DeclBase.cpp revision 6ed40e351a7c1fb3084434f1db19216b79623cf0 
1//===--- DeclBase.cpp - Declaration AST Node Implementation ---------------===//
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 Decl and DeclContext classes.
11//
12//===----------------------------------------------------------------------===//
13
14#include "clang/AST/DeclBase.h"
15#include "clang/AST/DeclObjC.h"
16#include "clang/AST/DeclCXX.h"
17#include "clang/AST/ASTContext.h"
18#include "clang/AST/Type.h"
19#include "llvm/ADT/DenseMap.h"
20#include <algorithm>
21#include <functional>
22#include <vector>
23using namespace clang;
24
25//===----------------------------------------------------------------------===//
26//  Statistics
27//===----------------------------------------------------------------------===//
28
29// temporary statistics gathering
30static unsigned nFuncs = 0;
31static unsigned nVars = 0;
32static unsigned nParmVars = 0;
33static unsigned nOriginalParmVars = 0;
34static unsigned nSUC = 0;
35static unsigned nCXXSUC = 0;
36static unsigned nEnumConst = 0;
37static unsigned nEnumDecls = 0;
38static unsigned nNamespaces = 0;
39static unsigned nOverFuncs = 0;
40static unsigned nTypedef = 0;
41static unsigned nFieldDecls = 0;
42static unsigned nInterfaceDecls = 0;
43static unsigned nClassDecls = 0;
44static unsigned nMethodDecls = 0;
45static unsigned nProtocolDecls = 0;
46static unsigned nForwardProtocolDecls = 0;
47static unsigned nCategoryDecls = 0;
48static unsigned nIvarDecls = 0;
49static unsigned nAtDefsFieldDecls = 0;
50static unsigned nObjCImplementationDecls = 0;
51static unsigned nObjCCategoryImpl = 0;
52static unsigned nObjCCompatibleAlias = 0;
53static unsigned nObjCPropertyDecl = 0;
54static unsigned nObjCPropertyImplDecl = 0;
55static unsigned nLinkageSpecDecl = 0;
56static unsigned nFileScopeAsmDecl = 0;
57static unsigned nBlockDecls = 0;
58
59static bool StatSwitch = false;
60
61// This keeps track of all decl attributes. Since so few decls have attrs, we
62// keep them in a hash map instead of wasting space in the Decl class.
63typedef llvm::DenseMap<const Decl*, Attr*> DeclAttrMapTy;
64
65static DeclAttrMapTy *DeclAttrs = 0;
66
67const char *Decl::getDeclKindName() const {
68  switch (DeclKind) {
69  default: assert(0 && "Unknown decl kind!");
70  case Namespace:           return "Namespace";
71  case OverloadedFunction:  return "OverloadedFunction";
72  case Typedef:             return "Typedef";
73  case Function:            return "Function";
74  case Var:                 return "Var";
75  case ParmVar:             return "ParmVar";
76  case OriginalParmVar:     return "OriginalParmVar";
77  case EnumConstant:        return "EnumConstant";
78  case ObjCIvar:            return "ObjCIvar";
79  case ObjCInterface:       return "ObjCInterface";
80  case ObjCImplementation:  return "ObjCImplementation";
81  case ObjCClass:           return "ObjCClass";
82  case ObjCMethod:          return "ObjCMethod";
83  case ObjCProtocol:        return "ObjCProtocol";
84  case ObjCProperty:        return "ObjCProperty";
85  case ObjCPropertyImpl:    return "ObjCPropertyImpl";
