llvm-project

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//===- ChainedIncludesSource.cpp - Chained PCHs in Memory -------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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//  This file defines the ChainedIncludesSource class, which converts headers
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//  to chained PCHs in memory, mainly used for testing.
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//
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//===----------------------------------------------------------------------===//
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#include "clang/Basic/Builtins.h"
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#include "clang/Basic/TargetInfo.h"
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#include "clang/Frontend/ASTUnit.h"
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#include "clang/Frontend/CompilerInstance.h"
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#include "clang/Frontend/TextDiagnosticPrinter.h"
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#include "clang/Lex/Preprocessor.h"
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#include "clang/Lex/PreprocessorOptions.h"
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#include "clang/Parse/ParseAST.h"
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#include "clang/Sema/MultiplexExternalSemaSource.h"
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#include "clang/Serialization/ASTReader.h"
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#include "clang/Serialization/ASTWriter.h"
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#include "llvm/Support/MemoryBuffer.h"
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using namespace clang;
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namespace {
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class ChainedIncludesSource : public ExternalSemaSource {
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public:
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  ChainedIncludesSource(std::vector<std::unique_ptr<CompilerInstance>> CIs)
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      : CIs(std::move(CIs)) {}
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protected:
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  //===--------------------------------------------------------------------===//
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  // ExternalASTSource interface.
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  //===--------------------------------------------------------------------===//
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  /// Return the amount of memory used by memory buffers, breaking down
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  /// by heap-backed versus mmap'ed memory.
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  void getMemoryBufferSizes(MemoryBufferSizes &sizes) const override {
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    for (unsigned i = 0, e = CIs.size(); i != e; ++i) {
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      if (const ExternalASTSource *eSrc =
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          CIs[i]->getASTContext().getExternalSource()) {
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        eSrc->getMemoryBufferSizes(sizes);
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      }
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    }
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  }
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private:
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  std::vector<std::unique_ptr<CompilerInstance>> CIs;
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};
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} // end anonymous namespace
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static ASTReader *
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createASTReader(CompilerInstance &CI, StringRef pchFile,
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                SmallVectorImpl<std::unique_ptr<llvm::MemoryBuffer>> &MemBufs,
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                SmallVectorImpl<std::string> &bufNames,
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                ASTDeserializationListener *deserialListener = nullptr) {
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  Preprocessor &PP = CI.getPreprocessor();
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  std::unique_ptr<ASTReader> Reader;
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  Reader.reset(new ASTReader(
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      PP, CI.getModuleCache(), &CI.getASTContext(), CI.getPCHContainerReader(),
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      /*Extensions=*/{},
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      /*isysroot=*/"", DisableValidationForModuleKind::PCH));
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  for (unsigned ti = 0; ti < bufNames.size(); ++ti) {
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    StringRef sr(bufNames[ti]);
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    Reader->addInMemoryBuffer(sr, std::move(MemBufs[ti]));
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  }
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  Reader->setDeserializationListener(deserialListener);
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  switch (Reader->ReadAST(pchFile, serialization::MK_PCH, SourceLocation(),
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                          ASTReader::ARR_None)) {
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  case ASTReader::Success:
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    // Set the predefines buffer as suggested by the PCH reader.
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    PP.setPredefines(Reader->getSuggestedPredefines());
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    return Reader.release();
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  case ASTReader::Failure:
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  case ASTReader::Missing:
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  case ASTReader::OutOfDate:
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  case ASTReader::VersionMismatch:
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  case ASTReader::ConfigurationMismatch:
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  case ASTReader::HadErrors:
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    break;
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  }
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  return nullptr;
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}
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IntrusiveRefCntPtr<ExternalSemaSource> clang::createChainedIncludesSource(
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    CompilerInstance &CI, IntrusiveRefCntPtr<ExternalSemaSource> &Reader) {
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  std::vector<std::string> &includes = CI.getPreprocessorOpts().ChainedIncludes;
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  assert(!includes.empty() && "No '-chain-include' in options!");
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  std::vector<std::unique_ptr<CompilerInstance>> CIs;
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  InputKind IK = CI.getFrontendOpts().Inputs[0].getKind();
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  SmallVector<std::unique_ptr<llvm::MemoryBuffer>, 4> SerialBufs;
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  SmallVector<std::string, 4> serialBufNames;
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  for (unsigned i = 0, e = includes.size(); i != e; ++i) {
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    bool firstInclude = (i == 0);
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    std::unique_ptr<CompilerInvocation> CInvok;
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    CInvok.reset(new CompilerInvocation(CI.getInvocation()));
