Bug Summary

File:tools/clang/lib/CodeGen/CGCXXABI.cpp
Warning:line 50, column 25
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 CGCXXABI.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/CodeGen -I /build/llvm-toolchain-snapshot-10~svn373517/tools/clang/lib/CodeGen -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/CodeGen -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/CodeGen/CGCXXABI.cpp
1//===----- CGCXXABI.cpp - Interface to C++ ABIs ---------------------------===//
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 an abstract class for C++ code generation. Concrete subclasses
10// of this implement code generation for specific C++ ABIs.
11//
12//===----------------------------------------------------------------------===//
13
14#include "CGCXXABI.h"
15#include "CGCleanup.h"
16
17using namespace clang;
18using namespace CodeGen;
19
20CGCXXABI::~CGCXXABI() { }
21
22void CGCXXABI::ErrorUnsupportedABI(CodeGenFunction &CGF, StringRef S) {
23 DiagnosticsEngine &Diags = CGF.CGM.getDiags();
24 unsigned DiagID = Diags.getCustomDiagID(DiagnosticsEngine::Error,
25 "cannot yet compile %0 in this ABI");
26 Diags.Report(CGF.getContext().getFullLoc(CGF.CurCodeDecl->getLocation()),
27 DiagID)
28 << S;
29}
30
31llvm::Constant *CGCXXABI::GetBogusMemberPointer(QualType T) {
32 return llvm::Constant::getNullValue(CGM.getTypes().ConvertType(T));
33}
34
35llvm::Type *
36CGCXXABI::ConvertMemberPointerType(const MemberPointerType *MPT) {
37 return CGM.getTypes().ConvertType(CGM.getContext().getPointerDiffType());
38}
39
40CGCallee CGCXXABI::EmitLoadOfMemberFunctionPointer(
41 CodeGenFunction &CGF, const Expr *E, Address This,
42 llvm::Value *&ThisPtrForCall,
43 llvm::Value *MemPtr, const MemberPointerType *MPT) {
44 ErrorUnsupportedABI(CGF, "calls through member pointers");
45
46 ThisPtrForCall = This.getPointer();
47 const FunctionProtoType *FPT =
48 MPT->getPointeeType()->getAs<FunctionProtoType>();
1
Assuming the object is not a 'FunctionProtoType'
→
49 const CXXRecordDecl *RD =
50 cast<CXXRecordDecl>(MPT->getClass()->getAs<RecordType>()->getDecl());
2
←
Assuming the object is not a 'RecordType'
→
3
←
Called C++ object pointer is null
51 llvm::FunctionType *FTy = CGM.getTypes().GetFunctionType(
52 CGM.getTypes().arrangeCXXMethodType(RD, FPT, /*FD=*/nullptr));
53 llvm::Constant *FnPtr = llvm::Constant::getNullValue(FTy->getPointerTo());
54 return CGCallee::forDirect(FnPtr, FPT);
55}
56
57llvm::Value *
58CGCXXABI::EmitMemberDataPointerAddress(CodeGenFunction &CGF, const Expr *E,
59 Address Base, llvm::Value *MemPtr,
60 const MemberPointerType *MPT) {
61 ErrorUnsupportedABI(CGF, "loads of member pointers");
62 llvm::Type *Ty = CGF.ConvertType(MPT->getPointeeType())
63 ->getPointerTo(Base.getAddressSpace());
64 return llvm::Constant::getNullValue(Ty);
65}
66
67llvm::Value *CGCXXABI::EmitMemberPointerConversion(CodeGenFunction &CGF,
68 const CastExpr *E,
69 llvm::Value *Src) {
70 ErrorUnsupportedABI(CGF, "member function pointer conversions");
71 return GetBogusMemberPointer(E->getType());
72}
73
74llvm::Constant *CGCXXABI::EmitMemberPointerConversion(const CastExpr *E,
75 llvm::Constant *Src) {
76 return GetBogusMemberPointer(E->getType());
77}
78
79llvm::Value *
80CGCXXABI::EmitMemberPointerComparison(CodeGenFunction &CGF,
81 llvm::Value *L,
82 llvm::Value *R,
83 const MemberPointerType *MPT,
84 bool Inequality) {
85 ErrorUnsupportedABI(CGF, "member function pointer comparison");
