IdentifierTable.cpp revision 195099 
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 <cstdio>
20
21using namespace clang;
22
23//===----------------------------------------------------------------------===//
24// IdentifierInfo Implementation
25//===----------------------------------------------------------------------===//
26
27IdentifierInfo::IdentifierInfo() {
28  TokenID = tok::identifier;
29  ObjCOrBuiltinID = 0;
30  HasMacro = false;
31  IsExtension = false;
32  IsPoisoned = false;
33  IsCPPOperatorKeyword = false;
34  NeedsHandleIdentifier = false;
35  FETokenInfo = 0;
36  Entry = 0;
37}
38
39//===----------------------------------------------------------------------===//
40// IdentifierTable Implementation
41//===----------------------------------------------------------------------===//
42
43IdentifierInfoLookup::~IdentifierInfoLookup() {}
44
45ExternalIdentifierLookup::~ExternalIdentifierLookup() {}
46
47IdentifierTable::IdentifierTable(const LangOptions &LangOpts,
48                                 IdentifierInfoLookup* externalLookup)
49  : HashTable(8192), // Start with space for 8K identifiers.
50    ExternalLookup(externalLookup) {
51
52  // Populate the identifier table with info about keywords for the current
53  // language.
54  AddKeywords(LangOpts);
55}
56
57//===----------------------------------------------------------------------===//
58// Language Keyword Implementation
59//===----------------------------------------------------------------------===//
60
61// Constants for TokenKinds.def
62namespace {
63  enum {
64    KEYALL = 1,
65    KEYC99 = 2,
66    KEYCXX = 4,
67    KEYCXX0X = 8,
68    KEYGNU = 16,
69    KEYMS = 32,
70    BOOLSUPPORT = 64
71  };
72}
73
74/// AddKeyword - This method is used to associate a token ID with specific
75/// identifiers because they are language keywords.  This causes the lexer to
76/// automatically map matching identifiers to specialized token codes.
77///
78/// The C90/C99/CPP/CPP0x flags are set to 0 if the token should be
79/// enabled in the specified langauge, set to 1 if it is an extension
80/// in the specified language, and set to 2 if disabled in the
81/// specified language.
82static void AddKeyword(const char *Keyword, unsigned KWLen,
83                       tok::TokenKind TokenCode, unsigned Flags,
84                       const LangOptions &LangOpts, IdentifierTable &Table) {
85  unsigned AddResult = 0;
86  if (Flags & KEYALL) AddResult = 2;
87  else if (LangOpts.CPlusPlus && (Flags & KEYCXX)) AddResult = 2;
88  else if (LangOpts.CPlusPlus0x && (Flags & KEYCXX0X)) AddResult = 2;
89  else if (LangOpts.C99 && (Flags & KEYC99)) AddResult = 2;
90  else if (LangOpts.GNUMode && (Flags & KEYGNU)) AddResult = 1;
91  else if (LangOpts.Microsoft && (Flags & KEYMS)) AddResult = 1;
92  else if (LangOpts.OpenCL && (Flags & BOOLSUPPORT)) AddResult = 2;
93
94  // Don't add this keyword if disabled in this language.
95  if (AddResult == 0) return;
96
97  IdentifierInfo &Info = Table.get(Keyword, Keyword+KWLen);
98  Info.setTokenID(TokenCode);
99  Info.setIsExtensionToken(AddResult == 1);
100}
101
102/// AddCXXOperatorKeyword - Register a C++ operator keyword alternative
103/// representations.
104static void AddCXXOperatorKeyword(const char *Keyword, unsigned KWLen,
105                                  tok::TokenKind TokenCode,
106                                  IdentifierTable &Table) {
107  IdentifierInfo &Info = Table.get(Keyword, Keyword + KWLen);
108  Info.setTokenID(TokenCode);
109  Info.setIsCPlusPlusOperatorKeyword();
110}
111
112/// AddObjCKeyword - Register an Objective-C @keyword like "class" "selector" or
113/// "property".
