//===- ChainedIncludesSource.cpp - Chained PCHs in Memory -------*- C++ -*-===//

//

// 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 defines the ChainedIncludesSource class, which converts headers

//  to chained PCHs in memory, mainly used for testing.

//

//===----------------------------------------------------------------------===//

#include "clang/Basic/Builtins.h"

#include "clang/Basic/TargetInfo.h"

#include "clang/Frontend/ASTUnit.h"

#include "clang/Frontend/CompilerInstance.h"

#include "clang/Frontend/TextDiagnosticPrinter.h"

#include "clang/Lex/Preprocessor.h"

#include "clang/Lex/PreprocessorOptions.h"

#include "clang/Parse/ParseAST.h"

#include "clang/Sema/MultiplexExternalSemaSource.h"

#include "clang/Serialization/ASTReader.h"

#include "clang/Serialization/ASTWriter.h"

#include "llvm/Support/MemoryBuffer.h"

using namespace clang;

namespace {

class ChainedIncludesSource : public ExternalSemaSource {

public:

  ChainedIncludesSource(std::vector<std::unique_ptr<CompilerInstance>> CIs)

      : CIs(std::move(CIs)) {}

protected:

  //===--------------------------------------------------------------------===//

  // ExternalASTSource interface.

  //===--------------------------------------------------------------------===//

  /// Return the amount of memory used by memory buffers, breaking down

  /// by heap-backed versus mmap'ed memory.

  void getMemoryBufferSizes(MemoryBufferSizes &sizes) const override {

    for (unsigned i = 0, e = CIs.size(); i != e; ++i) {

      if (const ExternalASTSource *eSrc =

          CIs[i]->getASTContext().getExternalSource()) {

        eSrc->getMemoryBufferSizes(sizes);

      }

    }

  }

private:

  std::vector<std::unique_ptr<CompilerInstance>> CIs;

};

} // end anonymous namespace

static ASTReader *

createASTReader(CompilerInstance &CI, StringRef pchFile,

                SmallVectorImpl<std::unique_ptr<llvm::MemoryBuffer>> &MemBufs,

                SmallVectorImpl<std::string> &bufNames,

                ASTDeserializationListener *deserialListener = nullptr) {

  Preprocessor &PP = CI.getPreprocessor();

  std::unique_ptr<ASTReader> Reader;

  Reader.reset(new ASTReader(

      PP, CI.getModuleCache(), &CI.getASTContext(), CI.getPCHContainerReader(),

      /*Extensions=*/{},

      /*isysroot=*/"", DisableValidationForModuleKind::PCH));

  for (unsigned ti = 0; ti < bufNames.size(); ++ti) {

    StringRef sr(bufNames[ti]);

    Reader->addInMemoryBuffer(sr, std::move(MemBufs[ti]));

  }

  Reader->setDeserializationListener(deserialListener);

  switch (Reader->ReadAST(pchFile, serialization::MK_PCH, SourceLocation(),

                          ASTReader::ARR_None)) {

  case ASTReader::Success:

    // Set the predefines buffer as suggested by the PCH reader.

    PP.setPredefines(Reader->getSuggestedPredefines());

    return Reader.release();

  case ASTReader::Failure:

  case ASTReader::Missing:

  case ASTReader::OutOfDate:

  case ASTReader::VersionMismatch:

  case ASTReader::ConfigurationMismatch:

  case ASTReader::HadErrors:

    break;

  }

  return nullptr;

}

IntrusiveRefCntPtr<ExternalSemaSource> clang::createChainedIncludesSource(

    CompilerInstance &CI, IntrusiveRefCntPtr<ExternalSemaSource> &Reader) {

  std::vector<std::string> &includes = CI.getPreprocessorOpts().ChainedIncludes;

  assert(!includes.empty() && "No '-chain-include' in options!");

  std::vector<std::unique_ptr<CompilerInstance>> CIs;

  InputKind IK = CI.getFrontendOpts().Inputs[0].getKind();

  SmallVector<std::unique_ptr<llvm::MemoryBuffer>, 4> SerialBufs;

  SmallVector<std::string, 4> serialBufNames;

  for (unsigned i = 0, e = includes.size(); i != e; ++i) {

    bool firstInclude = (i == 0);

    std::unique_ptr<CompilerInvocation> CInvok;

    CInvok.reset(new CompilerInvocation(CI.getInvocation()));

    CInvok->getPreprocessorOpts().ChainedIncludes.clear();

