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/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 
25 void FunctionScopeInfo::Clear() {
26   HasBranchProtectedScope = false;
27   HasBranchIntoScope = false;
28   HasIndirectGoto = false;
29   HasDroppedStmt = false;
30   ObjCShouldCallSuper = false;
31   ObjCIsDesignatedInit = false;
32   ObjCWarnForNoDesignatedInitChain = false;
33   ObjCIsSecondaryInit = false;
34   ObjCWarnForNoInitDelegation = false;
35 
36   SwitchStack.clear();
37   Returns.clear();
38   ErrorTrap.reset();
39   PossiblyUnreachableDiags.clear();
40   WeakObjectUses.clear();
41 }
42 
43 static const NamedDecl *getBestPropertyDecl(const ObjCPropertyRefExpr *PropE) {
44   if (PropE->isExplicitProperty())
45     return PropE->getExplicitProperty();
46 
47   return PropE->getImplicitPropertyGetter();
48 }
49 
50 FunctionScopeInfo::WeakObjectProfileTy::BaseInfoTy
51 FunctionScopeInfo::WeakObjectProfileTy::getBaseInfo(const Expr *E) {
52   E = E->IgnoreParenCasts();
53 
54   const NamedDecl *D = 0;
55   bool IsExact = false;
56 
57   switch (E->getStmtClass()) {
58   case Stmt::DeclRefExprClass:
59     D = cast<DeclRefExpr>(E)->getDecl();
60     IsExact = isa<VarDecl>(D);
61     break;
62   case Stmt::MemberExprClass: {
63     const MemberExpr *ME = cast<MemberExpr>(E);
64     D = ME->getMemberDecl();
65     IsExact = isa<CXXThisExpr>(ME->getBase()->IgnoreParenImpCasts());
66     break;
67   }
68   case Stmt::ObjCIvarRefExprClass: {
69     const ObjCIvarRefExpr *IE = cast<ObjCIvarRefExpr>(E);
70     D = IE->getDecl();
71     IsExact = IE->getBase()->isObjCSelfExpr();
72     break;
73   }
74   case Stmt::PseudoObjectExprClass: {
75     const PseudoObjectExpr *POE = cast<PseudoObjectExpr>(E);
76     const ObjCPropertyRefExpr *BaseProp =
77       dyn_cast<ObjCPropertyRefExpr>(POE->getSyntacticForm());
78     if (BaseProp) {
79       D = getBestPropertyDecl(BaseProp);
80 
81       const Expr *DoubleBase = BaseProp->getBase();
82       if (const OpaqueValueExpr *OVE = dyn_cast<OpaqueValueExpr>(DoubleBase))
83         DoubleBase = OVE->getSourceExpr();
84 
85       IsExact = DoubleBase->isObjCSelfExpr();
86     }
87     break;
88   }
89   default:
90     break;
91   }
92 
93   return BaseInfoTy(D, IsExact);
94 }
95 
96 
97 FunctionScopeInfo::WeakObjectProfileTy::WeakObjectProfileTy(
98                                           const ObjCPropertyRefExpr *PropE)
99     : Base(0, true), Property(getBestPropertyDecl(PropE)) {
100 
101   if (PropE->isObjectReceiver()) {
102     const OpaqueValueExpr *OVE = cast<OpaqueValueExpr>(PropE->getBase());
103     const Expr *E = OVE->getSourceExpr();
104     Base = getBaseInfo(E);
105   } else if (PropE->isClassReceiver()) {
106     Base.setPointer(PropE->getClassReceiver());
107   } else {
108     assert(PropE->isSuperReceiver());
109   }
110 }
111 
112 FunctionScopeInfo::WeakObjectProfileTy::WeakObjectProfileTy(const Expr *BaseE,
113                                                 const ObjCPropertyDecl *Prop)
114     : Base(0, true), Property(Prop) {
115   if (BaseE)
116     Base = getBaseInfo(BaseE);
117   // else, this is a message accessing a property on super.