86 return CGF.Builder.getFalse();
87}
88
89llvm::Value *
90CGCXXABI::EmitMemberPointerIsNotNull(CodeGenFunction &CGF,
91 llvm::Value *MemPtr,
92 const MemberPointerType *MPT) {
93 ErrorUnsupportedABI(CGF, "member function pointer null testing");
94 return CGF.Builder.getFalse();
95}
96
97llvm::Constant *
98CGCXXABI::EmitNullMemberPointer(const MemberPointerType *MPT) {
99 return GetBogusMemberPointer(QualType(MPT, 0));
100}
101
102llvm::Constant *CGCXXABI::EmitMemberFunctionPointer(const CXXMethodDecl *MD) {
103 return GetBogusMemberPointer(CGM.getContext().getMemberPointerType(
104 MD->getType(), MD->getParent()->getTypeForDecl()));
105}
106
107llvm::Constant *CGCXXABI::EmitMemberDataPointer(const MemberPointerType *MPT,
108 CharUnits offset) {
109 return GetBogusMemberPointer(QualType(MPT, 0));
110}
111
112llvm::Constant *CGCXXABI::EmitMemberPointer(const APValue &MP, QualType MPT) {
113 return GetBogusMemberPointer(MPT);
114}
115
116bool CGCXXABI::isZeroInitializable(const MemberPointerType *MPT) {
117 // Fake answer.
118 return true;
119}
120
121void CGCXXABI::buildThisParam(CodeGenFunction &CGF, FunctionArgList &params) {
122 const CXXMethodDecl *MD = cast<CXXMethodDecl>(CGF.CurGD.getDecl());
123
124 // FIXME: I'm not entirely sure I like using a fake decl just for code
125 // generation. Maybe we can come up with a better way?
126 auto *ThisDecl = ImplicitParamDecl::Create(
127 CGM.getContext(), nullptr, MD->getLocation(),
128 &CGM.getContext().Idents.get("this"), MD->getThisType(),
129 ImplicitParamDecl::CXXThis);
130 params.push_back(ThisDecl);
131 CGF.CXXABIThisDecl = ThisDecl;
132
133 // Compute the presumed alignment of 'this', which basically comes
134 // down to whether we know it's a complete object or not.
135 auto &Layout = CGF.getContext().getASTRecordLayout(MD->getParent());
136 if (MD->getParent()->getNumVBases() == 0 || // avoid vcall in common case
137 MD->getParent()->hasAttr<FinalAttr>() ||
138 !isThisCompleteObject(CGF.CurGD)) {
139 CGF.CXXABIThisAlignment = Layout.getAlignment();
140 } else {
141 CGF.CXXABIThisAlignment = Layout.getNonVirtualAlignment();
142 }
143}
144
145llvm::Value *CGCXXABI::loadIncomingCXXThis(CodeGenFunction &CGF) {
146 return CGF.Builder.CreateLoad(CGF.GetAddrOfLocalVar(getThisDecl(CGF)),
147 "this");
148}
149
150void CGCXXABI::setCXXABIThisValue(CodeGenFunction &CGF, llvm::Value *ThisPtr) {
151 /// Initialize the 'this' slot.
152 assert(getThisDecl(CGF) && "no 'this' variable for function")((getThisDecl(CGF) && "no 'this' variable for function"
) ? static_cast<void> (0) : __assert_fail ("getThisDecl(CGF) && \"no 'this' variable for function\""
, "/build/llvm-toolchain-snapshot-10~svn373517/tools/clang/lib/CodeGen/CGCXXABI.cpp"
, 152, __PRETTY_FUNCTION__));
153 CGF.CXXABIThisValue = ThisPtr;
154}
155
156void CGCXXABI::EmitReturnFromThunk(CodeGenFunction &CGF,
157 RValue RV, QualType ResultType) {
158 CGF.EmitReturnOfRValue(RV, ResultType);
159}
160
161CharUnits CGCXXABI::GetArrayCookieSize(const CXXNewExpr *expr) {
162 if (!requiresArrayCookie(expr))
163 return CharUnits::Zero();
164 return getArrayCookieSizeImpl(expr->getAllocatedType());
165}
166
167CharUnits CGCXXABI::getArrayCookieSizeImpl(QualType elementType) {
168 // BOGUS
169 return CharUnits::Zero();
170}
171
172Address CGCXXABI::InitializeArrayCookie(CodeGenFunction &CGF,
173 Address NewPtr,
174 llvm::Value *NumElements,
175 const CXXNewExpr *expr,
176 QualType ElementType) {
177 // Should never be called.
