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.
102///
103/// If 'Ctx' is an expansion statement, we use its enclosing function instead.
104bool IdentifierResolver::isDeclInScope(Decl *D, DeclContext *Ctx, Scope *S,
105 bool AllowInlineNamespace) const {
106 Ctx = Ctx->getRedeclContext();
107 // The names for HLSL cbuffer/tbuffers only used by the CPU-side
108 // reflection API which supports querying bindings. It will not have name
109 // conflict with other Decls.
110 if (LangOpt.HLSL && isa<HLSLBufferDecl>(Val: D))
111 return false;
112 if (Ctx->getEnclosingNonExpansionStatementContext()
113 ->getRedeclContext()
114 ->isFunctionOrMethod() ||
115 (S && S->isFunctionPrototypeScope())) {
116 // Ignore the scopes associated within transparent declaration contexts.
117 while (S->getEntity() &&
118 (S->getEntity()->isTransparentContext() ||
119 (!LangOpt.CPlusPlus && isa<RecordDecl>(Val: S->getEntity()))))
120 S = S->getParent();
121
122 if (S->isDeclScope(D))
123 return true;
124 if (LangOpt.CPlusPlus) {
125 // C++ 3.3.2p3:
126 // The name declared in a catch exception-declaration is local to the
127 // handler and shall not be redeclared in the outermost block of the
128 // handler.
129 // C++ 3.3.2p4:
130 // Names declared in the for-init-statement, and in the condition of if,
131 // while, for, and switch statements are local to the if, while, for, or
132 // switch statement (including the controlled statement), and shall not be
133 // redeclared in a subsequent condition of that statement nor in the
134 // outermost block (or, for the if statement, any of the outermost blocks)
135 // of the controlled statement.
136 //
137 assert(S->getParent() && "No TUScope?");
138 // If the current decl is in a lambda, we shouldn't consider this is a
139 // redefinition as lambda has its own scope.
140 if (S->getParent()->isControlScope() && !S->isFunctionScope()) {
141 S = S->getParent();
142 if (S->isDeclScope(D))
143 return true;
144 }
145 if (S->isFnTryCatchScope())
146 return S->getParent()->isDeclScope(D);
147 }
148 return false;
149 }
150
151 // FIXME: If D is a local extern declaration, this check doesn't make sense;
152 // we should be checking its lexical context instead in that case, because
153 // that is its scope.
154 DeclContext *DCtx = D->getDeclContext()->getRedeclContext();
155 return AllowInlineNamespace ? Ctx->InEnclosingNamespaceSetOf(NS: DCtx)
156 : Ctx->Equals(DC: DCtx);
157}
158
159/// AddDecl - Link the decl to its shadowed decl chain.
160void IdentifierResolver::AddDecl(NamedDecl *D) {
161 DeclarationName Name = D->getDeclName();
162 if (IdentifierInfo *II = Name.getAsIdentifierInfo())
163 updatingIdentifier(II&: *II);
164
165 void *Ptr = Name.getFETokenInfo();
166
167 if (!Ptr) {
168 Name.setFETokenInfo(D);
169 return;
170 }
171
172 IdDeclInfo *IDI;
173
174 if (isDeclPtr(Ptr)) {
175 Name.setFETokenInfo(nullptr);
176 IDI = &(*IdDeclInfos)[Name];
177 NamedDecl *PrevD = static_cast<NamedDecl*>(Ptr);
178 IDI->AddDecl(D: PrevD);
179 } else
180 IDI = toIdDeclInfo(Ptr);
181
182 IDI->AddDecl(D);
183}
184
185void IdentifierResolver::InsertDeclAfter(iterator Pos, NamedDecl *D) {
186 DeclarationName Name = D->getDeclName();
187 if (IdentifierInfo *II = Name.getAsIdentifierInfo())
188 updatingIdentifier(II&: *II);
189
190 void *Ptr = Name.getFETokenInfo();
191
192 if (!Ptr) {
193 AddDecl(D);
194 return;
195 }
196
197 if (isDeclPtr(Ptr)) {
198 // We only have a single declaration: insert before or after it,
199 // as appropriate.
200 if (Pos == iterator()) {
201 // Add the new declaration before the existing declaration.
