1 //===--- ScopeInfo.cpp - Information about a semantic context -------------===//
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 file implements FunctionScopeInfo and its subclasses, which contain
10 // information about a single function, block, lambda, or method body.
11 //
12 //===----------------------------------------------------------------------===//
13
14 #include "clang/Sema/ScopeInfo.h"
15 #include "clang/AST/Decl.h"
16 #include "clang/AST/DeclCXX.h"
17 #include "clang/AST/DeclObjC.h"
18 #include "clang/AST/Expr.h"
19 #include "clang/AST/ExprCXX.h"
20 #include "clang/AST/ExprObjC.h"
21
22 using namespace clang;
23 using namespace sema;
24
Clear()25 void FunctionScopeInfo::Clear() {
26 HasBranchProtectedScope = false;
27 HasBranchIntoScope = false;
28 HasIndirectGoto = false;
29 HasDroppedStmt = false;
30 HasOMPDeclareReductionCombiner = false;
31 HasFallthroughStmt = false;
32 HasPotentialAvailabilityViolations = false;
33 ObjCShouldCallSuper = false;
34 ObjCIsDesignatedInit = false;
35 ObjCWarnForNoDesignatedInitChain = false;
36 ObjCIsSecondaryInit = false;
37 ObjCWarnForNoInitDelegation = false;
38 FirstReturnLoc = SourceLocation();
39 FirstCXXTryLoc = SourceLocation();
40 FirstSEHTryLoc = SourceLocation();
41
42 // Coroutine state
43 FirstCoroutineStmtLoc = SourceLocation();
44 CoroutinePromise = nullptr;
45 CoroutineParameterMoves.clear();
46 NeedsCoroutineSuspends = true;
47 CoroutineSuspends.first = nullptr;
48 CoroutineSuspends.second = nullptr;
49
50 SwitchStack.clear();
51 Returns.clear();
52 ErrorTrap.reset();
53 PossiblyUnreachableDiags.clear();
54 WeakObjectUses.clear();
55 ModifiedNonNullParams.clear();
56 Blocks.clear();
57 ByrefBlockVars.clear();
58 }
59
getBestPropertyDecl(const ObjCPropertyRefExpr * PropE)60 static const NamedDecl *getBestPropertyDecl(const ObjCPropertyRefExpr *PropE) {
61 if (PropE->isExplicitProperty())
62 return PropE->getExplicitProperty();
63
64 return PropE->getImplicitPropertyGetter();
65 }
66
67 FunctionScopeInfo::WeakObjectProfileTy::BaseInfoTy
getBaseInfo(const Expr * E)68 FunctionScopeInfo::WeakObjectProfileTy::getBaseInfo(const Expr *E) {
69 E = E->IgnoreParenCasts();
70
71 const NamedDecl *D = nullptr;
72 bool IsExact = false;
73
74 switch (E->getStmtClass()) {
75 case Stmt::DeclRefExprClass:
76 D = cast<DeclRefExpr>(E)->getDecl();
77 IsExact = isa<VarDecl>(D);
78 break;
79 case Stmt::MemberExprClass: {
80 const MemberExpr *ME = cast<MemberExpr>(E);
81 D = ME->getMemberDecl();
82 IsExact = isa<CXXThisExpr>(ME->getBase()->IgnoreParenImpCasts());
83 break;
84 }
85 case Stmt::ObjCIvarRefExprClass: {
86 const ObjCIvarRefExpr *IE = cast<ObjCIvarRefExpr>(E);
87 D = IE->getDecl();
88 IsExact = IE->getBase()->isObjCSelfExpr();
89 break;
90 }
91 case Stmt::PseudoObjectExprClass: {
92 const PseudoObjectExpr *POE = cast<PseudoObjectExpr>(E);
93 const ObjCPropertyRefExpr *BaseProp =
