Bug Summary

File:tools/clang/lib/AST/Interp/Program.cpp
Warning:line 253, column 30
Called C++ object pointer is null

Annotated Source Code

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clang -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name Program.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 -analyzer-config-compatibility-mode=true -mrelocation-model pic -pic-level 2 -mthread-model posix -mframe-pointer=none -relaxed-aliasing -fmath-errno -masm-verbose -mconstructor-aliases -munwind-tables -fuse-init-array -target-cpu x86-64 -dwarf-column-info -debugger-tuning=gdb -ffunction-sections -fdata-sections -resource-dir /usr/lib/llvm-10/lib/clang/10.0.0 -D CLANG_VENDOR="Debian " -D _DEBUG -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I /build/llvm-toolchain-snapshot-10~svn373517/build-llvm/tools/clang/lib/AST -I /build/llvm-toolchain-snapshot-10~svn373517/tools/clang/lib/AST -I /build/llvm-toolchain-snapshot-10~svn373517/tools/clang/include -I /build/llvm-toolchain-snapshot-10~svn373517/build-llvm/tools/clang/include -I /build/llvm-toolchain-snapshot-10~svn373517/build-llvm/include -I /build/llvm-toolchain-snapshot-10~svn373517/include -U NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/x86_64-linux-gnu/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/x86_64-linux-gnu/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/c++/6.3.0/backward -internal-isystem /usr/local/include -internal-isystem /usr/lib/llvm-10/lib/clang/10.0.0/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-comment -std=c++14 -fdeprecated-macro -fdebug-compilation-dir /build/llvm-toolchain-snapshot-10~svn373517/build-llvm/tools/clang/lib/AST -fdebug-prefix-map=/build/llvm-toolchain-snapshot-10~svn373517=. -ferror-limit 19 -fmessage-length 0 -fvisibility-inlines-hidden -stack-protector 2 -fobjc-runtime=gcc -fno-common -fdiagnostics-show-option -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -faddrsig -o /tmp/scan-build-2019-10-02-234743-9763-1 -x c++ /build/llvm-toolchain-snapshot-10~svn373517/tools/clang/lib/AST/Interp/Program.cpp
1//===--- Program.cpp - Bytecode for the constexpr VM ------------*- 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 "Program.h"
10#include "ByteCodeStmtGen.h"
11#include "Context.h"
12#include "Function.h"
13#include "Opcode.h"
14#include "PrimType.h"
15#include "clang/AST/Decl.h"
16#include "clang/AST/DeclCXX.h"
17
18using namespace clang;
19using namespace clang::interp;
20
21unsigned Program::createGlobalString(const StringLiteral *S) {
22 const size_t CharWidth = S->getCharByteWidth();
23 const size_t BitWidth = CharWidth * Ctx.getCharBit();
24
25 PrimType CharType;
26 switch (CharWidth) {
27 case 1:
28 CharType = PT_Sint8;
29 break;
30 case 2:
31 CharType = PT_Uint16;
32 break;
33 case 4:
34 CharType = PT_Uint32;
35 break;
36 default:
37 llvm_unreachable("unsupported character width")::llvm::llvm_unreachable_internal("unsupported character width"
, "/build/llvm-toolchain-snapshot-10~svn373517/tools/clang/lib/AST/Interp/Program.cpp"
, 37);
38 }
39
40 // Create a descriptor for the string.
41 Descriptor *Desc = allocateDescriptor(S, CharType, S->getLength() + 1,
42 /*isConst=*/true,
43 /*isTemporary=*/false,
44 /*isMutable=*/false);
45
46 // Allocate storage for the string.
47 // The byte length does not include the null terminator.
48 unsigned I = Globals.size();
49 unsigned Sz = Desc->getAllocSize();
50 auto *G = new (Allocator, Sz) Global(Desc, /*isStatic=*/true,
51 /*isExtern=*/false);
52 Globals.push_back(G);
53
54 // Construct the string in storage.