114static void AddObjCKeyword(tok::ObjCKeywordKind ObjCID,
115                           const char *Name, unsigned NameLen,
116                           IdentifierTable &Table) {
117  Table.get(Name, Name+NameLen).setObjCKeywordID(ObjCID);
118}
119
120/// AddKeywords - Add all keywords to the symbol table.
121///
122void IdentifierTable::AddKeywords(const LangOptions &LangOpts) {
123  // Add keywords and tokens for the current language.
124#define KEYWORD(NAME, FLAGS) \
125  AddKeyword(#NAME, strlen(#NAME), tok::kw_ ## NAME,  \
126             FLAGS, LangOpts, *this);
127#define ALIAS(NAME, TOK, FLAGS) \
128  AddKeyword(NAME, strlen(NAME), tok::kw_ ## TOK,  \
129             FLAGS, LangOpts, *this);
130#define CXX_KEYWORD_OPERATOR(NAME, ALIAS) \
131  if (LangOpts.CXXOperatorNames)          \
132    AddCXXOperatorKeyword(#NAME, strlen(#NAME), tok::ALIAS, *this);
133#define OBJC1_AT_KEYWORD(NAME) \
134  if (LangOpts.ObjC1)          \
135    AddObjCKeyword(tok::objc_##NAME, #NAME, strlen(#NAME), *this);
136#define OBJC2_AT_KEYWORD(NAME) \
137  if (LangOpts.ObjC2)          \
138    AddObjCKeyword(tok::objc_##NAME, #NAME, strlen(#NAME), *this);
139#include "clang/Basic/TokenKinds.def"
140}
141
142tok::PPKeywordKind IdentifierInfo::getPPKeywordID() const {
143  // We use a perfect hash function here involving the length of the keyword,
144  // the first and third character.  For preprocessor ID's there are no
145  // collisions (if there were, the switch below would complain about duplicate
146  // case values).  Note that this depends on 'if' being null terminated.
147
148#define HASH(LEN, FIRST, THIRD) \
149  (LEN << 5) + (((FIRST-'a') + (THIRD-'a')) & 31)
150#define CASE(LEN, FIRST, THIRD, NAME) \
151  case HASH(LEN, FIRST, THIRD): \
152    return memcmp(Name, #NAME, LEN) ? tok::pp_not_keyword : tok::pp_ ## NAME
153
154  unsigned Len = getLength();
155  if (Len < 2) return tok::pp_not_keyword;
156  const char *Name = getName();
157  switch (HASH(Len, Name[0], Name[2])) {
158  default: return tok::pp_not_keyword;
159  CASE( 2, 'i', '\0', if);
160  CASE( 4, 'e', 'i', elif);
161  CASE( 4, 'e', 's', else);
162  CASE( 4, 'l', 'n', line);
163  CASE( 4, 's', 'c', sccs);
164  CASE( 5, 'e', 'd', endif);
165  CASE( 5, 'e', 'r', error);
166  CASE( 5, 'i', 'e', ident);
167  CASE( 5, 'i', 'd', ifdef);
168  CASE( 5, 'u', 'd', undef);
169
170  CASE( 6, 'a', 's', assert);
171  CASE( 6, 'd', 'f', define);
172  CASE( 6, 'i', 'n', ifndef);
173  CASE( 6, 'i', 'p', import);
174  CASE( 6, 'p', 'a', pragma);
175
176  CASE( 7, 'd', 'f', defined);
177  CASE( 7, 'i', 'c', include);
178  CASE( 7, 'w', 'r', warning);
179
180  CASE( 8, 'u', 'a', unassert);
181  CASE(12, 'i', 'c', include_next);
182
183  CASE(16, '_', 'i', __include_macros);
184#undef CASE
185#undef HASH
186  }
187}
188
189//===----------------------------------------------------------------------===//
190// Stats Implementation
191//===----------------------------------------------------------------------===//
192
193/// PrintStats - Print statistics about how well the identifier table is doing
194/// at hashing identifiers.
195void IdentifierTable::PrintStats() const {
196  unsigned NumBuckets = HashTable.getNumBuckets();
197  unsigned NumIdentifiers = HashTable.getNumItems();
198  unsigned NumEmptyBuckets = NumBuckets-NumIdentifiers;
199  unsigned AverageIdentifierSize = 0;
200  unsigned MaxIdentifierLength = 0;
201
202  // TODO: Figure out maximum times an identifier had to probe for -stats.
