1//===- TemplateArgumentHasher.cpp - Hash Template Arguments -----*- C++ -*-===//
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#include "TemplateArgumentHasher.h"
10#include "clang/AST/APValue.h"
11#include "clang/AST/Decl.h"
12#include "clang/AST/DeclCXX.h"
13#include "clang/AST/DeclTemplate.h"
14#include "clang/AST/DeclarationName.h"
15#include "clang/AST/TypeVisitor.h"
16#include "clang/Basic/IdentifierTable.h"
17#include "llvm/ADT/FoldingSet.h"
18#include "llvm/Support/TimeProfiler.h"
19
20using namespace clang;
21
22namespace {
23
24class TemplateArgumentHasher {
25 // If we bail out during the process of calculating hash values for
26 // template arguments for any reason. We're allowed to do it since
27 // TemplateArgumentHasher are only required to give the same hash value
28 // for the same template arguments, but not required to give different
29 // hash value for different template arguments.
30 //
31 // So in the worst case, it is still a valid implementation to give all
32 // inputs the same BailedOutValue as output.
33 bool BailedOut = false;
34 static constexpr unsigned BailedOutValue = 0x12345678;
35
36 llvm::FoldingSetNodeID ID;
37
38public:
39 TemplateArgumentHasher() = default;
40
41 void AddTemplateArgument(TemplateArgument TA);
42
43 void AddInteger(unsigned V) { ID.AddInteger(I: V); }
44
45 unsigned getValue() {
46 if (BailedOut)
47 return BailedOutValue;
48
49 return ID.computeStableHash();
50 }
51
52 void setBailedOut() { BailedOut = true; }
53
54 void AddType(const Type *T);
55 void AddQualType(QualType T);
56 void AddDecl(const Decl *D);
57 void AddStructuralValue(const APValue &);
58 void AddTemplateName(TemplateName Name);
59 void AddDeclarationName(DeclarationName Name);
60 void AddIdentifierInfo(const IdentifierInfo *II);
61};
62
63void TemplateArgumentHasher::AddTemplateArgument(TemplateArgument TA) {
64 const auto Kind = TA.getKind();
65 AddInteger(V: Kind);
66
67 switch (Kind) {
68 case TemplateArgument::Null:
69 // These can occur in incomplete substitutions performed with code
70 // completion (see PartialOverloading).
71 break;
72 case TemplateArgument::Type:
73 AddQualType(T: TA.getAsType());
74 break;
75 case TemplateArgument::Declaration:
76 AddDecl(D: TA.getAsDecl());
77 break;
78 case TemplateArgument::NullPtr:
79 ID.AddPointer(Ptr: nullptr);
80 break;
81 case TemplateArgument::Integral: {
82 // There are integrals (e.g.: _BitInt(128)) that cannot be represented as
83 // any builtin integral type, so we use the hash of APSInt instead.
84 TA.getAsIntegral().Profile(ID);
85 break;
86 }
87 case TemplateArgument::StructuralValue:
88 AddQualType(T: TA.getStructuralValueType());
89 AddStructuralValue(TA.getAsStructuralValue());
90 break;
91 case TemplateArgument::Template:
92 case TemplateArgument::TemplateExpansion:
93 AddTemplateName(Name: TA.getAsTemplateOrTemplatePattern());
94 break;
95 case TemplateArgument::Expression:
96 // If we meet expression in template argument, it implies
97 // that the template is still dependent. It is meaningless
98 // to get a stable hash for the template. Bail out simply.
99 BailedOut = true;
100 break;
101 case TemplateArgument::Pack:
102 AddInteger(V: TA.pack_size());
103 for (auto SubTA : TA.pack_elements()) {
104 AddTemplateArgument(TA: SubTA);
105 }
106 break;
107 }
108}
109
110void TemplateArgumentHasher::AddStructuralValue(const APValue &Value) {
111 auto Kind = Value.getKind();
112 AddInteger(V: Kind);
113
114 // 'APValue::Profile' uses pointer values to make hash for LValue and
115 // MemberPointer, but they differ from one compiler invocation to another.
