Bug Summary

File:clang/lib/AST/ItaniumCXXABI.cpp
Warning:line 48, column 29
Called C++ object pointer is null

Annotated Source Code

Press '?' to see keyboard shortcuts

clang -cc1 -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name ItaniumCXXABI.cpp -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -setup-static-analyzer -analyzer-config-compatibility-mode=true -mrelocation-model pic -pic-level 2 -mframe-pointer=none -relaxed-aliasing -fmath-errno -fno-rounding-math -mconstructor-aliases -munwind-tables -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -ffunction-sections -fdata-sections -fcoverage-compilation-dir=/build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/build-llvm/tools/clang/lib/AST -resource-dir /usr/lib/llvm-14/lib/clang/14.0.0 -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/build-llvm/tools/clang/lib/AST -I /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/clang/lib/AST -I /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/clang/include -I /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/build-llvm/tools/clang/include -I /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/build-llvm/include -I /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/llvm/include -D NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/x86_64-linux-gnu/c++/10 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/backward -internal-isystem /usr/lib/llvm-14/lib/clang/14.0.0/include -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../x86_64-linux-gnu/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -O2 -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-maybe-uninitialized -Wno-class-memaccess -Wno-redundant-move -Wno-pessimizing-move -Wno-noexcept-type -Wno-comment -std=c++14 -fdeprecated-macro -fdebug-compilation-dir=/build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/build-llvm/tools/clang/lib/AST -fdebug-prefix-map=/build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e=. -ferror-limit 19 -fvisibility-inlines-hidden -stack-protector 2 -fgnuc-version=4.2.1 -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/scan-build-2021-09-04-040900-46481-1 -x c++ /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/clang/lib/AST/ItaniumCXXABI.cpp
1//===------- ItaniumCXXABI.cpp - AST support for the Itanium C++ ABI ------===//
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 provides C++ AST support targeting the Itanium C++ ABI, which is
10// documented at:
11// http://www.codesourcery.com/public/cxx-abi/abi.html
12// http://www.codesourcery.com/public/cxx-abi/abi-eh.html
13//
14// It also supports the closely-related ARM C++ ABI, documented at:
15// http://infocenter.arm.com/help/topic/com.arm.doc.ihi0041c/IHI0041C_cppabi.pdf
16//
17//===----------------------------------------------------------------------===//
18
19#include "CXXABI.h"
20#include "clang/AST/ASTContext.h"
21#include "clang/AST/DeclCXX.h"
22#include "clang/AST/Mangle.h"
23#include "clang/AST/MangleNumberingContext.h"
24#include "clang/AST/RecordLayout.h"
25#include "clang/AST/Type.h"
26#include "clang/Basic/TargetInfo.h"
27#include "llvm/ADT/FoldingSet.h"
28#include "llvm/ADT/iterator.h"
29
30using namespace clang;
31
32namespace {
33
34/// According to Itanium C++ ABI 5.1.2:
35/// the name of an anonymous union is considered to be
36/// the name of the first named data member found by a pre-order,
37/// depth-first, declaration-order walk of the data members of
38/// the anonymous union.
39/// If there is no such data member (i.e., if all of the data members
40/// in the union are unnamed), then there is no way for a program to
41/// refer to the anonymous union, and there is therefore no need to mangle its name.
42///
43/// Returns the name of anonymous union VarDecl or nullptr if it is not found.
44static const IdentifierInfo *findAnonymousUnionVarDeclName(const VarDecl& VD) {
45 const RecordType *RT = VD.getType()->getAs<RecordType>();
5
←
Assuming the object is not a 'RecordType'
→
6
←
'RT' initialized to a null pointer value
→
46 assert(RT && "type of VarDecl is expected to be RecordType.")(static_cast<void> (0));
47 assert(RT->getDecl()->isUnion() && "RecordType is expected to be a union.")(static_cast<void> (0));
48 if (const FieldDecl *FD = RT->getDecl()->findFirstNamedDataMember()) {
7
←
Called C++ object pointer is null
49 return FD->getIdentifier();
50 }
51
52 return nullptr;
53}
54
55/// The name of a decomposition declaration.
56struct DecompositionDeclName {
57 using BindingArray = ArrayRef<const BindingDecl*>;
58
59 /// Representative example of a set of bindings with these names.
60 BindingArray Bindings;
61
62 /// Iterators over the sequence of identifiers in the name.