203  for (llvm::StringMap<IdentifierInfo*, llvm::BumpPtrAllocator>::const_iterator
204       I = HashTable.begin(), E = HashTable.end(); I != E; ++I) {
205    unsigned IdLen = I->getKeyLength();
206    AverageIdentifierSize += IdLen;
207    if (MaxIdentifierLength < IdLen)
208      MaxIdentifierLength = IdLen;
209  }
210
211  fprintf(stderr, "\n*** Identifier Table Stats:\n");
212  fprintf(stderr, "# Identifiers:   %d\n", NumIdentifiers);
213  fprintf(stderr, "# Empty Buckets: %d\n", NumEmptyBuckets);
214  fprintf(stderr, "Hash density (#identifiers per bucket): %f\n",
215          NumIdentifiers/(double)NumBuckets);
216  fprintf(stderr, "Ave identifier length: %f\n",
217          (AverageIdentifierSize/(double)NumIdentifiers));
218  fprintf(stderr, "Max identifier length: %d\n", MaxIdentifierLength);
219
220  // Compute statistics about the memory allocated for identifiers.
221  HashTable.getAllocator().PrintStats();
222}
223
224//===----------------------------------------------------------------------===//
225// SelectorTable Implementation
226//===----------------------------------------------------------------------===//
227
228unsigned llvm::DenseMapInfo<clang::Selector>::getHashValue(clang::Selector S) {
229  return DenseMapInfo<void*>::getHashValue(S.getAsOpaquePtr());
230}
231
232namespace clang {
233/// MultiKeywordSelector - One of these variable length records is kept for each
234/// selector containing more than one keyword. We use a folding set
235/// to unique aggregate names (keyword selectors in ObjC parlance). Access to
236/// this class is provided strictly through Selector.
237class MultiKeywordSelector
238  : public DeclarationNameExtra, public llvm::FoldingSetNode {
239  MultiKeywordSelector(unsigned nKeys) {
240    ExtraKindOrNumArgs = NUM_EXTRA_KINDS + nKeys;
241  }
242public:
243  // Constructor for keyword selectors.
244  MultiKeywordSelector(unsigned nKeys, IdentifierInfo **IIV) {
245    assert((nKeys > 1) && "not a multi-keyword selector");
246    ExtraKindOrNumArgs = NUM_EXTRA_KINDS + nKeys;
247
248    // Fill in the trailing keyword array.
249    IdentifierInfo **KeyInfo = reinterpret_cast<IdentifierInfo **>(this+1);
250    for (unsigned i = 0; i != nKeys; ++i)
251      KeyInfo[i] = IIV[i];
252  }
253
254  // getName - Derive the full selector name and return it.
255  std::string getName() const;
256
257  unsigned getNumArgs() const { return ExtraKindOrNumArgs - NUM_EXTRA_KINDS; }
258
259  typedef IdentifierInfo *const *keyword_iterator;
260  keyword_iterator keyword_begin() const {
261    return reinterpret_cast<keyword_iterator>(this+1);
262  }
263  keyword_iterator keyword_end() const {
264    return keyword_begin()+getNumArgs();
265  }
266  IdentifierInfo *getIdentifierInfoForSlot(unsigned i) const {
267    assert(i < getNumArgs() && "getIdentifierInfoForSlot(): illegal index");
268    return keyword_begin()[i];
269  }
270  static void Profile(llvm::FoldingSetNodeID &ID,
271                      keyword_iterator ArgTys, unsigned NumArgs) {
272    ID.AddInteger(NumArgs);
273    for (unsigned i = 0; i != NumArgs; ++i)
274      ID.AddPointer(ArgTys[i]);
275  }
276  void Profile(llvm::FoldingSetNodeID &ID) {
277    Profile(ID, keyword_begin(), getNumArgs());
278  }
279};
280} // end namespace clang.
