1//===- IdentifierResolver.cpp - Lexical Scope Name lookup -----------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file implements the IdentifierResolver class, which is used for lexical
10// scoped lookup, based on declaration names.
11//
12//===----------------------------------------------------------------------===//
13
14#include "clang/Sema/IdentifierResolver.h"
15#include "clang/AST/Decl.h"
16#include "clang/AST/DeclBase.h"
17#include "clang/AST/DeclarationName.h"
18#include "clang/Basic/IdentifierTable.h"
19#include "clang/Basic/LangOptions.h"
20#include "clang/Lex/ExternalPreprocessorSource.h"
21#include "clang/Lex/Preprocessor.h"
22#include "clang/Sema/Scope.h"
23#include "llvm/Support/ErrorHandling.h"
24#include <cassert>
25#include <cstdint>
26
27using namespace clang;
28
29//===----------------------------------------------------------------------===//
30// IdDeclInfoMap class
31//===----------------------------------------------------------------------===//
32
33/// IdDeclInfoMap - Associates IdDeclInfos with declaration names.
34/// Allocates 'pools' (vectors of IdDeclInfos) to avoid allocating each
35/// individual IdDeclInfo to heap.
36class IdentifierResolver::IdDeclInfoMap {
37 static const unsigned int POOL_SIZE = 512;
38
39 /// We use our own linked-list implementation because it is sadly
40 /// impossible to add something to a pre-C++0x STL container without
41 /// a completely unnecessary copy.
42 struct IdDeclInfoPool {
43 IdDeclInfoPool *Next;
44 IdDeclInfo Pool[POOL_SIZE];
45
46 IdDeclInfoPool(IdDeclInfoPool *Next) : Next(Next) {}
47 };
48
49 IdDeclInfoPool *CurPool = nullptr;
50 unsigned int CurIndex = POOL_SIZE;
51
52public:
53 IdDeclInfoMap() = default;
54
55 ~IdDeclInfoMap() {
56 IdDeclInfoPool *Cur = CurPool;
57 while (IdDeclInfoPool *P = Cur) {
58 Cur = Cur->Next;
59 delete P;
60 }
61 }
62
63 IdDeclInfoMap(const IdDeclInfoMap &) = delete;
64 IdDeclInfoMap &operator=(const IdDeclInfoMap &) = delete;
65
66 /// Returns the IdDeclInfo associated to the DeclarationName.
67 /// It creates a new IdDeclInfo if one was not created before for this id.
68 IdDeclInfo &operator[](DeclarationName Name);
69};
70
71//===----------------------------------------------------------------------===//
72// IdDeclInfo Implementation
73//===----------------------------------------------------------------------===//
74
75/// RemoveDecl - Remove the decl from the scope chain.
76/// The decl must already be part of the decl chain.
77void IdentifierResolver::IdDeclInfo::RemoveDecl(NamedDecl *D) {
78 for (DeclsTy::iterator I = Decls.end(); I != Decls.begin(); --I) {
79 if (D == *(I-1)) {
80 Decls.erase(CI: I-1);
81 return;
82 }
83 }
84
85 llvm_unreachable("Didn't find this decl on its identifier's chain!");
86}
87
88//===----------------------------------------------------------------------===//
89// IdentifierResolver Implementation
90//===----------------------------------------------------------------------===//
91
92IdentifierResolver::IdentifierResolver(Preprocessor &PP)
93 : LangOpt(PP.getLangOpts()), PP(PP), IdDeclInfos(new IdDeclInfoMap) {}
94
95IdentifierResolver::~IdentifierResolver() {
96 delete IdDeclInfos;
97}
98
99/// isDeclInScope - If 'Ctx' is a function/method, isDeclInScope returns true
100/// if 'D' is in Scope 'S', otherwise 'S' is ignored and isDeclInScope returns
101/// true if 'D' belongs to the given declaration context.
102bool IdentifierResolver::isDeclInScope(Decl *D, DeclContext *Ctx, Scope *S,
103 bool AllowInlineNamespace) const {
104 Ctx = Ctx->getRedeclContext();
105 // The names for HLSL cbuffer/tbuffers only used by the CPU-side
106 // reflection API which supports querying bindings. It will not have name
107 // conflict with other Decls.
