Builtins.h

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//===--- Builtins.h - Builtin function header -------------------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
///
/// \file
/// \brief Defines enum values for all the target-independent builtin
/// functions.
///
//===----------------------------------------------------------------------===//

#ifndef LLVM_CLANG_BASIC_BUILTINS_H
#define LLVM_CLANG_BASIC_BUILTINS_H

#include "clang/Basic/LLVM.h"
#include <cstring>

// VC++ defines 'alloca' as an object-like macro, which interferes with our
// builtins.
#undef alloca

namespace clang {
  class TargetInfo;
  class IdentifierTable;
  class ASTContext;
  class QualType;
  class LangOptions;
  
  enum LanguageID {
    GNU_LANG = 0x1,  // builtin requires GNU mode.
    C_LANG = 0x2,    // builtin for c only.
    CXX_LANG = 0x4,  // builtin for cplusplus only.
    OBJC_LANG = 0x8, // builtin for objective-c and objective-c++
    MS_LANG = 0x10,  // builtin requires MS mode.
    ALL_LANGUAGES = C_LANG | CXX_LANG | OBJC_LANG, // builtin for all languages.
    ALL_GNU_LANGUAGES = ALL_LANGUAGES | GNU_LANG,  // builtin requires GNU mode.
    ALL_MS_LANGUAGES = ALL_LANGUAGES | MS_LANG     // builtin requires MS mode.
  };
  
namespace Builtin {
enum ID {
  NotBuiltin  = 0,      // This is not a builtin function.
#define BUILTIN(ID, TYPE, ATTRS) BI##ID,
#include "clang/Basic/Builtins.def"
  FirstTSBuiltin
};

struct Info {
  const char *Name, *Type, *Attributes, *HeaderName;
  LanguageID builtin_lang;

  bool operator==(const Info &RHS) const {
    return !strcmp(Name, RHS.Name) &&
           !strcmp(Type, RHS.Type) &&
           !strcmp(Attributes, RHS.Attributes);
  }
  bool operator!=(const Info &RHS) const { return !(*this == RHS); }
};

/// \brief Holds information about both target-independent and
/// target-specific builtins, allowing easy queries by clients.
class Context {
  const Info *TSRecords;
  unsigned NumTSRecords;
public:
  Context();

  /// \brief Perform target-specific initialization
  void InitializeTarget(const TargetInfo &Target);
  
  /// \brief Mark the identifiers for all the builtins with their
  /// appropriate builtin ID # and mark any non-portable builtin identifiers as
  /// such.
  void InitializeBuiltins(IdentifierTable &Table, const LangOptions& LangOpts);

  /// \brief Populate the vector with the names of all of the builtins.
  void GetBuiltinNames(SmallVectorImpl<const char *> &Names);

  /// \brief Return the identifier name for the specified builtin,
  /// e.g. "__builtin_abs".
  const char *GetName(unsigned ID) const {
    return GetRecord(ID).Name;
  }

  /// \brief Get the type descriptor string for the specified builtin.
  const char *GetTypeString(unsigned ID) const {
    return GetRecord(ID).Type;
  }

  /// \brief Return true if this function has no side effects and doesn't
  /// read memory.
  bool isConst(unsigned ID) const {
    return strchr(GetRecord(ID).Attributes, 'c') != nullptr;
  }

  /// \brief Return true if we know this builtin never throws an exception.
  bool isNoThrow(unsigned ID) const {
    return strchr(GetRecord(ID).Attributes, 'n') != nullptr;
  }

  /// \brief Return true if we know this builtin never returns.
  bool isNoReturn(unsigned ID) const {
    return strchr(GetRecord(ID).Attributes, 'r') != nullptr;
  }

  /// \brief Return true if we know this builtin can return twice.
  bool isReturnsTwice(unsigned ID) const {
    return strchr(GetRecord(ID).Attributes, 'j') != nullptr;
  }

  /// \brief Returns true if this builtin does not perform the side-effects
  /// of its arguments.
  bool isUnevaluated(unsigned ID) const {
    return strchr(GetRecord(ID).Attributes, 'u') != nullptr;
  }

  /// \brief Return true if this is a builtin for a libc/libm function,
  /// with a "__builtin_" prefix (e.g. __builtin_abs).
  bool isLibFunction(unsigned ID) const {
    return strchr(GetRecord(ID).Attributes, 'F') != nullptr;
  }

  /// \brief Determines whether this builtin is a predefined libc/libm
  /// function, such as "malloc", where we know the signature a
  /// priori.
  bool isPredefinedLibFunction(unsigned ID) const {
    return strchr(GetRecord(ID).Attributes, 'f') != nullptr;
  }

  /// \brief Determines whether this builtin is a predefined compiler-rt/libgcc
  /// function, such as "__clear_cache", where we know the signature a
  /// priori.
  bool isPredefinedRuntimeFunction(unsigned ID) const {
    return strchr(GetRecord(ID).Attributes, 'i') != nullptr;
  }

  /// \brief Determines whether this builtin has custom typechecking.
  bool hasCustomTypechecking(unsigned ID) const {
    return strchr(GetRecord(ID).Attributes, 't') != nullptr;
  }

  /// \brief Completely forget that the given ID was ever considered a builtin,
  /// e.g., because the user provided a conflicting signature.
  void ForgetBuiltin(unsigned ID, IdentifierTable &Table);
  
  /// \brief If this is a library function that comes from a specific
  /// header, retrieve that header name.
  const char *getHeaderName(unsigned ID) const {
    return GetRecord(ID).HeaderName;
  }

  /// \brief Determine whether this builtin is like printf in its
  /// formatting rules and, if so, set the index to the format string
  /// argument and whether this function as a va_list argument.
  bool isPrintfLike(unsigned ID, unsigned &FormatIdx, bool &HasVAListArg);

  /// \brief Determine whether this builtin is like scanf in its
  /// formatting rules and, if so, set the index to the format string
  /// argument and whether this function as a va_list argument.
  bool isScanfLike(unsigned ID, unsigned &FormatIdx, bool &HasVAListArg);

  /// \brief Return true if this function has no side effects and doesn't
  /// read memory, except for possibly errno.
  ///
  /// Such functions can be const when the MathErrno lang option is disabled.
  bool isConstWithoutErrno(unsigned ID) const {
    return strchr(GetRecord(ID).Attributes, 'e') != nullptr;
  }

private:
  const Info &GetRecord(unsigned ID) const;

  /// \brief Is this builtin supported according to the given language options?
  bool BuiltinIsSupported(const Builtin::Info &BuiltinInfo,
                          const LangOptions &LangOpts);

  /// \brief Helper function for isPrintfLike and isScanfLike.
  bool isLike(unsigned ID, unsigned &FormatIdx, bool &HasVAListArg,
              const char *Fmt) const;
};

}
} // end namespace clang
#endif