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    CInvok->getPreprocessorOpts().ChainedIncludes.clear();
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    CInvok->getPreprocessorOpts().ImplicitPCHInclude.clear();
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    CInvok->getPreprocessorOpts().DisablePCHOrModuleValidation =
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        DisableValidationForModuleKind::PCH;
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    CInvok->getPreprocessorOpts().Includes.clear();
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    CInvok->getPreprocessorOpts().MacroIncludes.clear();
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    CInvok->getPreprocessorOpts().Macros.clear();
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    CInvok->getFrontendOpts().Inputs.clear();
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    FrontendInputFile InputFile(includes[i], IK);
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    CInvok->getFrontendOpts().Inputs.push_back(InputFile);
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    TextDiagnosticPrinter *DiagClient =
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      new TextDiagnosticPrinter(llvm::errs(), new DiagnosticOptions());
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    IntrusiveRefCntPtr<DiagnosticIDs> DiagID(new DiagnosticIDs());
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    IntrusiveRefCntPtr<DiagnosticsEngine> Diags(
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        new DiagnosticsEngine(DiagID, &CI.getDiagnosticOpts(), DiagClient));
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    std::unique_ptr<CompilerInstance> Clang(
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        new CompilerInstance(CI.getPCHContainerOperations()));
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    Clang->setInvocation(std::move(CInvok));
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    Clang->setDiagnostics(Diags.get());
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    Clang->setTarget(TargetInfo::CreateTargetInfo(
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        Clang->getDiagnostics(), Clang->getInvocation().TargetOpts));
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    Clang->createFileManager();
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    Clang->createSourceManager(Clang->getFileManager());
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    Clang->createPreprocessor(TU_Prefix);
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    Clang->getDiagnosticClient().BeginSourceFile(Clang->getLangOpts(),
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                                                 &Clang->getPreprocessor());
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    Clang->createASTContext();
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    auto Buffer = std::make_shared<PCHBuffer>();
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    ArrayRef<std::shared_ptr<ModuleFileExtension>> Extensions;
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    auto consumer = std::make_unique<PCHGenerator>(
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        Clang->getPreprocessor(), Clang->getModuleCache(), "-", /*isysroot=*/"",
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        Buffer, Extensions, /*AllowASTWithErrors=*/true);
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    Clang->getASTContext().setASTMutationListener(
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                                            consumer->GetASTMutationListener());
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    Clang->setASTConsumer(std::move(consumer));
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    Clang->createSema(TU_Prefix, nullptr);
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    if (firstInclude) {
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      Preprocessor &PP = Clang->getPreprocessor();
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      PP.getBuiltinInfo().initializeBuiltins(PP.getIdentifierTable(),
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                                             PP.getLangOpts());
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    } else {
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      assert(!SerialBufs.empty());
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      SmallVector<std::unique_ptr<llvm::MemoryBuffer>, 4> Bufs;
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      // TODO: Pass through the existing MemoryBuffer instances instead of
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      // allocating new ones.
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      for (auto &SB : SerialBufs)
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        Bufs.push_back(llvm::MemoryBuffer::getMemBuffer(SB->getBuffer()));
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      std::string pchName = includes[i-1];
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      llvm::raw_string_ostream os(pchName);
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      os << ".pch" << i-1;
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      serialBufNames.push_back(os.str());
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      IntrusiveRefCntPtr<ASTReader> Reader;
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      Reader = createASTReader(
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          *Clang, pchName, Bufs, serialBufNames,
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          Clang->getASTConsumer().GetASTDeserializationListener());
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      if (!Reader)
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        return nullptr;
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      Clang->setASTReader(Reader);
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      Clang->getASTContext().setExternalSource(Reader);
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    }
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    if (!Clang->InitializeSourceManager(InputFile))
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      return nullptr;
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    ParseAST(Clang->getSema());
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    Clang->getDiagnosticClient().EndSourceFile();
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    assert(Buffer->IsComplete && "serialization did not complete");
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    auto &serialAST = Buffer->Data;
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    SerialBufs.push_back(llvm::MemoryBuffer::getMemBufferCopy(
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        StringRef(serialAST.data(), serialAST.size())));
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    serialAST.clear();
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    CIs.push_back(std::move(Clang));
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  }
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  assert(!SerialBufs.empty());
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  std::string pchName = includes.back() + ".pch-final";
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  serialBufNames.push_back(pchName);
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  Reader = createASTReader(CI, pchName, SerialBufs, serialBufNames);
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  if (!Reader)
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    return nullptr;
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  auto ChainedSrc =
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      llvm::makeIntrusiveRefCnt<ChainedIncludesSource>(std::move(CIs));
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  return llvm::makeIntrusiveRefCnt<MultiplexExternalSemaSource>(
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      ChainedSrc.get(), Reader.get());
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}
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