lib/Basic/IdentifierTable.cpp

   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/StringRef.h"
  20 #include "llvm/Support/raw_ostream.h"
  21 #include <cstdio>
  22
  23 using namespace clang;
  24
  25 //===----------------------------------------------------------------------===//
  26 // IdentifierInfo Implementation
  27 //===----------------------------------------------------------------------===//
  28
  29 IdentifierInfo::IdentifierInfo() {
  30   TokenID = tok::identifier;
  31   ObjCOrBuiltinID = 0;
  32   HasMacro = false;
  33   IsExtension = false;
  34   IsPoisoned = false;
  35   IsCPPOperatorKeyword = false;
  36   NeedsHandleIdentifier = false;
  37   IsFromAST = false;
  38   RevertedTokenID = false;
  39   FETokenInfo = 0;
  40   Entry = 0;
  41 }
  42
  43 //===----------------------------------------------------------------------===//
  44 // IdentifierTable Implementation
  45 //===----------------------------------------------------------------------===//
  46
  47 IdentifierIterator::~IdentifierIterator() { }
  48
  49 IdentifierInfoLookup::~IdentifierInfoLookup() {}
  50
  51 namespace {
  52   /// \brief A simple identifier lookup iterator that represents an
  53   /// empty sequence of identifiers.
  54   class EmptyLookupIterator : public IdentifierIterator
  55   {
  56   public:
  57     virtual llvm::StringRef Next() { return llvm::StringRef(); }
  58   };
  59 }
  60
  61 IdentifierIterator *IdentifierInfoLookup::getIdentifiers() const {
  62   return new EmptyLookupIterator();
  63 }
  64
  65 ExternalIdentifierLookup::~ExternalIdentifierLookup() {}
  66
  67 IdentifierTable::IdentifierTable(const LangOptions &LangOpts,
  68                                  IdentifierInfoLookup* externalLookup)
  69   : HashTable(8192), // Start with space for 8K identifiers.
  70     ExternalLookup(externalLookup) {
  71
  72   // Populate the identifier table with info about keywords for the current
  73   // language.
  74   AddKeywords(LangOpts);
  75 }
  76
  77 //===----------------------------------------------------------------------===//
  78 // Language Keyword Implementation
  79 //===----------------------------------------------------------------------===//
  80
  81 // Constants for TokenKinds.def
  82 namespace {
  83   enum {
  84     KEYALL = 1,
  85     KEYC99 = 2,
  86     KEYCXX = 4,
  87     KEYCXX0X = 8,
  88     KEYGNU = 16,
  89     KEYMS = 32,
  90     BOOLSUPPORT = 64,
  91     KEYALTIVEC = 128,
  92     KEYNOCXX = 256,
  93     KEYBORLAND = 512,
  94     KEYOPENCL = 1024
  95   };
  96 }
  97
  98 /// AddKeyword - This method is used to associate a token ID with specific
  99 /// identifiers because they are language keywords.  This causes the lexer to
 100 /// automatically map matching identifiers to specialized token codes.
 101 ///
 102 /// The C90/C99/CPP/CPP0x flags are set to 2 if the token should be
 103 /// enabled in the specified langauge, set to 1 if it is an extension
 104 /// in the specified language, and set to 0 if disabled in the
 105 /// specified language.
 106 static void AddKeyword(llvm::StringRef Keyword,
 107                        tok::TokenKind TokenCode, unsigned Flags,
 108                        const LangOptions &LangOpts, IdentifierTable &Table) {
 109   unsigned AddResult = 0;
 110   if (Flags & KEYALL) AddResult = 2;
 111   else if (LangOpts.CPlusPlus && (Flags & KEYCXX)) AddResult = 2;
 112   else if (LangOpts.CPlusPlus0x && (Flags & KEYCXX0X)) AddResult = 2;
 113   else if (LangOpts.C99 && (Flags & KEYC99)) AddResult = 2;
 114   else if (LangOpts.GNUKeywords && (Flags & KEYGNU)) AddResult = 1;
 115   else if (LangOpts.Microsoft && (Flags & KEYMS)) AddResult = 1;
 116   else if (LangOpts.Borland && (Flags & KEYBORLAND)) AddResult = 1;
 117   else if (LangOpts.Bool && (Flags & BOOLSUPPORT)) AddResult = 2;
 118   else if (LangOpts.AltiVec && (Flags & KEYALTIVEC)) AddResult = 2;
 119   else if (LangOpts.OpenCL && (Flags & KEYOPENCL)) AddResult = 2;
 120   else if (!LangOpts.CPlusPlus && (Flags & KEYNOCXX)) AddResult = 2;
 121
 122   // Don't add this keyword if disabled in this language.