108 if (LangOpt.HLSL && isa<HLSLBufferDecl>(Val: D))
109 return false;
110 if (Ctx->isFunctionOrMethod() || (S && S->isFunctionPrototypeScope())) {
111 // Ignore the scopes associated within transparent declaration contexts.
112 while (S->getEntity() &&
113 (S->getEntity()->isTransparentContext() ||
114 (!LangOpt.CPlusPlus && isa<RecordDecl>(Val: S->getEntity()))))
115 S = S->getParent();
116
117 if (S->isDeclScope(D))
118 return true;
119 if (LangOpt.CPlusPlus) {
120 // C++ 3.3.2p3:
121 // The name declared in a catch exception-declaration is local to the
122 // handler and shall not be redeclared in the outermost block of the
123 // handler.
124 // C++ 3.3.2p4:
125 // Names declared in the for-init-statement, and in the condition of if,
126 // while, for, and switch statements are local to the if, while, for, or
127 // switch statement (including the controlled statement), and shall not be
128 // redeclared in a subsequent condition of that statement nor in the
129 // outermost block (or, for the if statement, any of the outermost blocks)
130 // of the controlled statement.
131 //
132 assert(S->getParent() && "No TUScope?");
133 // If the current decl is in a lambda, we shouldn't consider this is a
134 // redefinition as lambda has its own scope.
135 if (S->getParent()->isControlScope() && !S->isFunctionScope()) {
136 S = S->getParent();
137 if (S->isDeclScope(D))
138 return true;
139 }
140 if (S->isFnTryCatchScope())
141 return S->getParent()->isDeclScope(D);
142 }
143 return false;
144 }
145
146 // FIXME: If D is a local extern declaration, this check doesn't make sense;
147 // we should be checking its lexical context instead in that case, because
148 // that is its scope.
149 DeclContext *DCtx = D->getDeclContext()->getRedeclContext();
150 return AllowInlineNamespace ? Ctx->InEnclosingNamespaceSetOf(NS: DCtx)
151 : Ctx->Equals(DC: DCtx);
152}
153
154/// AddDecl - Link the decl to its shadowed decl chain.
155void IdentifierResolver::AddDecl(NamedDecl *D) {
156 DeclarationName Name = D->getDeclName();
157 if (IdentifierInfo *II = Name.getAsIdentifierInfo())
158 updatingIdentifier(II&: *II);
159
160 void *Ptr = Name.getFETokenInfo();
161
162 if (!Ptr) {
163 Name.setFETokenInfo(D);
164 return;
165 }
166
167 IdDeclInfo *IDI;
168
169 if (isDeclPtr(Ptr)) {
170 Name.setFETokenInfo(nullptr);
171 IDI = &(*IdDeclInfos)[Name];
172 NamedDecl *PrevD = static_cast<NamedDecl*>(Ptr);
173 IDI->AddDecl(D: PrevD);
174 } else
175 IDI = toIdDeclInfo(Ptr);
176
177 IDI->AddDecl(D);
178}
179
180void IdentifierResolver::InsertDeclAfter(iterator Pos, NamedDecl *D) {
181 DeclarationName Name = D->getDeclName();
182 if (IdentifierInfo *II = Name.getAsIdentifierInfo())
183 updatingIdentifier(II&: *II);
184
185 void *Ptr = Name.getFETokenInfo();
186
187 if (!Ptr) {
188 AddDecl(D);
189 return;
190 }
191
192 if (isDeclPtr(Ptr)) {
193 // We only have a single declaration: insert before or after it,
194 // as appropriate.
195 if (Pos == iterator()) {
196 // Add the new declaration before the existing declaration.
197 NamedDecl *PrevD = static_cast<NamedDecl*>(Ptr);
198 RemoveDecl(D: PrevD);
199 AddDecl(D);
200 AddDecl(D: PrevD);
201 } else {
202 // Add new declaration after the existing declaration.
203 AddDecl(D);
204 }
205
206 return;
207 }
208
209 // General case: insert the declaration at the appropriate point in the
210 // list, which already has at least two elements.
