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      1 //===--- Builtins.h - Builtin function header -------------------*- C++ -*-===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 ///
     10 /// \file
     11 /// \brief Defines enum values for all the target-independent builtin
     12 /// functions.
     13 ///
     14 //===----------------------------------------------------------------------===//
     15 
     16 #ifndef LLVM_CLANG_BASIC_BUILTINS_H
     17 #define LLVM_CLANG_BASIC_BUILTINS_H
     18 
     19 #include "clang/Basic/LLVM.h"
     20 #include <cstring>
     21 
     22 // VC++ defines 'alloca' as an object-like macro, which interferes with our
     23 // builtins.
     24 #undef alloca
     25 
     26 namespace clang {
     27   class TargetInfo;
     28   class IdentifierTable;
     29   class ASTContext;
     30   class QualType;
     31   class LangOptions;
     32 
     33   enum LanguageID {
     34     GNU_LANG = 0x1,  // builtin requires GNU mode.
     35     C_LANG = 0x2,    // builtin for c only.
     36     CXX_LANG = 0x4,  // builtin for cplusplus only.
     37     OBJC_LANG = 0x8, // builtin for objective-c and objective-c++
     38     MS_LANG = 0x10,  // builtin requires MS mode.
     39     ALL_LANGUAGES = C_LANG | CXX_LANG | OBJC_LANG, // builtin for all languages.
     40     ALL_GNU_LANGUAGES = ALL_LANGUAGES | GNU_LANG,  // builtin requires GNU mode.
     41     ALL_MS_LANGUAGES = ALL_LANGUAGES | MS_LANG     // builtin requires MS mode.
     42   };
     43 
     44 namespace Builtin {
     45 enum ID {
     46   NotBuiltin  = 0,      // This is not a builtin function.
     47 #define BUILTIN(ID, TYPE, ATTRS) BI##ID,
     48 #include "clang/Basic/Builtins.def"
     49   FirstTSBuiltin
     50 };
     51 
     52 struct Info {
     53   const char *Name, *Type, *Attributes, *HeaderName;
     54   LanguageID builtin_lang;
     55 
     56   bool operator==(const Info &RHS) const {
     57     return !strcmp(Name, RHS.Name) &&
     58            !strcmp(Type, RHS.Type) &&
     59            !strcmp(Attributes, RHS.Attributes);
     60   }
     61   bool operator!=(const Info &RHS) const { return !(*this == RHS); }
     62 };
     63 
     64 /// \brief Holds information about both target-independent and
     65 /// target-specific builtins, allowing easy queries by clients.
     66 class Context {
     67   const Info *TSRecords;
     68   unsigned NumTSRecords;
     69 public:
     70   Context();
     71 
     72   /// \brief Perform target-specific initialization
     73   void InitializeTarget(const TargetInfo &Target);
     74 
     75   /// \brief Mark the identifiers for all the builtins with their
     76   /// appropriate builtin ID # and mark any non-portable builtin identifiers as
     77   /// such.
     78   void InitializeBuiltins(IdentifierTable &Table, const LangOptions& LangOpts);
     79 
     80   /// \brief Populate the vector with the names of all of the builtins.
     81   void GetBuiltinNames(SmallVectorImpl<const char *> &Names);
     82 
     83   /// \brief Return the identifier name for the specified builtin,
     84   /// e.g. "__builtin_abs".
     85   const char *GetName(unsigned ID) const {
     86     return GetRecord(ID).Name;
     87   }
     88 
     89   /// \brief Get the type descriptor string for the specified builtin.
     90   const char *GetTypeString(unsigned ID) const {
     91     return GetRecord(ID).Type;
     92   }
     93 
     94   /// \brief Return true if this function has no side effects and doesn't
     95   /// read memory.
     96   bool isConst(unsigned ID) const {
     97     return strchr(GetRecord(ID).Attributes, 'c') != nullptr;
     98   }
     99 
    100   /// \brief Return true if we know this builtin never throws an exception.
