//===--- ObjectFilePCHContainerOperations.cpp -----------------------------===//

//

// 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 "clang/CodeGen/ObjectFilePCHContainerOperations.h"

#include "CGDebugInfo.h"

#include "CodeGenModule.h"

#include "clang/AST/ASTContext.h"

#include "clang/AST/DeclObjC.h"

#include "clang/AST/Expr.h"

#include "clang/AST/RecursiveASTVisitor.h"

#include "clang/Basic/CodeGenOptions.h"

#include "clang/Basic/Diagnostic.h"

#include "clang/Basic/TargetInfo.h"

#include "clang/CodeGen/BackendUtil.h"

#include "clang/Frontend/CompilerInstance.h"

#include "clang/Lex/HeaderSearch.h"

#include "clang/Lex/Preprocessor.h"

#include "llvm/ADT/StringRef.h"

#include "llvm/Bitstream/BitstreamReader.h"

#include "llvm/DebugInfo/DWARF/DWARFContext.h"

#include "llvm/IR/Constants.h"

#include "llvm/IR/DataLayout.h"

#include "llvm/IR/LLVMContext.h"

#include "llvm/IR/Module.h"

#include "llvm/MC/TargetRegistry.h"

#include "llvm/Object/COFF.h"

#include "llvm/Object/ObjectFile.h"

#include "llvm/Support/Path.h"

#include <memory>

#include <utility>

using namespace clang;

#define DEBUG_TYPE "pchcontainer"

namespace {

class PCHContainerGenerator : public ASTConsumer {

  DiagnosticsEngine &Diags;

  const std::string MainFileName;

  const std::string OutputFileName;

  ASTContext *Ctx;

  ModuleMap &MMap;

  const HeaderSearchOptions &HeaderSearchOpts;

  const PreprocessorOptions &PreprocessorOpts;

  CodeGenOptions CodeGenOpts;

  const TargetOptions TargetOpts;

  LangOptions LangOpts;

  std::unique_ptr<llvm::LLVMContext> VMContext;

  std::unique_ptr<llvm::Module> M;

  std::unique_ptr<CodeGen::CodeGenModule> Builder;

  std::unique_ptr<raw_pwrite_stream> OS;

  std::shared_ptr<PCHBuffer> Buffer;

  /// Visit every type and emit debug info for it.

  struct DebugTypeVisitor : public RecursiveASTVisitor<DebugTypeVisitor> {

    clang::CodeGen::CGDebugInfo &DI;

    ASTContext &Ctx;

    DebugTypeVisitor(clang::CodeGen::CGDebugInfo &DI, ASTContext &Ctx)

        : DI(DI), Ctx(Ctx) {}

    /// Determine whether this type can be represented in DWARF.

    static bool CanRepresent(const Type *Ty) {

      return !Ty->isDependentType() && 
!Ty->isUndeducedType()292k
;

    }

    bool VisitImportDecl(ImportDecl *D) {

      if (!D->getImportedOwningModule())

        DI.EmitImportDecl(*D);

      return true;

    }

    bool VisitTypeDecl(TypeDecl *D) {

      // TagDecls may be deferred until after all decls have been merged and we

      // know the complete type. Pure forward declarations will be skipped, but

      // they don't need to be emitted into the module anyway.

      if (auto *TD = dyn_cast<TagDecl>(D))

        if (!TD->isCompleteDefinition())

          return true;

      QualType QualTy = Ctx.getTypeDeclType(D);

      if (!QualTy.isNull() && CanRepresent(QualTy.getTypePtr()))

        DI.getOrCreateStandaloneType(QualTy, D->getLocation());

      return true;

    }

    bool VisitObjCInterfaceDecl(ObjCInterfaceDecl *D) {

      QualType QualTy(D->getTypeForDecl(), 0);

      if (!QualTy.isNull() && CanRepresent(QualTy.getTypePtr()))

        DI.getOrCreateStandaloneType(QualTy, D->getLocation());

      return true;

    }

    bool VisitFunctionDecl(FunctionDecl *D) {

      if (isa<CXXMethodDecl>(D))

