1 //===-- ODRHash.cpp - Hashing to diagnose ODR failures ----------*- 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 /// \file
11 /// This file implements the ODRHash class, which calculates a hash based
12 /// on AST nodes, which is stable across different runs.
13 ///
14 //===----------------------------------------------------------------------===//
15 
16 #include "clang/AST/ODRHash.h"
17 
18 #include "clang/AST/DeclVisitor.h"
19 #include "clang/AST/NestedNameSpecifier.h"
20 #include "clang/AST/StmtVisitor.h"
21 #include "clang/AST/TypeVisitor.h"
22 
23 using namespace clang;
24 
25 void ODRHash::AddStmt(const Stmt *S) {
26   assert(S && "Expecting non-null pointer.");
27   S->ProcessODRHash(ID, *this);
28 }
29 
30 void ODRHash::AddIdentifierInfo(const IdentifierInfo *II) {
31   assert(II && "Expecting non-null pointer.");
32   ID.AddString(II->getName());
33 }
34 
35 void ODRHash::AddDeclarationName(DeclarationName Name) {
36   AddBoolean(Name.isEmpty());
37   if (Name.isEmpty())
38     return;
39 
40   auto Kind = Name.getNameKind();
41   ID.AddInteger(Kind);
42   switch (Kind) {
43   case DeclarationName::Identifier:
44     AddIdentifierInfo(Name.getAsIdentifierInfo());
45     break;
46   case DeclarationName::ObjCZeroArgSelector:
47   case DeclarationName::ObjCOneArgSelector:
48   case DeclarationName::ObjCMultiArgSelector: {
49     Selector S = Name.getObjCSelector();
50     AddBoolean(S.isNull());
51     AddBoolean(S.isKeywordSelector());
52     AddBoolean(S.isUnarySelector());
53     unsigned NumArgs = S.getNumArgs();
54     for (unsigned i = 0; i < NumArgs; ++i) {
55       AddIdentifierInfo(S.getIdentifierInfoForSlot(i));
56     }
57     break;
58   }
59   case DeclarationName::CXXConstructorName:
60   case DeclarationName::CXXDestructorName:
61     AddQualType(Name.getCXXNameType());
62     break;
63   case DeclarationName::CXXOperatorName:
64     ID.AddInteger(Name.getCXXOverloadedOperator());
65     break;
66   case DeclarationName::CXXLiteralOperatorName:
67     AddIdentifierInfo(Name.getCXXLiteralIdentifier());
68     break;
69   case DeclarationName::CXXConversionFunctionName:
70     AddQualType(Name.getCXXNameType());
71     break;
72   case DeclarationName::CXXUsingDirective:
73     break;
74   case DeclarationName::CXXDeductionGuideName: {
75     auto *Template = Name.getCXXDeductionGuideTemplate();
76     AddBoolean(Template);
77     if (Template) {
78       AddDecl(Template);
79     }
80   }
81   }
82 }
83 
84 void ODRHash::AddNestedNameSpecifier(const NestedNameSpecifier *NNS) {}
85 void ODRHash::AddTemplateName(TemplateName Name) {}
86 void ODRHash::AddTemplateArgument(TemplateArgument TA) {}
87 void ODRHash::AddTemplateParameterList(const TemplateParameterList *TPL) {}
88 
89 void ODRHash::clear() {
90   DeclMap.clear();
91   TypeMap.clear();
92   Bools.clear();
93   ID.clear();
94 }
95 
96 unsigned ODRHash::CalculateHash() {
97   // Append the bools to the end of the data segment backwards.  This allows
98   // for the bools data to be compressed 32 times smaller compared to using
99   // ID.AddBoolean
100   const unsigned unsigned_bits = sizeof(unsigned) * CHAR_BIT;
101   const unsigned size = Bools.size();
102   const unsigned remainder = size % unsigned_bits;
103   const unsigned loops = size / unsigned_bits;
104   auto I = Bools.rbegin();
105   unsigned value = 0;
106   for (unsigned i = 0; i < remainder; ++i) {
107     value <<= 1;
108     value |= *I;
109     ++I;
110   }
111   ID.AddInteger(value);
112 
113   for (unsigned i = 0; i < loops; ++i) {
114     value = 0;
115     for (unsigned j = 0; j < unsigned_bits; ++j) {
116       value <<= 1;
117       value |= *I;
118       ++I;
119     }
120     ID.AddInteger(value);
121   }
122 
123   assert(I == Bools.rend());
124   Bools.clear();
125   return ID.ComputeHash();
126 }
127 
128 // Process a Decl pointer.  Add* methods call back into ODRHash while Visit*
129 // methods process the relevant parts of the Decl.
