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   CoroutineParameterMoves.clear();
47   NeedsCoroutineSuspends = true;
48   CoroutineSuspends.first = nullptr;
49   CoroutineSuspends.second = nullptr;
50 
51   SwitchStack.clear();
52   Returns.clear();
53   ErrorTrap.reset();
54   PossiblyUnreachableDiags.clear();
55   WeakObjectUses.clear();
56   ModifiedNonNullParams.clear();
57   Blocks.clear();
58   ByrefBlockVars.clear();
59 }
60 
61 static const NamedDecl *getBestPropertyDecl(const ObjCPropertyRefExpr *PropE) {
62   if (PropE->isExplicitProperty())
63     return PropE->getExplicitProperty();
64 
65   return PropE->getImplicitPropertyGetter();
66 }
67 
68 FunctionScopeInfo::WeakObjectProfileTy::BaseInfoTy
69 FunctionScopeInfo::WeakObjectProfileTy::getBaseInfo(const Expr *E) {
70   E = E->IgnoreParenCasts();
71 
72   const NamedDecl *D = nullptr;
73   bool IsExact = false;
74 
75   switch (E->getStmtClass()) {
76   case Stmt::DeclRefExprClass:
77     D = cast<DeclRefExpr>(E)->getDecl();
78     IsExact = isa<VarDecl>(D);
79     break;
80   case Stmt::MemberExprClass: {
81     const MemberExpr *ME = cast<MemberExpr>(E);
82     D = ME->getMemberDecl();
83     IsExact = isa<CXXThisExpr>(ME->getBase()->IgnoreParenImpCasts());
84     break;
85   }
86   case Stmt::ObjCIvarRefExprClass: {
87     const ObjCIvarRefExpr *IE = cast<ObjCIvarRefExpr>(E);
88     D = IE->getDecl();
89     IsExact = IE->getBase()->isObjCSelfExpr();
90     break;
91   }
92   case Stmt::PseudoObjectExprClass: {
93     const PseudoObjectExpr *POE = cast<PseudoObjectExpr>(E);
94     const ObjCPropertyRefExpr *BaseProp =
95       dyn_cast<ObjCPropertyRefExpr>(POE->getSyntacticForm());
96     if (BaseProp) {
97       D = getBestPropertyDecl(BaseProp);
98 
99       if (BaseProp->isObjectReceiver()) {
100         const Expr *DoubleBase = BaseProp->getBase();
101         if (const OpaqueValueExpr *OVE = dyn_cast<OpaqueValueExpr>(DoubleBase))
102           DoubleBase = OVE->getSourceExpr();
103 
104         IsExact = DoubleBase->isObjCSelfExpr();
105       }
106     }
107     break;
108   }
109   default:
110     break;
111   }
112 
113   return BaseInfoTy(D, IsExact);
114 }
115 
116 bool CapturingScopeInfo::isVLATypeCaptured(const VariableArrayType *VAT) const {
117   RecordDecl *RD = nullptr;
118   if (auto *LSI = dyn_cast<LambdaScopeInfo>(this))
119     RD = LSI->Lambda;
120   else if (auto CRSI = dyn_cast<CapturedRegionScopeInfo>(this))
121     RD = CRSI->TheRecordDecl;
122 
123   if (RD)
124     for (auto *FD : RD->fields()) {
125       if (FD->hasCapturedVLAType() && FD->getCapturedVLAType() == VAT)
126         return true;
127     }
128   return false;
129 }
130 
131 FunctionScopeInfo::WeakObjectProfileTy::WeakObjectProfileTy(
132                                           const ObjCPropertyRefExpr *PropE)
133     : Base(nullptr, true), Property(getBestPropertyDecl(PropE)) {
134 
135   if (PropE->isObjectReceiver()) {
136     const OpaqueValueExpr *OVE = cast<OpaqueValueExpr>(PropE->getBase());
137     const Expr *E = OVE->getSourceExpr();
138     Base = getBaseInfo(E);
139   } else if (PropE->isClassReceiver()) {
140     Base.setPointer(PropE->getClassReceiver());
141   } else {
142     assert(PropE->isSuperReceiver());
143   }
144 }
145 
146 FunctionScopeInfo::WeakObjectProfileTy::WeakObjectProfileTy(const Expr *BaseE,
147                                                 const ObjCPropertyDecl *Prop)
148     : Base(nullptr, true), Property(Prop) {
149   if (BaseE)
150     Base = getBaseInfo(BaseE);
151   // else, this is a message accessing a property on super.
