llvm/lib/ExecutionEngine/Orc/ExecutionUtils.cpp

//===---- ExecutionUtils.cpp - Utilities for executing functions in Orc ---===//
//
// 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 "llvm/ExecutionEngine/Orc/ExecutionUtils.h"
#include "llvm/ExecutionEngine/Orc/AbsoluteSymbols.h"
#include "llvm/ExecutionEngine/Orc/Layer.h"
#include "llvm/ExecutionEngine/Orc/LoadLinkableFile.h"
#include "llvm/ExecutionEngine/Orc/MachO.h"
#include "llvm/ExecutionEngine/Orc/ObjectFileInterface.h"
#include "llvm/ExecutionEngine/Orc/SymbolStringPool.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/GlobalVariable.h"
#include "llvm/IR/Module.h"
#include "llvm/Object/MachOUniversal.h"
#include "llvm/Target/TargetMachine.h"
#include <string>

namespace llvm {
namespace orc {

CtorDtorIterator::CtorDtorIterator(const GlobalVariable *GV, bool End)
  : InitList(
      GV ? dyn_cast_or_null<ConstantArray>(GV->getInitializer()) : nullptr),
    I((InitList && End) ? InitList->getNumOperands() : 0) {
}

bool CtorDtorIterator::operator==(const CtorDtorIterator &Other) const {
  assert(InitList == Other.InitList && "Incomparable iterators.");
  return I == Other.I;
}

bool CtorDtorIterator::operator!=(const CtorDtorIterator &Other) const {
  return !(*this == Other);
}

CtorDtorIterator& CtorDtorIterator::operator++() {
  ++I;
  return *this;
}

CtorDtorIterator CtorDtorIterator::operator++(int) {
  CtorDtorIterator Temp = *this;
  ++I;
  return Temp;
}

CtorDtorIterator::Element CtorDtorIterator::operator*() const {
  ConstantStruct *CS = dyn_cast<ConstantStruct>(InitList->getOperand(I));
  assert(CS && "Unrecognized type in llvm.global_ctors/llvm.global_dtors");

  Constant *FuncC = CS->getOperand(1);
  Function *Func = nullptr;

  // Extract function pointer, pulling off any casts.
  while (FuncC) {
    if (Function *F = dyn_cast_or_null<Function>(FuncC)) {
      Func = F;
      break;
    } else if (ConstantExpr *CE = dyn_cast_or_null<ConstantExpr>(FuncC)) {
      if (CE->isCast())
        FuncC = CE->getOperand(0);
      else
        break;
    } else {
      // This isn't anything we recognize. Bail out with Func left set to null.
      break;
    }
  }

  auto *Priority = cast<ConstantInt>(CS->getOperand(0));
  Value *Data = CS->getNumOperands() == 3 ? CS->getOperand(2) : nullptr;
  if (Data && !isa<GlobalValue>(Data))
    Data = nullptr;
  return Element(Priority->getZExtValue(), Func, Data);
}

iterator_range<CtorDtorIterator> getConstructors(const Module &M) {
  const GlobalVariable *CtorsList = M.getNamedGlobal("llvm.global_ctors");
  return make_range(CtorDtorIterator(CtorsList, false),
                    CtorDtorIterator(CtorsList, true));
}

iterator_range<CtorDtorIterator> getDestructors(const Module &M) {
  const GlobalVariable *DtorsList = M.getNamedGlobal("llvm.global_dtors");
  return make_range(CtorDtorIterator(DtorsList, false),
                    CtorDtorIterator(DtorsList, true));
}

bool StaticInitGVIterator::isStaticInitGlobal(GlobalValue &GV) {
  if (GV.isDeclaration())
    return false;

  if (GV.hasName() && (GV.getName() == "llvm.global_ctors" ||
                       GV.getName() == "llvm.global_dtors"))
    return true;

  if (ObjFmt == Triple::MachO) {
    // FIXME: These section checks are too strict: We should match first and
    // second word split by comma.
    if (GV.hasSection() &&
        (GV.getSection().starts_with("__DATA,__objc_classlist") ||
         GV.getSection().starts_with("__DATA,__objc_selrefs")))
      return true;
  }

  return false;
}

void CtorDtorRunner::add(iterator_range<CtorDtorIterator> CtorDtors) {
  if (CtorDtors.empty())
    return;

