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      1 //===--- IdentifierTable.cpp - Hash table for identifier lookup -----------===//
      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 // This file implements the IdentifierInfo, IdentifierVisitor, and
     11 // IdentifierTable interfaces.
     12 //
     13 //===----------------------------------------------------------------------===//
     14 
     15 #include "clang/Basic/IdentifierTable.h"
     16 #include "clang/Basic/LangOptions.h"
     17 #include "llvm/ADT/FoldingSet.h"
     18 #include "llvm/ADT/DenseMap.h"
     19 #include "llvm/ADT/SmallString.h"
     20 #include "llvm/ADT/StringSwitch.h"
     21 #include "llvm/Support/raw_ostream.h"
     22 #include "llvm/Support/ErrorHandling.h"
     23 #include <cstdio>
     24 
     25 using namespace clang;
     26 
     27 //===----------------------------------------------------------------------===//
     28 // IdentifierInfo Implementation
     29 //===----------------------------------------------------------------------===//
     30 
     31 IdentifierInfo::IdentifierInfo() {
     32   TokenID = tok::identifier;
     33   ObjCOrBuiltinID = 0;
     34   HasMacro = false;
     35   IsExtension = false;
     36   IsCXX11CompatKeyword = false;
     37   IsPoisoned = false;
     38   IsCPPOperatorKeyword = false;
     39   NeedsHandleIdentifier = false;
     40   IsFromAST = false;
     41   ChangedAfterLoad = false;
     42   RevertedTokenID = false;
     43   OutOfDate = false;
     44   IsModulesImport = false;
     45   FETokenInfo = 0;
     46   Entry = 0;
     47 }
     48 
     49 //===----------------------------------------------------------------------===//
     50 // IdentifierTable Implementation
     51 //===----------------------------------------------------------------------===//
     52 
     53 IdentifierIterator::~IdentifierIterator() { }
     54 
     55 IdentifierInfoLookup::~IdentifierInfoLookup() {}
     56 
     57 namespace {
     58   /// \brief A simple identifier lookup iterator that represents an
     59   /// empty sequence of identifiers.
     60   class EmptyLookupIterator : public IdentifierIterator
     61   {
     62   public:
     63     virtual StringRef Next() { return StringRef(); }
     64   };
     65 }
     66 
     67 IdentifierIterator *IdentifierInfoLookup::getIdentifiers() const {
     68   return new EmptyLookupIterator();
     69 }
     70 
     71 ExternalIdentifierLookup::~ExternalIdentifierLookup() {}
     72 
     73 IdentifierTable::IdentifierTable(const LangOptions &LangOpts,
     74                                  IdentifierInfoLookup* externalLookup)
     75   : HashTable(8192), // Start with space for 8K identifiers.
     76     ExternalLookup(externalLookup) {
     77 
     78   // Populate the identifier table with info about keywords for the current
     79   // language.
     80   AddKeywords(LangOpts);
     81 
     82 
     83   // Add the '_experimental_modules_import' contextual keyword.
     84   get("__experimental_modules_import").setModulesImport(true);
     85 }
     86 
     87 //===----------------------------------------------------------------------===//
     88 // Language Keyword Implementation
     89 //===----------------------------------------------------------------------===//
     90 
     91 // Constants for TokenKinds.def
     92 namespace {
     93   enum {
     94     KEYC99 = 0x1,
     95     KEYCXX = 0x2,
     96     KEYCXX0X = 0x4,
     97     KEYGNU = 0x8,
     98     KEYMS = 0x10,
     99     BOOLSUPPORT = 0x20,
    100     KEYALTIVEC = 0x40,
    101     KEYNOCXX = 0x80,
    102     KEYBORLAND = 0x100,
    103     KEYOPENCL = 0x200,
    104     KEYC11 = 0x400,
    105     KEYARC = 0x800,
    106     KEYALL = 0x0fff
    107   };
    108 }
    109 
    110 /// AddKeyword - This method is used to associate a token ID with specific
    111 /// identifiers because they are language keywords.  This causes the lexer to
    112 /// automatically map matching identifiers to specialized token codes.