86  case ObjCForwardProtocol: return "ObjCForwardProtocol";
87  case Record:              return "Record";
88  case CXXRecord:           return "CXXRecord";
89  case Enum:                return "Enum";
90  case Block:               return "Block";
91  }
92}
93
94bool Decl::CollectingStats(bool Enable) {
95  if (Enable)
96    StatSwitch = true;
97  return StatSwitch;
98}
99
100void Decl::PrintStats() {
101  fprintf(stderr, "*** Decl Stats:\n");
102  fprintf(stderr, "  %d decls total.\n",
103          int(nFuncs+nVars+nParmVars+nOriginalParmVars+nFieldDecls+nSUC+nCXXSUC+
104              nEnumDecls+nEnumConst+nTypedef+nInterfaceDecls+nClassDecls+
105              nMethodDecls+nProtocolDecls+nCategoryDecls+nIvarDecls+
106              nAtDefsFieldDecls+nNamespaces+nOverFuncs));
107  fprintf(stderr, "    %d namespace decls, %d each (%d bytes)\n",
108          nNamespaces, (int)sizeof(NamespaceDecl),
109          int(nNamespaces*sizeof(NamespaceDecl)));
110  fprintf(stderr, "    %d overloaded function decls, %d each (%d bytes)\n",
111          nOverFuncs, (int)sizeof(OverloadedFunctionDecl),
112          int(nOverFuncs*sizeof(OverloadedFunctionDecl)));
113  fprintf(stderr, "    %d function decls, %d each (%d bytes)\n",
114          nFuncs, (int)sizeof(FunctionDecl), int(nFuncs*sizeof(FunctionDecl)));
115  fprintf(stderr, "    %d variable decls, %d each (%d bytes)\n",
116          nVars, (int)sizeof(VarDecl),
117          int(nVars*sizeof(VarDecl)));
118  fprintf(stderr, "    %d parameter variable decls, %d each (%d bytes)\n",
119          nParmVars, (int)sizeof(ParmVarDecl),
120          int(nParmVars*sizeof(ParmVarDecl)));
121  fprintf(stderr, "    %d original parameter variable decls, %d each (%d bytes)\n",
122          nOriginalParmVars, (int)sizeof(ParmVarWithOriginalTypeDecl),
123          int(nOriginalParmVars*sizeof(ParmVarWithOriginalTypeDecl)));
124  fprintf(stderr, "    %d field decls, %d each (%d bytes)\n",
125          nFieldDecls, (int)sizeof(FieldDecl),
126          int(nFieldDecls*sizeof(FieldDecl)));
127  fprintf(stderr, "    %d @defs generated field decls, %d each (%d bytes)\n",
128          nAtDefsFieldDecls, (int)sizeof(ObjCAtDefsFieldDecl),
129          int(nAtDefsFieldDecls*sizeof(ObjCAtDefsFieldDecl)));
130  fprintf(stderr, "    %d struct/union/class decls, %d each (%d bytes)\n",
131          nSUC, (int)sizeof(RecordDecl),
132          int(nSUC*sizeof(RecordDecl)));
133  fprintf(stderr, "    %d C++ struct/union/class decls, %d each (%d bytes)\n",
134          nCXXSUC, (int)sizeof(CXXRecordDecl),
135          int(nCXXSUC*sizeof(CXXRecordDecl)));
136  fprintf(stderr, "    %d enum decls, %d each (%d bytes)\n",
137          nEnumDecls, (int)sizeof(EnumDecl),
138          int(nEnumDecls*sizeof(EnumDecl)));
139  fprintf(stderr, "    %d enum constant decls, %d each (%d bytes)\n",
140          nEnumConst, (int)sizeof(EnumConstantDecl),
141          int(nEnumConst*sizeof(EnumConstantDecl)));
142  fprintf(stderr, "    %d typedef decls, %d each (%d bytes)\n",
143          nTypedef, (int)sizeof(TypedefDecl),int(nTypedef*sizeof(TypedefDecl)));
144  // Objective-C decls...