  MangleAndInterner Mangle(
      JD.getExecutionSession(),
      (*CtorDtors.begin()).Func->getDataLayout());

  for (auto CtorDtor : CtorDtors) {
    assert(CtorDtor.Func && CtorDtor.Func->hasName() &&
           "Ctor/Dtor function must be named to be runnable under the JIT");

    // FIXME: Maybe use a symbol promoter here instead.
    if (CtorDtor.Func->hasLocalLinkage()) {
      CtorDtor.Func->setLinkage(GlobalValue::ExternalLinkage);
      CtorDtor.Func->setVisibility(GlobalValue::HiddenVisibility);
    }

    if (CtorDtor.Data && cast<GlobalValue>(CtorDtor.Data)->isDeclaration())
      continue;

    CtorDtorsByPriority[CtorDtor.Priority].push_back(
        Mangle(CtorDtor.Func->getName()));
  }
}

Error CtorDtorRunner::run() {
  using CtorDtorTy = void (*)();

  SymbolLookupSet LookupSet;
  for (auto &KV : CtorDtorsByPriority)
    for (auto &Name : KV.second)
      LookupSet.add(Name);
  assert(!LookupSet.containsDuplicates() &&
         "Ctor/Dtor list contains duplicates");

  auto &ES = JD.getExecutionSession();
  if (auto CtorDtorMap = ES.lookup(
          makeJITDylibSearchOrder(&JD, JITDylibLookupFlags::MatchAllSymbols),
          std::move(LookupSet))) {
    for (auto &KV : CtorDtorsByPriority) {
      for (auto &Name : KV.second) {
        assert(CtorDtorMap->count(Name) && "No entry for Name");
        auto CtorDtor = (*CtorDtorMap)[Name].getAddress().toPtr<CtorDtorTy>();
        CtorDtor();
      }
    }
    CtorDtorsByPriority.clear();
    return Error::success();
  } else
    return CtorDtorMap.takeError();
}

void LocalCXXRuntimeOverridesBase::runDestructors() {
  auto& CXXDestructorDataPairs = DSOHandleOverride;
  for (auto &P : CXXDestructorDataPairs)
    P.first(P.second);
  CXXDestructorDataPairs.clear();
}

int LocalCXXRuntimeOverridesBase::CXAAtExitOverride(DestructorPtr Destructor,
                                                    void *Arg,
                                                    void *DSOHandle) {
  auto& CXXDestructorDataPairs =
    *reinterpret_cast<CXXDestructorDataPairList*>(DSOHandle);
  CXXDestructorDataPairs.push_back(std::make_pair(Destructor, Arg));
  return 0;
}

Error LocalCXXRuntimeOverrides::enable(JITDylib &JD,
                                        MangleAndInterner &Mangle) {
  SymbolMap RuntimeInterposes;
  RuntimeInterposes[Mangle("__dso_handle")] = {
      ExecutorAddr::fromPtr(&DSOHandleOverride), JITSymbolFlags::Exported};
  RuntimeInterposes[Mangle("__cxa_atexit")] = {
      ExecutorAddr::fromPtr(&CXAAtExitOverride), JITSymbolFlags::Exported};

  return JD.define(absoluteSymbols(std::move(RuntimeInterposes)));
}

void ItaniumCXAAtExitSupport::registerAtExit(void (*F)(void *), void *Ctx,
                                             void *DSOHandle) {
  std::lock_guard<std::mutex> Lock(AtExitsMutex);
  AtExitRecords[DSOHandle].push_back({F, Ctx});
}

void ItaniumCXAAtExitSupport::runAtExits(void *DSOHandle) {
  std::vector<AtExitRecord> AtExitsToRun;