116 // It may be difficult to handle such cases. Bail out simply.
117
118 if (Kind == APValue::LValue || Kind == APValue::MemberPointer) {
119 BailedOut = true;
120 return;
121 }
122
123 Value.Profile(ID);
124}
125
126void TemplateArgumentHasher::AddTemplateName(TemplateName Name) {
127 switch (Name.getKind()) {
128 case TemplateName::Template:
129 AddDecl(D: Name.getAsTemplateDecl());
130 break;
131 case TemplateName::QualifiedTemplate: {
132 QualifiedTemplateName *QTN = Name.getAsQualifiedTemplateName();
133 AddTemplateName(Name: QTN->getUnderlyingTemplate());
134 break;
135 }
136 case TemplateName::OverloadedTemplate:
137 case TemplateName::AssumedTemplate:
138 case TemplateName::DependentTemplate:
139 case TemplateName::SubstTemplateTemplateParm:
140 case TemplateName::SubstTemplateTemplateParmPack:
141 BailedOut = true;
142 break;
143 case TemplateName::UsingTemplate: {
144 UsingShadowDecl *USD = Name.getAsUsingShadowDecl();
145 if (USD)
146 AddDecl(D: USD->getTargetDecl());
147 else
148 BailedOut = true;
149 break;
150 }
151 case TemplateName::DeducedTemplate:
152 AddTemplateName(Name: Name.getAsDeducedTemplateName()->getUnderlying());
153 break;
154 }
155}
156
157void TemplateArgumentHasher::AddIdentifierInfo(const IdentifierInfo *II) {
158 assert(II && "Expecting non-null pointer.");
159 ID.AddString(String: II->getName());
160}
161
162void TemplateArgumentHasher::AddDeclarationName(DeclarationName Name) {
163 if (Name.isEmpty())
164 return;
165
166 switch (Name.getNameKind()) {
167 case DeclarationName::Identifier:
168 AddIdentifierInfo(II: Name.getAsIdentifierInfo());
169 break;
170 case DeclarationName::ObjCZeroArgSelector:
171 case DeclarationName::ObjCOneArgSelector:
172 case DeclarationName::ObjCMultiArgSelector:
173 BailedOut = true;
174 break;
175 case DeclarationName::CXXConstructorName:
176 case DeclarationName::CXXDestructorName:
177 AddQualType(T: Name.getCXXNameType());
178 break;
179 case DeclarationName::CXXOperatorName:
180 AddInteger(V: Name.getCXXOverloadedOperator());
181 break;
182 case DeclarationName::CXXLiteralOperatorName:
183 AddIdentifierInfo(II: Name.getCXXLiteralIdentifier());
184 break;
185 case DeclarationName::CXXConversionFunctionName:
186 AddQualType(T: Name.getCXXNameType());
187 break;
188 case DeclarationName::CXXUsingDirective:
189 break;
190 case DeclarationName::CXXDeductionGuideName: {
191 if (auto *Template = Name.getCXXDeductionGuideTemplate())
192 AddDecl(D: Template);
193 }
194 }
195}
196
197void TemplateArgumentHasher::AddDecl(const Decl *D) {
198 const NamedDecl *ND = dyn_cast<NamedDecl>(Val: D);
199 if (!ND) {
200 BailedOut = true;
201 return;
202 }
203
204 AddDeclarationName(Name: ND->getDeclName());
205}
206
207void TemplateArgumentHasher::AddQualType(QualType T) {
208 if (T.isNull()) {
209 BailedOut = true;
210 return;
211 }
212 SplitQualType split = T.split();
213 AddInteger(V: split.Quals.getAsOpaqueValue());
214 AddType(T: split.Ty);
215}
216
217// Process a Type pointer. Add* methods call back into TemplateArgumentHasher
218// while Visit* methods process the relevant parts of the Type.
