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1 //===- IdentifierResolver.cpp - Lexical Scope Name lookup -------*- 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 // This file implements the IdentifierResolver class, which is used for lexical
11 // scoped lookup, based on declaration names.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "clang/Sema/IdentifierResolver.h"
16 #include "clang/AST/Decl.h"
17 #include "clang/Basic/LangOptions.h"
18 #include "clang/Lex/ExternalPreprocessorSource.h"
19 #include "clang/Lex/Preprocessor.h"
20 #include "clang/Sema/Scope.h"
21 
22 using namespace clang;
23 
24 //===----------------------------------------------------------------------===//
25 // IdDeclInfoMap class
26 //===----------------------------------------------------------------------===//
27 
28 /// IdDeclInfoMap - Associates IdDeclInfos with declaration names.
29 /// Allocates 'pools' (vectors of IdDeclInfos) to avoid allocating each
30 /// individual IdDeclInfo to heap.
31 class IdentifierResolver::IdDeclInfoMap {
32   static const unsigned int POOL_SIZE = 512;
33 
34   /// We use our own linked-list implementation because it is sadly
35   /// impossible to add something to a pre-C++0x STL container without
36   /// a completely unnecessary copy.
37   struct IdDeclInfoPool {
IdDeclInfoPoolIdentifierResolver::IdDeclInfoMap::IdDeclInfoPool38     IdDeclInfoPool(IdDeclInfoPool *Next) : Next(Next) {}
39 
40     IdDeclInfoPool *Next;
41     IdDeclInfo Pool[POOL_SIZE];
42   };
43 
44   IdDeclInfoPool *CurPool;
45   unsigned int CurIndex;
46 
47 public:
IdDeclInfoMap()48   IdDeclInfoMap() : CurPool(nullptr), CurIndex(POOL_SIZE) {}
49 
~IdDeclInfoMap()50   ~IdDeclInfoMap() {
51     IdDeclInfoPool *Cur = CurPool;
52     while (IdDeclInfoPool *P = Cur) {
53       Cur = Cur->Next;
54       delete P;
55     }
56   }
57 
58   /// Returns the IdDeclInfo associated to the DeclarationName.
59   /// It creates a new IdDeclInfo if one was not created before for this id.
60   IdDeclInfo &operator[](DeclarationName Name);
61 };
62 
63 
64 //===----------------------------------------------------------------------===//
65 // IdDeclInfo Implementation
66 //===----------------------------------------------------------------------===//
67 
68 /// RemoveDecl - Remove the decl from the scope chain.
69 /// The decl must already be part of the decl chain.
RemoveDecl(NamedDecl * D)70 void IdentifierResolver::IdDeclInfo::RemoveDecl(NamedDecl *D) {
71   for (DeclsTy::iterator I = Decls.end(); I != Decls.begin(); --I) {
72     if (D == *(I-1)) {
73       Decls.erase(I-1);
74       return;
75     }
76   }
77 
78   llvm_unreachable("Didn't find this decl on its identifier's chain!");
79 }
80 
81 //===----------------------------------------------------------------------===//
82 // IdentifierResolver Implementation
83 //===----------------------------------------------------------------------===//
84 
IdentifierResolver(Preprocessor & PP)85 IdentifierResolver::IdentifierResolver(Preprocessor &PP)
86   : LangOpt(PP.getLangOpts()), PP(PP),
87     IdDeclInfos(new IdDeclInfoMap) {
88 }
89 
~IdentifierResolver()90 IdentifierResolver::~IdentifierResolver() {
91   delete IdDeclInfos;
92 }
93 
94 /// isDeclInScope - If 'Ctx' is a function/method, isDeclInScope returns true
95 /// if 'D' is in Scope 'S', otherwise 'S' is ignored and isDeclInScope returns
96 /// true if 'D' belongs to the given declaration context.
isDeclInScope(Decl * D,DeclContext * Ctx,Scope * S,bool AllowInlineNamespace) const97 bool IdentifierResolver::isDeclInScope(Decl *D, DeclContext *Ctx, Scope *S,
98                                        bool AllowInlineNamespace) const {
99   Ctx = Ctx->getRedeclContext();
100 
101   if (Ctx->isFunctionOrMethod() || (S && S->isFunctionPrototypeScope())) {
102     // Ignore the scopes associated within transparent declaration contexts.