  {
    std::lock_guard<std::mutex> Lock(AtExitsMutex);
    auto I = AtExitRecords.find(DSOHandle);
    if (I != AtExitRecords.end()) {
      AtExitsToRun = std::move(I->second);
      AtExitRecords.erase(I);
    }
  }

  while (!AtExitsToRun.empty()) {
    AtExitsToRun.back().F(AtExitsToRun.back().Ctx);
    AtExitsToRun.pop_back();
  }
}

DynamicLibrarySearchGenerator::DynamicLibrarySearchGenerator(
    sys::DynamicLibrary Dylib, char GlobalPrefix, SymbolPredicate Allow,
    AddAbsoluteSymbolsFn AddAbsoluteSymbols)
    : Dylib(std::move(Dylib)), Allow(std::move(Allow)),
      AddAbsoluteSymbols(std::move(AddAbsoluteSymbols)),
      GlobalPrefix(GlobalPrefix) {}

Expected<std::unique_ptr<DynamicLibrarySearchGenerator>>
DynamicLibrarySearchGenerator::Load(const char *FileName, char GlobalPrefix,
                                    SymbolPredicate Allow,
                                    AddAbsoluteSymbolsFn AddAbsoluteSymbols) {
  std::string ErrMsg;
  auto Lib = sys::DynamicLibrary::getPermanentLibrary(FileName, &ErrMsg);
  if (!Lib.isValid())
    return make_error<StringError>(std::move(ErrMsg), inconvertibleErrorCode());
  return std::make_unique<DynamicLibrarySearchGenerator>(
      std::move(Lib), GlobalPrefix, std::move(Allow),
      std::move(AddAbsoluteSymbols));
}

Error DynamicLibrarySearchGenerator::tryToGenerate(
    LookupState &LS, LookupKind K, JITDylib &JD,
    JITDylibLookupFlags JDLookupFlags, const SymbolLookupSet &Symbols) {
  orc::SymbolMap NewSymbols;

  bool HasGlobalPrefix = (GlobalPrefix != '\0');

  for (auto &KV : Symbols) {
    auto &Name = KV.first;

    if ((*Name).empty())
      continue;

    if (Allow && !Allow(Name))
      continue;

    if (HasGlobalPrefix && (*Name).front() != GlobalPrefix)
      continue;

    std::string Tmp((*Name).data() + HasGlobalPrefix,
                    (*Name).size() - HasGlobalPrefix);
    if (void *P = Dylib.getAddressOfSymbol(Tmp.c_str()))
      NewSymbols[Name] = {ExecutorAddr::fromPtr(P), JITSymbolFlags::Exported};
  }

  if (NewSymbols.empty())
    return Error::success();

  if (AddAbsoluteSymbols)
    return AddAbsoluteSymbols(JD, std::move(NewSymbols));
  return JD.define(absoluteSymbols(std::move(NewSymbols)));
}

StaticLibraryDefinitionGenerator::VisitMembersFunction
StaticLibraryDefinitionGenerator::loadAllObjectFileMembers(ObjectLayer &L,
                                                           JITDylib &JD) {
  return [&](object::Archive &A, MemoryBufferRef Buf,
             size_t Index) -> Expected<bool> {
    switch (identify_magic(Buf.getBuffer())) {
    case file_magic::elf_relocatable:
    case file_magic::macho_object:
    case file_magic::coff_object:
      if (auto Err = L.add(JD, createMemberBuffer(A, Buf, Index)))
        return std::move(Err);
      // Since we've loaded it already, mark this as not loadable.
      return false;
    default:
      // Non-object-file members are not loadable.
      return false;
    }
  };
}

Expected<std::unique_ptr<StaticLibraryDefinitionGenerator>>
StaticLibraryDefinitionGenerator::Load(
    ObjectLayer &L, const char *FileName, VisitMembersFunction VisitMembers,
    GetObjectFileInterface GetObjFileInterface) {

  const auto &TT = L.getExecutionSession().getTargetTriple();
  auto Linkable = loadLinkableFile(FileName, TT, LoadArchives::Required);
  if (!Linkable)
    return Linkable.takeError();

  return Create(L, std::move(Linkable->first), std::move(VisitMembers),
                std::move(GetObjFileInterface));
}