    113 ///
    114 /// The C90/C99/CPP/CPP0x flags are set to 3 if the token is a keyword in a
    115 /// future language standard, set to 2 if the token should be enabled in the
    116 /// specified language, set to 1 if it is an extension in the specified
    117 /// language, and set to 0 if disabled in the specified language.
    118 static void AddKeyword(StringRef Keyword,
    119                        tok::TokenKind TokenCode, unsigned Flags,
    120                        const LangOptions &LangOpts, IdentifierTable &Table) {
    121   unsigned AddResult = 0;
    122   if (Flags == KEYALL) AddResult = 2;
    123   else if (LangOpts.CPlusPlus && (Flags & KEYCXX)) AddResult = 2;
    124   else if (LangOpts.CPlusPlus0x && (Flags & KEYCXX0X)) AddResult = 2;
    125   else if (LangOpts.C99 && (Flags & KEYC99)) AddResult = 2;
    126   else if (LangOpts.GNUKeywords && (Flags & KEYGNU)) AddResult = 1;
    127   else if (LangOpts.MicrosoftExt && (Flags & KEYMS)) AddResult = 1;
    128   else if (LangOpts.Borland && (Flags & KEYBORLAND)) AddResult = 1;
    129   else if (LangOpts.Bool && (Flags & BOOLSUPPORT)) AddResult = 2;
    130   else if (LangOpts.AltiVec && (Flags & KEYALTIVEC)) AddResult = 2;
    131   else if (LangOpts.OpenCL && (Flags & KEYOPENCL)) AddResult = 2;
    132   else if (!LangOpts.CPlusPlus && (Flags & KEYNOCXX)) AddResult = 2;
    133   else if (LangOpts.C11 && (Flags & KEYC11)) AddResult = 2;
    134   // We treat bridge casts as objective-C keywords so we can warn on them
    135   // in non-arc mode.
    136   else if (LangOpts.ObjC2 && (Flags & KEYARC)) AddResult = 2;
    137   else if (LangOpts.CPlusPlus && (Flags & KEYCXX0X)) AddResult = 3;
    138 
    139   // Don't add this keyword if disabled in this language.
    140   if (AddResult == 0) return;
    141 
    142   IdentifierInfo &Info =
    143       Table.get(Keyword, AddResult == 3 ? tok::identifier : TokenCode);
    144   Info.setIsExtensionToken(AddResult == 1);
    145   Info.setIsCXX11CompatKeyword(AddResult == 3);
    146 }
    147 
    148 /// AddCXXOperatorKeyword - Register a C++ operator keyword alternative
    149 /// representations.
    150 static void AddCXXOperatorKeyword(StringRef Keyword,
    151                                   tok::TokenKind TokenCode,
    152                                   IdentifierTable &Table) {
    153   IdentifierInfo &Info = Table.get(Keyword, TokenCode);
    154   Info.setIsCPlusPlusOperatorKeyword();
    155 }
    156 
    157 /// AddObjCKeyword - Register an Objective-C @keyword like "class" "selector" or
    158 /// "property".
    159 static void AddObjCKeyword(StringRef Name,
    160                            tok::ObjCKeywordKind ObjCID,
    161                            IdentifierTable &Table) {
    162   Table.get(Name).setObjCKeywordID(ObjCID);
    163 }
    164 
    165 /// AddKeywords - Add all keywords to the symbol table.
    166 ///
    167 void IdentifierTable::AddKeywords(const LangOptions &LangOpts) {
    168   // Add keywords and tokens for the current language.