178 ErrorUnsupportedABI(CGF, "array cookie initialization");
179 return Address::invalid();
180}
181
182bool CGCXXABI::requiresArrayCookie(const CXXDeleteExpr *expr,
183 QualType elementType) {
184 // If the class's usual deallocation function takes two arguments,
185 // it needs a cookie.
186 if (expr->doesUsualArrayDeleteWantSize())
187 return true;
188
189 return elementType.isDestructedType();
190}
191
192bool CGCXXABI::requiresArrayCookie(const CXXNewExpr *expr) {
193 // If the class's usual deallocation function takes two arguments,
194 // it needs a cookie.
195 if (expr->doesUsualArrayDeleteWantSize())
196 return true;
197
198 return expr->getAllocatedType().isDestructedType();
199}
200
201void CGCXXABI::ReadArrayCookie(CodeGenFunction &CGF, Address ptr,
202 const CXXDeleteExpr *expr, QualType eltTy,
203 llvm::Value *&numElements,
204 llvm::Value *&allocPtr, CharUnits &cookieSize) {
205 // Derive a char* in the same address space as the pointer.
206 ptr = CGF.Builder.CreateElementBitCast(ptr, CGF.Int8Ty);
207
208 // If we don't need an array cookie, bail out early.
209 if (!requiresArrayCookie(expr, eltTy)) {
210 allocPtr = ptr.getPointer();
211 numElements = nullptr;
212 cookieSize = CharUnits::Zero();
213 return;
214 }
215
216 cookieSize = getArrayCookieSizeImpl(eltTy);
217 Address allocAddr =
218 CGF.Builder.CreateConstInBoundsByteGEP(ptr, -cookieSize);
219 allocPtr = allocAddr.getPointer();
220 numElements = readArrayCookieImpl(CGF, allocAddr, cookieSize);
221}
222
223llvm::Value *CGCXXABI::readArrayCookieImpl(CodeGenFunction &CGF,
224 Address ptr,
225 CharUnits cookieSize) {
226 ErrorUnsupportedABI(CGF, "reading a new[] cookie");
227 return llvm::ConstantInt::get(CGF.SizeTy, 0);
228}
229
230/// Returns the adjustment, in bytes, required for the given
231/// member-pointer operation. Returns null if no adjustment is
232/// required.
233llvm::Constant *CGCXXABI::getMemberPointerAdjustment(const CastExpr *E) {
234 assert(E->getCastKind() == CK_DerivedToBaseMemberPointer ||((E->getCastKind() == CK_DerivedToBaseMemberPointer || E->
getCastKind() == CK_BaseToDerivedMemberPointer) ? static_cast
<void> (0) : __assert_fail ("E->getCastKind() == CK_DerivedToBaseMemberPointer || E->getCastKind() == CK_BaseToDerivedMemberPointer"
, "/build/llvm-toolchain-snapshot-10~svn373517/tools/clang/lib/CodeGen/CGCXXABI.cpp"
, 235, __PRETTY_FUNCTION__))
235 E->getCastKind() == CK_BaseToDerivedMemberPointer)((E->getCastKind() == CK_DerivedToBaseMemberPointer || E->
getCastKind() == CK_BaseToDerivedMemberPointer) ? static_cast
<void> (0) : __assert_fail ("E->getCastKind() == CK_DerivedToBaseMemberPointer || E->getCastKind() == CK_BaseToDerivedMemberPointer"
, "/build/llvm-toolchain-snapshot-10~svn373517/tools/clang/lib/CodeGen/CGCXXABI.cpp"
, 235, __PRETTY_FUNCTION__));
236
237 QualType derivedType;
238 if (E->getCastKind() == CK_DerivedToBaseMemberPointer)
239 derivedType = E->getSubExpr()->getType();
240 else
241 derivedType = E->getType();
242
243 const CXXRecordDecl *derivedClass =
244 derivedType->castAs<MemberPointerType>()->getClass()->getAsCXXRecordDecl();
245
246 return CGM.GetNonVirtualBaseClassOffset(derivedClass,
247 E->path_begin(),
248 E->path_end());
249}
250
251CharUnits CGCXXABI::getMemberPointerPathAdjustment(const APValue &MP) {
252 // TODO: Store base specifiers in APValue member pointer paths so we can
253 // easily reuse CGM.GetNonVirtualBaseClassOffset().