281
282unsigned Selector::getNumArgs() const {
283  unsigned IIF = getIdentifierInfoFlag();
284  if (IIF == ZeroArg)
285    return 0;
286  if (IIF == OneArg)
287    return 1;
288  // We point to a MultiKeywordSelector (pointer doesn't contain any flags).
289  MultiKeywordSelector *SI = reinterpret_cast<MultiKeywordSelector *>(InfoPtr);
290  return SI->getNumArgs();
291}
292
293IdentifierInfo *Selector::getIdentifierInfoForSlot(unsigned argIndex) const {
294  if (getIdentifierInfoFlag()) {
295    assert(argIndex == 0 && "illegal keyword index");
296    return getAsIdentifierInfo();
297  }
298  // We point to a MultiKeywordSelector (pointer doesn't contain any flags).
299  MultiKeywordSelector *SI = reinterpret_cast<MultiKeywordSelector *>(InfoPtr);
300  return SI->getIdentifierInfoForSlot(argIndex);
301}
302
303std::string MultiKeywordSelector::getName() const {
304  std::string Result;
305  unsigned Length = 0;
306  for (keyword_iterator I = keyword_begin(), E = keyword_end(); I != E; ++I) {
307    if (*I)
308      Length += (*I)->getLength();
309    ++Length;  // :
310  }
311
312  Result.reserve(Length);
313
314  for (keyword_iterator I = keyword_begin(), E = keyword_end(); I != E; ++I) {
315    if (*I)
316      Result.insert(Result.end(), (*I)->getName(),
317                    (*I)->getName()+(*I)->getLength());
318    Result.push_back(':');
319  }
320
321  return Result;
322}
323
324std::string Selector::getAsString() const {
325  if (InfoPtr == 0)
326    return "<null selector>";
327
328  if (InfoPtr & ArgFlags) {
329    IdentifierInfo *II = getAsIdentifierInfo();
330
331    // If the number of arguments is 0 then II is guaranteed to not be null.
332    if (getNumArgs() == 0)
333      return II->getName();
334
335    std::string Res = II ? II->getName() : "";
336    Res += ":";
337    return Res;
338  }
339
340  // We have a multiple keyword selector (no embedded flags).
341  return reinterpret_cast<MultiKeywordSelector *>(InfoPtr)->getName();
342}
343
344
345namespace {
346  struct SelectorTableImpl {
347    llvm::FoldingSet<MultiKeywordSelector> Table;
348    llvm::BumpPtrAllocator Allocator;
349  };
350} // end anonymous namespace.
351
352static SelectorTableImpl &getSelectorTableImpl(void *P) {
353  return *static_cast<SelectorTableImpl*>(P);
354}
355
356
357Selector SelectorTable::getSelector(unsigned nKeys, IdentifierInfo **IIV) {
358  if (nKeys < 2)
359    return Selector(IIV[0], nKeys);
360
361  SelectorTableImpl &SelTabImpl = getSelectorTableImpl(Impl);
362
363  // Unique selector, to guarantee there is one per name.
364  llvm::FoldingSetNodeID ID;
365  MultiKeywordSelector::Profile(ID, IIV, nKeys);
366
367  void *InsertPos = 0;
368  if (MultiKeywordSelector *SI =
369        SelTabImpl.Table.FindNodeOrInsertPos(ID, InsertPos))
370    return Selector(SI);
371
372  // MultiKeywordSelector objects are not allocated with new because they have a
373  // variable size array (for parameter types) at the end of them.
374  unsigned Size = sizeof(MultiKeywordSelector) + nKeys*sizeof(IdentifierInfo *);
375  MultiKeywordSelector *SI =
376    (MultiKeywordSelector*)SelTabImpl.Allocator.Allocate(Size,
377                                         llvm::alignof<MultiKeywordSelector>());
378  new (SI) MultiKeywordSelector(nKeys, IIV);
379  SelTabImpl.Table.InsertNode(SI, InsertPos);
380  return Selector(SI);
381}
382
383SelectorTable::SelectorTable() {
384  Impl = new SelectorTableImpl();
385}
386
387SelectorTable::~SelectorTable() {
388  delete &getSelectorTableImpl(Impl);
389}
390
391