 123   if (AddResult == 0) return;
 124
 125   IdentifierInfo &Info = Table.get(Keyword, TokenCode);
 126   Info.setIsExtensionToken(AddResult == 1);
 127 }
 128
 129 /// AddCXXOperatorKeyword - Register a C++ operator keyword alternative
 130 /// representations.
 131 static void AddCXXOperatorKeyword(llvm::StringRef Keyword,
 132                                   tok::TokenKind TokenCode,
 133                                   IdentifierTable &Table) {
 134   IdentifierInfo &Info = Table.get(Keyword, TokenCode);
 135   Info.setIsCPlusPlusOperatorKeyword();
 136 }
 137
 138 /// AddObjCKeyword - Register an Objective-C @keyword like "class" "selector" or
 139 /// "property".
 140 static void AddObjCKeyword(llvm::StringRef Name,
 141                            tok::ObjCKeywordKind ObjCID,
 142                            IdentifierTable &Table) {
 143   Table.get(Name).setObjCKeywordID(ObjCID);
 144 }
 145
 146 /// AddKeywords - Add all keywords to the symbol table.
 147 ///
 148 void IdentifierTable::AddKeywords(const LangOptions &LangOpts) {
 149   // Add keywords and tokens for the current language.
 150 #define KEYWORD(NAME, FLAGS) \
 151   AddKeyword(llvm::StringRef(#NAME), tok::kw_ ## NAME,  \
 152              FLAGS, LangOpts, *this);
 153 #define ALIAS(NAME, TOK, FLAGS) \
 154   AddKeyword(llvm::StringRef(NAME), tok::kw_ ## TOK,  \
 155              FLAGS, LangOpts, *this);
 156 #define CXX_KEYWORD_OPERATOR(NAME, ALIAS) \
 157   if (LangOpts.CXXOperatorNames)          \
 158     AddCXXOperatorKeyword(llvm::StringRef(#NAME), tok::ALIAS, *this);
 159 #define OBJC1_AT_KEYWORD(NAME) \
 160   if (LangOpts.ObjC1)          \
 161     AddObjCKeyword(llvm::StringRef(#NAME), tok::objc_##NAME, *this);
 162 #define OBJC2_AT_KEYWORD(NAME) \
 163   if (LangOpts.ObjC2)          \
 164     AddObjCKeyword(llvm::StringRef(#NAME), tok::objc_##NAME, *this);
 165 #include "clang/Basic/TokenKinds.def"
 166 }
 167
 168 tok::PPKeywordKind IdentifierInfo::getPPKeywordID() const {
 169   // We use a perfect hash function here involving the length of the keyword,
 170   // the first and third character.  For preprocessor ID's there are no
 171   // collisions (if there were, the switch below would complain about duplicate
 172   // case values).  Note that this depends on 'if' being null terminated.
 173
 174 #define HASH(LEN, FIRST, THIRD) \
 175   (LEN << 5) + (((FIRST-'a') + (THIRD-'a')) & 31)
 176 #define CASE(LEN, FIRST, THIRD, NAME) \
 177   case HASH(LEN, FIRST, THIRD): \
 178     return memcmp(Name, #NAME, LEN) ? tok::pp_not_keyword : tok::pp_ ## NAME
 179
 180   unsigned Len = getLength();
 181   if (Len < 2) return tok::pp_not_keyword;
 182   const char *Name = getNameStart();
 183   switch (HASH(Len, Name[0], Name[2])) {
 184   default: return tok::pp_not_keyword;
 185   CASE( 2, 'i', '\0', if);
 186   CASE( 4, 'e', 'i', elif);
 187   CASE( 4, 'e', 's', else);
 188   CASE( 4, 'l', 'n', line);
 189   CASE( 4, 's', 'c', sccs);
 190   CASE( 5, 'e', 'd', endif);
 191   CASE( 5, 'e', 'r', error);
 192   CASE( 5, 'i', 'e', ident);
 193   CASE( 5, 'i', 'd', ifdef);
 194   CASE( 5, 'u', 'd', undef);
 195
 196   CASE( 6, 'a', 's', assert);
 197   CASE( 6, 'd', 'f', define);
 198   CASE( 6, 'i', 'n', ifndef);
 199   CASE( 6, 'i', 'p', import);
 200   CASE( 6, 'p', 'a', pragma);
 201
 202   CASE( 7, 'd', 'f', defined);
 203   CASE( 7, 'i', 'c', include);
 204   CASE( 7, 'w', 'r', warning);
 205
 206   CASE( 8, 'u', 'a', unassert);
 207   CASE(12, 'i', 'c', include_next);
 208
 209   CASE(16, '_', 'i', __include_macros);
 210 #undef CASE
 211 #undef HASH
 212   }
 213 }
 214
 215 //===----------------------------------------------------------------------===//
 216 // Stats Implementation
 217 //===----------------------------------------------------------------------===//
 218
 219 /// PrintStats - Print statistics about how well the identifier table is doing
 220 /// at hashing identifiers.
