Interpreter.cpp

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//===------ Interpreter.cpp - Incremental Compilation and Execution -------===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// This file implements the component which performs incremental code
// compilation and execution.
//
//===----------------------------------------------------------------------===//
 
#include "DeviceOffload.h"
#include "IncrementalAction.h"
#include "IncrementalParser.h"
#include "InterpreterUtils.h"
 
#include "clang/AST/ASTConsumer.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/Mangle.h"
#include "clang/AST/TypeVisitor.h"
#include "clang/Basic/DiagnosticSema.h"
#include "clang/Basic/FileManager.h"
#include "clang/Basic/TargetInfo.h"
#include "clang/CodeGen/CodeGenAction.h"
#include "clang/CodeGen/ObjectFilePCHContainerWriter.h"
#include "clang/Driver/Compilation.h"
#include "clang/Driver/Driver.h"
#include "clang/Driver/Job.h"
#include "clang/Driver/Tool.h"
#include "clang/Frontend/CompilerInstance.h"
#include "clang/Frontend/FrontendAction.h"
#include "clang/Frontend/FrontendOptions.h"
#include "clang/Frontend/MultiplexConsumer.h"
#include "clang/Frontend/TextDiagnosticBuffer.h"
#include "clang/FrontendTool/Utils.h"
#include "clang/Interpreter/IncrementalExecutor.h"
#include "clang/Interpreter/Interpreter.h"
#include "clang/Interpreter/Value.h"
#include "clang/Lex/PreprocessorOptions.h"
#include "clang/Options/OptionUtils.h"
#include "clang/Options/Options.h"
#include "clang/Sema/Lookup.h"
#include "clang/Serialization/ASTReader.h"
#include "clang/Serialization/ModuleCache.h"
#include "clang/Serialization/ObjectFilePCHContainerReader.h"
#include "llvm/ExecutionEngine/JITSymbol.h"
#include "llvm/ExecutionEngine/Orc/EPCDynamicLibrarySearchGenerator.h"
#include "llvm/ExecutionEngine/Orc/LLJIT.h"
#include "llvm/IR/Module.h"
#include "llvm/Support/Errc.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/VirtualFileSystem.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/TargetParser/Host.h"
#include "llvm/TargetParser/Triple.h"
#include "llvm/Transforms/Utils/Cloning.h" // for CloneModule
 
#define DEBUG_TYPE "clang-repl"
 
using namespace clang;
// FIXME: Figure out how to unify with namespace init_convenience from
//        tools/clang-import-test/clang-import-test.cpp
namespace {
/// Retrieves the clang CC1 specific flags out of the compilation's jobs.
/// \returns NULL on error.
static llvm::Expected<const llvm::opt::ArgStringList *>
GetCC1Arguments(DiagnosticsEngine *Diagnostics,
                driver::Compilation *Compilation) {
  // We expect to get back exactly one Command job, if we didn't something
  // failed. Extract that job from the Compilation.
  const driver::JobList &Jobs = Compilation->getJobs();
  if (!Jobs.size())
    return llvm::createStringError(llvm::errc::not_supported,
                                   "Driver initialization failed. "
                                   "Unable to create a driver job");
 
  // The one job we find should be to invoke clang again.
  const driver::Command *Cmd = &*Jobs.begin();
  if (llvm::StringRef(Cmd->getCreator().getName()) != "clang")
    return llvm::createStringError(llvm::errc::not_supported,
                                   "Driver initialization failed");
 
  return &Cmd->getArguments();
}
 
// ASTReaderListener that captures the PIC level stored in a serialized AST
// file (PCH or PCM) so the interpreter can compare it against its own.
class PICLevelReader : public ASTReaderListener {
  unsigned &PICLevel;
 
public:
  PICLevelReader(unsigned &PICLevel) : PICLevel(PICLevel) {}
 
  bool ReadLanguageOptions(const LangOptions &LangOpts,
                           StringRef ModuleFilename, bool Complain,
                           bool AllowCompatibleDifferences) override {
    PICLevel = LangOpts.PICLevel;
    return false;
  }
};
 