130 class ODRDeclVisitor : public ConstDeclVisitor<ODRDeclVisitor> {
131   typedef ConstDeclVisitor<ODRDeclVisitor> Inherited;
132   llvm::FoldingSetNodeID &ID;
133   ODRHash &Hash;
134 
135 public:
136   ODRDeclVisitor(llvm::FoldingSetNodeID &ID, ODRHash &Hash)
137       : ID(ID), Hash(Hash) {}
138 
139   void AddStmt(const Stmt *S) {
140     Hash.AddBoolean(S);
141     if (S) {
142       Hash.AddStmt(S);
143     }
144   }
145 
146   void AddIdentifierInfo(const IdentifierInfo *II) {
147     Hash.AddBoolean(II);
148     if (II) {
149       Hash.AddIdentifierInfo(II);
150     }
151   }
152 
153   void AddQualType(QualType T) {
154     Hash.AddQualType(T);
155   }
156 
157   void Visit(const Decl *D) {
158     ID.AddInteger(D->getKind());
159     Inherited::Visit(D);
160   }
161 
162   void VisitNamedDecl(const NamedDecl *D) {
163     Hash.AddDeclarationName(D->getDeclName());
164     Inherited::VisitNamedDecl(D);
165   }
166 
167   void VisitValueDecl(const ValueDecl *D) {
168     AddQualType(D->getType());
169     Inherited::VisitValueDecl(D);
170   }
171 
172   void VisitParmVarDecl(const ParmVarDecl *D) {
173     // TODO: Handle default arguments.
174     Inherited::VisitParmVarDecl(D);
175   }
176 
177   void VisitAccessSpecDecl(const AccessSpecDecl *D) {
178     ID.AddInteger(D->getAccess());
179     Inherited::VisitAccessSpecDecl(D);
180   }
181 
182   void VisitStaticAssertDecl(const StaticAssertDecl *D) {
183     AddStmt(D->getAssertExpr());
184     AddStmt(D->getMessage());
185 
186     Inherited::VisitStaticAssertDecl(D);
187   }
188 
189   void VisitFieldDecl(const FieldDecl *D) {
190     const bool IsBitfield = D->isBitField();
191     Hash.AddBoolean(IsBitfield);
192 
193     if (IsBitfield) {
194       AddStmt(D->getBitWidth());
195     }
196 
197     Hash.AddBoolean(D->isMutable());
198     AddStmt(D->getInClassInitializer());
199 
200     Inherited::VisitFieldDecl(D);
201   }
202 
203   void VisitFunctionDecl(const FunctionDecl *D) {
204     ID.AddInteger(D->getStorageClass());
205     Hash.AddBoolean(D->isInlineSpecified());
206     Hash.AddBoolean(D->isVirtualAsWritten());
207     Hash.AddBoolean(D->isPure());
208     Hash.AddBoolean(D->isDeletedAsWritten());
209 
210     ID.AddInteger(D->param_size());
211 
212     for (auto *Param : D->parameters()) {
213       Hash.AddSubDecl(Param);
214     }
215 
216     Inherited::VisitFunctionDecl(D);
217   }
218 
219   void VisitCXXMethodDecl(const CXXMethodDecl *D) {
220     Hash.AddBoolean(D->isConst());
221     Hash.AddBoolean(D->isVolatile());
222 
223     Inherited::VisitCXXMethodDecl(D);
224   }
225 
226   void VisitTypedefNameDecl(const TypedefNameDecl *D) {
227     AddQualType(D->getUnderlyingType());
228 
229     Inherited::VisitTypedefNameDecl(D);
230   }
231 
232   void VisitTypedefDecl(const TypedefDecl *D) {
233     Inherited::VisitTypedefDecl(D);
234   }
235 
236   void VisitTypeAliasDecl(const TypeAliasDecl *D) {
237     Inherited::VisitTypeAliasDecl(D);
238   }
239 };
240 
241 // Only allow a small portion of Decl's to be processed.  Remove this once
242 // all Decl's can be handled.