55 const Pointer Ptr(G->block());
56 for (unsigned I = 0, N = S->getLength(); I <= N; ++I) {
57 Pointer Field = Ptr.atIndex(I).narrow();
58 const uint32_t CodePoint = I == N ? 0 : S->getCodeUnit(I);
59 switch (CharType) {
60 case PT_Sint8: {
61 using T = PrimConv<PT_Sint8>::T;
62 Field.deref<T>() = T::from(CodePoint, BitWidth);
63 break;
64 }
65 case PT_Uint16: {
66 using T = PrimConv<PT_Uint16>::T;
67 Field.deref<T>() = T::from(CodePoint, BitWidth);
68 break;
69 }
70 case PT_Uint32: {
71 using T = PrimConv<PT_Uint32>::T;
72 Field.deref<T>() = T::from(CodePoint, BitWidth);
73 break;
74 }
75 default:
76 llvm_unreachable("unsupported character type")::llvm::llvm_unreachable_internal("unsupported character type"
, "/build/llvm-toolchain-snapshot-10~svn373517/tools/clang/lib/AST/Interp/Program.cpp"
, 76);
77 }
78 }
79 return I;
80}
81
82Pointer Program::getPtrGlobal(unsigned Idx) {
83 assert(Idx < Globals.size())((Idx < Globals.size()) ? static_cast<void> (0) : __assert_fail
("Idx < Globals.size()", "/build/llvm-toolchain-snapshot-10~svn373517/tools/clang/lib/AST/Interp/Program.cpp"
, 83, __PRETTY_FUNCTION__));
84 return Pointer(Globals[Idx]->block());
85}
86
87llvm::Optional<unsigned> Program::getGlobal(const ValueDecl *VD) {
88 auto It = GlobalIndices.find(VD);
89 if (It != GlobalIndices.end())
90 return It->second;
91
92 // Find any previous declarations which were aleady evaluated.
93 llvm::Optional<unsigned> Index;
94 for (const Decl *P = VD; P; P = P->getPreviousDecl()) {
95 auto It = GlobalIndices.find(P);
96 if (It != GlobalIndices.end()) {
97 Index = It->second;
98 break;
99 }
100 }
101
102 // Map the decl to the existing index.
103 if (Index) {
104 GlobalIndices[VD] = *Index;
105 return {};
106 }
107
108 return Index;
109}
110
111llvm::Optional<unsigned> Program::getOrCreateGlobal(const ValueDecl *VD) {
112 if (auto Idx = getGlobal(VD))
113 return Idx;
114
115 if (auto Idx = createGlobal(VD)) {
116 GlobalIndices[VD] = *Idx;
117 return Idx;
118 }
119 return {};
120}
121
122llvm::Optional<unsigned> Program::getOrCreateDummy(const ParmVarDecl *PD) {
123 auto &ASTCtx = Ctx.getASTContext();
124
125 // Create a pointer to an incomplete array of the specified elements.
126 QualType ElemTy = PD->getType()->getAs<PointerType>()->getPointeeType();
127 QualType Ty = ASTCtx.getIncompleteArrayType(ElemTy, ArrayType::Normal, 0);
128
129 // Dedup blocks since they are immutable and pointers cannot be compared.
130 auto It = DummyParams.find(PD);
131 if (It != DummyParams.end())
132 return It->second;
133
134 if (auto Idx = createGlobal(PD, Ty, /*isStatic=*/true, /*isExtern=*/true)) {
135 DummyParams[PD] = *Idx;
136 return Idx;
137 }
138 return {};
139}
140
141llvm::Optional<unsigned> Program::createGlobal(const ValueDecl *VD) {
142 bool IsStatic, IsExtern;
143 if (auto *Var = dyn_cast<VarDecl>(VD)) {
144 IsStatic = !Var->hasLocalStorage();
145 IsExtern = !Var->getAnyInitializer();
146 } else {
147 IsStatic = false;
148 IsExtern = true;
149 }
150 if (auto Idx = createGlobal(VD, VD->getType(), IsStatic, IsExtern)) {
151 for (const Decl *P = VD; P; P = P->getPreviousDecl())
152 GlobalIndices[P] = *Idx;
153 return *Idx;
154 }
155 return {};
156}
157
158llvm::Optional<unsigned> Program::createGlobal(const Expr *E) {
159 return createGlobal(E, E->getType(), /*isStatic=*/true, /*isExtern=*/false);
160}
161
162llvm::Optional<unsigned> Program::createGlobal(const DeclTy &D, QualType Ty,
163 bool IsStatic, bool IsExtern) {
164 // Create a descriptor for the global.
165 Descriptor *Desc;
166 const bool IsConst = Ty.isConstQualified();
167 const bool IsTemporary = D.dyn_cast<const Expr *>();
168 if (auto T = Ctx.classify(Ty)) {
1
Assuming the condition is false
→
2
←
Taking false branch
→
169 Desc = createDescriptor(D, *T, IsConst, IsTemporary);
170 } else {
171 Desc = createDescriptor(D, Ty.getTypePtr(), IsConst, IsTemporary);
3
←
Calling 'Program::createDescriptor'
→
172 }
173 if (!Desc)
174 return {};
175
176 // Allocate a block for storage.