94 dyn_cast<ObjCPropertyRefExpr>(POE->getSyntacticForm());
95 if (BaseProp) {
96 D = getBestPropertyDecl(BaseProp);
97
98 if (BaseProp->isObjectReceiver()) {
99 const Expr *DoubleBase = BaseProp->getBase();
100 if (const OpaqueValueExpr *OVE = dyn_cast<OpaqueValueExpr>(DoubleBase))
101 DoubleBase = OVE->getSourceExpr();
102
103 IsExact = DoubleBase->isObjCSelfExpr();
104 }
105 }
106 break;
107 }
108 default:
109 break;
110 }
111
112 return BaseInfoTy(D, IsExact);
113 }
114
WeakObjectProfileTy(const ObjCPropertyRefExpr * PropE)115 FunctionScopeInfo::WeakObjectProfileTy::WeakObjectProfileTy(
116 const ObjCPropertyRefExpr *PropE)
117 : Base(nullptr, true), Property(getBestPropertyDecl(PropE)) {
118
119 if (PropE->isObjectReceiver()) {
120 const OpaqueValueExpr *OVE = cast<OpaqueValueExpr>(PropE->getBase());
121 const Expr *E = OVE->getSourceExpr();
122 Base = getBaseInfo(E);
123 } else if (PropE->isClassReceiver()) {
124 Base.setPointer(PropE->getClassReceiver());
125 } else {
126 assert(PropE->isSuperReceiver());
127 }
128 }
129
WeakObjectProfileTy(const Expr * BaseE,const ObjCPropertyDecl * Prop)130 FunctionScopeInfo::WeakObjectProfileTy::WeakObjectProfileTy(const Expr *BaseE,
131 const ObjCPropertyDecl *Prop)
132 : Base(nullptr, true), Property(Prop) {
133 if (BaseE)
134 Base = getBaseInfo(BaseE);
135 // else, this is a message accessing a property on super.
136 }
137
WeakObjectProfileTy(const DeclRefExpr * DRE)138 FunctionScopeInfo::WeakObjectProfileTy::WeakObjectProfileTy(
139 const DeclRefExpr *DRE)
140 : Base(nullptr, true), Property(DRE->getDecl()) {
141 assert(isa<VarDecl>(Property));
142 }
143
WeakObjectProfileTy(const ObjCIvarRefExpr * IvarE)144 FunctionScopeInfo::WeakObjectProfileTy::WeakObjectProfileTy(
145 const ObjCIvarRefExpr *IvarE)
146 : Base(getBaseInfo(IvarE->getBase())), Property(IvarE->getDecl()) {
147 }
148
recordUseOfWeak(const ObjCMessageExpr * Msg,const ObjCPropertyDecl * Prop)149 void FunctionScopeInfo::recordUseOfWeak(const ObjCMessageExpr *Msg,
150 const ObjCPropertyDecl *Prop) {
151 assert(Msg && Prop);
152 WeakUseVector &Uses =
153 WeakObjectUses[WeakObjectProfileTy(Msg->getInstanceReceiver(), Prop)];
154 Uses.push_back(WeakUseTy(Msg, Msg->getNumArgs() == 0));
155 }
156
markSafeWeakUse(const Expr * E)157 void FunctionScopeInfo::markSafeWeakUse(const Expr *E) {
158 E = E->IgnoreParenCasts();
159
160 if (const PseudoObjectExpr *POE = dyn_cast<PseudoObjectExpr>(E)) {
161 markSafeWeakUse(POE->getSyntacticForm());
162 return;
163 }
164
165 if (const ConditionalOperator *Cond = dyn_cast<ConditionalOperator>(E)) {
166 markSafeWeakUse(Cond->getTrueExpr());
167 markSafeWeakUse(Cond->getFalseExpr());
168 return;
169 }
170
171 if (const BinaryConditionalOperator *Cond =
172 dyn_cast<BinaryConditionalOperator>(E)) {
173 markSafeWeakUse(Cond->getCommon());
174 markSafeWeakUse(Cond->getFalseExpr());
175 return;
176 }
177
178 // Has this weak object been seen before?