Expected<std::unique_ptr<StaticLibraryDefinitionGenerator>>
StaticLibraryDefinitionGenerator::Create(
    ObjectLayer &L, std::unique_ptr<MemoryBuffer> ArchiveBuffer,
    std::unique_ptr<object::Archive> Archive, VisitMembersFunction VisitMembers,
    GetObjectFileInterface GetObjFileInterface) {

  DenseSet<uint64_t> Excluded;

  if (VisitMembers) {
    size_t Index = 0;
    Error Err = Error::success();
    for (auto Child : Archive->children(Err)) {
      if (auto ChildBuf = Child.getMemoryBufferRef()) {
        if (auto Loadable = VisitMembers(*Archive, *ChildBuf, Index++)) {
          if (!*Loadable)
            Excluded.insert(Child.getDataOffset());
        } else
          return Loadable.takeError();
      } else {
        // We silently allow non-object archive members. This matches the
        // behavior of ld.
        consumeError(ChildBuf.takeError());
      }
    }
    if (Err)
      return std::move(Err);
  }

  DenseMap<SymbolStringPtr, size_t> SymbolToMemberIndexMap;
  {
    DenseMap<uint64_t, size_t> OffsetToIndex;
    size_t Index = 0;
    Error Err = Error::success();
    for (auto &Child : Archive->children(Err)) {
      // For all members not excluded above, add them to the OffsetToIndex map.
      if (!Excluded.count(Child.getDataOffset()))
        OffsetToIndex[Child.getDataOffset()] = Index;
      ++Index;
    }
    if (Err)
      return Err;

    auto &ES = L.getExecutionSession();
    for (auto &Sym : Archive->symbols()) {
      auto Member = Sym.getMember();
      if (!Member)
        return Member.takeError();
      auto EntryItr = OffsetToIndex.find(Member->getDataOffset());

      // Missing entry means this member should be ignored.
      if (EntryItr == OffsetToIndex.end())
        continue;

      SymbolToMemberIndexMap[ES.intern(Sym.getName())] = EntryItr->second;
    }
  }

  return std::unique_ptr<StaticLibraryDefinitionGenerator>(
      new StaticLibraryDefinitionGenerator(
          L, std::move(ArchiveBuffer), std::move(Archive),
          std::move(GetObjFileInterface), std::move(SymbolToMemberIndexMap)));
}

Expected<std::unique_ptr<StaticLibraryDefinitionGenerator>>
StaticLibraryDefinitionGenerator::Create(
    ObjectLayer &L, std::unique_ptr<MemoryBuffer> ArchiveBuffer,
    VisitMembersFunction VisitMembers,
    GetObjectFileInterface GetObjFileInterface) {

  auto B = object::createBinary(ArchiveBuffer->getMemBufferRef());
  if (!B)
    return B.takeError();

  // If this is a regular archive then create an instance from it.
  if (isa<object::Archive>(*B))
    return Create(L, std::move(ArchiveBuffer),
                  std::unique_ptr<object::Archive>(
                      static_cast<object::Archive *>(B->release())),
                  std::move(VisitMembers), std::move(GetObjFileInterface));

  // If this is a universal binary then search for a slice matching the given
  // Triple.
  if (auto *UB = dyn_cast<object::MachOUniversalBinary>(B->get())) {

    const auto &TT = L.getExecutionSession().getTargetTriple();

    auto SliceRange = getMachOSliceRangeForTriple(*UB, TT);
    if (!SliceRange)
      return SliceRange.takeError();