177 unsigned I = Globals.size();
178
179 auto *G = new (Allocator, Desc->getAllocSize())
180 Global(getCurrentDecl(), Desc, IsStatic, IsExtern);
181 G->block()->invokeCtor();
182
183 Globals.push_back(G);
184
185 return I;
186}
187
188Function *Program::getFunction(const FunctionDecl *F) {
189 F = F->getDefinition();
190 auto It = Funcs.find(F);
191 return It == Funcs.end() ? nullptr : It->second.get();
192}
193
194llvm::Expected<Function *> Program::getOrCreateFunction(const FunctionDecl *F) {
195 if (Function *Func = getFunction(F)) {
196 return Func;
197 }
198
199 // Try to compile the function if it wasn't compiled yet.
200 if (const FunctionDecl *FD = F->getDefinition())
201 return ByteCodeStmtGen<ByteCodeEmitter>(Ctx, *this).compileFunc(FD);
202
203 // A relocation which traps if not resolved.
204 return nullptr;
205}
206
207Record *Program::getOrCreateRecord(const RecordDecl *RD) {
208 // Use the actual definition as a key.
209 RD = RD->getDefinition();
210 if (!RD
18.1
'RD' is non-null
)
19
←
Taking false branch
→
211 return nullptr;
212
213 // Deduplicate records.
214 auto It = Records.find(RD);
215 if (It != Records.end()) {
20
←
Assuming the condition is false
→
21
←
Taking false branch
→
216 return It->second;
217 }
218
219 // Number of bytes required by fields and base classes.
220 unsigned Size = 0;
221 // Number of bytes required by virtual base.
222 unsigned VirtSize = 0;
223
224 // Helper to get a base descriptor.
225 auto GetBaseDesc = [this](const RecordDecl *BD, Record *BR) -> Descriptor * {
226 if (!BR)
227 return nullptr;
228 return allocateDescriptor(BD, BR, /*isConst=*/false,
229 /*isTemporary=*/false,
230 /*isMutable=*/false);
231 };
232
233 // Reserve space for base classes.
234 Record::BaseList Bases;
235 Record::VirtualBaseList VirtBases;
236 if (auto *CD
22.1
'CD' is non-null
 = dyn_cast<CXXRecordDecl>(RD)) {
22
←
Assuming 'RD' is a 'CXXRecordDecl'
→
23
←
Taking true branch
→
237 for (const CXXBaseSpecifier &Spec : CD->bases()) {
24
←
Assuming '__begin2' is equal to '__end2'
→
238 if (Spec.isVirtual())
239 continue;
240
241 const RecordDecl *BD = Spec.getType()->getAs<RecordType>()->getDecl();
242 Record *BR = getOrCreateRecord(BD);
243 if (Descriptor *Desc = GetBaseDesc(BD, BR)) {
244 Size += align(sizeof(InlineDescriptor));
245 Bases.push_back({BD, Size, Desc, BR});
246 Size += align(BR->getSize());
247 continue;
248 }
249 return nullptr;
250 }
251
252 for (const CXXBaseSpecifier &Spec : CD->vbases()) {
25
←
Assuming '__begin2' is not equal to '__end2'
→
253 const RecordDecl *BD = Spec.getType()->getAs<RecordType>()->getDecl();
26
←
Assuming the object is not a 'RecordType'
→
27
←
Called C++ object pointer is null
254 Record *BR = getOrCreateRecord(BD);
255
256 if (Descriptor *Desc = GetBaseDesc(BD, BR)) {
257 VirtSize += align(sizeof(InlineDescriptor));
258 VirtBases.push_back({BD, VirtSize, Desc, BR});
259 VirtSize += align(BR->getSize());
260 continue;
261 }
262 return nullptr;
263 }
264 }
265
266 // Reserve space for fields.
267 Record::FieldList Fields;
268 for (const FieldDecl *FD : RD->fields()) {
269 // Reserve space for the field's descriptor and the offset.
270 Size += align(sizeof(InlineDescriptor));
271
272 // Classify the field and add its metadata.