145  fprintf(stderr, "    %d interface decls, %d each (%d bytes)\n",
146          nInterfaceDecls, (int)sizeof(ObjCInterfaceDecl),
147          int(nInterfaceDecls*sizeof(ObjCInterfaceDecl)));
148  fprintf(stderr, "    %d instance variable decls, %d each (%d bytes)\n",
149          nIvarDecls, (int)sizeof(ObjCIvarDecl),
150          int(nIvarDecls*sizeof(ObjCIvarDecl)));
151  fprintf(stderr, "    %d class decls, %d each (%d bytes)\n",
152          nClassDecls, (int)sizeof(ObjCClassDecl),
153          int(nClassDecls*sizeof(ObjCClassDecl)));
154  fprintf(stderr, "    %d method decls, %d each (%d bytes)\n",
155          nMethodDecls, (int)sizeof(ObjCMethodDecl),
156          int(nMethodDecls*sizeof(ObjCMethodDecl)));
157  fprintf(stderr, "    %d protocol decls, %d each (%d bytes)\n",
158          nProtocolDecls, (int)sizeof(ObjCProtocolDecl),
159          int(nProtocolDecls*sizeof(ObjCProtocolDecl)));
160  fprintf(stderr, "    %d forward protocol decls, %d each (%d bytes)\n",
161          nForwardProtocolDecls, (int)sizeof(ObjCForwardProtocolDecl),
162          int(nForwardProtocolDecls*sizeof(ObjCForwardProtocolDecl)));
163  fprintf(stderr, "    %d category decls, %d each (%d bytes)\n",
164          nCategoryDecls, (int)sizeof(ObjCCategoryDecl),
165          int(nCategoryDecls*sizeof(ObjCCategoryDecl)));
166
167  fprintf(stderr, "    %d class implementation decls, %d each (%d bytes)\n",
168          nObjCImplementationDecls, (int)sizeof(ObjCImplementationDecl),
169          int(nObjCImplementationDecls*sizeof(ObjCImplementationDecl)));
170
171  fprintf(stderr, "    %d class implementation decls, %d each (%d bytes)\n",
172          nObjCCategoryImpl, (int)sizeof(ObjCCategoryImplDecl),
173          int(nObjCCategoryImpl*sizeof(ObjCCategoryImplDecl)));
174
175  fprintf(stderr, "    %d compatibility alias decls, %d each (%d bytes)\n",
176          nObjCCompatibleAlias, (int)sizeof(ObjCCompatibleAliasDecl),
177          int(nObjCCompatibleAlias*sizeof(ObjCCompatibleAliasDecl)));
178
179  fprintf(stderr, "    %d property decls, %d each (%d bytes)\n",
180          nObjCPropertyDecl, (int)sizeof(ObjCPropertyDecl),
181          int(nObjCPropertyDecl*sizeof(ObjCPropertyDecl)));
182
183  fprintf(stderr, "    %d property implementation decls, %d each (%d bytes)\n",
184          nObjCPropertyImplDecl, (int)sizeof(ObjCPropertyImplDecl),
185          int(nObjCPropertyImplDecl*sizeof(ObjCPropertyImplDecl)));
186
187  fprintf(stderr, "Total bytes = %d\n",
188          int(nFuncs*sizeof(FunctionDecl)+
189              nVars*sizeof(VarDecl)+nParmVars*sizeof(ParmVarDecl)+
190              nOriginalParmVars*sizeof(ParmVarWithOriginalTypeDecl)+
191              nFieldDecls*sizeof(FieldDecl)+nSUC*sizeof(RecordDecl)+
192              nCXXSUC*sizeof(CXXRecordDecl)+
193              nEnumDecls*sizeof(EnumDecl)+nEnumConst*sizeof(EnumConstantDecl)+
194              nTypedef*sizeof(TypedefDecl)+
195              nInterfaceDecls*sizeof(ObjCInterfaceDecl)+
196              nIvarDecls*sizeof(ObjCIvarDecl)+
197              nClassDecls*sizeof(ObjCClassDecl)+
198              nMethodDecls*sizeof(ObjCMethodDecl)+
199              nProtocolDecls*sizeof(ObjCProtocolDecl)+
200              nForwardProtocolDecls*sizeof(ObjCForwardProtocolDecl)+
201              nCategoryDecls*sizeof(ObjCCategoryDecl)+
202              nObjCImplementationDecls*sizeof(ObjCImplementationDecl)+
203              nObjCCategoryImpl*sizeof(ObjCCategoryImplDecl)+
204              nObjCCompatibleAlias*sizeof(ObjCCompatibleAliasDecl)+
205              nObjCPropertyDecl*sizeof(ObjCPropertyDecl)+
206              nObjCPropertyImplDecl*sizeof(ObjCPropertyImplDecl)+
207              nLinkageSpecDecl*sizeof(LinkageSpecDecl)+
208              nFileScopeAsmDecl*sizeof(FileScopeAsmDecl)+
