//===------ 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 "clang/Interpreter/Interpreter.h"

#include "IncrementalExecutor.h"
#include "IncrementalParser.h"

#include "clang/AST/ASTContext.h"
#include "clang/Basic/TargetInfo.h"
#include "clang/CodeGen/ModuleBuilder.h"
#include "clang/CodeGen/ObjectFilePCHContainerOperations.h"
#include "clang/Driver/Compilation.h"
#include "clang/Driver/Driver.h"
#include "clang/Driver/Job.h"
#include "clang/Driver/Options.h"
#include "clang/Driver/Tool.h"
#include "clang/Frontend/CompilerInstance.h"
#include "clang/Frontend/TextDiagnosticBuffer.h"
#include "clang/Lex/PreprocessorOptions.h"

#include "llvm/IR/Module.h"
#include "llvm/Support/Errc.h"
#include "llvm/Support/Host.h"

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() || !isa<driver::Command>(*Jobs.begin()))
    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 = cast<driver::Command>(&(*Jobs.begin()));
  if (llvm::StringRef(Cmd->getCreator().getName()) != "clang")
    return llvm::createStringError(llvm::errc::not_supported,
                                   "Driver initialization failed");

  return &Cmd->getArguments();
}

static llvm::Expected<std::unique_ptr<CompilerInstance>>
CreateCI(const llvm::opt::ArgStringList &Argv) {
  std::unique_ptr<CompilerInstance> Clang(new CompilerInstance());
  IntrusiveRefCntPtr<DiagnosticIDs> DiagID(new DiagnosticIDs());

  // 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.
  IntrusiveRefCntPtr<DiagnosticOptions> DiagOpts = new DiagnosticOptions();
  TextDiagnosticBuffer *DiagsBuffer = new TextDiagnosticBuffer;
  DiagnosticsEngine Diags(DiagID, &*DiagOpts, DiagsBuffer);
  bool Success = CompilerInvocation::CreateFromArgs(
      Clang->getInvocation(), llvm::makeArrayRef(Argv.begin(), Argv.size()),
      Diags);

  // Infer the builtin include path if unspecified.
  if (Clang->getHeaderSearchOpts().UseBuiltinIncludes &&
      Clang->getHeaderSearchOpts().ResourceDir.empty())
    Clang->getHeaderSearchOpts().ResourceDir =
        CompilerInvocation::GetResourcesPath(Argv[0], nullptr);

  // Create the actual diagnostics engine.
  Clang->createDiagnostics();
  if (!Clang->hasDiagnostics())
    return llvm::createStringError(llvm::errc::not_supported,
                                   "Initialization failed. "
                                   "Unable to create diagnostics engine");

  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().TargetOpts));
  if (!Clang->hasTarget())
    return llvm::createStringError(llvm::errc::not_supported,
                                   "Initialization failed. "
                                   "Target is missing");

  Clang->getTarget().adjust(Clang->getDiagnostics(), Clang->getLangOpts());

  // 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;

  return std::move(Clang);
}

} // anonymous namespace

llvm::Expected<std::unique_ptr<CompilerInstance>>
IncrementalCompilerBuilder::create(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());

  // 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.
  ClangArgv.insert(ClangArgv.begin() + 1, "-c");

  if (!llvm::is_contained(ClangArgv, " -x")) {
    // We do C++ by default; append right after argv[0] if no "-x" given
    ClangArgv.push_back("-x");
    ClangArgv.push_back("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.
  IntrusiveRefCntPtr<DiagnosticIDs> DiagID(new DiagnosticIDs());
  IntrusiveRefCntPtr<DiagnosticOptions> DiagOpts =
      CreateAndPopulateDiagOpts(ClangArgv);
  TextDiagnosticBuffer *DiagsBuffer = new TextDiagnosticBuffer;
  DiagnosticsEngine Diags(DiagID, &*DiagOpts, DiagsBuffer);

  driver::Driver Driver(/*MainBinaryName=*/ClangArgv[0],
                        llvm::sys::getProcessTriple(), Diags);
  Driver.setCheckInputsExist(false); // the input comes from mem buffers
  llvm::ArrayRef<const char *> RF = llvm::makeArrayRef(ClangArgv);
  std::unique_ptr<driver::Compilation> Compilation(Driver.BuildCompilation(RF));

  if (Compilation->getArgs().hasArg(driver::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);
}

Interpreter::Interpreter(std::unique_ptr<CompilerInstance> CI,
                         llvm::Error &Err) {
  llvm::ErrorAsOutParameter EAO(&Err);
  auto LLVMCtx = std::make_unique<llvm::LLVMContext>();
  TSCtx = std::make_unique<llvm::orc::ThreadSafeContext>(std::move(LLVMCtx));
  IncrParser = std::make_unique<IncrementalParser>(std::move(CI),
                                                   *TSCtx->getContext(), Err);
}

Interpreter::~Interpreter() {}

llvm::Expected<std::unique_ptr<Interpreter>>
Interpreter::create(std::unique_ptr<CompilerInstance> CI) {
  llvm::Error Err = llvm::Error::success();
  auto Interp =
      std::unique_ptr<Interpreter>(new Interpreter(std::move(CI), Err));
  if (Err)
    return std::move(Err);
  return std::move(Interp);
}

const CompilerInstance *Interpreter::getCompilerInstance() const {
  return IncrParser->getCI();
}

const llvm::orc::LLJIT *Interpreter::getExecutionEngine() const {
  if (IncrExecutor)
    return IncrExecutor->getExecutionEngine();
  return nullptr;
}

llvm::Expected<PartialTranslationUnit &>
Interpreter::Parse(llvm::StringRef Code) {
  return IncrParser->Parse(Code);
}

llvm::Error Interpreter::Execute(PartialTranslationUnit &T) {
  assert(T.TheModule);
  if (!IncrExecutor) {
    const clang::TargetInfo &TI =
        getCompilerInstance()->getASTContext().getTargetInfo();
    llvm::Error Err = llvm::Error::success();
    IncrExecutor = std::make_unique<IncrementalExecutor>(*TSCtx, Err, TI);

    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::Expected<llvm::JITTargetAddress>
Interpreter::getSymbolAddress(GlobalDecl GD) const {
  if (!IncrExecutor)
    return llvm::make_error<llvm::StringError>("Operation failed. "
                                               "No execution engine",
                                               std::error_code());
  llvm::StringRef MangledName = IncrParser->GetMangledName(GD);
  return getSymbolAddress(MangledName);
}

llvm::Expected<llvm::JITTargetAddress>
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::JITTargetAddress>
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) {

  std::list<PartialTranslationUnit> &PTUs = IncrParser->getPTUs();
  if (N > PTUs.size())
    return llvm::make_error<llvm::StringError>("Operation failed. "
                                               "Too many undos",
                                               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());
    PTUs.pop_back();
  }
  return llvm::Error::success();
}