254 const ValueDecl *MPD = MP.getMemberPointerDecl();
255 CharUnits ThisAdjustment = CharUnits::Zero();
256 ArrayRef<const CXXRecordDecl*> Path = MP.getMemberPointerPath();
257 bool DerivedMember = MP.isMemberPointerToDerivedMember();
258 const CXXRecordDecl *RD = cast<CXXRecordDecl>(MPD->getDeclContext());
259 for (unsigned I = 0, N = Path.size(); I != N; ++I) {
260 const CXXRecordDecl *Base = RD;
261 const CXXRecordDecl *Derived = Path[I];
262 if (DerivedMember)
263 std::swap(Base, Derived);
264 ThisAdjustment +=
265 getContext().getASTRecordLayout(Derived).getBaseClassOffset(Base);
266 RD = Path[I];
267 }
268 if (DerivedMember)
269 ThisAdjustment = -ThisAdjustment;
270 return ThisAdjustment;
271}
272
273llvm::BasicBlock *
274CGCXXABI::EmitCtorCompleteObjectHandler(CodeGenFunction &CGF,
275 const CXXRecordDecl *RD) {
276 if (CGM.getTarget().getCXXABI().hasConstructorVariants())
277 llvm_unreachable("shouldn't be called in this ABI")::llvm::llvm_unreachable_internal("shouldn't be called in this ABI"
, "/build/llvm-toolchain-snapshot-10~svn373517/tools/clang/lib/CodeGen/CGCXXABI.cpp"
, 277);
278
279 ErrorUnsupportedABI(CGF, "complete object detection in ctor");
280 return nullptr;
281}
282
283void CGCXXABI::setCXXDestructorDLLStorage(llvm::GlobalValue *GV,
284 const CXXDestructorDecl *Dtor,
285 CXXDtorType DT) const {
286 // Assume the base C++ ABI has no special rules for destructor variants.
287 CGM.setDLLImportDLLExport(GV, Dtor);
288}
289
290llvm::GlobalValue::LinkageTypes CGCXXABI::getCXXDestructorLinkage(
291 GVALinkage Linkage, const CXXDestructorDecl *Dtor, CXXDtorType DT) const {
292 // Delegate back to CGM by default.
293 return CGM.getLLVMLinkageForDeclarator(Dtor, Linkage,
294 /*IsConstantVariable=*/false);
295}
296
297bool CGCXXABI::NeedsVTTParameter(GlobalDecl GD) {
298 return false;
299}
300
301llvm::CallInst *
302CGCXXABI::emitTerminateForUnexpectedException(CodeGenFunction &CGF,
303 llvm::Value *Exn) {
304 // Just call std::terminate and ignore the violating exception.
305 return CGF.EmitNounwindRuntimeCall(CGF.CGM.getTerminateFn());
306}
307
308CatchTypeInfo CGCXXABI::getCatchAllTypeInfo() {
309 return CatchTypeInfo{nullptr, 0};
310}
311
312std::vector<CharUnits> CGCXXABI::getVBPtrOffsets(const CXXRecordDecl *RD) {
313 return std::vector<CharUnits>();
314}