        // This is not yet supported. Constructing the `this' argument

        // mandates a CodeGenFunction.

        return true;

      SmallVector<QualType, 16> ArgTypes;

      for (auto i : D->parameters())

        ArgTypes.push_back(i->getType());

      QualType RetTy = D->getReturnType();

      QualType FnTy = Ctx.getFunctionType(RetTy, ArgTypes,

                                          FunctionProtoType::ExtProtoInfo());

      if (CanRepresent(FnTy.getTypePtr()))

        DI.EmitFunctionDecl(D, D->getLocation(), FnTy);

      return true;

    }

    bool VisitObjCMethodDecl(ObjCMethodDecl *D) {

      if (!D->getClassInterface())

        return true;

      bool selfIsPseudoStrong, selfIsConsumed;

      SmallVector<QualType, 16> ArgTypes;

      ArgTypes.push_back(D->getSelfType(Ctx, D->getClassInterface(),

                                        selfIsPseudoStrong, selfIsConsumed));

      ArgTypes.push_back(Ctx.getObjCSelType());

      for (auto i : D->parameters())

        ArgTypes.push_back(i->getType());

      QualType RetTy = D->getReturnType();

      QualType FnTy = Ctx.getFunctionType(RetTy, ArgTypes,

                                          FunctionProtoType::ExtProtoInfo());

      if (CanRepresent(FnTy.getTypePtr()))

        DI.EmitFunctionDecl(D, D->getLocation(), FnTy);

      return true;

    }

  };

public:

  PCHContainerGenerator(CompilerInstance &CI, const std::string &MainFileName,

                        const std::string &OutputFileName,

                        std::unique_ptr<raw_pwrite_stream> OS,

                        std::shared_ptr<PCHBuffer> Buffer)

      : Diags(CI.getDiagnostics()), MainFileName(MainFileName),

        OutputFileName(OutputFileName), Ctx(nullptr),

        MMap(CI.getPreprocessor().getHeaderSearchInfo().getModuleMap()),

        HeaderSearchOpts(CI.getHeaderSearchOpts()),

        PreprocessorOpts(CI.getPreprocessorOpts()),

        TargetOpts(CI.getTargetOpts()), LangOpts(CI.getLangOpts()),

        OS(std::move(OS)), Buffer(std::move(Buffer)) {

    // The debug info output isn't affected by CodeModel and

    // ThreadModel, but the backend expects them to be nonempty.

    CodeGenOpts.CodeModel = "default";

    LangOpts.setThreadModel(LangOptions::ThreadModelKind::Single);

    CodeGenOpts.DebugTypeExtRefs = true;

    // When building a module MainFileName is the name of the modulemap file.

    CodeGenOpts.MainFileName =

        LangOpts.CurrentModule.empty() ? 
MainFileName13
 : 
LangOpts.CurrentModule250
;

    CodeGenOpts.setDebugInfo(codegenoptions::FullDebugInfo);

    CodeGenOpts.setDebuggerTuning(CI.getCodeGenOpts().getDebuggerTuning());

    CodeGenOpts.DebugPrefixMap =

        CI.getInvocation().getCodeGenOpts().DebugPrefixMap;

    CodeGenOpts.DebugStrictDwarf = CI.getCodeGenOpts().DebugStrictDwarf;

  }

  ~PCHContainerGenerator() override = default;

  void Initialize(ASTContext &Context) override {

    assert(!Ctx && "initialized multiple times");

    Ctx = &Context;

    VMContext.reset(new llvm::LLVMContext());

    M.reset(new llvm::Module(MainFileName, *VMContext));

    M->setDataLayout(Ctx->getTargetInfo().getDataLayoutString());

    Builder.reset(new CodeGen::CodeGenModule(

        *Ctx, HeaderSearchOpts, PreprocessorOpts, CodeGenOpts, *M, Diags));

    // Prepare CGDebugInfo to emit debug info for a clang module.

    auto *DI = Builder->getModuleDebugInfo();

    StringRef ModuleName = llvm::sys::path::filename(MainFileName);

    DI->setPCHDescriptor(

        {ModuleName, "", OutputFileName, ASTFileSignature::createDISentinel()});