179 FunctionScopeInfo::WeakObjectUseMap::iterator Uses = WeakObjectUses.end();
180 if (const ObjCPropertyRefExpr *RefExpr = dyn_cast<ObjCPropertyRefExpr>(E)) {
181 if (!RefExpr->isObjectReceiver())
182 return;
183 if (isa<OpaqueValueExpr>(RefExpr->getBase()))
184 Uses = WeakObjectUses.find(WeakObjectProfileTy(RefExpr));
185 else {
186 markSafeWeakUse(RefExpr->getBase());
187 return;
188 }
189 }
190 else if (const ObjCIvarRefExpr *IvarE = dyn_cast<ObjCIvarRefExpr>(E))
191 Uses = WeakObjectUses.find(WeakObjectProfileTy(IvarE));
192 else if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E)) {
193 if (isa<VarDecl>(DRE->getDecl()))
194 Uses = WeakObjectUses.find(WeakObjectProfileTy(DRE));
195 } else if (const ObjCMessageExpr *MsgE = dyn_cast<ObjCMessageExpr>(E)) {
196 if (const ObjCMethodDecl *MD = MsgE->getMethodDecl()) {
197 if (const ObjCPropertyDecl *Prop = MD->findPropertyDecl()) {
198 Uses =
199 WeakObjectUses.find(WeakObjectProfileTy(MsgE->getInstanceReceiver(),
200 Prop));
201 }
202 }
203 }
204 else
205 return;
206
207 if (Uses == WeakObjectUses.end())
208 return;
209
210 // Has there been a read from the object using this Expr?
211 FunctionScopeInfo::WeakUseVector::reverse_iterator ThisUse =
212 llvm::find(llvm::reverse(Uses->second), WeakUseTy(E, true));
213 if (ThisUse == Uses->second.rend())
214 return;
215
216 ThisUse->markSafe();
217 }
218
isInitCapture() const219 bool Capture::isInitCapture() const {
220 // Note that a nested capture of an init-capture is not itself an
221 // init-capture.
222 return !isNested() && isVariableCapture() && getVariable()->isInitCapture();
223 }
224
isVLATypeCaptured(const VariableArrayType * VAT) const225 bool CapturingScopeInfo::isVLATypeCaptured(const VariableArrayType *VAT) const {
226 for (auto &Cap : Captures)
227 if (Cap.isVLATypeCapture() && Cap.getCapturedVLAType() == VAT)
228 return true;
229 return false;
230 }
231
visitPotentialCaptures(llvm::function_ref<void (VarDecl *,Expr *)> Callback) const232 void LambdaScopeInfo::visitPotentialCaptures(
233 llvm::function_ref<void(VarDecl *, Expr *)> Callback) const {
234 for (Expr *E : PotentiallyCapturingExprs) {
235 if (auto *DRE = dyn_cast<DeclRefExpr>(E)) {
236 Callback(cast<VarDecl>(DRE->getFoundDecl()), E);
237 } else if (auto *ME = dyn_cast<MemberExpr>(E)) {
238 Callback(cast<VarDecl>(ME->getMemberDecl()), E);
239 } else if (auto *FP = dyn_cast<FunctionParmPackExpr>(E)) {
240 for (VarDecl *VD : *FP)
241 Callback(VD, E);
242 } else {
243 llvm_unreachable("unexpected expression in potential captures list");
244 }
245 }
246 }
247
~FunctionScopeInfo()248 FunctionScopeInfo::~FunctionScopeInfo() { }
~BlockScopeInfo()249 BlockScopeInfo::~BlockScopeInfo() { }
~CapturedRegionScopeInfo()250 CapturedRegionScopeInfo::~CapturedRegionScopeInfo() { }
251