243 bool ODRHash::isWhitelistedDecl(const Decl *D, const CXXRecordDecl *Parent) {
244   if (D->isImplicit()) return false;
245   if (D->getDeclContext() != Parent) return false;
246 
247   switch (D->getKind()) {
248     default:
249       return false;
250     case Decl::AccessSpec:
251     case Decl::CXXMethod:
252     case Decl::Field:
253     case Decl::StaticAssert:
254     case Decl::TypeAlias:
255     case Decl::Typedef:
256       return true;
257   }
258 }
259 
260 void ODRHash::AddSubDecl(const Decl *D) {
261   assert(D && "Expecting non-null pointer.");
262   AddDecl(D);
263 
264   ODRDeclVisitor(ID, *this).Visit(D);
265 }
266 
267 void ODRHash::AddCXXRecordDecl(const CXXRecordDecl *Record) {
268   assert(Record && Record->hasDefinition() &&
269          "Expected non-null record to be a definition.");
270 
271   if (isa<ClassTemplateSpecializationDecl>(Record)) {
272     return;
273   }
274 
275   AddDecl(Record);
276 
277   // Filter out sub-Decls which will not be processed in order to get an
278   // accurate count of Decl's.
279   llvm::SmallVector<const Decl *, 16> Decls;
280   for (const Decl *SubDecl : Record->decls()) {
281     if (isWhitelistedDecl(SubDecl, Record)) {
282       Decls.push_back(SubDecl);
283     }
284   }
285 
286   ID.AddInteger(Decls.size());
287   for (auto SubDecl : Decls) {
288     AddSubDecl(SubDecl);
289   }
290 }
291 
292 void ODRHash::AddDecl(const Decl *D) {
293   assert(D && "Expecting non-null pointer.");
294   auto Result = DeclMap.insert(std::make_pair(D, DeclMap.size()));
295   ID.AddInteger(Result.first->second);
296   // On first encounter of a Decl pointer, process it.  Every time afterwards,
297   // only the index value is needed.
298   if (!Result.second) {
299     return;
300   }
301 
302   ID.AddInteger(D->getKind());
303 
304   if (const NamedDecl *ND = dyn_cast<NamedDecl>(D)) {
305     AddDeclarationName(ND->getDeclName());
306   }
307 }
308 
309 // Process a Type pointer.  Add* methods call back into ODRHash while Visit*
310 // methods process the relevant parts of the Type.
