1 //===--- ScopeInfo.cpp - Information about a semantic context -------------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file implements FunctionScopeInfo and its subclasses, which contain
11 // information about a single function, block, lambda, or method body.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "clang/Sema/ScopeInfo.h"
16 #include "clang/AST/Decl.h"
17 #include "clang/AST/DeclCXX.h"
18 #include "clang/AST/DeclObjC.h"
19 #include "clang/AST/Expr.h"
20 #include "clang/AST/ExprCXX.h"
21 #include "clang/AST/ExprObjC.h"
22 
23 using namespace clang;
24 using namespace sema;
25 
26 void FunctionScopeInfo::Clear() {
27   HasBranchProtectedScope = false;
28   HasBranchIntoScope = false;
29   HasIndirectGoto = false;
30   HasDroppedStmt = false;
31   HasOMPDeclareReductionCombiner = false;
32   HasFallthroughStmt = false;
33   HasPotentialAvailabilityViolations = false;
34   ObjCShouldCallSuper = false;
35   ObjCIsDesignatedInit = false;
36   ObjCWarnForNoDesignatedInitChain = false;
37   ObjCIsSecondaryInit = false;
38   ObjCWarnForNoInitDelegation = false;
39   FirstReturnLoc = SourceLocation();
40   FirstCXXTryLoc = SourceLocation();
41   FirstSEHTryLoc = SourceLocation();
42 
43   // Coroutine state
44   FirstCoroutineStmtLoc = SourceLocation();
45   CoroutinePromise = nullptr;
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 }
57 
58 static const NamedDecl *getBestPropertyDecl(const ObjCPropertyRefExpr *PropE) {
59   if (PropE->isExplicitProperty())
60     return PropE->getExplicitProperty();
61 
62   return PropE->getImplicitPropertyGetter();
63 }
64 
65 FunctionScopeInfo::WeakObjectProfileTy::BaseInfoTy
66 FunctionScopeInfo::WeakObjectProfileTy::getBaseInfo(const Expr *E) {
67   E = E->IgnoreParenCasts();
68 
69   const NamedDecl *D = nullptr;
70   bool IsExact = false;
71 
72   switch (E->getStmtClass()) {
73   case Stmt::DeclRefExprClass:
74     D = cast<DeclRefExpr>(E)->getDecl();
75     IsExact = isa<VarDecl>(D);
76     break;
77   case Stmt::MemberExprClass: {
78     const MemberExpr *ME = cast<MemberExpr>(E);
79     D = ME->getMemberDecl();
80     IsExact = isa<CXXThisExpr>(ME->getBase()->IgnoreParenImpCasts());
81     break;
82   }
83   case Stmt::ObjCIvarRefExprClass: {
84     const ObjCIvarRefExpr *IE = cast<ObjCIvarRefExpr>(E);
85     D = IE->getDecl();
86     IsExact = IE->getBase()->isObjCSelfExpr();
87     break;
88   }
89   case Stmt::PseudoObjectExprClass: {
90     const PseudoObjectExpr *POE = cast<PseudoObjectExpr>(E);
91     const ObjCPropertyRefExpr *BaseProp =
92       dyn_cast<ObjCPropertyRefExpr>(POE->getSyntacticForm());
93     if (BaseProp) {
94       D = getBestPropertyDecl(BaseProp);
95 
96       if (BaseProp->isObjectReceiver()) {
97         const Expr *DoubleBase = BaseProp->getBase();
98         if (const OpaqueValueExpr *OVE = dyn_cast<OpaqueValueExpr>(DoubleBase))
99           DoubleBase = OVE->getSourceExpr();
100 
101         IsExact = DoubleBase->isObjCSelfExpr();
102       }
103     }
104     break;
105   }
106   default:
107     break;
108   }
109 
110   return BaseInfoTy(D, IsExact);
111 }
112 
113 bool CapturingScopeInfo::isVLATypeCaptured(const VariableArrayType *VAT) const {
114   RecordDecl *RD = nullptr;
115   if (auto *LSI = dyn_cast<LambdaScopeInfo>(this))
116     RD = LSI->Lambda;
117   else if (auto CRSI = dyn_cast<CapturedRegionScopeInfo>(this))
118     RD = CRSI->TheRecordDecl;
119 
120   if (RD)
121     for (auto *FD : RD->fields()) {
122       if (FD->hasCapturedVLAType() && FD->getCapturedVLAType() == VAT)
123         return true;
124     }
125   return false;
126 }
127 
128 FunctionScopeInfo::WeakObjectProfileTy::WeakObjectProfileTy(
129                                           const ObjCPropertyRefExpr *PropE)
130     : Base(nullptr, true), Property(getBestPropertyDecl(PropE)) {
131 
132   if (PropE->isObjectReceiver()) {
133     const OpaqueValueExpr *OVE = cast<OpaqueValueExpr>(PropE->getBase());
134     const Expr *E = OVE->getSourceExpr();
135     Base = getBaseInfo(E);
136   } else if (PropE->isClassReceiver()) {
137     Base.setPointer(PropE->getClassReceiver());
138   } else {
139     assert(PropE->isSuperReceiver());
140   }
141 }
142 
143 FunctionScopeInfo::WeakObjectProfileTy::WeakObjectProfileTy(const Expr *BaseE,
144                                                 const ObjCPropertyDecl *Prop)
145     : Base(nullptr, true), Property(Prop) {
146   if (BaseE)
147     Base = getBaseInfo(BaseE);
148   // else, this is a message accessing a property on super.