209              nNamespaces*sizeof(NamespaceDecl)+
210              nOverFuncs*sizeof(OverloadedFunctionDecl)));
211
212}
213
214void Decl::addDeclKind(Kind k) {
215  switch (k) {
216  case Namespace:           nNamespaces++; break;
217  case OverloadedFunction:  nOverFuncs++; break;
218  case Typedef:             nTypedef++; break;
219  case Function:            nFuncs++; break;
220  case Var:                 nVars++; break;
221  case ParmVar:             nParmVars++; break;
222  case OriginalParmVar:     nOriginalParmVars++; break;
223  case EnumConstant:        nEnumConst++; break;
224  case Field:               nFieldDecls++; break;
225  case Record:              nSUC++; break;
226  case Enum:                nEnumDecls++; break;
227  case ObjCInterface:       nInterfaceDecls++; break;
228  case ObjCClass:           nClassDecls++; break;
229  case ObjCMethod:          nMethodDecls++; break;
230  case ObjCProtocol:        nProtocolDecls++; break;
231  case ObjCForwardProtocol: nForwardProtocolDecls++; break;
232  case ObjCCategory:        nCategoryDecls++; break;
233  case ObjCIvar:            nIvarDecls++; break;
234  case ObjCAtDefsField:     nAtDefsFieldDecls++; break;
235  case ObjCImplementation:  nObjCImplementationDecls++; break;
236  case ObjCCategoryImpl:    nObjCCategoryImpl++; break;
237  case ObjCCompatibleAlias: nObjCCompatibleAlias++; break;
238  case ObjCProperty:        nObjCPropertyDecl++; break;
239  case ObjCPropertyImpl:    nObjCPropertyImplDecl++; break;
240  case LinkageSpec:         nLinkageSpecDecl++; break;
241  case FileScopeAsm:        nFileScopeAsmDecl++; break;
242  case Block:               nBlockDecls++; break;
243  case ImplicitParam:
244  case TranslationUnit:     break;
245
246  case CXXRecord:           nCXXSUC++; break;
247  // FIXME: Statistics for C++ decls.
248  case TemplateTypeParm:
249  case NonTypeTemplateParm:
250  case CXXMethod:
251  case CXXConstructor:
252  case CXXDestructor:
253  case CXXConversion:
254  case CXXClassVar:
255    break;
256  }
257}
258
259//===----------------------------------------------------------------------===//
260// Decl Implementation
261//===----------------------------------------------------------------------===//
262
263// Out-of-line virtual method providing a home for Decl.
264Decl::~Decl() {
265  if (!HasAttrs)
266    return;
267
268  DeclAttrMapTy::iterator it = DeclAttrs->find(this);
269  assert(it != DeclAttrs->end() && "No attrs found but HasAttrs is true!");
270
271  // release attributes.
272  delete it->second;
273  invalidateAttrs();
274}
275
276void Decl::addAttr(Attr *NewAttr) {
277  if (!DeclAttrs)
278    DeclAttrs = new DeclAttrMapTy();
279
280  Attr *&ExistingAttr = (*DeclAttrs)[this];
281
282  NewAttr->setNext(ExistingAttr);
283  ExistingAttr = NewAttr;
284
285  HasAttrs = true;
286}
287
288void Decl::invalidateAttrs() {
289  if (!HasAttrs) return;
290
291  HasAttrs = false;
292  (*DeclAttrs)[this] = 0;
293  DeclAttrs->erase(this);
294
295  if (DeclAttrs->empty()) {
296    delete DeclAttrs;
297    DeclAttrs = 0;
298  }
299}
300
301const Attr *Decl::getAttrs() const {
302  if (!HasAttrs)
303    return 0;
304
305  return (*DeclAttrs)[this];
306}
307
308void Decl::swapAttrs(Decl *RHS) {
309  bool HasLHSAttr = this->HasAttrs;
310  bool HasRHSAttr = RHS->HasAttrs;
311
312  // Usually, neither decl has attrs, nothing to do.
313  if (!HasLHSAttr && !HasRHSAttr) return;
314
315  // If 'this' has no attrs, swap the other way.
316  if (!HasLHSAttr)
317    return RHS->swapAttrs(this);
318
319  // Handle the case when both decls have attrs.
320  if (HasRHSAttr) {
321    std::swap((*DeclAttrs)[this], (*DeclAttrs)[RHS]);
322    return;
323  }
324
325  // Otherwise, LHS has an attr and RHS doesn't.