103     while (S->getEntity() && S->getEntity()->isTransparentContext())
104       S = S->getParent();
105 
106     if (S->isDeclScope(D))
107       return true;
108     if (LangOpt.CPlusPlus) {
109       // C++ 3.3.2p3:
110       // The name declared in a catch exception-declaration is local to the
111       // handler and shall not be redeclared in the outermost block of the
112       // handler.
113       // C++ 3.3.2p4:
114       // Names declared in the for-init-statement, and in the condition of if,
115       // while, for, and switch statements are local to the if, while, for, or
116       // switch statement (including the controlled statement), and shall not be
117       // redeclared in a subsequent condition of that statement nor in the
118       // outermost block (or, for the if statement, any of the outermost blocks)
119       // of the controlled statement.
120       //
121       assert(S->getParent() && "No TUScope?");
122       if (S->getParent()->getFlags() & Scope::ControlScope) {
123         S = S->getParent();
124         if (S->isDeclScope(D))
125           return true;
126       }
127       if (S->getFlags() & Scope::FnTryCatchScope)
128         return S->getParent()->isDeclScope(D);
129     }
130     return false;
131   }
132 
133   // FIXME: If D is a local extern declaration, this check doesn't make sense;
134   // we should be checking its lexical context instead in that case, because
135   // that is its scope.
136   DeclContext *DCtx = D->getDeclContext()->getRedeclContext();
137   return AllowInlineNamespace ? Ctx->InEnclosingNamespaceSetOf(DCtx)
138                               : Ctx->Equals(DCtx);
139 }
140 
141 /// AddDecl - Link the decl to its shadowed decl chain.
AddDecl(NamedDecl * D)142 void IdentifierResolver::AddDecl(NamedDecl *D) {
143   DeclarationName Name = D->getDeclName();
144   if (IdentifierInfo *II = Name.getAsIdentifierInfo())
145     updatingIdentifier(*II);
146 
147   void *Ptr = Name.getFETokenInfo<void>();
148 
149   if (!Ptr) {
150     Name.setFETokenInfo(D);
151     return;
152   }
153 
154   IdDeclInfo *IDI;
155 
156   if (isDeclPtr(Ptr)) {
157     Name.setFETokenInfo(nullptr);
158     IDI = &(*IdDeclInfos)[Name];
159     NamedDecl *PrevD = static_cast<NamedDecl*>(Ptr);
160     IDI->AddDecl(PrevD);
161   } else
162     IDI = toIdDeclInfo(Ptr);
163 
164   IDI->AddDecl(D);
165 }
166 
InsertDeclAfter(iterator Pos,NamedDecl * D)167 void IdentifierResolver::InsertDeclAfter(iterator Pos, NamedDecl *D) {
168   DeclarationName Name = D->getDeclName();
169   if (IdentifierInfo *II = Name.getAsIdentifierInfo())
170     updatingIdentifier(*II);
171 
172   void *Ptr = Name.getFETokenInfo<void>();
173 
174   if (!Ptr) {
175     AddDecl(D);
176     return;
177   }
178 
179   if (isDeclPtr(Ptr)) {
180     // We only have a single declaration: insert before or after it,
181     // as appropriate.
182     if (Pos == iterator()) {
183       // Add the new declaration before the existing declaration.
184       NamedDecl *PrevD = static_cast<NamedDecl*>(Ptr);
185       RemoveDecl(PrevD);
186       AddDecl(D);
187       AddDecl(PrevD);
188     } else {
189       // Add new declaration after the existing declaration.
190       AddDecl(D);
191     }
192 
193     return;
194   }
195 
196   // General case: insert the declaration at the appropriate point in the
197   // list, which already has at least two elements.
198   IdDeclInfo *IDI = toIdDeclInfo(Ptr);
199   if (Pos.isIterator()) {
200     IDI->InsertDecl(Pos.getIterator() + 1, D);
201   } else
202     IDI->InsertDecl(IDI->decls_begin(), D);
203 }
204 
205 /// RemoveDecl - Unlink the decl from its shadowed decl chain.