202 NamedDecl *PrevD = static_cast<NamedDecl*>(Ptr);
203 RemoveDecl(D: PrevD);
204 AddDecl(D);
205 AddDecl(D: PrevD);
206 } else {
207 // Add new declaration after the existing declaration.
208 AddDecl(D);
209 }
210
211 return;
212 }
213
214 // General case: insert the declaration at the appropriate point in the
215 // list, which already has at least two elements.
216 IdDeclInfo *IDI = toIdDeclInfo(Ptr);
217 if (Pos.isIterator()) {
218 IDI->InsertDecl(Pos: Pos.getIterator() + 1, D);
219 } else
220 IDI->InsertDecl(Pos: IDI->decls_begin(), D);
221}
222
223/// RemoveDecl - Unlink the decl from its shadowed decl chain.
224/// The decl must already be part of the decl chain.
225void IdentifierResolver::RemoveDecl(NamedDecl *D) {
226 assert(D && "null param passed");
227 DeclarationName Name = D->getDeclName();
228 if (IdentifierInfo *II = Name.getAsIdentifierInfo())
229 updatingIdentifier(II&: *II);
230
231 void *Ptr = Name.getFETokenInfo();
232
233 assert(Ptr && "Didn't find this decl on its identifier's chain!");
234
235 if (isDeclPtr(Ptr)) {
236 assert(D == Ptr && "Didn't find this decl on its identifier's chain!");
237 Name.setFETokenInfo(nullptr);
238 return;
239 }
240
241 return toIdDeclInfo(Ptr)->RemoveDecl(D);
242}
243
244llvm::iterator_range<IdentifierResolver::iterator>
245IdentifierResolver::decls(DeclarationName Name) {
246 return {begin(Name), end()};
247}
248
249IdentifierResolver::iterator IdentifierResolver::begin(DeclarationName Name) {
250 if (IdentifierInfo *II = Name.getAsIdentifierInfo())
251 readingIdentifier(II&: *II);
252
253 void *Ptr = Name.getFETokenInfo();
254 if (!Ptr) return end();
255
256 if (isDeclPtr(Ptr))
257 return iterator(static_cast<NamedDecl*>(Ptr));
258
259 IdDeclInfo *IDI = toIdDeclInfo(Ptr);
260
261 IdDeclInfo::DeclsTy::iterator I = IDI->decls_end();
262 if (I != IDI->decls_begin())
263 return iterator(I-1);
264 // No decls found.
265 return end();
266}
267
268namespace {
269
270enum DeclMatchKind {
271 DMK_Different,
272 DMK_Replace,
273 DMK_Ignore
274};
275
276} // namespace
277
278/// Compare two declarations to see whether they are different or,
279/// if they are the same, whether the new declaration should replace the
280/// existing declaration.
281static DeclMatchKind compareDeclarations(NamedDecl *Existing, NamedDecl *New) {
282 // If the declarations are identical, ignore the new one.
283 if (Existing == New)
284 return DMK_Ignore;
285
286 // If the declarations have different kinds, they're obviously different.
287 if (Existing->getKind() != New->getKind())
288 return DMK_Different;
289
290 // If the declarations are redeclarations of each other, keep the newest one.
291 if (Existing->getCanonicalDecl() == New->getCanonicalDecl()) {
292 // If we're adding an imported declaration, don't replace another imported
293 // declaration.
294 if (Existing->isFromASTFile() && New->isFromASTFile())
295 return DMK_Different;
296
297 // If either of these is the most recent declaration, use it.
298 Decl *MostRecent = Existing->getMostRecentDecl();
299 if (Existing == MostRecent)
300 return DMK_Ignore;
301
302 if (New == MostRecent)
303 return DMK_Replace;
304
305 // If the existing declaration is somewhere in the previous declaration
306 // chain of the new declaration, then prefer the new declaration.