219// Any unhandled type will make the hash computation bail out.
220class TypeVisitorHelper : public TypeVisitor<TypeVisitorHelper> {
221 typedef TypeVisitor<TypeVisitorHelper> Inherited;
222 llvm::FoldingSetNodeID &ID;
223 TemplateArgumentHasher &Hash;
224
225public:
226 TypeVisitorHelper(llvm::FoldingSetNodeID &ID, TemplateArgumentHasher &Hash)
227 : ID(ID), Hash(Hash) {}
228
229 void AddDecl(const Decl *D) {
230 if (D)
231 Hash.AddDecl(D);
232 else
233 Hash.AddInteger(V: 0);
234 }
235
236 void AddQualType(QualType T) { Hash.AddQualType(T); }
237
238 void AddType(const Type *T) {
239 if (T)
240 Hash.AddType(T);
241 else
242 Hash.AddInteger(V: 0);
243 }
244
245 void VisitQualifiers(Qualifiers Quals) {
246 Hash.AddInteger(V: Quals.getAsOpaqueValue());
247 }
248
249 void Visit(const Type *T) { Inherited::Visit(T); }
250
251 // Unhandled types. Bail out simply.
252 void VisitType(const Type *T) { Hash.setBailedOut(); }
253
254 void VisitAdjustedType(const AdjustedType *T) {
255 AddQualType(T: T->getOriginalType());
256 }
257
258 void VisitDecayedType(const DecayedType *T) {
259 // getDecayedType and getPointeeType are derived from getAdjustedType
260 // and don't need to be separately processed.
261 VisitAdjustedType(T);
262 }
263
264 void VisitArrayType(const ArrayType *T) {
265 AddQualType(T: T->getElementType());
266 Hash.AddInteger(V: llvm::to_underlying(E: T->getSizeModifier()));
267 VisitQualifiers(Quals: T->getIndexTypeQualifiers());
268 }
269 void VisitConstantArrayType(const ConstantArrayType *T) {
270 T->getSize().Profile(id&: ID);
271 VisitArrayType(T);
272 }
273
274 void VisitAttributedType(const AttributedType *T) {
275 Hash.AddInteger(V: T->getAttrKind());
276 AddQualType(T: T->getModifiedType());
277 }
278
279 void VisitBuiltinType(const BuiltinType *T) { Hash.AddInteger(V: T->getKind()); }
280
281 void VisitComplexType(const ComplexType *T) {
282 AddQualType(T: T->getElementType());
283 }
284
285 void VisitDecltypeType(const DecltypeType *T) {
286 AddQualType(T: T->getUnderlyingType());
287 }
288
289 void VisitDeducedType(const DeducedType *T) {
290 AddQualType(T: T->getDeducedType());
291 }
292
293 void VisitAutoType(const AutoType *T) { VisitDeducedType(T); }
294
295 void VisitDeducedTemplateSpecializationType(
296 const DeducedTemplateSpecializationType *T) {
297 Hash.AddTemplateName(Name: T->getTemplateName());
298 VisitDeducedType(T);
299 }
300
301 void VisitFunctionType(const FunctionType *T) {
302 AddQualType(T: T->getReturnType());
303 T->getExtInfo().Profile(ID);
304 Hash.AddInteger(V: T->isConst());
305 Hash.AddInteger(V: T->isVolatile());
306 Hash.AddInteger(V: T->isRestrict());
307 }
308
309 void VisitFunctionNoProtoType(const FunctionNoProtoType *T) {
310 VisitFunctionType(T);
311 }
312
313 void VisitFunctionProtoType(const FunctionProtoType *T) {
314 Hash.AddInteger(V: T->getNumParams());
315 for (auto ParamType : T->getParamTypes())
316 AddQualType(T: ParamType);
317
318 VisitFunctionType(T);
319 }
320
321 void VisitMemberPointerType(const MemberPointerType *T) {