311 class ODRTypeVisitor : public TypeVisitor<ODRTypeVisitor> {
312   typedef TypeVisitor<ODRTypeVisitor> Inherited;
313   llvm::FoldingSetNodeID &ID;
314   ODRHash &Hash;
315 
316 public:
317   ODRTypeVisitor(llvm::FoldingSetNodeID &ID, ODRHash &Hash)
318       : ID(ID), Hash(Hash) {}
319 
320   void AddStmt(Stmt *S) {
321     Hash.AddBoolean(S);
322     if (S) {
323       Hash.AddStmt(S);
324     }
325   }
326 
327   void AddDecl(Decl *D) {
328     Hash.AddBoolean(D);
329     if (D) {
330       Hash.AddDecl(D);
331     }
332   }
333 
334   void AddQualType(QualType T) {
335     Hash.AddQualType(T);
336   }
337 
338   void VisitQualifiers(Qualifiers Quals) {
339     ID.AddInteger(Quals.getAsOpaqueValue());
340   }
341 
342   void Visit(const Type *T) {
343     ID.AddInteger(T->getTypeClass());
344     Inherited::Visit(T);
345   }
346 
347   void VisitType(const Type *T) {}
348 
349   void VisitAdjustedType(const AdjustedType *T) {
350     AddQualType(T->getOriginalType());
351     AddQualType(T->getAdjustedType());
352     VisitType(T);
353   }
354 
355   void VisitDecayedType(const DecayedType *T) {
356     AddQualType(T->getDecayedType());
357     AddQualType(T->getPointeeType());
358     VisitAdjustedType(T);
359   }
360 
361   void VisitArrayType(const ArrayType *T) {
362     AddQualType(T->getElementType());
363     ID.AddInteger(T->getSizeModifier());
364     VisitQualifiers(T->getIndexTypeQualifiers());
365     VisitType(T);
366   }
367   void VisitConstantArrayType(const ConstantArrayType *T) {
368     T->getSize().Profile(ID);
369     VisitArrayType(T);
370   }
371 
372   void VisitDependentSizedArrayType(const DependentSizedArrayType *T) {
373     AddStmt(T->getSizeExpr());
374     VisitArrayType(T);
375   }
376 
377   void VisitIncompleteArrayType(const IncompleteArrayType *T) {
378     VisitArrayType(T);
379   }
380 
381   void VisitVariableArrayType(const VariableArrayType *T) {
382     AddStmt(T->getSizeExpr());
383     VisitArrayType(T);
384   }
385 
386   void VisitBuiltinType(const BuiltinType *T) {
387     ID.AddInteger(T->getKind());
388     VisitType(T);
389   }
390 
391   void VisitFunctionType(const FunctionType *T) {
392     AddQualType(T->getReturnType());
393     T->getExtInfo().Profile(ID);
394     Hash.AddBoolean(T->isConst());
395     Hash.AddBoolean(T->isVolatile());
396     Hash.AddBoolean(T->isRestrict());
397     VisitType(T);
398   }
399 
400   void VisitFunctionNoProtoType(const FunctionNoProtoType *T) {
401     VisitFunctionType(T);
402   }
403 
404   void VisitFunctionProtoType(const FunctionProtoType *T) {
405     ID.AddInteger(T->getNumParams());
406     for (auto ParamType : T->getParamTypes())
407       AddQualType(ParamType);
408 
409     VisitFunctionType(T);
410   }
411 
412   void VisitTypedefType(const TypedefType *T) {
413     AddDecl(T->getDecl());
414     AddQualType(T->getDecl()->getUnderlyingType().getCanonicalType());
415     VisitType(T);
416   }
417 };
418 
419 void ODRHash::AddType(const Type *T) {
420   assert(T && "Expecting non-null pointer.");
421   auto Result = TypeMap.insert(std::make_pair(T, TypeMap.size()));
422   ID.AddInteger(Result.first->second);
423   // On first encounter of a Type pointer, process it.  Every time afterwards,
424   // only the index value is needed.
425   if (!Result.second) {
426     return;
427   }
428 
429   ODRTypeVisitor(ID, *this).Visit(T);
430 }
431 
432 void ODRHash::AddQualType(QualType T) {
433   AddBoolean(T.isNull());
434   if (T.isNull())
435     return;
436   SplitQualType split = T.split();
437   ID.AddInteger(split.Quals.getAsOpaqueValue());
438   AddType(split.Ty);
439 }
440 
441 void ODRHash::AddBoolean(bool Value) {
442   Bools.push_back(Value);
443 }
444