307 for (auto *RD : New->redecls()) {
308 if (RD == Existing)
309 return DMK_Replace;
310
311 if (RD->isCanonicalDecl())
312 break;
313 }
314
315 return DMK_Ignore;
316 }
317
318 return DMK_Different;
319}
320
321bool IdentifierResolver::tryAddTopLevelDecl(NamedDecl *D, DeclarationName Name){
322 if (IdentifierInfo *II = Name.getAsIdentifierInfo())
323 readingIdentifier(II&: *II);
324
325 void *Ptr = Name.getFETokenInfo();
326
327 if (!Ptr) {
328 Name.setFETokenInfo(D);
329 return true;
330 }
331
332 IdDeclInfo *IDI;
333
334 if (isDeclPtr(Ptr)) {
335 NamedDecl *PrevD = static_cast<NamedDecl*>(Ptr);
336
337 switch (compareDeclarations(Existing: PrevD, New: D)) {
338 case DMK_Different:
339 break;
340
341 case DMK_Ignore:
342 return false;
343
344 case DMK_Replace:
345 Name.setFETokenInfo(D);
346 return true;
347 }
348
349 Name.setFETokenInfo(nullptr);
350 IDI = &(*IdDeclInfos)[Name];
351
352 // If the existing declaration is not visible in translation unit scope,
353 // then add the new top-level declaration first.
354 if (!PrevD->getDeclContext()->getRedeclContext()->isTranslationUnit()) {
355 IDI->AddDecl(D);
356 IDI->AddDecl(D: PrevD);
357 } else {
358 IDI->AddDecl(D: PrevD);
359 IDI->AddDecl(D);
360 }
361 return true;
362 }
363
364 IDI = toIdDeclInfo(Ptr);
365
366 // See whether this declaration is identical to any existing declarations.
367 // If not, find the right place to insert it.
368 for (IdDeclInfo::DeclsTy::iterator I = IDI->decls_begin(),
369 IEnd = IDI->decls_end();
370 I != IEnd; ++I) {
371
372 switch (compareDeclarations(Existing: *I, New: D)) {
373 case DMK_Different:
374 break;
375
376 case DMK_Ignore:
377 return false;
378
379 case DMK_Replace:
380 *I = D;
381 return true;
382 }
383
384 if (!(*I)->getDeclContext()->getRedeclContext()->isTranslationUnit()) {
385 // We've found a declaration that is not visible from the translation
386 // unit (it's in an inner scope). Insert our declaration here.
387 IDI->InsertDecl(Pos: I, D);
388 return true;
389 }
390 }
391
392 // Add the declaration to the end.
393 IDI->AddDecl(D);
394 return true;
395}
396
397void IdentifierResolver::readingIdentifier(IdentifierInfo &II) {
398 if (II.isOutOfDate())
399 PP.getExternalSource()->updateOutOfDateIdentifier(II);
400}
401
402void IdentifierResolver::updatingIdentifier(IdentifierInfo &II) {
403 if (II.isOutOfDate())
404 PP.getExternalSource()->updateOutOfDateIdentifier(II);
405
406 if (II.isFromAST())
407 II.setFETokenInfoChangedSinceDeserialization();
408}
409
410//===----------------------------------------------------------------------===//
411// IdDeclInfoMap Implementation
412//===----------------------------------------------------------------------===//
413
414/// Returns the IdDeclInfo associated to the DeclarationName.
415/// It creates a new IdDeclInfo if one was not created before for this id.
416IdentifierResolver::IdDeclInfo &
417IdentifierResolver::IdDeclInfoMap::operator[](DeclarationName Name) {
418 void *Ptr = Name.getFETokenInfo();
419
420 if (Ptr) return *toIdDeclInfo(Ptr);
421
422 if (CurIndex == POOL_SIZE) {
423 CurPool = new IdDeclInfoPool(CurPool);
424 CurIndex = 0;
425 }
426 IdDeclInfo *IDI = &CurPool->Pool[CurIndex];
427 Name.setFETokenInfo(reinterpret_cast<void*>(
428 reinterpret_cast<uintptr_t>(IDI) | 0x1)
429 );
430 ++CurIndex;
431 return *IDI;
432}
433
434void IdentifierResolver::iterator::incrementSlowCase() {
435 NamedDecl *D = **this;
436 void *InfoPtr = D->getDeclName().getFETokenInfo();
437 assert(!isDeclPtr(InfoPtr) && "Decl with wrong id ?");
438 IdDeclInfo *Info = toIdDeclInfo(Ptr: InfoPtr);
439
440 BaseIter I = getIterator();
441 if (I != Info->decls_begin())
442 *this = iterator(I-1);
443 else // No more decls.
444 *this = iterator();
445}
446