206 /// The decl must already be part of the decl chain.
RemoveDecl(NamedDecl * D)207 void IdentifierResolver::RemoveDecl(NamedDecl *D) {
208   assert(D && "null param passed");
209   DeclarationName Name = D->getDeclName();
210   if (IdentifierInfo *II = Name.getAsIdentifierInfo())
211     updatingIdentifier(*II);
212 
213   void *Ptr = Name.getFETokenInfo<void>();
214 
215   assert(Ptr && "Didn't find this decl on its identifier's chain!");
216 
217   if (isDeclPtr(Ptr)) {
218     assert(D == Ptr && "Didn't find this decl on its identifier's chain!");
219     Name.setFETokenInfo(nullptr);
220     return;
221   }
222 
223   return toIdDeclInfo(Ptr)->RemoveDecl(D);
224 }
225 
226 /// begin - Returns an iterator for decls with name 'Name'.
227 IdentifierResolver::iterator
begin(DeclarationName Name)228 IdentifierResolver::begin(DeclarationName Name) {
229   if (IdentifierInfo *II = Name.getAsIdentifierInfo())
230     readingIdentifier(*II);
231 
232   void *Ptr = Name.getFETokenInfo<void>();
233   if (!Ptr) return end();
234 
235   if (isDeclPtr(Ptr))
236     return iterator(static_cast<NamedDecl*>(Ptr));
237 
238   IdDeclInfo *IDI = toIdDeclInfo(Ptr);
239 
240   IdDeclInfo::DeclsTy::iterator I = IDI->decls_end();
241   if (I != IDI->decls_begin())
242     return iterator(I-1);
243   // No decls found.
244   return end();
245 }
246 
247 namespace {
248   enum DeclMatchKind {
249     DMK_Different,
250     DMK_Replace,
251     DMK_Ignore
252   };
253 }
254 
255 /// \brief Compare two declarations to see whether they are different or,
256 /// if they are the same, whether the new declaration should replace the
257 /// existing declaration.
compareDeclarations(NamedDecl * Existing,NamedDecl * New)258 static DeclMatchKind compareDeclarations(NamedDecl *Existing, NamedDecl *New) {
259   // If the declarations are identical, ignore the new one.
260   if (Existing == New)
261     return DMK_Ignore;
262 
263   // If the declarations have different kinds, they're obviously different.
264   if (Existing->getKind() != New->getKind())
265     return DMK_Different;
266 
267   // If the declarations are redeclarations of each other, keep the newest one.
268   if (Existing->getCanonicalDecl() == New->getCanonicalDecl()) {
269     // If we're adding an imported declaration, don't replace another imported
270     // declaration.
271     if (Existing->isFromASTFile() && New->isFromASTFile())
272       return DMK_Different;
273 
274     // If either of these is the most recent declaration, use it.
275     Decl *MostRecent = Existing->getMostRecentDecl();
276     if (Existing == MostRecent)
277       return DMK_Ignore;
278 
279     if (New == MostRecent)
280       return DMK_Replace;
281 
282     // If the existing declaration is somewhere in the previous declaration
283     // chain of the new declaration, then prefer the new declaration.
284     for (auto RD : New->redecls()) {
285       if (RD == Existing)
286         return DMK_Replace;
287 
288       if (RD->isCanonicalDecl())
289         break;
290     }
291 
292     return DMK_Ignore;
293   }
294 
295   return DMK_Different;
296 }
297 
tryAddTopLevelDecl(NamedDecl * D,DeclarationName Name)298 bool IdentifierResolver::tryAddTopLevelDecl(NamedDecl *D, DeclarationName Name){
299   if (IdentifierInfo *II = Name.getAsIdentifierInfo())
300     readingIdentifier(*II);
301 
302   void *Ptr = Name.getFETokenInfo<void>();
303 
304   if (!Ptr) {
305     Name.setFETokenInfo(D);
306     return true;
307   }
308 
309   IdDeclInfo *IDI;
310 
311   if (isDeclPtr(Ptr)) {
312     NamedDecl *PrevD = static_cast<NamedDecl*>(Ptr);
313 
314     switch (compareDeclarations(PrevD, D)) {
315     case DMK_Different:
316       break;
317 
318     case DMK_Ignore:
319       return false;
320 
321     case DMK_Replace:
322       Name.setFETokenInfo(D);
323       return true;
324     }
325 
326     Name.setFETokenInfo(nullptr);
327     IDI = &(*IdDeclInfos)[Name];
328 
329     // If the existing declaration is not visible in translation unit scope,
330     // then add the new top-level declaration first.