322 AddQualType(T: T->getPointeeType());
323 AddType(T: T->getQualifier()->getAsType());
324 if (auto *RD = T->getMostRecentCXXRecordDecl())
325 AddDecl(D: RD->getCanonicalDecl());
326 }
327
328 void VisitPackExpansionType(const PackExpansionType *T) {
329 AddQualType(T: T->getPattern());
330 }
331
332 void VisitParenType(const ParenType *T) { AddQualType(T: T->getInnerType()); }
333
334 void VisitPointerType(const PointerType *T) {
335 AddQualType(T: T->getPointeeType());
336 }
337
338 void VisitReferenceType(const ReferenceType *T) {
339 AddQualType(T: T->getPointeeTypeAsWritten());
340 }
341
342 void VisitLValueReferenceType(const LValueReferenceType *T) {
343 VisitReferenceType(T);
344 }
345
346 void VisitRValueReferenceType(const RValueReferenceType *T) {
347 VisitReferenceType(T);
348 }
349
350 void
351 VisitSubstTemplateTypeParmPackType(const SubstTemplateTypeParmPackType *T) {
352 AddDecl(D: T->getAssociatedDecl());
353 Hash.AddTemplateArgument(TA: T->getArgumentPack());
354 }
355
356 void VisitSubstTemplateTypeParmType(const SubstTemplateTypeParmType *T) {
357 AddDecl(D: T->getAssociatedDecl());
358 AddQualType(T: T->getReplacementType());
359 }
360
361 void VisitTagType(const TagType *T) { AddDecl(D: T->getDecl()); }
362
363 void VisitRecordType(const RecordType *T) { VisitTagType(T); }
364 void VisitEnumType(const EnumType *T) { VisitTagType(T); }
365
366 void VisitTemplateSpecializationType(const TemplateSpecializationType *T) {
367 Hash.AddInteger(V: T->template_arguments().size());
368 for (const auto &TA : T->template_arguments()) {
369 Hash.AddTemplateArgument(TA);
370 }
371 Hash.AddTemplateName(Name: T->getTemplateName());
372 }
373
374 void VisitTemplateTypeParmType(const TemplateTypeParmType *T) {
375 Hash.AddInteger(V: T->getDepth());
376 Hash.AddInteger(V: T->getIndex());
377 Hash.AddInteger(V: T->isParameterPack());
378 }
379
380 void VisitTypedefType(const TypedefType *T) { AddDecl(D: T->getDecl()); }
381
382 void VisitElaboratedType(const ElaboratedType *T) {
383 AddQualType(T: T->getNamedType());
384 }
385
386 void VisitUnaryTransformType(const UnaryTransformType *T) {
387 AddQualType(T: T->getUnderlyingType());
388 AddQualType(T: T->getBaseType());
389 }
390
391 void VisitVectorType(const VectorType *T) {
392 AddQualType(T: T->getElementType());
393 Hash.AddInteger(V: T->getNumElements());
394 Hash.AddInteger(V: llvm::to_underlying(E: T->getVectorKind()));
395 }
396
397 void VisitExtVectorType(const ExtVectorType *T) { VisitVectorType(T); }
398};
399
400void TemplateArgumentHasher::AddType(const Type *T) {
401 assert(T && "Expecting non-null pointer.");
402 TypeVisitorHelper(ID, *this).Visit(T);
403}
404
405} // namespace
406
407unsigned clang::serialization::StableHashForTemplateArguments(
408 llvm::ArrayRef<TemplateArgument> Args) {
409 llvm::TimeTraceScope TimeScope("Stable Hash for Template Arguments");
410 TemplateArgumentHasher Hasher;
411 Hasher.AddInteger(V: Args.size());
412 for (TemplateArgument Arg : Args)
413 Hasher.AddTemplateArgument(TA: Arg);
414 return Hasher.getValue();
415}
416