149 }
150 
151 FunctionScopeInfo::WeakObjectProfileTy::WeakObjectProfileTy(
152                                                       const DeclRefExpr *DRE)
153   : Base(nullptr, true), Property(DRE->getDecl()) {
154   assert(isa<VarDecl>(Property));
155 }
156 
157 FunctionScopeInfo::WeakObjectProfileTy::WeakObjectProfileTy(
158                                                   const ObjCIvarRefExpr *IvarE)
159   : Base(getBaseInfo(IvarE->getBase())), Property(IvarE->getDecl()) {
160 }
161 
162 void FunctionScopeInfo::recordUseOfWeak(const ObjCMessageExpr *Msg,
163                                         const ObjCPropertyDecl *Prop) {
164   assert(Msg && Prop);
165   WeakUseVector &Uses =
166     WeakObjectUses[WeakObjectProfileTy(Msg->getInstanceReceiver(), Prop)];
167   Uses.push_back(WeakUseTy(Msg, Msg->getNumArgs() == 0));
168 }
169 
170 void FunctionScopeInfo::markSafeWeakUse(const Expr *E) {
171   E = E->IgnoreParenCasts();
172 
173   if (const PseudoObjectExpr *POE = dyn_cast<PseudoObjectExpr>(E)) {
174     markSafeWeakUse(POE->getSyntacticForm());
175     return;
176   }
177 
178   if (const ConditionalOperator *Cond = dyn_cast<ConditionalOperator>(E)) {
179     markSafeWeakUse(Cond->getTrueExpr());
180     markSafeWeakUse(Cond->getFalseExpr());
181     return;
182   }
183 
184   if (const BinaryConditionalOperator *Cond =
185         dyn_cast<BinaryConditionalOperator>(E)) {
186     markSafeWeakUse(Cond->getCommon());
187     markSafeWeakUse(Cond->getFalseExpr());
188     return;
189   }
190 
191   // Has this weak object been seen before?
192   FunctionScopeInfo::WeakObjectUseMap::iterator Uses = WeakObjectUses.end();
193   if (const ObjCPropertyRefExpr *RefExpr = dyn_cast<ObjCPropertyRefExpr>(E)) {
194     if (!RefExpr->isObjectReceiver())
195       return;
196     if (isa<OpaqueValueExpr>(RefExpr->getBase()))
197      Uses = WeakObjectUses.find(WeakObjectProfileTy(RefExpr));
198     else {
199       markSafeWeakUse(RefExpr->getBase());
200       return;
201     }
202   }
203   else if (const ObjCIvarRefExpr *IvarE = dyn_cast<ObjCIvarRefExpr>(E))
204     Uses = WeakObjectUses.find(WeakObjectProfileTy(IvarE));
205   else if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E)) {
206     if (isa<VarDecl>(DRE->getDecl()))
207       Uses = WeakObjectUses.find(WeakObjectProfileTy(DRE));
208   } else if (const ObjCMessageExpr *MsgE = dyn_cast<ObjCMessageExpr>(E)) {
209     if (const ObjCMethodDecl *MD = MsgE->getMethodDecl()) {
210       if (const ObjCPropertyDecl *Prop = MD->findPropertyDecl()) {
211         Uses =
212           WeakObjectUses.find(WeakObjectProfileTy(MsgE->getInstanceReceiver(),
213                                                   Prop));
214       }
215     }
216   }
217   else
218     return;
219 
220   if (Uses == WeakObjectUses.end())
221     return;
222 
223   // Has there been a read from the object using this Expr?
224   FunctionScopeInfo::WeakUseVector::reverse_iterator ThisUse =
225       llvm::find(llvm::reverse(Uses->second), WeakUseTy(E, true));
226   if (ThisUse == Uses->second.rend())
227     return;
228 
229   ThisUse->markSafe();
230 }
231 
232 void LambdaScopeInfo::getPotentialVariableCapture(unsigned Idx, VarDecl *&VD,
233                                                   Expr *&E) const {
234   assert(Idx < getNumPotentialVariableCaptures() &&
235          "Index of potential capture must be within 0 to less than the "
236          "number of captures!");
237   E = PotentiallyCapturingExprs[Idx];
238   if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
239     VD = dyn_cast<VarDecl>(DRE->getFoundDecl());
240   else if (MemberExpr *ME = dyn_cast<MemberExpr>(E))
241     VD = dyn_cast<VarDecl>(ME->getMemberDecl());
242   else
243     llvm_unreachable("Only DeclRefExprs or MemberExprs should be added for "
244     "potential captures");
245   assert(VD);
246 }
247 
248 FunctionScopeInfo::~FunctionScopeInfo() { }
249 BlockScopeInfo::~BlockScopeInfo() { }
250 CapturedRegionScopeInfo::~CapturedRegionScopeInfo() { }
251