path: root/include/clang/Frontend/PCHReader.h

//===--- PCHReader.h - Precompiled Headers Reader ---------------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
//  This file defines the PCHReader class, which reads a precompiled header.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_CLANG_FRONTEND_PCH_READER_H
#define LLVM_CLANG_FRONTEND_PCH_READER_H

#include "clang/Frontend/PCHBitCodes.h"
#include "clang/AST/DeclarationName.h"
#include "clang/Sema/ExternalSemaSource.h"
#include "clang/AST/DeclObjC.h"
#include "clang/AST/Type.h"
#include "clang/Basic/Diagnostic.h"
#include "clang/Basic/IdentifierTable.h"
#include "clang/Basic/SourceManager.h"
#include "llvm/ADT/APFloat.h"
#include "llvm/ADT/APInt.h"
#include "llvm/ADT/APSInt.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/OwningPtr.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/Bitcode/BitstreamReader.h"
#include "llvm/Support/DataTypes.h"
#include <deque>
#include <map>
#include <string>
#include <utility>
#include <vector>

namespace llvm {
  class MemoryBuffer;
}

namespace clang {

class AddrLabelExpr;
class ASTConsumer;
class ASTContext;
class Attr;
class Decl;
class DeclContext;
class GotoStmt;
class LabelStmt;
class NamedDecl;
class Preprocessor;
class Sema;
class SwitchCase;
class PCHReader;
struct HeaderFileInfo;

/// \brief Abstract interface for callback invocations by the PCHReader.
///
/// While reading a PCH file, the PCHReader will call the methods of the
/// listener to pass on specific information. Some of the listener methods can
/// return true to indicate to the PCHReader that the information (and
/// consequently the PCH file) is invalid.
class PCHReaderListener {
public:
  virtual ~PCHReaderListener();
  
  /// \brief Receives the language options.
  ///
  /// \returns true to indicate the options are invalid or false otherwise.
  virtual bool ReadLanguageOptions(const LangOptions &LangOpts) {
    return false;
  }
  
  /// \brief Receives the target triple.
  ///
  /// \returns true to indicate the target triple is invalid or false otherwise.
  virtual bool ReadTargetTriple(const std::string &Triple) {
    return false;
  }
  
  /// \brief Receives the contents of the predefines buffer.
  ///
  /// \param PCHPredef The start of the predefines buffer in the PCH
  /// file.
  ///
  /// \param PCHPredefLen The length of the predefines buffer in the PCH
  /// file.
  ///
  /// \param PCHBufferID The FileID for the PCH predefines buffer.
  ///
  /// \param SuggestedPredefines If necessary, additional definitions are added
  /// here.
  ///
  /// \returns true to indicate the predefines are invalid or false otherwise.
  virtual bool ReadPredefinesBuffer(const char *PCHPredef, 
                                    unsigned PCHPredefLen,
                                    FileID PCHBufferID,
                                    std::string &SuggestedPredefines) {
    return false;
  }
  
  /// \brief Receives a HeaderFileInfo entry.
  virtual void ReadHeaderFileInfo(const HeaderFileInfo &HFI) {}
  
  /// \brief Receives __COUNTER__ value.
  virtual void ReadCounter(unsigned Value) {}
};

/// \brief PCHReaderListener implementation to validate the information of
/// the PCH file against an initialized Preprocessor.
class PCHValidator : public PCHReaderListener {
  Preprocessor &PP;
  PCHReader &Reader;
  
  unsigned NumHeaderInfos;
  
public:
  PCHValidator(Preprocessor &PP, PCHReader &Reader)
    : PP(PP), Reader(Reader), NumHeaderInfos(0) {}
  
  virtual bool ReadLanguageOptions(const LangOptions &LangOpts);
  virtual bool ReadTargetTriple(const std::string &Triple);
  virtual bool ReadPredefinesBuffer(const char *PCHPredef, 
                                    unsigned PCHPredefLen,
                                    FileID PCHBufferID,
                                    std::string &SuggestedPredefines);
  virtual void ReadHeaderFileInfo(const HeaderFileInfo &HFI);
  virtual void ReadCounter(unsigned Value);
};

/// \brief Reads a precompiled head containing the contents of a
/// translation unit.
///
/// The PCHReader class reads a bitstream (produced by the PCHWriter
/// class) containing the serialized representation of a given
/// abstract syntax tree and its supporting data structures. An
/// instance of the PCHReader can be attached to an ASTContext object,
/// which will provide access to the contents of the PCH file.
///
/// The PCH reader provides lazy de-serialization of declarations, as
/// required when traversing the AST. Only those AST nodes that are
/// actually required will be de-serialized.
class PCHReader 
  : public ExternalSemaSource, 
    public IdentifierInfoLookup,
    public ExternalIdentifierLookup,
    public ExternalSLocEntrySource {
public:
  enum PCHReadResult { Success, Failure, IgnorePCH };

private:
  /// \ brief The receiver of some callbacks invoked by PCHReader.
  llvm::OwningPtr<PCHReaderListener> Listener;
  