    169 #define KEYWORD(NAME, FLAGS) \
    170   AddKeyword(StringRef(#NAME), tok::kw_ ## NAME,  \
    171              FLAGS, LangOpts, *this);
    172 #define ALIAS(NAME, TOK, FLAGS) \
    173   AddKeyword(StringRef(NAME), tok::kw_ ## TOK,  \
    174              FLAGS, LangOpts, *this);
    175 #define CXX_KEYWORD_OPERATOR(NAME, ALIAS) \
    176   if (LangOpts.CXXOperatorNames)          \
    177     AddCXXOperatorKeyword(StringRef(#NAME), tok::ALIAS, *this);
    178 #define OBJC1_AT_KEYWORD(NAME) \
    179   if (LangOpts.ObjC1)          \
    180     AddObjCKeyword(StringRef(#NAME), tok::objc_##NAME, *this);
    181 #define OBJC2_AT_KEYWORD(NAME) \
    182   if (LangOpts.ObjC2)          \
    183     AddObjCKeyword(StringRef(#NAME), tok::objc_##NAME, *this);
    184 #define TESTING_KEYWORD(NAME, FLAGS)
    185 #include "clang/Basic/TokenKinds.def"
    186 
    187   if (LangOpts.ParseUnknownAnytype)
    188     AddKeyword("__unknown_anytype", tok::kw___unknown_anytype, KEYALL,
    189                LangOpts, *this);
    190 }
    191 
    192 tok::PPKeywordKind IdentifierInfo::getPPKeywordID() const {
    193   // We use a perfect hash function here involving the length of the keyword,
    194   // the first and third character.  For preprocessor ID's there are no
    195   // collisions (if there were, the switch below would complain about duplicate
    196   // case values).  Note that this depends on 'if' being null terminated.
    197 
    198 #define HASH(LEN, FIRST, THIRD) \
    199   (LEN << 5) + (((FIRST-'a') + (THIRD-'a')) & 31)
    200 #define CASE(LEN, FIRST, THIRD, NAME) \
    201   case HASH(LEN, FIRST, THIRD): \
    202     return memcmp(Name, #NAME, LEN) ? tok::pp_not_keyword : tok::pp_ ## NAME
    203 
    204   unsigned Len = getLength();
    205   if (Len < 2) return tok::pp_not_keyword;
    206   const char *Name = getNameStart();
    207   switch (HASH(Len, Name[0], Name[2])) {
    208   default: return tok::pp_not_keyword;
    209   CASE( 2, 'i', '\0', if);
    210   CASE( 4, 'e', 'i', elif);
    211   CASE( 4, 'e', 's', else);
    212   CASE( 4, 'l', 'n', line);
    213   CASE( 4, 's', 'c', sccs);
    214   CASE( 5, 'e', 'd', endif);
    215   CASE( 5, 'e', 'r', error);
    216   CASE( 5, 'i', 'e', ident);
    217   CASE( 5, 'i', 'd', ifdef);
    218   CASE( 5, 'u', 'd', undef);
    219 
    220   CASE( 6, 'a', 's', assert);
    221   CASE( 6, 'd', 'f', define);
    222   CASE( 6, 'i', 'n', ifndef);
    223   CASE( 6, 'i', 'p', import);
    224   CASE( 6, 'p', 'a', pragma);
    225 
    226   CASE( 7, 'd', 'f', defined);
    227   CASE( 7, 'i', 'c', include);
    228   CASE( 7, 'w', 'r', warning);
    229 
    230   CASE( 8, 'u', 'a', unassert);
    231   CASE(12, 'i', 'c', include_next);
    232 
    233   CASE(14, '_', 'p', __public_macro);
    234 
    235   CASE(15, '_', 'p', __private_macro);
    236 
    237   CASE(16, '_', 'i', __include_macros);
    238 #undef CASE
    239 #undef HASH
    240   }
    241 }
    242 
    243 //===----------------------------------------------------------------------===//
    244 // Stats Implementation
    245 //===----------------------------------------------------------------------===//
    246 
    247 /// PrintStats - Print statistics about how well the identifier table is doing
    248 /// at hashing identifiers.
    249 void IdentifierTable::PrintStats() const {
    250   unsigned NumBuckets = HashTable.getNumBuckets();
    251   unsigned NumIdentifiers = HashTable.getNumItems();
    252   unsigned NumEmptyBuckets = NumBuckets-NumIdentifiers;
    253   unsigned AverageIdentifierSize = 0;
    254   unsigned MaxIdentifierLength = 0;
    255 
    256   // TODO: Figure out maximum times an identifier had to probe for -stats.