326  (*DeclAttrs)[RHS] = (*DeclAttrs)[this];
327  (*DeclAttrs).erase(this);
328  this->HasAttrs = false;
329  RHS->HasAttrs = true;
330}
331
332
333void Decl::Destroy(ASTContext& C) {
334  if (ScopedDecl* SD = dyn_cast<ScopedDecl>(this)) {
335
336    // Observe the unrolled recursion.  By setting N->NextDeclarator = 0x0
337    // within the loop, only the Destroy method for the first ScopedDecl
338    // will deallocate all of the ScopedDecls in a chain.
339
340    ScopedDecl* N = SD->getNextDeclarator();
341
342    while (N) {
343      ScopedDecl* Tmp = N->getNextDeclarator();
344      N->NextDeclarator = 0x0;
345      N->Destroy(C);
346      N = Tmp;
347    }
348  }
349
350  this->~Decl();
351  C.getAllocator().Deallocate((void *)this);
352}
353
354Decl *Decl::castFromDeclContext (const DeclContext *D) {
355  return DeclContext::CastTo<Decl>(D);
356}
357
358DeclContext *Decl::castToDeclContext(const Decl *D) {
359  return DeclContext::CastTo<DeclContext>(D);
360}
361
362//===----------------------------------------------------------------------===//
363// DeclContext Implementation
364//===----------------------------------------------------------------------===//
365
366const DeclContext *DeclContext::getParent() const {
367  if (const ScopedDecl *SD = dyn_cast<ScopedDecl>(this))
368    return SD->getDeclContext();
369  else if (const BlockDecl *BD = dyn_cast<BlockDecl>(this))
370    return BD->getParentContext();
371  else
372    return NULL;
373}
374
375const DeclContext *DeclContext::getLexicalParent() const {
376  if (const ScopedDecl *SD = dyn_cast<ScopedDecl>(this))
377    return SD->getLexicalDeclContext();
378  return getParent();
379}
380
381// FIXME: We really want to use a DenseSet here to eliminate the
382// redundant storage of the declaration names, but (1) it doesn't give
383// us the ability to search based on DeclarationName, (2) we really
384// need something more like a DenseMultiSet, and (3) it's
385// implemented in terms of DenseMap anyway. However, this data
386// structure is really space-inefficient, so we'll have to do
387// something.
388typedef llvm::DenseMap<DeclarationName, std::vector<ScopedDecl*> >
389  StoredDeclsMap;
390
391DeclContext::~DeclContext() {
392  unsigned Size = LookupPtr.getInt();
393  if (Size == LookupIsMap) {
394    StoredDeclsMap *Map = static_cast<StoredDeclsMap*>(LookupPtr.getPointer());
395    delete Map;
396  } else {
397    ScopedDecl **Array = static_cast<ScopedDecl**>(LookupPtr.getPointer());
398    delete [] Array;
399  }
400}
401
402void DeclContext::DestroyDecls(ASTContext &C) {
403  for (decl_iterator D = Decls.begin(); D != Decls.end(); ++D) {
404    if ((*D)->getLexicalDeclContext() == this)
405      (*D)->Destroy(C);
406  }
407}
408
409DeclContext *DeclContext::getPrimaryContext(ASTContext &Context) {
410  switch (DeclKind) {
411  case Decl::Block:
412  case Decl::TranslationUnit:
413    // There is only one DeclContext for these entities.
414    return this;
415
416  case Decl::Namespace:
417    // The original namespace is our primary context.
418    return static_cast<NamespaceDecl*>(this)->getOriginalNamespace();
419
420  case Decl::Enum:
421    // The declaration associated with the enumeration type is our
422    // primary context.
423    return Context.getTypeDeclType(static_cast<EnumDecl*>(this))
424             ->getAsEnumType()->getDecl();
425
426  case Decl::Record:
427  case Decl::CXXRecord: {
428    // The declaration associated with the type is be our primary
429    // context.
430#if 0
431    // FIXME: This is what we expect to do. However, it doesn't work
432    // because ASTContext::setTagDefinition changes the result of
433    // Context.getTypeDeclType, meaning that our "primary" declaration
434    // of a RecordDecl/CXXRecordDecl will change, and we won't be able
435    // to find any values inserted into the earlier "primary"
436    // declaration. We need better tracking of redeclarations and
437    // definitions.
