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