    MemoryBufferRef SliceRef(
        StringRef(ArchiveBuffer->getBufferStart() + SliceRange->first,
                  SliceRange->second),
        ArchiveBuffer->getBufferIdentifier());

    auto Archive = object::Archive::create(SliceRef);
    if (!Archive)
      return Archive.takeError();

    return Create(L, std::move(ArchiveBuffer), std::move(*Archive),
                  std::move(VisitMembers), std::move(GetObjFileInterface));
  }

  return make_error<StringError>(Twine("Unrecognized file type for ") +
                                     ArchiveBuffer->getBufferIdentifier(),
                                 inconvertibleErrorCode());
}

Error StaticLibraryDefinitionGenerator::tryToGenerate(
    LookupState &LS, LookupKind K, JITDylib &JD,
    JITDylibLookupFlags JDLookupFlags, const SymbolLookupSet &Symbols) {
  // Don't materialize symbols from static archives unless this is a static
  // lookup.
  if (K != LookupKind::Static)
    return Error::success();

  // Bail out early if we've already freed the archive.
  if (!Archive)
    return Error::success();

  DenseMap<size_t, MemoryBufferRef> ToLoad;

  for (const auto &[Name, _] : Symbols) {
    // Check whehter the archive contains this symbol.
    auto It = SymbolToMemberIndexMap.find(Name);
    if (It == SymbolToMemberIndexMap.end())
      continue;
    size_t Index = It->second;

    // If we're already loading the member containing this symbol then we're
    // done.
    if (ToLoad.count(Index))
      continue;

    auto Member = Archive->findSym(*Name);
    if (!Member)
      return Member.takeError();
    if (!*Member) // Skip "none" children.
      continue;

    auto MemberBuf = (*Member)->getMemoryBufferRef();
    if (!MemberBuf)
      return MemberBuf.takeError();

    ToLoad[Index] = *MemberBuf;
  }

  // Remove symbols to be loaded.
  {
    // FIXME: Enable DenseMap removal using NonOwningSymbolStringPtr?
    std::vector<SymbolStringPtr> ToRemove;
    for (auto &[Name, Index] : SymbolToMemberIndexMap)
      if (ToLoad.count(Index))
        ToRemove.push_back(Name);
    for (auto &Name : ToRemove)
      SymbolToMemberIndexMap.erase(Name);
  }

  // Add loaded files to JITDylib.
  for (auto &[Index, Buf] : ToLoad) {
    auto MemberBuf = createMemberBuffer(*Archive, Buf, Index);

    auto Interface = GetObjFileInterface(L.getExecutionSession(),
                                         MemberBuf->getMemBufferRef());
    if (!Interface)
      return Interface.takeError();

    if (auto Err = L.add(JD, std::move(MemberBuf), std::move(*Interface)))
      return Err;
  }

  return Error::success();
}

std::unique_ptr<MemoryBuffer>
StaticLibraryDefinitionGenerator::createMemberBuffer(object::Archive &A,
                                                     MemoryBufferRef BufRef,
                                                     size_t Index) {
  return MemoryBuffer::getMemBuffer(BufRef.getBuffer(),
                                    (A.getFileName() + "[" + Twine(Index) +
                                     "](" + BufRef.getBufferIdentifier() + ")")
                                        .str(),
                                    false);
}

StaticLibraryDefinitionGenerator::StaticLibraryDefinitionGenerator(
    ObjectLayer &L, std::unique_ptr<MemoryBuffer> ArchiveBuffer,
    std::unique_ptr<object::Archive> Archive,
    GetObjectFileInterface GetObjFileInterface,
    DenseMap<SymbolStringPtr, size_t> SymbolToMemberIndexMap)
    : L(L), GetObjFileInterface(std::move(GetObjFileInterface)),
      ArchiveBuffer(std::move(ArchiveBuffer)), Archive(std::move(Archive)),
      SymbolToMemberIndexMap(std::move(SymbolToMemberIndexMap)) {
  if (!this->GetObjFileInterface)
    this->GetObjFileInterface = getObjectFileInterface;
}

std::unique_ptr<DLLImportDefinitionGenerator>
DLLImportDefinitionGenerator::Create(ExecutionSession &ES,
                                     ObjectLinkingLayer &L) {
  return std::unique_ptr<DLLImportDefinitionGenerator>(
      new DLLImportDefinitionGenerator(ES, L));
}