    257   for (llvm::StringMap<IdentifierInfo*, llvm::BumpPtrAllocator>::const_iterator
    258        I = HashTable.begin(), E = HashTable.end(); I != E; ++I) {
    259     unsigned IdLen = I->getKeyLength();
    260     AverageIdentifierSize += IdLen;
    261     if (MaxIdentifierLength < IdLen)
    262       MaxIdentifierLength = IdLen;
    263   }
    264 
    265   fprintf(stderr, "\n*** Identifier Table Stats:\n");
    266   fprintf(stderr, "# Identifiers:   %d\n", NumIdentifiers);
    267   fprintf(stderr, "# Empty Buckets: %d\n", NumEmptyBuckets);
    268   fprintf(stderr, "Hash density (#identifiers per bucket): %f\n",
    269           NumIdentifiers/(double)NumBuckets);
    270   fprintf(stderr, "Ave identifier length: %f\n",
    271           (AverageIdentifierSize/(double)NumIdentifiers));
    272   fprintf(stderr, "Max identifier length: %d\n", MaxIdentifierLength);
    273 
    274   // Compute statistics about the memory allocated for identifiers.
    275   HashTable.getAllocator().PrintStats();
    276 }
    277 
    278 //===----------------------------------------------------------------------===//
    279 // SelectorTable Implementation
    280 //===----------------------------------------------------------------------===//
    281 
    282 unsigned llvm::DenseMapInfo<clang::Selector>::getHashValue(clang::Selector S) {
    283   return DenseMapInfo<void*>::getHashValue(S.getAsOpaquePtr());
    284 }
    285 
    286 namespace clang {
    287 /// MultiKeywordSelector - One of these variable length records is kept for each
    288 /// selector containing more than one keyword. We use a folding set
    289 /// to unique aggregate names (keyword selectors in ObjC parlance). Access to
    290 /// this class is provided strictly through Selector.
    291 class MultiKeywordSelector
    292   : public DeclarationNameExtra, public llvm::FoldingSetNode {
    293   MultiKeywordSelector(unsigned nKeys) {
    294     ExtraKindOrNumArgs = NUM_EXTRA_KINDS + nKeys;
    295   }
    296 public:
    297   // Constructor for keyword selectors.
    298   MultiKeywordSelector(unsigned nKeys, IdentifierInfo **IIV) {
    299     assert((nKeys > 1) && "not a multi-keyword selector");
    300     ExtraKindOrNumArgs = NUM_EXTRA_KINDS + nKeys;
    301 
    302     // Fill in the trailing keyword array.
    303     IdentifierInfo **KeyInfo = reinterpret_cast<IdentifierInfo **>(this+1);
    304     for (unsigned i = 0; i != nKeys; ++i)
    305       KeyInfo[i] = IIV[i];
    306   }
    307 
    308   // getName - Derive the full selector name and return it.
    309   std::string getName() const;
    310 
    311   unsigned getNumArgs() const { return ExtraKindOrNumArgs - NUM_EXTRA_KINDS; }
    312 
    313   typedef IdentifierInfo *const *keyword_iterator;
    314   keyword_iterator keyword_begin() const {
    315     return reinterpret_cast<keyword_iterator>(this+1);
    316   }
    317   keyword_iterator keyword_end() const {
    318     return keyword_begin()+getNumArgs();
    319   }
    320   IdentifierInfo *getIdentifierInfoForSlot(unsigned i) const {
    321     assert(i < getNumArgs() && "getIdentifierInfoForSlot(): illegal index");
    322     return keyword_begin()[i];
    323   }
    324   static void Profile(llvm::FoldingSetNodeID &ID,
    325                       keyword_iterator ArgTys, unsigned NumArgs) {
    326     ID.AddInteger(NumArgs);
    327     for (unsigned i = 0; i != NumArgs; ++i)
    328       ID.AddPointer(ArgTys[i]);
    329   }
    330   void Profile(llvm::FoldingSetNodeID &ID) {
    331     Profile(ID, keyword_begin(), getNumArgs());
    332   }
    333 };
    334 } // end namespace clang.