 221 void IdentifierTable::PrintStats() const {
 222   unsigned NumBuckets = HashTable.getNumBuckets();
 223   unsigned NumIdentifiers = HashTable.getNumItems();
 224   unsigned NumEmptyBuckets = NumBuckets-NumIdentifiers;
 225   unsigned AverageIdentifierSize = 0;
 226   unsigned MaxIdentifierLength = 0;
 227
 228   // TODO: Figure out maximum times an identifier had to probe for -stats.
 229   for (llvm::StringMap<IdentifierInfo*, llvm::BumpPtrAllocator>::const_iterator
 230        I = HashTable.begin(), E = HashTable.end(); I != E; ++I) {
 231     unsigned IdLen = I->getKeyLength();
 232     AverageIdentifierSize += IdLen;
 233     if (MaxIdentifierLength < IdLen)
 234       MaxIdentifierLength = IdLen;
 235   }
 236
 237   fprintf(stderr, "\n*** Identifier Table Stats:\n");
 238   fprintf(stderr, "# Identifiers:   %d\n", NumIdentifiers);
 239   fprintf(stderr, "# Empty Buckets: %d\n", NumEmptyBuckets);
 240   fprintf(stderr, "Hash density (#identifiers per bucket): %f\n",
 241           NumIdentifiers/(double)NumBuckets);
 242   fprintf(stderr, "Ave identifier length: %f\n",
 243           (AverageIdentifierSize/(double)NumIdentifiers));
 244   fprintf(stderr, "Max identifier length: %d\n", MaxIdentifierLength);
 245
 246   // Compute statistics about the memory allocated for identifiers.
 247   HashTable.getAllocator().PrintStats();
 248 }
 249
 250 //===----------------------------------------------------------------------===//
 251 // SelectorTable Implementation
 252 //===----------------------------------------------------------------------===//
 253
 254 unsigned llvm::DenseMapInfo<clang::Selector>::getHashValue(clang::Selector S) {
 255   return DenseMapInfo<void*>::getHashValue(S.getAsOpaquePtr());
 256 }
 257
 258 namespace clang {
 259 /// MultiKeywordSelector - One of these variable length records is kept for each
 260 /// selector containing more than one keyword. We use a folding set
 261 /// to unique aggregate names (keyword selectors in ObjC parlance). Access to
 262 /// this class is provided strictly through Selector.
 263 class MultiKeywordSelector
 264   : public DeclarationNameExtra, public llvm::FoldingSetNode {
 265   MultiKeywordSelector(unsigned nKeys) {
 266     ExtraKindOrNumArgs = NUM_EXTRA_KINDS + nKeys;
 267   }
 268 public:
 269   // Constructor for keyword selectors.
 270   MultiKeywordSelector(unsigned nKeys, IdentifierInfo **IIV) {
 271     assert((nKeys > 1) && "not a multi-keyword selector");
 272     ExtraKindOrNumArgs = NUM_EXTRA_KINDS + nKeys;
 273
 274     // Fill in the trailing keyword array.
 275     IdentifierInfo **KeyInfo = reinterpret_cast<IdentifierInfo **>(this+1);
 276     for (unsigned i = 0; i != nKeys; ++i)
 277       KeyInfo[i] = IIV[i];
 278   }
 279
 280   // getName - Derive the full selector name and return it.
 281   std::string getName() const;
 282
 283   unsigned getNumArgs() const { return ExtraKindOrNumArgs - NUM_EXTRA_KINDS; }
 284
 285   typedef IdentifierInfo *const *keyword_iterator;
 286   keyword_iterator keyword_begin() const {
 287     return reinterpret_cast<keyword_iterator>(this+1);
 288   }
 289   keyword_iterator keyword_end() const {
 290     return keyword_begin()+getNumArgs();
 291   }
 292   IdentifierInfo *getIdentifierInfoForSlot(unsigned i) const {
 293     assert(i < getNumArgs() && "getIdentifierInfoForSlot(): illegal index");
 294     return keyword_begin()[i];
 295   }
 296   static void Profile(llvm::FoldingSetNodeID &ID,
 297                       keyword_iterator ArgTys, unsigned NumArgs) {
 298     ID.AddInteger(NumArgs);
 299     for (unsigned i = 0; i != NumArgs; ++i)
 300       ID.AddPointer(ArgTys[i]);
 301   }
 302   void Profile(llvm::FoldingSetNodeID &ID) {
 303     Profile(ID, keyword_begin(), getNumArgs());
 304   }
 305 };
 306 } // end namespace clang.