    DI->setModuleMap(MMap);

  }

  bool HandleTopLevelDecl(DeclGroupRef D) override {

    if (Diags.hasErrorOccurred())

      return true;

    // Collect debug info for all decls in this group.

    for (auto *I : D)

      if (!I->isFromASTFile()) {

        DebugTypeVisitor DTV(*Builder->getModuleDebugInfo(), *Ctx);

        DTV.TraverseDecl(I);

      }

    return true;

  }

  void HandleTopLevelDeclInObjCContainer(DeclGroupRef D) override {

    HandleTopLevelDecl(D);

  }

  void HandleTagDeclDefinition(TagDecl *D) override {

    if (Diags.hasErrorOccurred())

      return;

    if (D->isFromASTFile())

      return;

    // Anonymous tag decls are deferred until we are building their declcontext.

    if (D->getName().empty())

      return;

    // Defer tag decls until their declcontext is complete.

    auto *DeclCtx = D->getDeclContext();

    while (DeclCtx) {

      if (auto *D = dyn_cast<TagDecl>(DeclCtx))

        if (!D->isCompleteDefinition())

          return;

      DeclCtx = DeclCtx->getParent();

    }

    DebugTypeVisitor DTV(*Builder->getModuleDebugInfo(), *Ctx);

    DTV.TraverseDecl(D);

    Builder->UpdateCompletedType(D);

  }

  void HandleTagDeclRequiredDefinition(const TagDecl *D) override {

    if (Diags.hasErrorOccurred())

      return;

    if (const RecordDecl *RD = dyn_cast<RecordDecl>(D))

      Builder->getModuleDebugInfo()->completeRequiredType(RD);

  }

  void HandleImplicitImportDecl(ImportDecl *D) override {

    if (!D->getImportedOwningModule())

      Builder->getModuleDebugInfo()->EmitImportDecl(*D);

  }

  /// Emit a container holding the serialized AST.

  void HandleTranslationUnit(ASTContext &Ctx) override {

    assert(M && VMContext && Builder);

    // Delete these on function exit.

    std::unique_ptr<llvm::LLVMContext> VMContext = std::move(this->VMContext);

    std::unique_ptr<llvm::Module> M = std::move(this->M);

    std::unique_ptr<CodeGen::CodeGenModule> Builder = std::move(this->Builder);

    if (Diags.hasErrorOccurred())

      return;

    M->setTargetTriple(Ctx.getTargetInfo().getTriple().getTriple());

    M->setDataLayout(Ctx.getTargetInfo().getDataLayoutString());

    // PCH files don't have a signature field in the control block,

    // but LLVM detects DWO CUs by looking for a non-zero DWO id.

    // We use the lower 64 bits for debug info.

    uint64_t Signature =

        Buffer->Signature ? 
Buffer->Signature.truncatedValue()241
 : 
~1ULL22
;

    Builder->getModuleDebugInfo()->setDwoId(Signature);

    // Finalize the Builder.

    if (Builder)

      Builder->Release();

    // Ensure the target exists.

    std::string Error;

    auto Triple = Ctx.getTargetInfo().getTriple();

    if (!llvm::TargetRegistry::lookupTarget(Triple.getTriple(), Error))

      llvm::report_fatal_error(llvm::Twine(Error));

    // Emit the serialized Clang AST into its own section.

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

    auto &SerializedAST = Buffer->Data;

    auto Size = SerializedAST.size();

    if (Triple.isOSBinFormatWasm()) {

      // Emit __clangast in custom section instead of named data segment

      // to find it while iterating sections.

      // This could be avoided if all data segements (the wasm sense) were

      // represented as their own sections (in the llvm sense).