    335 
    336 unsigned Selector::getNumArgs() const {
    337   unsigned IIF = getIdentifierInfoFlag();
    338   if (IIF == ZeroArg)
    339     return 0;
    340   if (IIF == OneArg)
    341     return 1;
    342   // We point to a MultiKeywordSelector (pointer doesn't contain any flags).
    343   MultiKeywordSelector *SI = reinterpret_cast<MultiKeywordSelector *>(InfoPtr);
    344   return SI->getNumArgs();
    345 }
    346 
    347 IdentifierInfo *Selector::getIdentifierInfoForSlot(unsigned argIndex) const {
    348   if (getIdentifierInfoFlag()) {
    349     assert(argIndex == 0 && "illegal keyword index");
    350     return getAsIdentifierInfo();
    351   }
    352   // We point to a MultiKeywordSelector (pointer doesn't contain any flags).
    353   MultiKeywordSelector *SI = reinterpret_cast<MultiKeywordSelector *>(InfoPtr);
    354   return SI->getIdentifierInfoForSlot(argIndex);
    355 }
    356 
    357 StringRef Selector::getNameForSlot(unsigned int argIndex) const {
    358   IdentifierInfo *II = getIdentifierInfoForSlot(argIndex);
    359   return II? II->getName() : StringRef();
    360 }
    361 
    362 std::string MultiKeywordSelector::getName() const {
    363   SmallString<256> Str;
    364   llvm::raw_svector_ostream OS(Str);
    365   for (keyword_iterator I = keyword_begin(), E = keyword_end(); I != E; ++I) {
    366     if (*I)
    367       OS << (*I)->getName();
    368     OS << ':';
    369   }
    370 
    371   return OS.str();
    372 }
    373 
    374 std::string Selector::getAsString() const {
    375   if (InfoPtr == 0)
    376     return "<null selector>";
    377 
    378   if (InfoPtr & ArgFlags) {
    379     IdentifierInfo *II = getAsIdentifierInfo();
    380 
    381     // If the number of arguments is 0 then II is guaranteed to not be null.
    382     if (getNumArgs() == 0)
    383       return II->getName();
    384 
    385     if (!II)
    386       return ":";
    387 
    388     return II->getName().str() + ":";
    389   }
    390 
    391   // We have a multiple keyword selector (no embedded flags).
    392   return reinterpret_cast<MultiKeywordSelector *>(InfoPtr)->getName();
    393 }
    394 
    395 /// Interpreting the given string using the normal CamelCase
    396 /// conventions, determine whether the given string starts with the
    397 /// given "word", which is assumed to end in a lowercase letter.
    398 static bool startsWithWord(StringRef name, StringRef word) {
    399   if (name.size() < word.size()) return false;
    400   return ((name.size() == word.size() ||
    401            !islower(name[word.size()]))
    402           && name.startswith(word));
    403 }
    404 
    405 ObjCMethodFamily Selector::getMethodFamilyImpl(Selector sel) {
    406   IdentifierInfo *first = sel.getIdentifierInfoForSlot(0);
    407   if (!first) return OMF_None;
    408 
    409   StringRef name = first->getName();
    410   if (sel.isUnarySelector()) {
    411     if (name == "autorelease") return OMF_autorelease;
    412     if (name == "dealloc") return OMF_dealloc;
    413     if (name == "finalize") return OMF_finalize;
    414     if (name == "release") return OMF_release;
    415     if (name == "retain") return OMF_retain;
    416     if (name == "retainCount") return OMF_retainCount;
    417     if (name == "self") return OMF_self;
    418   }
    419 
    420   if (name == "performSelector") return OMF_performSelector;
    421 
    422   // The other method families may begin with a prefix of underscores.