331     if (!PrevD->getDeclContext()->getRedeclContext()->isTranslationUnit()) {
332       IDI->AddDecl(D);
333       IDI->AddDecl(PrevD);
334     } else {
335       IDI->AddDecl(PrevD);
336       IDI->AddDecl(D);
337     }
338     return true;
339   }
340 
341   IDI = toIdDeclInfo(Ptr);
342 
343   // See whether this declaration is identical to any existing declarations.
344   // If not, find the right place to insert it.
345   for (IdDeclInfo::DeclsTy::iterator I = IDI->decls_begin(),
346                                   IEnd = IDI->decls_end();
347        I != IEnd; ++I) {
348 
349     switch (compareDeclarations(*I, D)) {
350     case DMK_Different:
351       break;
352 
353     case DMK_Ignore:
354       return false;
355 
356     case DMK_Replace:
357       *I = D;
358       return true;
359     }
360 
361     if (!(*I)->getDeclContext()->getRedeclContext()->isTranslationUnit()) {
362       // We've found a declaration that is not visible from the translation
363       // unit (it's in an inner scope). Insert our declaration here.
364       IDI->InsertDecl(I, D);
365       return true;
366     }
367   }
368 
369   // Add the declaration to the end.
370   IDI->AddDecl(D);
371   return true;
372 }
373 
readingIdentifier(IdentifierInfo & II)374 void IdentifierResolver::readingIdentifier(IdentifierInfo &II) {
375   if (II.isOutOfDate())
376     PP.getExternalSource()->updateOutOfDateIdentifier(II);
377 }
378 
updatingIdentifier(IdentifierInfo & II)379 void IdentifierResolver::updatingIdentifier(IdentifierInfo &II) {
380   if (II.isOutOfDate())
381     PP.getExternalSource()->updateOutOfDateIdentifier(II);
382 
383   if (II.isFromAST())
384     II.setFETokenInfoChangedSinceDeserialization();
385 }
386 
387 //===----------------------------------------------------------------------===//
388 // IdDeclInfoMap Implementation
389 //===----------------------------------------------------------------------===//
390 
391 /// Returns the IdDeclInfo associated to the DeclarationName.
392 /// It creates a new IdDeclInfo if one was not created before for this id.
393 IdentifierResolver::IdDeclInfo &
operator [](DeclarationName Name)394 IdentifierResolver::IdDeclInfoMap::operator[](DeclarationName Name) {
395   void *Ptr = Name.getFETokenInfo<void>();
396 
397   if (Ptr) return *toIdDeclInfo(Ptr);
398 
399   if (CurIndex == POOL_SIZE) {
400     CurPool = new IdDeclInfoPool(CurPool);
401     CurIndex = 0;
402   }
403   IdDeclInfo *IDI = &CurPool->Pool[CurIndex];
404   Name.setFETokenInfo(reinterpret_cast<void*>(
405                               reinterpret_cast<uintptr_t>(IDI) | 0x1)
406                                                                      );
407   ++CurIndex;
408   return *IDI;
409 }
410 
incrementSlowCase()411 void IdentifierResolver::iterator::incrementSlowCase() {
412   NamedDecl *D = **this;
413   void *InfoPtr = D->getDeclName().getFETokenInfo<void>();
414   assert(!isDeclPtr(InfoPtr) && "Decl with wrong id ?");
415   IdDeclInfo *Info = toIdDeclInfo(InfoPtr);
416 
417   BaseIter I = getIterator();
418   if (I != Info->decls_begin())
419     *this = iterator(I-1);
420   else // No more decls.
421     *this = iterator();
422 }
423