 307
 308 unsigned Selector::getNumArgs() const {
 309   unsigned IIF = getIdentifierInfoFlag();
 310   if (IIF == ZeroArg)
 311     return 0;
 312   if (IIF == OneArg)
 313     return 1;
 314   // We point to a MultiKeywordSelector (pointer doesn't contain any flags).
 315   MultiKeywordSelector *SI = reinterpret_cast<MultiKeywordSelector *>(InfoPtr);
 316   return SI->getNumArgs();
 317 }
 318
 319 IdentifierInfo *Selector::getIdentifierInfoForSlot(unsigned argIndex) const {
 320   if (getIdentifierInfoFlag()) {
 321     assert(argIndex == 0 && "illegal keyword index");
 322     return getAsIdentifierInfo();
 323   }
 324   // We point to a MultiKeywordSelector (pointer doesn't contain any flags).
 325   MultiKeywordSelector *SI = reinterpret_cast<MultiKeywordSelector *>(InfoPtr);
 326   return SI->getIdentifierInfoForSlot(argIndex);
 327 }
 328
 329 std::string MultiKeywordSelector::getName() const {
 330   llvm::SmallString<256> Str;
 331   llvm::raw_svector_ostream OS(Str);
 332   for (keyword_iterator I = keyword_begin(), E = keyword_end(); I != E; ++I) {
 333     if (*I)
 334       OS << (*I)->getName();
 335     OS << ':';
 336   }
 337
 338   return OS.str();
 339 }
 340
 341 std::string Selector::getAsString() const {
 342   if (InfoPtr == 0)
 343     return "<null selector>";
 344
 345   if (InfoPtr & ArgFlags) {
 346     IdentifierInfo *II = getAsIdentifierInfo();
 347
 348     // If the number of arguments is 0 then II is guaranteed to not be null.
 349     if (getNumArgs() == 0)
 350       return II->getName();
 351
 352     if (!II)
 353       return ":";
 354
 355     return II->getName().str() + ":";
 356   }
 357
 358   // We have a multiple keyword selector (no embedded flags).
 359   return reinterpret_cast<MultiKeywordSelector *>(InfoPtr)->getName();
 360 }
 361
 362
 363 namespace {
 364   struct SelectorTableImpl {
 365     llvm::FoldingSet<MultiKeywordSelector> Table;
 366     llvm::BumpPtrAllocator Allocator;
 367   };
 368 } // end anonymous namespace.
 369
 370 static SelectorTableImpl &getSelectorTableImpl(void *P) {
 371   return *static_cast<SelectorTableImpl*>(P);
 372 }
 373
 374
 375 Selector SelectorTable::getSelector(unsigned nKeys, IdentifierInfo **IIV) {
 376   if (nKeys < 2)
 377     return Selector(IIV[0], nKeys);
 378
 379   SelectorTableImpl &SelTabImpl = getSelectorTableImpl(Impl);
 380
 381   // Unique selector, to guarantee there is one per name.
 382   llvm::FoldingSetNodeID ID;
 383   MultiKeywordSelector::Profile(ID, IIV, nKeys);
 384
 385   void *InsertPos = 0;
 386   if (MultiKeywordSelector *SI =
 387         SelTabImpl.Table.FindNodeOrInsertPos(ID, InsertPos))
 388     return Selector(SI);
 389
 390   // MultiKeywordSelector objects are not allocated with new because they have a
 391   // variable size array (for parameter types) at the end of them.
 392   unsigned Size = sizeof(MultiKeywordSelector) + nKeys*sizeof(IdentifierInfo *);
 393   MultiKeywordSelector *SI =
 394     (MultiKeywordSelector*)SelTabImpl.Allocator.Allocate(Size,
 395                                          llvm::alignOf<MultiKeywordSelector>());
 396   new (SI) MultiKeywordSelector(nKeys, IIV);
 397   SelTabImpl.Table.InsertNode(SI, InsertPos);
 398   return Selector(SI);
 399 }
 400
 401 SelectorTable::SelectorTable() {
 402   Impl = new SelectorTableImpl();
 403 }
 404
 405 SelectorTable::~SelectorTable() {
 406   delete &getSelectorTableImpl(Impl);
 407 }
 408
 409 const char *clang::getOperatorSpelling(OverloadedOperatorKind Operator) {
 410   switch (Operator) {
 411   case OO_None:
 412   case NUM_OVERLOADED_OPERATORS:
 413     return 0;
 414
 415 #define OVERLOADED_OPERATOR(Name,Spelling,Token,Unary,Binary,MemberOnly) \
 416   case OO_##Name: return Spelling;
 417 #include "clang/Basic/OperatorKinds.def"
 418   }
 419
 420   return 0;
 421 }
 422