// clang-repl always compiles position-independent code (it injects -fPIC), so a
// PCH/PCM that was built with a different PIC level is incompatible: mixing the
// two leads to relocations that may be out of range once the JIT maps code more
// than 2GB away. PICLevel is a "compatible" language option, so the ASTReader
// would otherwise accept the mismatch silently. Reject it up front.
//
// The file is probed with its own FileManager and ModuleCache (sharing only the
// VFS) so this read leaves the CompilerInstance's state untouched for the real
// load performed later by ExecuteAction().
static llvm::Error checkASTFilePICLevel(CompilerInstance &Clang,
                                        StringRef Filename) {
  llvm::IntrusiveRefCntPtr<FileManager> FileMgr(new FileManager(
      Clang.getFileSystemOpts(), Clang.getVirtualFileSystemPtr()));
  std::shared_ptr<ModuleCache> ModCache = createCrossProcessModuleCache();
  unsigned ASTPICLevel = 0;
  PICLevelReader Reader(ASTPICLevel);
  if (!ASTReader::readASTFileControlBlock(
          Filename, *FileMgr, *ModCache, Clang.getPCHContainerReader(),
          /*FindModuleFileExtensions=*/false, Reader,
          /*ValidateDiagnosticOptions=*/false) &&
      ASTPICLevel != Clang.getLangOpts().PICLevel)
    return llvm::createStringError(
        llvm::errc::not_supported,
        "AST file '%s' was built with PIC level %u, which is incompatible "
        "with clang-repl's PIC level %u",
        Filename.str().c_str(), ASTPICLevel, Clang.getLangOpts().PICLevel);
  return llvm::Error::success();
}
 
static llvm::Expected<std::unique_ptr<CompilerInstance>>
CreateCI(const llvm::opt::ArgStringList &Argv) {
  std::unique_ptr<CompilerInstance> Clang(new CompilerInstance());
 
  // Register the support for object-file-wrapped Clang modules.
  // FIXME: Clang should register these container operations automatically.
  auto PCHOps = Clang->getPCHContainerOperations();
  PCHOps->registerWriter(std::make_unique<ObjectFilePCHContainerWriter>());
  PCHOps->registerReader(std::make_unique<ObjectFilePCHContainerReader>());
 
  // Buffer diagnostics from argument parsing so that we can output them using
  // a well formed diagnostic object.
  DiagnosticOptions DiagOpts;
  TextDiagnosticBuffer *DiagsBuffer = new TextDiagnosticBuffer;
  DiagnosticsEngine Diags(DiagnosticIDs::create(), DiagOpts, DiagsBuffer);
  bool Success = CompilerInvocation::CreateFromArgs(
      Clang->getInvocation(), llvm::ArrayRef(Argv.begin(), Argv.size()), Diags);
 
  // Infer the builtin include path if unspecified.
  if (Clang->getHeaderSearchOpts().UseBuiltinIncludes &&
      Clang->getHeaderSearchOpts().ResourceDir.empty())
    Clang->getHeaderSearchOpts().ResourceDir =
        GetResourcesPath(Argv[0], nullptr);
 
  Clang->createVirtualFileSystem();
 
  // Create the actual diagnostics engine.
  Clang->createDiagnostics();
 
  DiagsBuffer->FlushDiagnostics(Clang->getDiagnostics());
  if (!Success)
    return llvm::createStringError(llvm::errc::not_supported,
                                   "Initialization failed. "
                                   "Unable to flush diagnostics");
 
  // FIXME: Merge with CompilerInstance::ExecuteAction.
  llvm::MemoryBuffer *MB = llvm::MemoryBuffer::getMemBuffer("").release();
  Clang->getPreprocessorOpts().addRemappedFile("<<< inputs >>>", MB);
 
  Clang->setTarget(TargetInfo::CreateTargetInfo(
      Clang->getDiagnostics(), Clang->getInvocation().getTargetOpts()));
  if (!Clang->hasTarget())
    return llvm::createStringError(llvm::errc::not_supported,
                                   "Initialization failed. "
                                   "Target is missing");
 
  Clang->getTarget().adjust(Clang->getDiagnostics(), Clang->getLangOpts(),
                            Clang->getAuxTarget());
 
  // Don't clear the AST before backend codegen since we do codegen multiple
  // times, reusing the same AST.
  Clang->getCodeGenOpts().ClearASTBeforeBackend = false;
 
  Clang->getFrontendOpts().DisableFree = false;
  Clang->getCodeGenOpts().DisableFree = false;
 
  // Reject any precompiled input (PCH or PCM) built with a PIC level that
  // differs from clang-repl's own, before any Interpreter/FrontendAction is
  // constructed. See checkASTFilePICLevel for the rationale.
  StringRef PCHInclude = Clang->getPreprocessorOpts().ImplicitPCHInclude;
  if (!PCHInclude.empty())
    if (llvm::Error Err = checkASTFilePICLevel(*Clang, PCHInclude))
      return std::move(Err);
 
