Coverage Report

Created: 2018-08-19 14:04

/Users/buildslave/jenkins/workspace/clang-stage2-coverage-R/llvm/tools/lld/wasm/LTO.cpp
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//===- LTO.cpp ------------------------------------------------------------===//
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//
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//                             The LLVM Linker
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#include "LTO.h"
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#include "Config.h"
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#include "InputFiles.h"
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#include "Symbols.h"
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#include "lld/Common/ErrorHandler.h"
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#include "lld/Common/Strings.h"
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#include "lld/Common/TargetOptionsCommandFlags.h"
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#include "llvm/ADT/STLExtras.h"
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#include "llvm/ADT/SmallString.h"
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#include "llvm/ADT/StringRef.h"
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#include "llvm/ADT/Twine.h"
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#include "llvm/IR/DiagnosticPrinter.h"
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#include "llvm/LTO/Caching.h"
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#include "llvm/LTO/Config.h"
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#include "llvm/LTO/LTO.h"
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#include "llvm/Object/SymbolicFile.h"
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#include "llvm/Support/CodeGen.h"
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#include "llvm/Support/Error.h"
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#include "llvm/Support/FileSystem.h"
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#include "llvm/Support/MemoryBuffer.h"
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#include "llvm/Support/raw_ostream.h"
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#include <algorithm>
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#include <cstddef>
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#include <memory>
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#include <string>
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#include <system_error>
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#include <vector>
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using namespace llvm;
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using namespace llvm::object;
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using namespace lld;
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using namespace lld::wasm;
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static std::unique_ptr<lto::LTO> createLTO() {
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  lto::Config C;
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  C.Options = InitTargetOptionsFromCodeGenFlags();
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  // Always emit a section per function/data with LTO.
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  C.Options.FunctionSections = true;
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  C.Options.DataSections = true;
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  // Wasm currently only supports ThreadModel::Single
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  C.Options.ThreadModel = ThreadModel::Single;
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  C.DisableVerify = Config->DisableVerify;
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  C.DiagHandler = diagnosticHandler;
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  C.OptLevel = Config->LTOO;
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  if (Config->SaveTemps)
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    checkError(C.addSaveTemps(Config->OutputFile.str() + ".",
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                              /*UseInputModulePath*/ true));
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  lto::ThinBackend Backend;
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  if (Config->ThinLTOJobs != -1U)
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    Backend = lto::createInProcessThinBackend(Config->ThinLTOJobs);
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  return llvm::make_unique<lto::LTO>(std::move(C), Backend,
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                                     Config->LTOPartitions);
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}
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BitcodeCompiler::BitcodeCompiler() : LTOObj(createLTO()) {}
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BitcodeCompiler::~BitcodeCompiler() = default;
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static void undefine(Symbol *S) {
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  if (isa<DefinedFunction>(S))
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    replaceSymbol<UndefinedFunction>(S, S->getName(), 0);
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  else if (isa<DefinedData>(S))
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    replaceSymbol<UndefinedData>(S, S->getName(), 0);
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  else
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    llvm_unreachable("unexpected symbol kind");
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}
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void BitcodeCompiler::add(BitcodeFile &F) {
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  lto::InputFile &Obj = *F.Obj;
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  unsigned SymNum = 0;
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  ArrayRef<Symbol *> Syms = F.getSymbols();
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  std::vector<lto::SymbolResolution> Resols(Syms.size());
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  // Provide a resolution to the LTO API for each symbol.
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  for (const lto::InputFile::Symbol &ObjSym : Obj.symbols()) {
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    Symbol *Sym = Syms[SymNum];
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    lto::SymbolResolution &R = Resols[SymNum];
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    ++SymNum;
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    // Ideally we shouldn't check for SF_Undefined but currently IRObjectFile
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    // reports two symbols for module ASM defined. Without this check, lld
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    // flags an undefined in IR with a definition in ASM as prevailing.
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    // Once IRObjectFile is fixed to report only one symbol this hack can
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    // be removed.
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    R.Prevailing = !ObjSym.isUndefined() && Sym->getFile() == &F;
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    R.VisibleToRegularObj = Config->Relocatable || Sym->IsUsedInRegularObj ||
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                            (R.Prevailing && Sym->isExported());
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    if (R.Prevailing)
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      undefine(Sym);
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  }
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  checkError(LTOObj->add(std::move(F.Obj), Resols));
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}
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// Merge all the bitcode files we have seen, codegen the result
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// and return the resulting objects.
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std::vector<StringRef> BitcodeCompiler::compile() {
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  unsigned MaxTasks = LTOObj->getMaxTasks();
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  Buf.resize(MaxTasks);
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  Files.resize(MaxTasks);
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  // The --thinlto-cache-dir option specifies the path to a directory in which
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  // to cache native object files for ThinLTO incremental builds. If a path was
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  // specified, configure LTO to use it as the cache directory.
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  lto::NativeObjectCache Cache;
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  if (!Config->ThinLTOCacheDir.empty())
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    Cache = check(
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        lto::localCache(Config->ThinLTOCacheDir,
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                        [&](size_t Task, std::unique_ptr<MemoryBuffer> MB) {
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                          Files[Task] = std::move(MB);
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                        }));
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  checkError(LTOObj->run(
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      [&](size_t Task) {
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        return llvm::make_unique<lto::NativeObjectStream>(
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            llvm::make_unique<raw_svector_ostream>(Buf[Task]));
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      },
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      Cache));
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  if (!Config->ThinLTOCacheDir.empty())
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    pruneCache(Config->ThinLTOCacheDir, Config->ThinLTOCachePolicy);
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  std::vector<StringRef> Ret;
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  for (unsigned I = 0; I != MaxTasks; ++I) {
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    if (Buf[I].empty())
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      continue;
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    if (Config->SaveTemps) {
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      if (I == 0)
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        saveBuffer(Buf[I], Config->OutputFile + ".lto.o");
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      else
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        saveBuffer(Buf[I], Config->OutputFile + Twine(I) + ".lto.o");
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    }
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    Ret.emplace_back(Buf[I].data(), Buf[I].size());
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  }
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  for (std::unique_ptr<MemoryBuffer> &File : Files)
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    if (File)
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      Ret.push_back(File->getBuffer());
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  return Ret;
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}