      // TODO: https://github.com/WebAssembly/tool-conventions/issues/138

      llvm::NamedMDNode *MD =

          M->getOrInsertNamedMetadata("wasm.custom_sections");

      llvm::Metadata *Ops[2] = {

          llvm::MDString::get(*VMContext, "__clangast"),

          llvm::MDString::get(*VMContext,

                              StringRef(SerializedAST.data(), Size))};

      auto *NameAndContent = llvm::MDTuple::get(*VMContext, Ops);

      MD->addOperand(NameAndContent);

    } else {

      auto Int8Ty = llvm::Type::getInt8Ty(*VMContext);

      auto *Ty = llvm::ArrayType::get(Int8Ty, Size);

      auto *Data = llvm::ConstantDataArray::getString(

          *VMContext, StringRef(SerializedAST.data(), Size),

          /*AddNull=*/false);

      auto *ASTSym = new llvm::GlobalVariable(

          *M, Ty, /*constant*/ true, llvm::GlobalVariable::InternalLinkage,

          Data, "__clang_ast");

      // The on-disk hashtable needs to be aligned.

      ASTSym->setAlignment(llvm::Align(8));

      // Mach-O also needs a segment name.

      if (Triple.isOSBinFormatMachO())

        ASTSym->setSection("__CLANG,__clangast");

      // COFF has an eight character length limit.

      else if (Triple.isOSBinFormatCOFF())

        ASTSym->setSection("clangast");

      else

        ASTSym->setSection("__clangast");

    }

    LLVM_DEBUG({

      // Print the IR for the PCH container to the debug output.

      llvm::SmallString<0> Buffer;

      clang::EmitBackendOutput(

          Diags, HeaderSearchOpts, CodeGenOpts, TargetOpts, LangOpts,

          Ctx.getTargetInfo().getDataLayoutString(), M.get(),

          BackendAction::Backend_EmitLL,

          std::make_unique<llvm::raw_svector_ostream>(Buffer));

      llvm::dbgs() << Buffer;

    });

    // Use the LLVM backend to emit the pch container.

    clang::EmitBackendOutput(Diags, HeaderSearchOpts, CodeGenOpts, TargetOpts,

                             LangOpts,

                             Ctx.getTargetInfo().getDataLayoutString(), M.get(),

                             BackendAction::Backend_EmitObj, std::move(OS));

    // Free the memory for the temporary buffer.

    llvm::SmallVector<char, 0> Empty;

    SerializedAST = std::move(Empty);

  }

};

} // anonymous namespace

std::unique_ptr<ASTConsumer>

ObjectFilePCHContainerWriter::CreatePCHContainerGenerator(

    CompilerInstance &CI, const std::string &MainFileName,

    const std::string &OutputFileName,

    std::unique_ptr<llvm::raw_pwrite_stream> OS,

    std::shared_ptr<PCHBuffer> Buffer) const {

  return std::make_unique<PCHContainerGenerator>(

      CI, MainFileName, OutputFileName, std::move(OS), Buffer);

}

StringRef

ObjectFilePCHContainerReader::ExtractPCH(llvm::MemoryBufferRef Buffer) const {

  StringRef PCH;

  auto OFOrErr = llvm::object::ObjectFile::createObjectFile(Buffer);

  if (OFOrErr) {

    auto &OF = OFOrErr.get();

    bool IsCOFF = isa<llvm::object::COFFObjectFile>(*OF);

    // Find the clang AST section in the container.

    for (auto &Section : OF->sections()) {

      StringRef Name;

      if (Expected<StringRef> NameOrErr = Section.getName())

        Name = *NameOrErr;

      else

        consumeError(NameOrErr.takeError());

      if ((!IsCOFF && 
Name == "__clangast"17.6k
) || 
(8.85k
IsCOFF8.85k
 && 
Name == "clangast"8
)) {

        if (Expected<StringRef> E = Section.getContents())

          return *E;

        else {

          handleAllErrors(E.takeError(), [&](const llvm::ErrorInfoBase &EIB) {

            EIB.log(llvm::errs());

          });

          return "";

        }

      }

    }

  }

  handleAllErrors(OFOrErr.takeError(), [&](const llvm::ErrorInfoBase &EIB) {

    if (EIB.convertToErrorCode() ==

        llvm::object::object_error::invalid_file_type)

      // As a fallback, treat the buffer as a raw AST.

      PCH = Buffer.getBuffer();

    else

      EIB.log(llvm::errs());

  });

  return PCH;

}