  // Explicitly loaded modules: -fmodule-file=<path> and
  // -fmodule-file=<name>=<path>.
  for (StringRef ModuleFile : Clang->getFrontendOpts().ModuleFiles)
    if (llvm::Error Err = checkASTFilePICLevel(*Clang, ModuleFile))
      return std::move(Err);
  for (const auto &NameAndFile :
       Clang->getHeaderSearchOpts().PrebuiltModuleFiles)
    if (llvm::Error Err = checkASTFilePICLevel(*Clang, NameAndFile.second))
      return std::move(Err);
 
  return std::move(Clang);
}
 
static llvm::Error ExecuteIncrementalAction(CompilerInstance &CI,
                                            IncrementalAction &Act) {
  if (!CI.ExecuteAction(Act) || CI.getDiagnostics().hasErrorOccurred()) {
    return llvm::createStringError(llvm::errc::not_supported,
                                   "Failed to execute incremental action");
  }
  return llvm::Error::success();
}
 
} // anonymous namespace
 
namespace clang {
 
llvm::Expected<std::unique_ptr<CompilerInstance>>
IncrementalCompilerBuilder::create(std::string TT,
                                   std::vector<const char *> &ClangArgv) {
 
  // If we don't know ClangArgv0 or the address of main() at this point, try
  // to guess it anyway (it's possible on some platforms).
  std::string MainExecutableName =
      llvm::sys::fs::getMainExecutable(nullptr, nullptr);
 
  ClangArgv.insert(ClangArgv.begin(), MainExecutableName.c_str());
 
  // Compile as position-independent code. This prevents the frontend from
  // marking external symbols (e.g. C++ type-info such as _ZTIPKc used for
  // exception handling) as dso_local and emitting direct PC-relative
  // references. JITLink can place the GOT entry near the JIT'd code, keeping
  // the relocation in range. Without -fPIC, a direct Delta32 relocation to a
  // host symbol may be out of range when the JIT memory is mapped more than
  // 2GB away (as on FreeBSD), breaking tests such as
  // Interpreter/simple-exception.cpp. Insert before user arguments so it can
  // still be overridden. On Windows (excluding Cygwin/MinGW) an explicit
  // -fPIC is an unsupported driver option that would drop non-x86_64 targets
  // to PIC level 0; PIC is already the forced default there where relevant,
  // so don't inject it.
  llvm::Triple TargetTriple(TT);
  if (!TargetTriple.isOSWindows() || TargetTriple.isOSCygMing())
    ClangArgv.insert(ClangArgv.begin() + 1, "-fPIC");
 
  // Prepending -c to force the driver to do something if no action was
  // specified. By prepending we allow users to override the default
  // action and use other actions in incremental mode.
  // FIXME: Print proper driver diagnostics if the driver flags are wrong.
  // We do C++ by default; append right after argv[0] if no "-x" given
  ClangArgv.insert(ClangArgv.end(), "-Xclang");
  ClangArgv.insert(ClangArgv.end(), "-fincremental-extensions");
  ClangArgv.insert(ClangArgv.end(), "-c");
 
  // Put a dummy C++ file on to ensure there's at least one compile job for the
  // driver to construct.
  ClangArgv.push_back("<<< inputs >>>");
 
  // Buffer diagnostics from argument parsing so that we can output them using a
  // well formed diagnostic object.
  std::unique_ptr<DiagnosticOptions> DiagOpts =
      CreateAndPopulateDiagOpts(ClangArgv);
  TextDiagnosticBuffer *DiagsBuffer = new TextDiagnosticBuffer;
  DiagnosticsEngine Diags(DiagnosticIDs::create(), *DiagOpts, DiagsBuffer);
 
  driver::Driver Driver(/*MainBinaryName=*/ClangArgv[0], TT, Diags);
  Driver.setCheckInputsExist(false); // the input comes from mem buffers
  llvm::ArrayRef<const char *> RF = llvm::ArrayRef(ClangArgv);
  std::unique_ptr<driver::Compilation> Compilation(Driver.BuildCompilation(RF));
 
  if (CompilationCB)
    if (auto Err = (*CompilationCB)(*Compilation.get()))
      return std::move(Err);
 