    423   while (!name.empty() && name.front() == '_')
    424     name = name.substr(1);
    425 
    426   if (name.empty()) return OMF_None;
    427   switch (name.front()) {
    428   case 'a':
    429     if (startsWithWord(name, "alloc")) return OMF_alloc;
    430     break;
    431   case 'c':
    432     if (startsWithWord(name, "copy")) return OMF_copy;
    433     break;
    434   case 'i':
    435     if (startsWithWord(name, "init")) return OMF_init;
    436     break;
    437   case 'm':
    438     if (startsWithWord(name, "mutableCopy")) return OMF_mutableCopy;
    439     break;
    440   case 'n':
    441     if (startsWithWord(name, "new")) return OMF_new;
    442     break;
    443   default:
    444     break;
    445   }
    446 
    447   return OMF_None;
    448 }
    449 
    450 namespace {
    451   struct SelectorTableImpl {
    452     llvm::FoldingSet<MultiKeywordSelector> Table;
    453     llvm::BumpPtrAllocator Allocator;
    454   };
    455 } // end anonymous namespace.
    456 
    457 static SelectorTableImpl &getSelectorTableImpl(void *P) {
    458   return *static_cast<SelectorTableImpl*>(P);
    459 }
    460 
    461 /*static*/ Selector
    462 SelectorTable::constructSetterName(IdentifierTable &Idents,
    463                                    SelectorTable &SelTable,
    464                                    const IdentifierInfo *Name) {
    465   SmallString<100> SelectorName;
    466   SelectorName = "set";
    467   SelectorName += Name->getName();
    468   SelectorName[3] = toupper(SelectorName[3]);
    469   IdentifierInfo *SetterName = &Idents.get(SelectorName);
    470   return SelTable.getUnarySelector(SetterName);
    471 }
    472 
    473 size_t SelectorTable::getTotalMemory() const {
    474   SelectorTableImpl &SelTabImpl = getSelectorTableImpl(Impl);
    475   return SelTabImpl.Allocator.getTotalMemory();
    476 }
    477 
    478 Selector SelectorTable::getSelector(unsigned nKeys, IdentifierInfo **IIV) {
    479   if (nKeys < 2)
    480     return Selector(IIV[0], nKeys);
    481 
    482   SelectorTableImpl &SelTabImpl = getSelectorTableImpl(Impl);
    483 
    484   // Unique selector, to guarantee there is one per name.
    485   llvm::FoldingSetNodeID ID;
    486   MultiKeywordSelector::Profile(ID, IIV, nKeys);
    487 
    488   void *InsertPos = 0;
    489   if (MultiKeywordSelector *SI =
    490         SelTabImpl.Table.FindNodeOrInsertPos(ID, InsertPos))
    491     return Selector(SI);
    492 
    493   // MultiKeywordSelector objects are not allocated with new because they have a
    494   // variable size array (for parameter types) at the end of them.
    495   unsigned Size = sizeof(MultiKeywordSelector) + nKeys*sizeof(IdentifierInfo *);
    496   MultiKeywordSelector *SI =
    497     (MultiKeywordSelector*)SelTabImpl.Allocator.Allocate(Size,
    498                                          llvm::alignOf<MultiKeywordSelector>());
    499   new (SI) MultiKeywordSelector(nKeys, IIV);
    500   SelTabImpl.Table.InsertNode(SI, InsertPos);
    501   return Selector(SI);
    502 }
    503 
    504 SelectorTable::SelectorTable() {
    505   Impl = new SelectorTableImpl();
    506 }
    507 
    508 SelectorTable::~SelectorTable() {
    509   delete &getSelectorTableImpl(Impl);
    510 }
    511 
    512 const char *clang::getOperatorSpelling(OverloadedOperatorKind Operator) {
    513   switch (Operator) {
    514   case OO_None:
    515   case NUM_OVERLOADED_OPERATORS:
    516     return 0;
    517 
    518 #define OVERLOADED_OPERATOR(Name,Spelling,Token,Unary,Binary,MemberOnly) \
    519   case OO_##Name: return Spelling;
    520 #include "clang/Basic/OperatorKinds.def"
    521   }
    522 
    523   llvm_unreachable("Invalid OverloadedOperatorKind!");
    524 }
    525