211 IdDeclInfo *IDI = toIdDeclInfo(Ptr);
212 if (Pos.isIterator()) {
213 IDI->InsertDecl(Pos: Pos.getIterator() + 1, D);
214 } else
215 IDI->InsertDecl(Pos: IDI->decls_begin(), D);
216}
217
218/// RemoveDecl - Unlink the decl from its shadowed decl chain.
219/// The decl must already be part of the decl chain.
220void IdentifierResolver::RemoveDecl(NamedDecl *D) {
221 assert(D && "null param passed");
222 DeclarationName Name = D->getDeclName();
223 if (IdentifierInfo *II = Name.getAsIdentifierInfo())
224 updatingIdentifier(II&: *II);
225
226 void *Ptr = Name.getFETokenInfo();
227
228 assert(Ptr && "Didn't find this decl on its identifier's chain!");
229
230 if (isDeclPtr(Ptr)) {
231 assert(D == Ptr && "Didn't find this decl on its identifier's chain!");
232 Name.setFETokenInfo(nullptr);
233 return;
234 }
235
236 return toIdDeclInfo(Ptr)->RemoveDecl(D);
237}
238
239llvm::iterator_range<IdentifierResolver::iterator>
240IdentifierResolver::decls(DeclarationName Name) {
241 return {begin(Name), end()};
242}
243
244IdentifierResolver::iterator IdentifierResolver::begin(DeclarationName Name) {
245 if (IdentifierInfo *II = Name.getAsIdentifierInfo())
246 readingIdentifier(II&: *II);
247
248 void *Ptr = Name.getFETokenInfo();
249 if (!Ptr) return end();
250
251 if (isDeclPtr(Ptr))
252 return iterator(static_cast<NamedDecl*>(Ptr));
253
254 IdDeclInfo *IDI = toIdDeclInfo(Ptr);
255
256 IdDeclInfo::DeclsTy::iterator I = IDI->decls_end();
257 if (I != IDI->decls_begin())
258 return iterator(I-1);
259 // No decls found.
260 return end();
261}
262
263namespace {
264
265enum DeclMatchKind {
266 DMK_Different,
267 DMK_Replace,
268 DMK_Ignore
269};
270
271} // namespace
272
273/// Compare two declarations to see whether they are different or,
274/// if they are the same, whether the new declaration should replace the
275/// existing declaration.
276static DeclMatchKind compareDeclarations(NamedDecl *Existing, NamedDecl *New) {
277 // If the declarations are identical, ignore the new one.
278 if (Existing == New)
279 return DMK_Ignore;
280
281 // If the declarations have different kinds, they're obviously different.
282 if (Existing->getKind() != New->getKind())
283 return DMK_Different;
284
285 // If the declarations are redeclarations of each other, keep the newest one.
286 if (Existing->getCanonicalDecl() == New->getCanonicalDecl()) {
287 // If we're adding an imported declaration, don't replace another imported
288 // declaration.
289 if (Existing->isFromASTFile() && New->isFromASTFile())
290 return DMK_Different;
291
292 // If either of these is the most recent declaration, use it.
293 Decl *MostRecent = Existing->getMostRecentDecl();
294 if (Existing == MostRecent)
295 return DMK_Ignore;
296
297 if (New == MostRecent)
298 return DMK_Replace;
299
300 // If the existing declaration is somewhere in the previous declaration
301 // chain of the new declaration, then prefer the new declaration.