438    QualType Type = Context.getTypeDeclType(static_cast<RecordDecl*>(this));
439    return Type->getAsRecordType()->getDecl();
440#else
441    // FIXME: This hack will work for now, because the declaration we
442    // create when we're defining the record is the one we'll use as
443    // the definition later.
444    return this;
445#endif
446  }
447
448  case Decl::ObjCMethod:
449    return this;
450
451  case Decl::ObjCInterface:
452    // FIXME: Can Objective-C interfaces be forward-declared?
453    return this;
454
455  default:
456    assert(DeclKind >= Decl::FunctionFirst && DeclKind <= Decl::FunctionLast &&
457          "Unknown DeclContext kind");
458    return this;
459  }
460}
461
462DeclContext *DeclContext::getNextContext() {
463  switch (DeclKind) {
464  case Decl::Block:
465  case Decl::TranslationUnit:
466  case Decl::Enum:
467  case Decl::Record:
468  case Decl::CXXRecord:
469  case Decl::ObjCMethod:
470  case Decl::ObjCInterface:
471    // There is only one DeclContext for these entities.
472    return 0;
473
474  case Decl::Namespace:
475    // Return the next namespace
476    return static_cast<NamespaceDecl*>(this)->getNextNamespace();
477
478  default:
479    assert(DeclKind >= Decl::FunctionFirst && DeclKind <= Decl::FunctionLast &&
480          "Unknown DeclContext kind");
481    return 0;
482  }
483}
484
485void DeclContext::addDecl(ASTContext &Context, ScopedDecl *D, bool AllowLookup) {
486  Decls.push_back(D);
487  if (AllowLookup)
488    D->getDeclContext()->insert(Context, D);
489}
490
491DeclContext::lookup_result
492DeclContext::lookup(ASTContext &Context, DeclarationName Name) {
493  DeclContext *PrimaryContext = getPrimaryContext(Context);
494  if (PrimaryContext != this)
495    return PrimaryContext->lookup(Context, Name);
496
497  /// If there is no lookup data structure, build one now by walking
498  /// all of the linked DeclContexts (in declaration order!) and
499  /// inserting their values.
500  if (LookupPtr.getPointer() == 0) {
501    for (DeclContext *DCtx = this; DCtx; DCtx = DCtx->getNextContext())
502      for (decl_iterator D = DCtx->decls_begin(); D != DCtx->decls_end(); ++D)
503        insertImpl(*D);
504  }
505
506  if (isLookupMap()) {
507    StoredDeclsMap *Map = static_cast<StoredDeclsMap*>(LookupPtr.getPointer());
508    StoredDeclsMap::iterator Pos = Map->find(Name);
509    if (Pos != Map->end())
510      return lookup_result(&Pos->second.front(),
511                           &Pos->second.front() + Pos->second.size());
512    return lookup_result(0, 0);
513  }
514
515  // We have a small array. Look into it.
516  unsigned Size = LookupPtr.getInt();
517  ScopedDecl **Array = static_cast<ScopedDecl**>(LookupPtr.getPointer());
518  for (unsigned Idx = 0; Idx != Size; ++Idx)
519    if (Array[Idx]->getDeclName() == Name) {
520      unsigned Last = Idx + 1;
521      while (Last != Size && Array[Last]->getDeclName() == Name)
522        ++Last;
523      return lookup_result(&Array[Idx], &Array[Last]);
524    }
525
526  return lookup_result(0, 0);
527}
528
529DeclContext::lookup_const_result
530DeclContext::lookup(ASTContext &Context, DeclarationName Name) const {
531  return const_cast<DeclContext*>(this)->lookup(Context, Name);
532}
533
534void DeclContext::insert(ASTContext &Context, ScopedDecl *D) {
535  DeclContext *PrimaryContext = getPrimaryContext(Context);
536  if (PrimaryContext != this) {
537    PrimaryContext->insert(Context, D);
538    return;
539  }
540
541  // If we already have a lookup data structure, perform the insertion
542  // into it. Otherwise, be lazy and don't build that structure until
543  // someone asks for it.