118 }
119 
120 FunctionScopeInfo::WeakObjectProfileTy::WeakObjectProfileTy(
121                                                       const DeclRefExpr *DRE)
122   : Base(0, true), Property(DRE->getDecl()) {
123   assert(isa<VarDecl>(Property));
124 }
125 
126 FunctionScopeInfo::WeakObjectProfileTy::WeakObjectProfileTy(
127                                                   const ObjCIvarRefExpr *IvarE)
128   : Base(getBaseInfo(IvarE->getBase())), Property(IvarE->getDecl()) {
129 }
130 
131 void FunctionScopeInfo::recordUseOfWeak(const ObjCMessageExpr *Msg,
132                                         const ObjCPropertyDecl *Prop) {
133   assert(Msg && Prop);
134   WeakUseVector &Uses =
135     WeakObjectUses[WeakObjectProfileTy(Msg->getInstanceReceiver(), Prop)];
136   Uses.push_back(WeakUseTy(Msg, Msg->getNumArgs() == 0));
137 }
138 
139 void FunctionScopeInfo::markSafeWeakUse(const Expr *E) {
140   E = E->IgnoreParenCasts();
141 
142   if (const PseudoObjectExpr *POE = dyn_cast<PseudoObjectExpr>(E)) {
143     markSafeWeakUse(POE->getSyntacticForm());
144     return;
145   }
146 
147   if (const ConditionalOperator *Cond = dyn_cast<ConditionalOperator>(E)) {
148     markSafeWeakUse(Cond->getTrueExpr());
149     markSafeWeakUse(Cond->getFalseExpr());
150     return;
151   }
152 
153   if (const BinaryConditionalOperator *Cond =
154         dyn_cast<BinaryConditionalOperator>(E)) {
155     markSafeWeakUse(Cond->getCommon());
156     markSafeWeakUse(Cond->getFalseExpr());
157     return;
158   }
159 
160   // Has this weak object been seen before?
161   FunctionScopeInfo::WeakObjectUseMap::iterator Uses;
162   if (const ObjCPropertyRefExpr *RefExpr = dyn_cast<ObjCPropertyRefExpr>(E))
163     Uses = WeakObjectUses.find(WeakObjectProfileTy(RefExpr));
164   else if (const ObjCIvarRefExpr *IvarE = dyn_cast<ObjCIvarRefExpr>(E))
165     Uses = WeakObjectUses.find(WeakObjectProfileTy(IvarE));
166   else if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
167     Uses = WeakObjectUses.find(WeakObjectProfileTy(DRE));
168   else if (const ObjCMessageExpr *MsgE = dyn_cast<ObjCMessageExpr>(E)) {
169     Uses = WeakObjectUses.end();
170     if (const ObjCMethodDecl *MD = MsgE->getMethodDecl()) {
171       if (const ObjCPropertyDecl *Prop = MD->findPropertyDecl()) {
172         Uses =
173           WeakObjectUses.find(WeakObjectProfileTy(MsgE->getInstanceReceiver(),
174                                                   Prop));
175       }
176     }
177   }
178   else
179     return;
180 
181   if (Uses == WeakObjectUses.end())
182     return;
183 
184   // Has there been a read from the object using this Expr?
185   FunctionScopeInfo::WeakUseVector::reverse_iterator ThisUse =
186     std::find(Uses->second.rbegin(), Uses->second.rend(), WeakUseTy(E, true));
187   if (ThisUse == Uses->second.rend())
188     return;
189 
190   ThisUse->markSafe();
191 }
192 
193 void LambdaScopeInfo::getPotentialVariableCapture(unsigned Idx, VarDecl *&VD, Expr *&E) {
194   assert(Idx < getNumPotentialVariableCaptures() &&
195     "Index of potential capture must be within 0 to less than the "
196     "number of captures!");
197   E = PotentiallyCapturingExprs[Idx];
198   if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
199     VD = dyn_cast<VarDecl>(DRE->getFoundDecl());
200   else if (MemberExpr *ME = dyn_cast<MemberExpr>(E))
201     VD = dyn_cast<VarDecl>(ME->getMemberDecl());
202   else
203     llvm_unreachable("Only DeclRefExprs or MemberExprs should be added for "
204     "potential captures");
205   assert(VD);
206 }
207 
208 FunctionScopeInfo::~FunctionScopeInfo() { }
209 BlockScopeInfo::~BlockScopeInfo() { }
210 LambdaScopeInfo::~LambdaScopeInfo() { }
211 CapturedRegionScopeInfo::~CapturedRegionScopeInfo() { }
212