302 for (auto *RD : New->redecls()) {
303 if (RD == Existing)
304 return DMK_Replace;
305
306 if (RD->isCanonicalDecl())
307 break;
308 }
309
310 return DMK_Ignore;
311 }
312
313 return DMK_Different;
314}
315
316bool IdentifierResolver::tryAddTopLevelDecl(NamedDecl *D, DeclarationName Name){
317 if (IdentifierInfo *II = Name.getAsIdentifierInfo())
318 readingIdentifier(II&: *II);
319
320 void *Ptr = Name.getFETokenInfo();
321
322 if (!Ptr) {
323 Name.setFETokenInfo(D);
324 return true;
325 }
326
327 IdDeclInfo *IDI;
328
329 if (isDeclPtr(Ptr)) {
330 NamedDecl *PrevD = static_cast<NamedDecl*>(Ptr);
331
332 switch (compareDeclarations(Existing: PrevD, New: D)) {
333 case DMK_Different:
334 break;
335
336 case DMK_Ignore:
337 return false;
338
339 case DMK_Replace:
340 Name.setFETokenInfo(D);
341 return true;
342 }
343
344 Name.setFETokenInfo(nullptr);
345 IDI = &(*IdDeclInfos)[Name];
346
347 // If the existing declaration is not visible in translation unit scope,
348 // then add the new top-level declaration first.
349 if (!PrevD->getDeclContext()->getRedeclContext()->isTranslationUnit()) {
350 IDI->AddDecl(D);
351 IDI->AddDecl(D: PrevD);
352 } else {
353 IDI->AddDecl(D: PrevD);
354 IDI->AddDecl(D);
355 }
356 return true;
357 }
358
359 IDI = toIdDeclInfo(Ptr);
360
361 // See whether this declaration is identical to any existing declarations.
362 // If not, find the right place to insert it.
363 for (IdDeclInfo::DeclsTy::iterator I = IDI->decls_begin(),
364 IEnd = IDI->decls_end();
365 I != IEnd; ++I) {
366
367 switch (compareDeclarations(Existing: *I, New: D)) {
368 case DMK_Different:
369 break;
370
371 case DMK_Ignore:
372 return false;
373
374 case DMK_Replace:
375 *I = D;
376 return true;
377 }
378
379 if (!(*I)->getDeclContext()->getRedeclContext()->isTranslationUnit()) {
380 // We've found a declaration that is not visible from the translation
381 // unit (it's in an inner scope). Insert our declaration here.
382 IDI->InsertDecl(Pos: I, D);
383 return true;
384 }
385 }
386
387 // Add the declaration to the end.
388 IDI->AddDecl(D);
389 return true;
390}
391
392void IdentifierResolver::readingIdentifier(IdentifierInfo &II) {
393 if (II.isOutOfDate())
394 PP.getExternalSource()->updateOutOfDateIdentifier(II);
395}
396
397void IdentifierResolver::updatingIdentifier(IdentifierInfo &II) {
398 if (II.isOutOfDate())
399 PP.getExternalSource()->updateOutOfDateIdentifier(II);
400
401 if (II.isFromAST())
402 II.setFETokenInfoChangedSinceDeserialization();
403}
404
405//===----------------------------------------------------------------------===//
406// IdDeclInfoMap Implementation
407//===----------------------------------------------------------------------===//
408
409/// Returns the IdDeclInfo associated to the DeclarationName.
410/// It creates a new IdDeclInfo if one was not created before for this id.
411IdentifierResolver::IdDeclInfo &
412IdentifierResolver::IdDeclInfoMap::operator[](DeclarationName Name) {
413 void *Ptr = Name.getFETokenInfo();
414
415 if (Ptr) return *toIdDeclInfo(Ptr);
416
417 if (CurIndex == POOL_SIZE) {
418 CurPool = new IdDeclInfoPool(CurPool);
419 CurIndex = 0;
420 }
421 IdDeclInfo *IDI = &CurPool->Pool[CurIndex];
422 Name.setFETokenInfo(reinterpret_cast<void*>(
423 reinterpret_cast<uintptr_t>(IDI) | 0x1)
424 );
425 ++CurIndex;
426 return *IDI;
427}
428
429void IdentifierResolver::iterator::incrementSlowCase() {
430 NamedDecl *D = **this;
431 void *InfoPtr = D->getDeclName().getFETokenInfo();
432 assert(!isDeclPtr(InfoPtr) && "Decl with wrong id ?");
433 IdDeclInfo *Info = toIdDeclInfo(Ptr: InfoPtr);
434
435 BaseIter I = getIterator();
436 if (I != Info->decls_begin())
437 *this = iterator(I-1);
438 else // No more decls.
439 *this = iterator();
440}
441