152 }
153 
154 FunctionScopeInfo::WeakObjectProfileTy::WeakObjectProfileTy(
155                                                       const DeclRefExpr *DRE)
156   : Base(nullptr, true), Property(DRE->getDecl()) {
157   assert(isa<VarDecl>(Property));
158 }
159 
160 FunctionScopeInfo::WeakObjectProfileTy::WeakObjectProfileTy(
161                                                   const ObjCIvarRefExpr *IvarE)
162   : Base(getBaseInfo(IvarE->getBase())), Property(IvarE->getDecl()) {
163 }
164 
165 void FunctionScopeInfo::recordUseOfWeak(const ObjCMessageExpr *Msg,
166                                         const ObjCPropertyDecl *Prop) {
167   assert(Msg && Prop);
168   WeakUseVector &Uses =
169     WeakObjectUses[WeakObjectProfileTy(Msg->getInstanceReceiver(), Prop)];
170   Uses.push_back(WeakUseTy(Msg, Msg->getNumArgs() == 0));
171 }
172 
173 void FunctionScopeInfo::markSafeWeakUse(const Expr *E) {
174   E = E->IgnoreParenCasts();
175 
176   if (const PseudoObjectExpr *POE = dyn_cast<PseudoObjectExpr>(E)) {
177     markSafeWeakUse(POE->getSyntacticForm());
178     return;
179   }
180 
181   if (const ConditionalOperator *Cond = dyn_cast<ConditionalOperator>(E)) {
182     markSafeWeakUse(Cond->getTrueExpr());
183     markSafeWeakUse(Cond->getFalseExpr());
184     return;
185   }
186 
187   if (const BinaryConditionalOperator *Cond =
188         dyn_cast<BinaryConditionalOperator>(E)) {
189     markSafeWeakUse(Cond->getCommon());
190     markSafeWeakUse(Cond->getFalseExpr());
191     return;
192   }
193 
194   // Has this weak object been seen before?
195   FunctionScopeInfo::WeakObjectUseMap::iterator Uses = WeakObjectUses.end();
196   if (const ObjCPropertyRefExpr *RefExpr = dyn_cast<ObjCPropertyRefExpr>(E)) {
197     if (!RefExpr->isObjectReceiver())
198       return;
199     if (isa<OpaqueValueExpr>(RefExpr->getBase()))
200      Uses = WeakObjectUses.find(WeakObjectProfileTy(RefExpr));
201     else {
202       markSafeWeakUse(RefExpr->getBase());
203       return;
204     }
205   }
206   else if (const ObjCIvarRefExpr *IvarE = dyn_cast<ObjCIvarRefExpr>(E))
207     Uses = WeakObjectUses.find(WeakObjectProfileTy(IvarE));
208   else if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E)) {
209     if (isa<VarDecl>(DRE->getDecl()))
210       Uses = WeakObjectUses.find(WeakObjectProfileTy(DRE));
211   } else if (const ObjCMessageExpr *MsgE = dyn_cast<ObjCMessageExpr>(E)) {
212     if (const ObjCMethodDecl *MD = MsgE->getMethodDecl()) {
213       if (const ObjCPropertyDecl *Prop = MD->findPropertyDecl()) {
214         Uses =
215           WeakObjectUses.find(WeakObjectProfileTy(MsgE->getInstanceReceiver(),
216                                                   Prop));
217       }
218     }
219   }
220   else
221     return;
222 
223   if (Uses == WeakObjectUses.end())
224     return;
225 
226   // Has there been a read from the object using this Expr?
227   FunctionScopeInfo::WeakUseVector::reverse_iterator ThisUse =
228       llvm::find(llvm::reverse(Uses->second), WeakUseTy(E, true));
229   if (ThisUse == Uses->second.rend())
230     return;
231 
232   ThisUse->markSafe();
233 }
234 
235 void LambdaScopeInfo::getPotentialVariableCapture(unsigned Idx, VarDecl *&VD,
236                                                   Expr *&E) const {
237   assert(Idx < getNumPotentialVariableCaptures() &&
238          "Index of potential capture must be within 0 to less than the "
239          "number of captures!");
240   E = PotentiallyCapturingExprs[Idx];
241   if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
242     VD = dyn_cast<VarDecl>(DRE->getFoundDecl());
243   else if (MemberExpr *ME = dyn_cast<MemberExpr>(E))
244     VD = dyn_cast<VarDecl>(ME->getMemberDecl());
245   else
246     llvm_unreachable("Only DeclRefExprs or MemberExprs should be added for "
247     "potential captures");
248   assert(VD);
249 }
250 
251 FunctionScopeInfo::~FunctionScopeInfo() { }
252 BlockScopeInfo::~BlockScopeInfo() { }
253 CapturedRegionScopeInfo::~CapturedRegionScopeInfo() { }
254