63 struct Iterator
64 : llvm::iterator_adaptor_base<Iterator, BindingArray::const_iterator,
65 std::random_access_iterator_tag,
66 const IdentifierInfo *> {
67 Iterator(BindingArray::const_iterator It) : iterator_adaptor_base(It) {}
68 const IdentifierInfo *operator*() const {
69 return (*this->I)->getIdentifier();
70 }
71 };
72 Iterator begin() const { return Iterator(Bindings.begin()); }
73 Iterator end() const { return Iterator(Bindings.end()); }
74};
75}
76
77namespace llvm {
78template<typename T> bool isDenseMapKeyEmpty(T V) {
79 return llvm::DenseMapInfo<T>::isEqual(
80 V, llvm::DenseMapInfo<T>::getEmptyKey());
81}
82template<typename T> bool isDenseMapKeyTombstone(T V) {
83 return llvm::DenseMapInfo<T>::isEqual(
84 V, llvm::DenseMapInfo<T>::getTombstoneKey());
85}
86
87template<typename T>
88Optional<bool> areDenseMapKeysEqualSpecialValues(T LHS, T RHS) {
89 bool LHSEmpty = isDenseMapKeyEmpty(LHS);
90 bool RHSEmpty = isDenseMapKeyEmpty(RHS);
91 if (LHSEmpty || RHSEmpty)
92 return LHSEmpty && RHSEmpty;
93
94 bool LHSTombstone = isDenseMapKeyTombstone(LHS);
95 bool RHSTombstone = isDenseMapKeyTombstone(RHS);
96 if (LHSTombstone || RHSTombstone)
97 return LHSTombstone && RHSTombstone;
98
99 return None;
100}
101
102template<>
103struct DenseMapInfo<DecompositionDeclName> {
104 using ArrayInfo = llvm::DenseMapInfo<ArrayRef<const BindingDecl*>>;
105 static DecompositionDeclName getEmptyKey() {
106 return {ArrayInfo::getEmptyKey()};
107 }
108 static DecompositionDeclName getTombstoneKey() {
109 return {ArrayInfo::getTombstoneKey()};
110 }
111 static unsigned getHashValue(DecompositionDeclName Key) {
112 assert(!isEqual(Key, getEmptyKey()) && !isEqual(Key, getTombstoneKey()))(static_cast<void> (0));
113 return llvm::hash_combine_range(Key.begin(), Key.end());
114 }
115 static bool isEqual(DecompositionDeclName LHS, DecompositionDeclName RHS) {
116 if (Optional<bool> Result = areDenseMapKeysEqualSpecialValues(
117 LHS.Bindings, RHS.Bindings))
118 return *Result;
119
120 return LHS.Bindings.size() == RHS.Bindings.size() &&
121 std::equal(LHS.begin(), LHS.end(), RHS.begin());
122 }
123};
124}
125
126namespace {
127
128/// Keeps track of the mangled names of lambda expressions and block
129/// literals within a particular context.
130class ItaniumNumberingContext : public MangleNumberingContext {
131 ItaniumMangleContext *Mangler;
132 llvm::StringMap<unsigned> LambdaManglingNumbers;
133 unsigned BlockManglingNumber = 0;
134 llvm::DenseMap<const IdentifierInfo *, unsigned> VarManglingNumbers;
135 llvm::DenseMap<const IdentifierInfo *, unsigned> TagManglingNumbers;
136 llvm::DenseMap<DecompositionDeclName, unsigned>
137 DecompsitionDeclManglingNumbers;
138
139public:
140 ItaniumNumberingContext(ItaniumMangleContext *Mangler) : Mangler(Mangler) {}
141
142 unsigned getManglingNumber(const CXXMethodDecl *CallOperator) override {
143 const CXXRecordDecl *Lambda = CallOperator->getParent();
144 assert(Lambda->isLambda())(static_cast<void> (0));
145
146 // Computation of the <lambda-sig> is non-trivial and subtle. Rather than
147 // duplicating it here, just mangle the <lambda-sig> directly.
148 llvm::SmallString<128> LambdaSig;
149 llvm::raw_svector_ostream Out(LambdaSig);
150 Mangler->mangleLambdaSig(Lambda, Out);
151
152 return ++LambdaManglingNumbers[LambdaSig];
153 }
154
155 unsigned getManglingNumber(const BlockDecl *BD) override {
156 return ++BlockManglingNumber;
157 }
158
159 unsigned getStaticLocalNumber(const VarDecl *VD) override {
160 return 0;
161 }
162
163 /// Variable decls are numbered by identifier.