  if (Compilation->getArgs().hasArg(options::OPT_v))
    Compilation->getJobs().Print(llvm::errs(), "\n", /*Quote=*/false);
 
  auto ErrOrCC1Args = GetCC1Arguments(&Diags, Compilation.get());
  if (auto Err = ErrOrCC1Args.takeError())
    return std::move(Err);
 
  return CreateCI(**ErrOrCC1Args);
}
 
llvm::Expected<std::unique_ptr<CompilerInstance>>
IncrementalCompilerBuilder::CreateCpp() {
  std::vector<const char *> Argv;
  Argv.reserve(5 + 1 + UserArgs.size());
  Argv.push_back("-xc++");
#ifdef __EMSCRIPTEN__
  Argv.push_back("-target");
  Argv.push_back("wasm32-unknown-emscripten");
  Argv.push_back("-fvisibility=default");
#endif
  llvm::append_range(Argv, UserArgs);
 
  std::string TT = TargetTriple ? *TargetTriple : llvm::sys::getProcessTriple();
  return IncrementalCompilerBuilder::create(TT, Argv);
}
 
llvm::Expected<std::unique_ptr<CompilerInstance>>
IncrementalCompilerBuilder::createCuda(bool device) {
  std::vector<const char *> Argv;
  Argv.reserve(5 + 4 + UserArgs.size());
 
  Argv.push_back("-xcuda");
  if (device)
    Argv.push_back("--cuda-device-only");
  else
    Argv.push_back("--cuda-host-only");
 
  std::string SDKPathArg = "--cuda-path=";
  if (!CudaSDKPath.empty()) {
    SDKPathArg += CudaSDKPath;
    Argv.push_back(SDKPathArg.c_str());
  }
 
  std::string ArchArg = "--offload-arch=";
  if (!OffloadArch.empty()) {
    ArchArg += OffloadArch;
    Argv.push_back(ArchArg.c_str());
  }
 
  llvm::append_range(Argv, UserArgs);
 
  std::string TT = TargetTriple ? *TargetTriple : llvm::sys::getProcessTriple();
  return IncrementalCompilerBuilder::create(TT, Argv);
}
 
llvm::Expected<std::unique_ptr<CompilerInstance>>
IncrementalCompilerBuilder::CreateCudaDevice() {
  return IncrementalCompilerBuilder::createCuda(true);
}
 
llvm::Expected<std::unique_ptr<CompilerInstance>>
IncrementalCompilerBuilder::CreateCudaHost() {
  return IncrementalCompilerBuilder::createCuda(false);
}
 
Interpreter::Interpreter(std::unique_ptr<CompilerInstance> Instance,
                         llvm::Error &ErrOut,
                         std::unique_ptr<IncrementalExecutorBuilder> IEB,
                         std::unique_ptr<clang::ASTConsumer> Consumer)
    : IncrExecutorBuilder(std::move(IEB)) {
  CI = std::move(Instance);
  llvm::ErrorAsOutParameter EAO(&ErrOut);
  auto LLVMCtx = std::make_unique<llvm::LLVMContext>();
  TSCtx = std::make_unique<llvm::orc::ThreadSafeContext>(std::move(LLVMCtx));
 
  Act = TSCtx->withContextDo([&](llvm::LLVMContext *Ctx) {
    return std::make_unique<IncrementalAction>(*CI, *Ctx, ErrOut, *this,
                                               std::move(Consumer));
  });
 
  if (ErrOut)
    return;
 
  if (llvm::Error E = ExecuteIncrementalAction(*CI, *Act)) {
    ErrOut = joinErrors(std::move(ErrOut), std::move(E));
    return;
  }
 
  IncrParser =
      std::make_unique<IncrementalParser>(*CI, Act.get(), ErrOut, PTUs);
 
  if (ErrOut)
    return;
 
  if (Act->getCodeGen()) {
    Act->CacheCodeGenModule();
    // The initial PTU is filled by `-include`/`-include-pch` or by CUDA
    // includes automatically.
    if (!CI->getPreprocessorOpts().Includes.empty() ||
        !CI->getPreprocessorOpts().ImplicitPCHInclude.empty()) {
      // We can't really directly pass the CachedInCodeGenModule to the Jit
      // because it will steal it, causing dangling references as explained in
      // Interpreter::Execute
      auto M = llvm::CloneModule(*Act->getCachedCodeGenModule());
      ASTContext &C = CI->getASTContext();
      IncrParser->RegisterPTU(C.getTranslationUnitDecl(), std::move(M));
    }
    if (llvm::Error Err = CreateExecutor()) {
      ErrOut = joinErrors(std::move(ErrOut), std::move(Err));
      return;
    }
  }
 