273 QualType FT = FD->getType();
274 const bool IsConst = FT.isConstQualified();
275 const bool IsMutable = FD->isMutable();
276 Descriptor *Desc;
277 if (llvm::Optional<PrimType> T = Ctx.classify(FT)) {
278 Desc = createDescriptor(FD, *T, IsConst, /*isTemporary=*/false,
279 IsMutable);
280 } else {
281 Desc = createDescriptor(FD, FT.getTypePtr(), IsConst,
282 /*isTemporary=*/false, IsMutable);
283 }
284 if (!Desc)
285 return nullptr;
286 Fields.push_back({FD, Size, Desc});
287 Size += align(Desc->getAllocSize());
288 }
289
290 Record *R = new (Allocator) Record(RD, std::move(Bases), std::move(Fields),
291 std::move(VirtBases), VirtSize, Size);
292 Records.insert({RD, R});
293 return R;
294}
295
296Descriptor *Program::createDescriptor(const DeclTy &D, const Type *Ty,
297 bool IsConst, bool IsTemporary,
298 bool IsMutable) {
299 // Classes and structures.
300 if (auto *RT
4.1
'RT' is null
10.1
'RT' is null
16.1
'RT' is non-null
 = Ty->getAs<RecordType>()) {
4
←
Assuming 'Ty' is not a 'RecordType'
→
5
←
Taking false branch
→
10
←
Assuming 'Ty' is not a 'RecordType'
→
11
←
Taking false branch
→
16
←
Assuming 'Ty' is a 'RecordType'
→
17
←
Taking true branch
→
301 if (auto *Record = getOrCreateRecord(RT->getDecl()))
18
←
Calling 'Program::getOrCreateRecord'
→
302 return allocateDescriptor(D, Record, IsConst, IsTemporary, IsMutable);
303 }
304
305 // Arrays.
306 if (auto ArrayType
5.1
'ArrayType' is null
11.1
'ArrayType' is null
 = Ty->getAsArrayTypeUnsafe()) {
6
←
Taking false branch
→
12
←
Taking false branch
→
307 QualType ElemTy = ArrayType->getElementType();
308 // Array of well-known bounds.
309 if (auto CAT = dyn_cast<ConstantArrayType>(ArrayType)) {
310 size_t NumElems = CAT->getSize().getZExtValue();
311 if (llvm::Optional<PrimType> T = Ctx.classify(ElemTy)) {
312 // Arrays of primitives.
313 unsigned ElemSize = primSize(*T);
314 if (std::numeric_limits<unsigned>::max() / ElemSize <= NumElems) {
315 return {};
316 }
317 return allocateDescriptor(D, *T, NumElems, IsConst, IsTemporary,
318 IsMutable);
319 } else {
320 // Arrays of composites. In this case, the array is a list of pointers,
321 // followed by the actual elements.
322 Descriptor *Desc =
323 createDescriptor(D, ElemTy.getTypePtr(), IsConst, IsTemporary);
324 if (!Desc)
325 return nullptr;
326 InterpSize ElemSize = Desc->getAllocSize() + sizeof(InlineDescriptor);
327 if (std::numeric_limits<unsigned>::max() / ElemSize <= NumElems)
328 return {};
329 return allocateDescriptor(D, Desc, NumElems, IsConst, IsTemporary,
330 IsMutable);
331 }
332 }
333
334 // Array of unknown bounds - cannot be accessed and pointer arithmetic
335 // is forbidden on pointers to such objects.
336 if (isa<IncompleteArrayType>(ArrayType)) {
337 if (llvm::Optional<PrimType> T = Ctx.classify(ElemTy)) {
338 return allocateDescriptor(D, *T, IsTemporary,
339 Descriptor::UnknownSize{});
340 } else {
341 Descriptor *Desc =
342 createDescriptor(D, ElemTy.getTypePtr(), IsConst, IsTemporary);
343 if (!Desc)
344 return nullptr;
345 return allocateDescriptor(D, Desc, IsTemporary,
346 Descriptor::UnknownSize{});
347 }
348 }
349 }
350
351 // Atomic types.
352 if (auto *AT
7.1
'AT' is non-null
13.1
'AT' is non-null
 = Ty->getAs<AtomicType>()) {
7
←
Assuming 'Ty' is a 'AtomicType'
→
8
←
Taking true branch
→
13
←
Assuming 'Ty' is a 'AtomicType'
→
14
←
Taking true branch
→
353 const Type *InnerTy = AT->getValueType().getTypePtr();
354 return createDescriptor(D, InnerTy, IsConst, IsTemporary, IsMutable);
9
←
Calling 'Program::createDescriptor'
→
15
←
Calling 'Program::createDescriptor'
→
355 }
356
357 // Complex types - represented as arrays of elements.
358 if (auto *CT = Ty->getAs<ComplexType>()) {
359 PrimType ElemTy = *Ctx.classify(CT->getElementType());
360 return allocateDescriptor(D, ElemTy, 2, IsConst, IsTemporary, IsMutable);
361 }
362
363 return nullptr;
364}