    101   bool isNoThrow(unsigned ID) const {
    102     return strchr(GetRecord(ID).Attributes, 'n') != nullptr;
    103   }
    104 
    105   /// \brief Return true if we know this builtin never returns.
    106   bool isNoReturn(unsigned ID) const {
    107     return strchr(GetRecord(ID).Attributes, 'r') != nullptr;
    108   }
    109 
    110   /// \brief Return true if we know this builtin can return twice.
    111   bool isReturnsTwice(unsigned ID) const {
    112     return strchr(GetRecord(ID).Attributes, 'j') != nullptr;
    113   }
    114 
    115   /// \brief Returns true if this builtin does not perform the side-effects
    116   /// of its arguments.
    117   bool isUnevaluated(unsigned ID) const {
    118     return strchr(GetRecord(ID).Attributes, 'u') != nullptr;
    119   }
    120 
    121   /// \brief Return true if this is a builtin for a libc/libm function,
    122   /// with a "__builtin_" prefix (e.g. __builtin_abs).
    123   bool isLibFunction(unsigned ID) const {
    124     return strchr(GetRecord(ID).Attributes, 'F') != nullptr;
    125   }
    126 
    127   /// \brief Determines whether this builtin is a predefined libc/libm
    128   /// function, such as "malloc", where we know the signature a
    129   /// priori.
    130   bool isPredefinedLibFunction(unsigned ID) const {
    131     return strchr(GetRecord(ID).Attributes, 'f') != nullptr;
    132   }
    133 
    134   /// \brief Determines whether this builtin is a predefined compiler-rt/libgcc
    135   /// function, such as "__clear_cache", where we know the signature a
    136   /// priori.
    137   bool isPredefinedRuntimeFunction(unsigned ID) const {
    138     return strchr(GetRecord(ID).Attributes, 'i') != nullptr;
    139   }
    140 
    141   /// \brief Determines whether this builtin has custom typechecking.
    142   bool hasCustomTypechecking(unsigned ID) const {
    143     return strchr(GetRecord(ID).Attributes, 't') != nullptr;
    144   }
    145 
    146   /// \brief Completely forget that the given ID was ever considered a builtin,
    147   /// e.g., because the user provided a conflicting signature.
    148   void ForgetBuiltin(unsigned ID, IdentifierTable &Table);
    149 
    150   /// \brief If this is a library function that comes from a specific
    151   /// header, retrieve that header name.
    152   const char *getHeaderName(unsigned ID) const {
    153     return GetRecord(ID).HeaderName;
    154   }
    155 
    156   /// \brief Determine whether this builtin is like printf in its
    157   /// formatting rules and, if so, set the index to the format string
    158   /// argument and whether this function as a va_list argument.
    159   bool isPrintfLike(unsigned ID, unsigned &FormatIdx, bool &HasVAListArg);
    160 
    161   /// \brief Determine whether this builtin is like scanf in its
    162   /// formatting rules and, if so, set the index to the format string
    163   /// argument and whether this function as a va_list argument.
    164   bool isScanfLike(unsigned ID, unsigned &FormatIdx, bool &HasVAListArg);
    165 
    166   /// \brief Return true if this function has no side effects and doesn't
    167   /// read memory, except for possibly errno.
    168   ///
    169   /// Such functions can be const when the MathErrno lang option is disabled.
    170   bool isConstWithoutErrno(unsigned ID) const {
    171     return strchr(GetRecord(ID).Attributes, 'e') != nullptr;
    172   }
    173 
    174 private:
    175   const Info &GetRecord(unsigned ID) const;
    176 
    177   /// \brief Is this builtin supported according to the given language options?
    178   bool BuiltinIsSupported(const Builtin::Info &BuiltinInfo,
    179                           const LangOptions &LangOpts);
    180 
    181   /// \brief Helper function for isPrintfLike and isScanfLike.
    182   bool isLike(unsigned ID, unsigned &FormatIdx, bool &HasVAListArg,
    183               const char *Fmt) const;
    184 };
    185 
    186 }
    187 } // end namespace clang
    188 #endif
    189