  // Not all frontends support code-generation, e.g. ast-dump actions don't
  if (Act->getCodeGen()) {
    // Process the PTUs that came from initialization. For example -include will
    // give us a header that's processed at initialization of the preprocessor.
    for (PartialTranslationUnit &PTU : PTUs)
      if (llvm::Error Err = Execute(PTU)) {
        ErrOut = joinErrors(std::move(ErrOut), std::move(Err));
        return;
      }
  }
}
 
Interpreter::~Interpreter() {
  IncrParser.reset();
  Act->FinalizeAction();
  if (DeviceParser)
    DeviceParser.reset();
  if (DeviceAct)
    DeviceAct->FinalizeAction();
  if (IncrExecutor) {
    if (llvm::Error Err = IncrExecutor->cleanUp())
      llvm::report_fatal_error(
          llvm::Twine("Failed to clean up IncrementalExecutor: ") +
          toString(std::move(Err)));
  }
}
 
// These better to put in a runtime header but we can't. This is because we
// can't find the precise resource directory in unittests so we have to hard
// code them.
const char *const Runtimes = R"(
    #define __CLANG_REPL__ 1
#ifdef __cplusplus
    #define EXTERN_C extern "C"
    struct __clang_Interpreter_NewTag{} __ci_newtag;
    void* operator new(__SIZE_TYPE__, void* __p, __clang_Interpreter_NewTag) noexcept;
    template <class T, class = T (*)() /*disable for arrays*/>
    void __clang_Interpreter_SetValueCopyArr(const T* Src, void* Placement, unsigned long Size) {
      for (unsigned long Idx = 0; Idx < Size; ++Idx)
        new ((void*)(((T*)Placement) + Idx), __ci_newtag) T(Src[Idx]);
    }
    template <class T, unsigned long N>
    void __clang_Interpreter_SetValueCopyArr(const T (*Src)[N], void* Placement, unsigned long Size) {
      __clang_Interpreter_SetValueCopyArr(Src[0], Placement, Size);
    }
#else
    #if __STDC_VERSION__ < 199901L
      #define CI_RESTRICT
      #define CI_INLINE
    #else
      #define CI_RESTRICT restrict
      #define CI_INLINE inline
    #endif
    #define EXTERN_C extern
    EXTERN_C void *memcpy(void *CI_RESTRICT dst, const void *CI_RESTRICT src, __SIZE_TYPE__ n);
    EXTERN_C CI_INLINE void __clang_Interpreter_SetValueCopyArr(const void* Src, void* Placement, unsigned long Size) {
      memcpy(Placement, Src, Size);
    }
#endif // __cplusplus
  EXTERN_C void *__clang_Interpreter_SetValueWithAlloc(void*, void*, void*);
  EXTERN_C void __clang_Interpreter_SetValueNoAlloc(void *This, void *OutVal, void *OpaqueType, ...);
)";
 
llvm::Expected<std::unique_ptr<Interpreter>> Interpreter::create(
    std::unique_ptr<CompilerInstance> CI,
    std::unique_ptr<IncrementalExecutorBuilder> IEB /*=nullptr*/) {
  llvm::Error Err = llvm::Error::success();
 
  auto Interp = std::unique_ptr<Interpreter>(new Interpreter(
      std::move(CI), Err, std::move(IEB), /*Consumer=*/nullptr));
  if (auto E = std::move(Err))
    return std::move(E);
 
  // Add runtime code and set a marker to hide it from user code. Undo will not
  // go through that.
  if (auto E = Interp->ParseAndExecute(Runtimes))
    return std::move(E);
 