    CInvok->getPreprocessorOpts().ImplicitPCHInclude.clear();

    CInvok->getPreprocessorOpts().DisablePCHOrModuleValidation =

        DisableValidationForModuleKind::PCH;

    CInvok->getPreprocessorOpts().Includes.clear();

    CInvok->getPreprocessorOpts().MacroIncludes.clear();

    CInvok->getPreprocessorOpts().Macros.clear();

    CInvok->getFrontendOpts().Inputs.clear();

    FrontendInputFile InputFile(includes[i], IK);

    CInvok->getFrontendOpts().Inputs.push_back(InputFile);

    TextDiagnosticPrinter *DiagClient =

      new TextDiagnosticPrinter(llvm::errs(), new DiagnosticOptions());

    IntrusiveRefCntPtr<DiagnosticIDs> DiagID(new DiagnosticIDs());

    IntrusiveRefCntPtr<DiagnosticsEngine> Diags(

        new DiagnosticsEngine(DiagID, &CI.getDiagnosticOpts(), DiagClient));

    std::unique_ptr<CompilerInstance> Clang(

        new CompilerInstance(CI.getPCHContainerOperations()));

    Clang->setInvocation(std::move(CInvok));

    Clang->setDiagnostics(Diags.get());

    Clang->setTarget(TargetInfo::CreateTargetInfo(

        Clang->getDiagnostics(), Clang->getInvocation().TargetOpts));

    Clang->createFileManager();

    Clang->createSourceManager(Clang->getFileManager());

    Clang->createPreprocessor(TU_Prefix);

    Clang->getDiagnosticClient().BeginSourceFile(Clang->getLangOpts(),

                                                 &Clang->getPreprocessor());

    Clang->createASTContext();

    auto Buffer = std::make_shared<PCHBuffer>();

    ArrayRef<std::shared_ptr<ModuleFileExtension>> Extensions;

    auto consumer = std::make_unique<PCHGenerator>(

        Clang->getPreprocessor(), Clang->getModuleCache(), "-", /*isysroot=*/"",

        Buffer, Extensions, /*AllowASTWithErrors=*/true);

    Clang->getASTContext().setASTMutationListener(

                                            consumer->GetASTMutationListener());

    Clang->setASTConsumer(std::move(consumer));

    Clang->createSema(TU_Prefix, nullptr);

    if (firstInclude) {

      Preprocessor &PP = Clang->getPreprocessor();

      PP.getBuiltinInfo().initializeBuiltins(PP.getIdentifierTable(),

                                             PP.getLangOpts());

    } else {

      assert(!SerialBufs.empty());

      SmallVector<std::unique_ptr<llvm::MemoryBuffer>, 4> Bufs;

      // TODO: Pass through the existing MemoryBuffer instances instead of

      // allocating new ones.

      for (auto &SB : SerialBufs)

        Bufs.push_back(llvm::MemoryBuffer::getMemBuffer(SB->getBuffer()));

      std::string pchName = includes[i-1];

      llvm::raw_string_ostream os(pchName);

      os << ".pch" << i-1;

      serialBufNames.push_back(os.str());

      IntrusiveRefCntPtr<ASTReader> Reader;

      Reader = createASTReader(

          *Clang, pchName, Bufs, serialBufNames,

          Clang->getASTConsumer().GetASTDeserializationListener());

      if (!Reader)

        return nullptr;

      Clang->setASTReader(Reader);

      Clang->getASTContext().setExternalSource(Reader);

    }

    if (!Clang->InitializeSourceManager(InputFile))

      return nullptr;

    ParseAST(Clang->getSema());

    Clang->getDiagnosticClient().EndSourceFile();

    assert(Buffer->IsComplete && "serialization did not complete");

    auto &serialAST = Buffer->Data;

    SerialBufs.push_back(llvm::MemoryBuffer::getMemBufferCopy(

        StringRef(serialAST.data(), serialAST.size())));

    serialAST.clear();

    CIs.push_back(std::move(Clang));

  }

  assert(!SerialBufs.empty());

  std::string pchName = includes.back() + ".pch-final";

  serialBufNames.push_back(pchName);

  Reader = createASTReader(CI, pchName, SerialBufs, serialBufNames);

  if (!Reader)

    return nullptr;

  auto ChainedSrc =

      llvm::makeIntrusiveRefCnt<ChainedIncludesSource>(std::move(CIs));

  return llvm::makeIntrusiveRefCnt<MultiplexExternalSemaSource>(

      ChainedSrc.get(), Reader.get());

}