544  if (LookupPtr.getPointer())
545    insertImpl(D);
546}
547
548void DeclContext::insertImpl(ScopedDecl *D) {
549  bool MayBeRedeclaration = true;
550
551  if (!isLookupMap()) {
552    unsigned Size = LookupPtr.getInt();
553
554    // The lookup data is stored as an array. Search through the array
555    // to find the insertion location.
556    ScopedDecl **Array;
557    if (Size == 0) {
558      Array = new ScopedDecl*[LookupIsMap - 1];
559      LookupPtr.setPointer(Array);
560    } else {
561      Array = static_cast<ScopedDecl **>(LookupPtr.getPointer());
562    }
563
564    // We always keep declarations of the same name next to each other
565    // in the array, so that it is easy to return multiple results
566    // from lookup().
567    unsigned FirstMatch;
568    for (FirstMatch = 0; FirstMatch != Size; ++FirstMatch)
569      if (Array[FirstMatch]->getDeclName() == D->getDeclName())
570        break;
571
572    unsigned InsertPos = FirstMatch;
573    if (FirstMatch != Size) {
574      // We found another declaration with the same name. First
575      // determine whether this is a redeclaration of an existing
576      // declaration in this scope, in which case we will replace the
577      // existing declaration.
578      unsigned LastMatch = FirstMatch;
579      for (; LastMatch != Size; ++LastMatch) {
580        if (Array[LastMatch]->getDeclName() != D->getDeclName())
581          break;
582
583        if (D->declarationReplaces(Array[LastMatch])) {
584          // D is a redeclaration of an existing element in the
585          // array. Replace that element with D.
586          Array[LastMatch] = D;
587          return;
588        }
589      }
590
591      // [FirstMatch, LastMatch) contains the set of declarations that
592      // have the same name as this declaration. Determine where the
593      // declaration D will be inserted into this range.
594      if (D->getIdentifierNamespace() == Decl::IDNS_Tag)
595        InsertPos = LastMatch;
596      else if (Array[LastMatch-1]->getIdentifierNamespace() == Decl::IDNS_Tag)
597        InsertPos = LastMatch - 1;
598      else
599        InsertPos = LastMatch;
600    }
601
602    if (Size < LookupIsMap - 1) {
603      // The new declaration will fit in the array. Insert the new
604      // declaration at the position Match in the array.
605      for (unsigned Idx = Size; Idx > InsertPos; --Idx)
606       Array[Idx] = Array[Idx-1];
607
608      Array[InsertPos] = D;
609      LookupPtr.setInt(Size + 1);
610      return;
611    }
612
613    // We've reached capacity in this array. Create a map and copy in
614    // all of the declarations that were stored in the array.
615    StoredDeclsMap *Map = new StoredDeclsMap(16);
616    LookupPtr.setPointer(Map);
617    LookupPtr.setInt(LookupIsMap);
618    for (unsigned Idx = 0; Idx != LookupIsMap - 1; ++Idx)
619      insertImpl(Array[Idx]);
620    delete [] Array;
621
622    // Fall through to perform insertion into the map.
623    MayBeRedeclaration = false;
624  }
625
626  // Insert this declaration into the map.
627  StoredDeclsMap *Map = static_cast<StoredDeclsMap*>(LookupPtr.getPointer());
628  StoredDeclsMap::iterator Pos = Map->find(D->getDeclName());
629  if (Pos != Map->end()) {
630    if (MayBeRedeclaration) {
631      // Determine if this declaration is actually a redeclaration.
632      std::vector<ScopedDecl *>::iterator Redecl
633        = std::find_if(Pos->second.begin(), Pos->second.end(),
634                     std::bind1st(std::mem_fun(&ScopedDecl::declarationReplaces),
635                                  D));
636      if (Redecl != Pos->second.end()) {
637        *Redecl = D;
638        return;
639      }
640    }
641
642    // Put this declaration into the appropriate slot.
643    if (D->getIdentifierNamespace() == Decl::IDNS_Tag || Pos->second.empty())
644      Pos->second.push_back(D);
645    else if (Pos->second.back()->getIdentifierNamespace() == Decl::IDNS_Tag) {
646      ScopedDecl *TagD = Pos->second.back();
647      Pos->second.back() = D;
648      Pos->second.push_back(TagD);
649    } else
650      Pos->second.push_back(D);
651  } else {
652    (*Map)[D->getDeclName()].push_back(D);
653  }
654}
655