  Interp->markUserCodeStart();
 
  return std::move(Interp);
}
 
llvm::Expected<std::unique_ptr<Interpreter>>
Interpreter::createWithCUDA(std::unique_ptr<CompilerInstance> CI,
                            std::unique_ptr<CompilerInstance> DCI) {
  // avoid writing fat binary to disk using an in-memory virtual file system
  llvm::IntrusiveRefCntPtr<llvm::vfs::InMemoryFileSystem> IMVFS =
      std::make_unique<llvm::vfs::InMemoryFileSystem>();
  llvm::IntrusiveRefCntPtr<llvm::vfs::OverlayFileSystem> OverlayVFS =
      std::make_unique<llvm::vfs::OverlayFileSystem>(
          llvm::vfs::getRealFileSystem());
  OverlayVFS->pushOverlay(IMVFS);
  CI->createVirtualFileSystem(OverlayVFS);
  CI->createFileManager();
 
  llvm::Expected<std::unique_ptr<Interpreter>> InterpOrErr =
      Interpreter::create(std::move(CI));
  if (!InterpOrErr)
    return InterpOrErr;
 
  std::unique_ptr<Interpreter> Interp = std::move(*InterpOrErr);
 
  llvm::Error Err = llvm::Error::success();
 
  auto DeviceAct = Interp->TSCtx->withContextDo([&](llvm::LLVMContext *Ctx) {
    return std::make_unique<IncrementalAction>(*DCI, *Ctx, Err, *Interp);
  });
 
  if (Err)
    return std::move(Err);
 
  Interp->DeviceAct = std::move(DeviceAct);
 
  if (llvm::Error E = ExecuteIncrementalAction(*DCI, *Interp->DeviceAct))
    return std::move(E);
 
  Interp->DeviceCI = std::move(DCI);
 
  auto DeviceParser = std::make_unique<IncrementalCUDADeviceParser>(
      *Interp->DeviceCI, *Interp->getCompilerInstance(),
      Interp->DeviceAct.get(), IMVFS, Err, Interp->PTUs);
 
  if (Err)
    return std::move(Err);
 
  Interp->DeviceParser = std::move(DeviceParser);
  return std::move(Interp);
}
 
CompilerInstance *Interpreter::getCompilerInstance() { return CI.get(); }
const CompilerInstance *Interpreter::getCompilerInstance() const {
  return const_cast<Interpreter *>(this)->getCompilerInstance();
}
 
llvm::Expected<IncrementalExecutor &> Interpreter::getExecutionEngine() {
  if (!IncrExecutor) {
    if (auto Err = CreateExecutor())
      return std::move(Err);
  }
 
  return *IncrExecutor.get();
}
 
ASTContext &Interpreter::getASTContext() {
  return getCompilerInstance()->getASTContext();
}
 
const ASTContext &Interpreter::getASTContext() const {
  return getCompilerInstance()->getASTContext();
}
 
void Interpreter::markUserCodeStart() {
  assert(!InitPTUSize && "We only do this once");
  InitPTUSize = PTUs.size();
}
 
size_t Interpreter::getEffectivePTUSize() const {
  assert(PTUs.size() >= InitPTUSize && "empty PTU list?");
  return PTUs.size() - InitPTUSize;
}
 
llvm::Expected<PartialTranslationUnit &>
Interpreter::Parse(llvm::StringRef Code) {
  // If we have a device parser, parse it first. The generated code will be
  // included in the host compilation
  if (DeviceParser) {
    llvm::Expected<TranslationUnitDecl *> DeviceTU = DeviceParser->Parse(Code);
    if (auto E = DeviceTU.takeError())
      return std::move(E);
 
    DeviceParser->RegisterPTU(*DeviceTU);
 
    llvm::Expected<llvm::StringRef> PTX = DeviceParser->GeneratePTX();
    if (!PTX)
      return PTX.takeError();
 
    llvm::Error Err = DeviceParser->GenerateFatbinary();
    if (Err)
      return std::move(Err);
  }
 
  // Tell the interpreter sliently ignore unused expressions since value
  // printing could cause it.
  getCompilerInstance()->getDiagnostics().setSeverity(
      clang::diag::warn_unused_expr, diag::Severity::Ignored, SourceLocation());
 
  llvm::Expected<TranslationUnitDecl *> TuOrErr = IncrParser->Parse(Code);
  if (!TuOrErr)
    return TuOrErr.takeError();
 
  PartialTranslationUnit &LastPTU = IncrParser->RegisterPTU(*TuOrErr);
 