164 unsigned getManglingNumber(const VarDecl *VD, unsigned) override {
165 if (auto *DD
1.1
'DD' is null
 = dyn_cast<DecompositionDecl>(VD)) {
1
Assuming 'VD' is not a 'DecompositionDecl'
→
2
←
Taking false branch
→
166 DecompositionDeclName Name{DD->bindings()};
167 return ++DecompsitionDeclManglingNumbers[Name];
168 }
169
170 const IdentifierInfo *Identifier = VD->getIdentifier();
171 if (!Identifier
2.1
'Identifier' is null
) {
3
←
Taking true branch
→
172 // VarDecl without an identifier represents an anonymous union
173 // declaration.
174 Identifier = findAnonymousUnionVarDeclName(*VD);
4
←
Calling 'findAnonymousUnionVarDeclName'
→
175 }
176 return ++VarManglingNumbers[Identifier];
177 }
178
179 unsigned getManglingNumber(const TagDecl *TD, unsigned) override {
180 return ++TagManglingNumbers[TD->getIdentifier()];
181 }
182};
183
184class ItaniumCXXABI : public CXXABI {
185private:
186 std::unique_ptr<MangleContext> Mangler;
187protected:
188 ASTContext &Context;
189public:
190 ItaniumCXXABI(ASTContext &Ctx)
191 : Mangler(Ctx.createMangleContext()), Context(Ctx) {}
192
193 MemberPointerInfo
194 getMemberPointerInfo(const MemberPointerType *MPT) const override {
195 const TargetInfo &Target = Context.getTargetInfo();
196 TargetInfo::IntType PtrDiff = Target.getPtrDiffType(0);
197 MemberPointerInfo MPI;
198 MPI.Width = Target.getTypeWidth(PtrDiff);
199 MPI.Align = Target.getTypeAlign(PtrDiff);
200 MPI.HasPadding = false;
201 if (MPT->isMemberFunctionPointer())
202 MPI.Width *= 2;
203 return MPI;
204 }
205
206 CallingConv getDefaultMethodCallConv(bool isVariadic) const override {
207 const llvm::Triple &T = Context.getTargetInfo().getTriple();
208 if (!isVariadic && T.isWindowsGNUEnvironment() &&
209 T.getArch() == llvm::Triple::x86)
210 return CC_X86ThisCall;
211 return Context.getTargetInfo().getDefaultCallingConv();
212 }
213
214 // We cheat and just check that the class has a vtable pointer, and that it's
215 // only big enough to have a vtable pointer and nothing more (or less).
216 bool isNearlyEmpty(const CXXRecordDecl *RD) const override {
217
218 // Check that the class has a vtable pointer.
219 if (!RD->isDynamicClass())
220 return false;
221
222 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
223 CharUnits PointerSize =
224 Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(0));
225 return Layout.getNonVirtualSize() == PointerSize;
226 }
227
228 const CXXConstructorDecl *
229 getCopyConstructorForExceptionObject(CXXRecordDecl *RD) override {
230 return nullptr;
231 }
232
233 void addCopyConstructorForExceptionObject(CXXRecordDecl *RD,
234 CXXConstructorDecl *CD) override {}
235
236 void addTypedefNameForUnnamedTagDecl(TagDecl *TD,
237 TypedefNameDecl *DD) override {}
238
239 TypedefNameDecl *getTypedefNameForUnnamedTagDecl(const TagDecl *TD) override {
240 return nullptr;
241 }
242
243 void addDeclaratorForUnnamedTagDecl(TagDecl *TD,
244 DeclaratorDecl *DD) override {}
245
246 DeclaratorDecl *getDeclaratorForUnnamedTagDecl(const TagDecl *TD) override {
247 return nullptr;
248 }
249
250 std::unique_ptr<MangleNumberingContext>
251 createMangleNumberingContext() const override {
252 return std::make_unique<ItaniumNumberingContext>(
253 cast<ItaniumMangleContext>(Mangler.get()));
254 }
255};
256}
257
258CXXABI *clang::CreateItaniumCXXABI(ASTContext &Ctx) {
259 return new ItaniumCXXABI(Ctx);
260}
261
262std::unique_ptr<MangleNumberingContext>
263clang::createItaniumNumberingContext(MangleContext *Mangler) {
264 return std::make_unique<ItaniumNumberingContext>(
265 cast<ItaniumMangleContext>(Mangler));
266}