  SourceManager &SourceMgr;
  FileManager &FileMgr;
  Diagnostic &Diags;
  
  /// \brief The semantic analysis object that will be processing the
  /// PCH file and the translation unit that uses it.
  Sema *SemaObj;

  /// \brief The preprocessor that will be loading the source file.
  Preprocessor *PP;

  /// \brief The AST context into which we'll read the PCH file.
  ASTContext *Context;

  /// \brief The AST consumer.
  ASTConsumer *Consumer;

  /// \brief The bitstream reader from which we'll read the PCH file.
  llvm::BitstreamReader StreamFile;
  llvm::BitstreamCursor Stream;

  /// DeclsCursor - This is a cursor to the start of the DECLS_BLOCK block.  It
  /// has read all the abbreviations at the start of the block and is ready to
  /// jump around with these in context.
  llvm::BitstreamCursor DeclsCursor;

  /// \brief The file name of the PCH file.
  std::string FileName;

  /// \brief The memory buffer that stores the data associated with
  /// this PCH file.
  llvm::OwningPtr<llvm::MemoryBuffer> Buffer;

  /// \brief Offset type for all of the source location entries in the
  /// PCH file.
  const uint32_t *SLocOffsets;

  /// \brief The number of source location entries in the PCH file.
  unsigned TotalNumSLocEntries;

  /// \brief Cursor used to read source location entries.
  llvm::BitstreamCursor SLocEntryCursor;

  /// \brief Offset of each type within the bitstream, indexed by the
  /// type ID, or the representation of a Type*.
  const uint32_t *TypeOffsets;

  /// \brief Types that have already been loaded from the PCH file.
  /// 
  /// When the pointer at index I is non-NULL, the type with 
  /// ID = (I + 1) << 3 has already been loaded from the PCH file.
  std::vector<Type *> TypesLoaded;

  /// \brief Offset of each declaration within the bitstream, indexed
  /// by the declaration ID (-1).
  const uint32_t *DeclOffsets;

  /// \brief Declarations that have already been loaded from the PCH file.
  ///
  /// When the pointer at index I is non-NULL, the declaration with ID
  /// = I + 1 has already been loaded.
  std::vector<Decl *> DeclsLoaded;

  typedef llvm::DenseMap<const DeclContext *, std::pair<uint64_t, uint64_t> >
    DeclContextOffsetsMap;

  /// \brief Offsets of the lexical and visible declarations for each
  /// DeclContext.
  DeclContextOffsetsMap DeclContextOffsets;

  /// \brief Actual data for the on-disk hash table.
  ///
  // This pointer points into a memory buffer, where the on-disk hash
  // table for identifiers actually lives.
  const char *IdentifierTableData;

  /// \brief A pointer to an on-disk hash table of opaque type
  /// IdentifierHashTable.
  void *IdentifierLookupTable;

  /// \brief Offsets into the identifier table data.
  ///
  /// This array is indexed by the identifier ID (-1), and provides
  /// the offset into IdentifierTableData where the string data is
  /// stored.
  const uint32_t *IdentifierOffsets;

  /// \brief A vector containing identifiers that have already been
  /// loaded.
  ///
  /// If the pointer at index I is non-NULL, then it refers to the
  /// IdentifierInfo for the identifier with ID=I+1 that has already
  /// been loaded.
  std::vector<IdentifierInfo *> IdentifiersLoaded;

  /// \brief A pointer to an on-disk hash table of opaque type
  /// PCHMethodPoolLookupTable.
  ///
  /// This hash table provides the instance and factory methods
  /// associated with every selector known in the PCH file.
  void *MethodPoolLookupTable;

  /// \brief A pointer to the character data that comprises the method
  /// pool.
  ///
  /// The SelectorOffsets table refers into this memory.
  const unsigned char *MethodPoolLookupTableData;

  /// \brief The number of selectors stored in the method pool itself.
  unsigned TotalSelectorsInMethodPool;

  /// \brief Offsets into the method pool lookup table's data array
  /// where each selector resides.
  const uint32_t *SelectorOffsets;

  /// \brief The total number of selectors stored in the PCH file.
  unsigned TotalNumSelectors;

  /// \brief A vector containing selectors that have already been loaded. 
  ///