  // Under -emit-llvm, print the module IR.
  if (InitPTUSize && LastPTU.TheModule &&
      getCompilerInstance()->getFrontendOpts().ProgramAction ==
          frontend::EmitLLVM)
    LastPTU.TheModule->print(llvm::outs(), /*AAW=*/nullptr);
 
  return LastPTU;
}
 
llvm::Error Interpreter::CreateExecutor() {
  if (IncrExecutor)
    return llvm::make_error<llvm::StringError>("Operation failed. "
                                               "Execution engine exists",
                                               std::error_code());
  if (!Act->getCodeGen())
    return llvm::make_error<llvm::StringError>("Operation failed. "
                                               "No code generator available",
                                               std::error_code());
 
  if (!IncrExecutorBuilder)
    IncrExecutorBuilder = std::make_unique<IncrementalExecutorBuilder>();
 
  auto ExecutorOrErr = IncrExecutorBuilder->create(*TSCtx, CI->getTarget());
  if (ExecutorOrErr)
    IncrExecutor = std::move(*ExecutorOrErr);
 
  return ExecutorOrErr.takeError();
}
 
llvm::Error Interpreter::Execute(PartialTranslationUnit &T) {
  assert(T.TheModule);
  LLVM_DEBUG(
      llvm::dbgs() << "execute-ptu "
                   << (llvm::is_contained(PTUs, T)
                           ? std::distance(PTUs.begin(), llvm::find(PTUs, T))
                           : -1)
                   << ": [TU=" << T.TUPart << ", M=" << T.TheModule.get()
                   << " (" << T.TheModule->getName() << ")]\n");
  if (!IncrExecutor) {
    auto Err = CreateExecutor();
    if (Err)
      return Err;
  }
  // FIXME: Add a callback to retain the llvm::Module once the JIT is done.
  if (auto Err = IncrExecutor->addModule(T))
    return Err;
 
  if (auto Err = IncrExecutor->runCtors())
    return Err;
 
  return llvm::Error::success();
}
 
llvm::Error Interpreter::ParseAndExecute(llvm::StringRef Code, Value *V) {
 
  auto PTU = Parse(Code);
  if (!PTU)
    return PTU.takeError();
  if (PTU->TheModule)
    if (llvm::Error Err = Execute(*PTU))
      return Err;
 
  if (LastValue.isValid()) {
    if (!V) {
      LastValue.dump();
      LastValue.clear();
    } else
      *V = std::move(LastValue);
  }
  return llvm::Error::success();
}
 
llvm::Expected<llvm::orc::ExecutorAddr>
Interpreter::getSymbolAddress(GlobalDecl GD) const {
  if (!IncrExecutor)
    return llvm::make_error<llvm::StringError>("Operation failed. "
                                               "No execution engine",
                                               std::error_code());
  llvm::StringRef MangledName = Act->getCodeGen()->GetMangledName(GD);
  return getSymbolAddress(MangledName);
}
 
llvm::Expected<llvm::orc::ExecutorAddr>
Interpreter::getSymbolAddress(llvm::StringRef IRName) const {
  if (!IncrExecutor)
    return llvm::make_error<llvm::StringError>("Operation failed. "
                                               "No execution engine",
                                               std::error_code());
 
  return IncrExecutor->getSymbolAddress(IRName, IncrementalExecutor::IRName);
}
 
llvm::Expected<llvm::orc::ExecutorAddr>
Interpreter::getSymbolAddressFromLinkerName(llvm::StringRef Name) const {
  if (!IncrExecutor)
    return llvm::make_error<llvm::StringError>("Operation failed. "
                                               "No execution engine",
                                               std::error_code());
 
  return IncrExecutor->getSymbolAddress(Name, IncrementalExecutor::LinkerName);
}
 
llvm::Error Interpreter::Undo(unsigned N) {
 
  if (getEffectivePTUSize() == 0) {
    return llvm::make_error<llvm::StringError>("Operation failed. "
                                               "No input left to undo",
                                               std::error_code());
  } else if (N > getEffectivePTUSize()) {
    return llvm::make_error<llvm::StringError>(
        llvm::formatv(
            "Operation failed. Wanted to undo {0} inputs, only have {1}.", N,
            getEffectivePTUSize()),
        std::error_code());
  }
 
  for (unsigned I = 0; I < N; I++) {
    if (IncrExecutor) {
      if (llvm::Error Err = IncrExecutor->removeModule(PTUs.back()))
        return Err;
    }
 
    IncrParser->CleanUpPTU(PTUs.back().TUPart);
    PTUs.pop_back();
  }
  return llvm::Error::success();
}
 
llvm::Error Interpreter::LoadDynamicLibrary(const char *name) {
  auto EEOrErr = getExecutionEngine();
  if (!EEOrErr)
    return EEOrErr.takeError();
 
  return EEOrErr->LoadDynamicLibrary(name);
}
} // end namespace clang