_ptr<MemoryBuffer> MB) { |
| Files[Task] = std::move(MB); |
| })); |
| |
| checkError(LTOObj->run( |
| [&](size_t Task) { |
| return llvm::make_unique<lto::NativeObjectStream>( |
| llvm::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; |
| } |