Error DLLImportDefinitionGenerator::tryToGenerate(
    LookupState &LS, LookupKind K, JITDylib &JD,
    JITDylibLookupFlags JDLookupFlags, const SymbolLookupSet &Symbols) {
  JITDylibSearchOrder LinkOrder;
  JD.withLinkOrderDo([&](const JITDylibSearchOrder &LO) {
    LinkOrder.reserve(LO.size());
    for (auto &KV : LO) {
      if (KV.first == &JD)
        continue;
      LinkOrder.push_back(KV);
    }
  });

  // FIXME: if regular symbol name start with __imp_ we have to issue lookup of
  // both __imp_ and stripped name and use the lookup information to resolve the
  // real symbol name.
  SymbolLookupSet LookupSet;
  DenseMap<StringRef, SymbolLookupFlags> ToLookUpSymbols;
  for (auto &KV : Symbols) {
    StringRef Deinterned = *KV.first;
    if (Deinterned.starts_with(getImpPrefix()))
      Deinterned = Deinterned.drop_front(StringRef(getImpPrefix()).size());
    // Don't degrade the required state
    auto [It, Inserted] = ToLookUpSymbols.try_emplace(Deinterned);
    if (Inserted || It->second != SymbolLookupFlags::RequiredSymbol)
      It->second = KV.second;
  }

  for (auto &KV : ToLookUpSymbols)
    LookupSet.add(ES.intern(KV.first), KV.second);

  auto Resolved = ES.lookup(LinkOrder, LookupSet, LookupKind::Static,
                            SymbolState::Resolved);
  if (!Resolved)
    return Resolved.takeError();

  auto G = createStubsGraph(*Resolved);
  if (!G)
    return G.takeError();
  return L.add(JD, std::move(*G));
}

Expected<std::unique_ptr<jitlink::LinkGraph>>
DLLImportDefinitionGenerator::createStubsGraph(const SymbolMap &Resolved) {
  Triple TT = ES.getTargetTriple();

  auto CreatePointer = jitlink::getAnonymousPointerCreator(TT);
  if (!CreatePointer)
    return make_error<StringError>(
        "DLLImportDefinitionGenerator: no pointer creator for " + TT.str(),
        inconvertibleErrorCode());

  auto CreateStub = jitlink::getPointerJumpStubCreator(TT);
  if (!CreateStub)
    return make_error<StringError>(
        "DLLImportDefinitionGenerator: no stub creator for " + TT.str(),
        inconvertibleErrorCode());

  auto G = std::make_unique<jitlink::LinkGraph>(
      "<DLLIMPORT_STUBS>", ES.getSymbolStringPool(), TT,
      TT.getArchPointerBitWidth() / 8, SubtargetFeatures(),
      jitlink::getGenericEdgeKindName);
  jitlink::Section &Sec =
      G->createSection(getSectionName(), MemProt::Read | MemProt::Exec);

  for (auto &KV : Resolved) {
    jitlink::Symbol &Target = G->addAbsoluteSymbol(
        *KV.first, KV.second.getAddress(), G->getPointerSize(),
        jitlink::Linkage::Strong, jitlink::Scope::Local, false);

    // Create __imp_ symbol
    jitlink::Symbol &Ptr = CreatePointer(*G, Sec, &Target, 0);
    Ptr.setName(G->intern((Twine(getImpPrefix()) + *KV.first).str()));
    Ptr.setLinkage(jitlink::Linkage::Strong);
    Ptr.setScope(jitlink::Scope::Default);

    // Create PLT stub
    // FIXME: check PLT stub of data symbol is not accessed
    jitlink::Symbol &Stub = CreateStub(*G, Sec, Ptr);
    Stub.setName(G->intern(*KV.first));
    Stub.setLinkage(jitlink::Linkage::Strong);
    Stub.setScope(jitlink::Scope::Default);
  }

  return std::move(G);
}

} // End namespace orc.
} // End namespace llvm.